Top 10 Diet and Lifestyle Strategies to Lower Your Cancer Risk (2025): 1,000+ Studies Analyzed

By Editorial Team - January 07, 2025

Current large language models (LLMs) like ChatGPT, Gemini from Google and Copilot from Microsoft might return generic answers to your questions. While these can be a starting point, they often lack the depth you might crave.

That's where this article comes in. We've delved into the research to provide you with more than just basic advice. We'll not only share supporting evidence, but also explain our methodology for selecting the most valuable information. It would also be impossible to review all the studies on the internet; rather, we have focused on, curated, filtered, summarised, evaluated and shared the information that appear to have the greatest clinical utility.

Studies suggest that simple lifestyle changes, such as following a healthy diet, could prevent 30–50% of all cancers (Source).

What’s more, nutrition is thought to play an important role in treating and coping with cancer.

This article covers significant evidence that you need to know about the link between diet and cancer.

Methodology

We’ve combed and reviewed over 500 studies so that you don’t have to. When interpreting and filtering scientific research, it’s crucial to consider the hierarchy and quality of evidence. Not all evidence is equal.

Cell culture findings carry less weight than results from studies conducted on mice. Similarly, conclusions drawn from mouse studies are surpassed by findings from human studies.

Case studies and preliminary results from small-scale human trials hold less significance than outcomes from umbrella reviews, randomized controlled trials (RCTs), and more extensive, long-term human trials.

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Contents

Eating Too Much of Certain Foods May Increase Cancer Risk
Certain Foods Contain Cancer-Fighting Properties
Plant-Based Diets May Help Protect Against Cancer
Supplements: Use or Not to Use?
Avoid tobacco and alcohol
Being Overweight or Obese Is Linked to Increased Cancer Risk
Be physically active
Sleep, Stress and Desk Job
Fasting, Keto Diet and Cancer
People With Cancer: The Right Diet Can Have Beneficial Effects

1. Eating Too Much of Certain Foods May Increase Cancer Risk

It’s difficult to prove that certain foods cause cancer.

However, observational studies have repeatedly indicated that high consumption of certain foods may increase the likelihood of developing cancer.

Sugar, Refined Carbs and Ultra-processed Foods

At this point, there is simply no question that processed foods that are high in sugar and low in fiber and nutrients, have been linked to a higher cancer risk.

A 2024 umbrella review* (BMJ) of the literature confirmed what multiple studies have shown — the higher your intake of ultraprocessed food, the higher your risk of adverse health outcomes. The analysis, which included 14 meta-analysis studies, 45 unique pooled analyses and 9,888,373 participants, found direct associations between 32 health parameters and exposure to ultra processed food, including metabolic dysfunction, cancer, mental, respiratory, cardiovascular and gastrointestinal issues, as well as all-cause mortality.

*Umbrella review: An umbrella review, or a review of reviews, is a systematic review that only considers other systematic reviews as an eligible study type for inclusion. An umbrella review compiles evidence from multiple existing reviews and is one of the strongest and highest levels of evidence.

Evidence from another umbrella review (BMJ 2023) of more than 8,000 studies supports the limiting dietary sugar recommendation.

Limiting sugar and processed foods are part of the recommendations according to both the and the American Cancer Society Guidelines on Diet and Physical Activity for Cancer Prevention (2020) and the WCRF/AICR (World Cancer Research Fund/American Institute for Cancer Research) recommendations (2018).

Researchers have also found that a diet that causes blood glucose levels to spike is associated with an increased risk of several cancers, including stomach, breast and colorectal cancers (Source, Source, Source, Source).

One 2015 study in over 47,000 adults found that those who consumed a diet high in refined carbs were almost twice as likely to die from colon cancer than those who ate a diet low in refined carbs (Trusted Source).

It’s thought that higher levels of blood glucose and insulin are cancer risk factors. Insulin has been shown to stimulate cell division, supporting the growth and spread of cancer cells and making them more difficult to eliminate (Trusted Source, Trusted Source, Trusted Source).

In addition, higher levels of insulin and blood glucose can contribute to inflammation in your body. In the long term, this can lead to the growth of abnormal cells and possibly contribute to cancer (Trusted Source).

This may be why people with diabetes — a condition characterized by high blood glucose and insulin levels — have an increased risk of certain types of cancer (Trusted Source).

For example, your risk of colorectal cancer is 22% higher if you have diabetes (Trusted Source).

Processed Meat

The International Agency for Research on Cancer (IARC) deems processed meat a carcinogen — something that causes cancer (Source).

Processed meat refers to meat that has been treated to preserve flavor by undergoing salting, curing or smoking. It includes hot dogs, ham, bacon, chorizo, salami and some deli meats.

Observational studies have found an association between consuming processed meat and an increased cancer risk, particularly colorectal cancer (Trusted Source).

A large review of studies found that people who ate large amounts of processed meat had a 20–50% increased risk of colorectal cancer, compared to those who ate very little or none of this type of food (Trusted Source).

Another review of over 800 studies found that consuming just 50 grams of processed meat each day — around four slices of bacon or one hot dog — raised the risk of colorectal cancer by 18% (Trusted Source, Trusted Source.

Some observational studies have also linked red meat consumption to an increased cancer risk (Trusted Source, Trusted Source, Trusted Source).

However, these studies often don’t distinguish between processed meat and unprocessed red meat, which skews results.

Overcooked Food

Cooking certain foods at high temperatures, such as grilling, frying, sautéing, broiling and barbequing, can produce harmful compounds like heterocyclic amines (HA) and advanced glycation end-products (AGEs) (Source).

Excess buildup of these harmful compounds can contribute to inflammation and may play a role in the development of cancer and other diseases (Source, Source).

Certain foods, such as animal foods high in fat and protein, as well as highly processed foods, are most likely to produce these harmful compounds when subjected to high temperatures.

These include meat — particularly red meat — certain cheeses, fried eggs, butter, margarine, cream cheese, mayonnaise, oils and nuts.

To minimize cancer risk, avoid burning food and choose gentler cooking methods, especially when cooking meat, such as steaming, stewing or boiling. Marinating food can also help (Trusted Source).
Dairy

Several observational studies have indicated that high dairy consumption may increase the risk of prostate cancer (Trusted Source, Trusted Source, Trusted Source).

One study followed almost 4,000 men with prostate cancer. Results showed that high intakes of whole milk increased the risk of disease progression and death (Trusted Source).

More research is needed to determine possible cause and effect.

Theories suggest that these findings are due to an increased intake of calcium, insulin-like growth factor 1 (IGF-1) or estrogen hormones from pregnant cows — all of which have been weakly linked to prostate cancer (Source, Trusted Source, Trusted Source).

Unhealthy oils

Avoid seed oils high in linoleic acid. Linoleic acid is an Omega-6 fatty acid that our bodies require in small amounts. Unfortunately, many people eat up to 10 times the desired amount of linoleic acid, because of excess consumption of foods made with seed oils. Too much linoleic acid is associated with inflammation, obesity, heart disease, and other unfavorable conditions. Therefore, avoid:

• Soybean oil

• Corn oil

• Cottonseed oil

• Sunflower oil

• Sesame oil

• Grapeseed oil

• Safflower oil

• Margarine

• Rice bran oil

2. Best Cancer-Fighting Foods

There is no single superfood that can prevent cancer. Rather, a holistic dietary approach is likely to be most beneficial.

Scientists estimate that eating the optimal diet for cancer may reduce your risk by up to 70% and would likely help recovery from cancer as well (Source).

They believe that certain foods can fight cancer by blocking the blood vessels that feed cancer in a process called anti-angiogenesis (Source).

However, nutrition is complex, and how effective certain foods are at fighting cancer varies depending on how they’re cultivated, processed, stored and cooked.

People who eat a Mediterranean diet that includes extra-virgin olive oil and mixed nuts might have a reduced risk of breast cancer. The Mediterranean diet focuses mostly on plant-based foods, such as fruits and vegetables, whole grains, legumes and nuts. People who follow the Mediterranean diet choose healthy fats, such as olive oil, over butter. They eat fish instead of red meat.

Some of the key anti-cancer food groups include:

Vegetables

Many vegetables contain cancer-fighting antioxidants and phytochemicals.

A 2022 umbrella review* of 41 systematic reviews and meta-analyses of 303 observational studies

revealed that CV (cruciferous vegetable intake might be associated with beneficial effects on several health-related outcomes (gastric cancer, lung cancer, endometrial cancer, and all-cause mortality).

Vegetables, such as tomatoes and carrots, are linked to a decreased risk of prostate, stomach and lung cancer (Source, Source, Source, Source).

It has long been known that tomato consumption reduces the risk of developing cancer and cardiovascular disease, due to its high lycopene content (Ratto 2022). There are more than 1,500 search results on lycopene and cancer on PubMed.

In a 2020 prospective study of 27,934 Adventist men, published in the journal Cancer Causes & Control (The Adventist Health Study 2) found that men who ate tomatoes almost every day had a 28 percent lower risk of prostate cancer than men who didn’t. Lycopene may also protect the skin from the sun damage that can cause skin cancer, and some research suggests that it helps women maintain bone mass as they age.

A review of 17 studies also found that a higher intake of raw tomatoes, cooked tomatoes and lycopene were all associated with a reduced risk of prostate cancer (J Nutr Sci Vitaminol. 2013).

Broccoli contains sulforaphane, a plant compound found in cruciferous vegetables that may have potent anticancer properties. There are more than 1,000 search results on broccoli and cancer on PubMed.

One analysis of 35 human studies showed that eating more cruciferous vegetables was associated with a lower risk of colorectal and colon cancer (Ann Oncol. 2013).

Caution and Concern

It wasn't long ago that, after finding that people who ate a diet rich in foods containing beta-carotene had a lower risk of lung cancer, researchers set out to study the potential effect of supplements of beta-carotene on risk. Unlike the reduced risk seen with dietary beta-carotene, however, beta-carotene in supplement form was associated with an increased risk of developing the disease.

The Mediterranean-DASH diet

A meta-analysis of 45 studies published in 2022 found that people who consume olive oil daily have a 31 percent lower risk of any cancer compared to those who consume olive oil less frequently.

The Mediterranean-DASH (MIND) diet combines elements of the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) diet. Here’s what we know:

MIND Diet and Breast Cancer Risk: A 2022 study investigated the association between the MIND diet and breast cancer risk among Tehranian adult women. The study included 134 women with recently diagnosed breast cancer (confirmed histologically) and 272 women of the same age as controls. Results showed that individuals in the highest tertile of the MIND diet had a 45% lower risk of breast cancer compared to those in the lowest tertile.
Mediterranean Diet and Cancer: The Mediterranean diet is characterized by high consumption of vegetables, fruits, whole grains, and olive oil, while limiting meat, sweets, and saturated fat. Research suggests that the Mediterranean diet is linked to lower risks of cancer and may help alleviate symptoms and imbalances common among people with cancer.
The abundance of antioxidants and cancer-fighting phytochemicals in this diet contributes to its potential protective effects against cancer (American Institute of Cancer Research 2013).

Dietary Fibers

A 2023 umbrella review (more than 180 studies analyzed) of the literature indicated that a high intake of dietary fiber is associated with a reduced risk of several types of cancer, including esophageal, gastric, colon, rectal, colorectal adenoma, breast, endometrial, ovarian, renal cell, prostate, and pancreatic cancers. Conclusions: Dietary fiber intake has different protective effects on different cancers.

Fruits

Similar to vegetables, fruits contain antioxidants and other phytochemicals, which may help prevent cancer (Source, Trusted Source).

One review found that at least three servings of citrus fruits per week reduced stomach cancer risk by 28% (Trusted Source).

Spices and Curcumin

A review paper published in 2022, analysed 21 human studies. Sixteen out of 21 clinical trials were associated with the effectiveness of curcumin or turmeric on various types of cancer, and the other five clinical trials were related to the evaluation of the efficacy of curcumin or turmeric in relieving the side effects of cancer chemotherapy and radiotherapy. The emerging data from the clinical trials confirm that curcumin has the potential for cancer prevention and intervention. Interestingly, curcumin appears to be universally useful for just about every type of cancer (Arslan 2022), which is really odd since cancer consists of a wide variety of different molecular pathologies.

Many different forms of cancer appear to be affected by curcumin supplements.

In fact, curcumin has been studied as a beneficial herb in cancer treatment and has been found to affect cancer growth and development.

Studies have shown that it can:

contribute to the death of cancerous cells
reduce angiogenesis (growth of new blood vessels in tumors)
reduce metastasis (spread of cancer)

There is also evidence that curcumin may prevent cancer from occurring in the first place, especially cancers of the digestive system like colorectal cancer.

The use of fenbendazole and curcumin, has achieved much attention due to the reported experience of Joe Tippens. In 2016, Tippens was diagnosed with non-small-cell lung cancer with extensive metastatic disease. At the advice of a veterinarian friend, he took Fenbendazole together with nanocurcumin, and three months after starting these drugs his PET scan was completely clear.

Click here to buy Bioavailable Curcumin.

Beans and Legumes

Beans and legumes are high in fiber, and some studies suggest that higher intake of this nutrient may protect against colorectal cancer (Source, Source).

One study in over 3,500 people found that those eating the most legumes had up to a 50% lower risk of certain types of cancers (Trusted Source).
Nuts

Regularly eating nuts may be linked to a lower risk of certain types of cancer (Trusted Source, Trusted Source).

For example, one study in more than 19,000 people found that those who ate more nuts had a reduced risk of dying from cancer (Trusted Source).

Healthy Oils

Opt for healthy oils and fats such as the ones listed below. Use only high-quality products and check production and expiration dates.

Olive oil (oleic acid, Omega-9 monounsaturated fatty acids); never heat olive oil to the point where it produces smoke. A 2022 meta-analysis of 45 studies found that people who consume olive oil daily have a 31 percent lower risk of any cancer compared to those who consume olive oil less frequently.
Avocado oil (oleic acid, Omega-9 monounsaturated fatty acids)
Coconut oil (medium chain fatty acid)
Flaxseed oil (alpha-linolenic acid, ALA Omega-3)
Walnut and Pecan oils; should be refrigerated to avoid spoilage
Butter (saturated fat)

Fish

There’s evidence that eating fresh fish can help protect against cancer, possibly due to healthy fats that can reduce inflammation.

A large review of 41 studies found that regularly eating fish reduced the risk of colorectal cancer by 12% (Source).

Dairy

The majority of evidence suggests that eating certain dairy products may reduce the risk of colorectal cancer.

A 2021 umbrella review (Nature) of the literature concluded that consumption of dairy products, milk, calcium and wholegrains are inversely associated with colorectal cancer risk.

The type and amount of dairy consumed are important.

For example, moderate consumption of high-quality dairy products, such as raw milk, fermented milk products and milk from grass-fed cows, may have a protective effect.

This is likely due to higher levels of beneficial fatty acids, conjugated linoleic acid and fat-soluble vitamins (Trusted Source, Trusted Source, Trusted Source).

On the other hand, high consumption of mass-produced and processed dairy products are associated with an increased risk of certain diseases, including cancer (Trusted Source, Trusted Source, Trusted Source).

The reasons behind these results aren’t fully understood but may be due to hormones present in milk from pregnant cows or IGF-1.

Nuts

Research has found that eating nuts may be linked to a lower risk of certain types of cancer. There are more than 1,000 search results on nuts and cancer on PubMed.

For instance, a study looked at the diets of 19,386 people and found that eating a greater amount of nuts was associated with a decreased risk of dying from cancer (Br J Nutr. 2015).

Another 2015 study followed 30,708 participants for up to 30 years and found that eating nuts regularly was associated with a decreased risk of colorectal, pancreatic and endometrial cancers (Source).

Another meta-analysis of 14 cohort studies (2015), found that dietary legume consumption reduces risk of colorectal cancer. Legumes are a diverse group of foods, including soybeans, peas, beans, lentils, peanuts, and other podded plants, which are widely cultivated and consumed.

Other studies have found that specific types of nuts may be linked to a lower cancer risk. For example, Brazil nuts are high in selenium, which may help protect against lung cancer in those with a low selenium status (Source).

These results suggest that adding a serving of nuts to your diet each day may reduce your risk of developing cancer in the future.

Still, more studies in humans are needed to determine whether nuts are responsible for this association, or whether other factors are involved.

Caution: Whilst we don't want to avoid nuts unnecessarily, limiting nuts may be helpful if you are experiencing recurrent cold sore (Herpes type 1) infections. While nuts are usually a great way to add to a healthy diet in order to pack in some extra protein, fibre and minerals, they are also a high source of arginine. In particular, peanuts, walnuts and hazelnuts are the worst offenders so steer clear of these. This includes peanut butter and other nut butters, unfortunately. (source)

Soy

A review of 14 studies (Plos One. 2020) found that tofu intake was associated with a
lower risk of breast cancer. Tofu (bean curd), is a popular food derived from soy in Asia.

A review of 35 studies (Plos One. 2014) found that soy intake could lower the risk of breast cancer for both pre- and post-menopausal women in Asian countries. However, for women in Western countries, pre- or post-menopausal, there is no evidence to suggest an association between intake of soy isoflavone and breast cancer.

In another study, The Shanghai Breast Cancer Survival Study (JAMA. 2009), a large, population-based cohort study of 5,042 female breast cancer survivors. Over an average follow-up of 3.9 years, soy food consumption was significantly associated with lower risk of death and breast cancer recurrence.

Coffee and Cancer

A 2021 umbrella review (Nature) of the literature concluded that coffee consumption is inversely associated with risk of liver cancer and skin basal cell carcinoma.

In addition, based on data from another large observational study nested in a clinical trial, are in line with earlier studies showing a connection between regular coffee consumption and improved outcomes in patients with non-metastatic colorectal cancer. The study is being published by JAMA Oncology (2020).

According to a 2019 systematic review of four studies, coffee has a weak to strong inverse association with liver cancer. The researchers concluded that the Japanese population was likely to experience a decrease in the risk of primary liver cancer due to coffee consumption.

3. Plant-Based Diets May Help Protect Against Cancer

Higher intake of plant-based foods has been associated with a reduced risk of cancer. The umbrella review, published in May 2024 in PLOS One, evaluated 48 previous reviews and meta-analyses published between 2000 and 2023 and concluded that vegetarian or vegan diets “significantly reduce the risk” of ischemic heart disease, gastrointestinal cancer, and prostate cancer, as well as associated mortality.

Caution: What are the nutrients of concern for vegetarians and vegans? Vitamin B12 and K2. Anybody who is eating a vegan diet or a vegetarian diet or just a mostly plant-based diet should be taking vitamin B12 and K2 supplements. Vitamin B12 is only found in significant amounts in animal products and fortified foods, and a deficiency can cause anemia, mood changes, or permanent neurological damage. Plant-based diets may also be low in vitamin D, omega-3 fatty acids, and minerals like iodine, selenium, iron, and zinc.

Studies have found that people who follow a vegetarian or vegan diet have a reduced risk of developing or dying from cancer (Source).

In fact, a large review of 96 studies found that vegetarians and vegans may have an 8% and 15% lower risk of cancer, respectively (Trusted Source).

However, these results are based on observational studies, making it difficult to identify possible reasons.

It’s likely that vegans and vegetarians eat more vegetables, fruits, soy and whole grains, which may protect against cancer (Trusted Source, Trusted Source).

Moreover, they’re less likely to consume foods that have been processed or overcooked — two factors that have been linked to a higher cancer risk (Trusted Source, Trusted Source, Trusted Source).

4. Supplements: Use or Not to Use?

One of the 10 WCRF/AICR (World Cancer Research Fund/American Institute for Cancer Research) recommendations in 2018 is "not to use supplements to prevent cancer". However, articles from established and reputable sites like Healthline and Medical News Today are recommending supplements to prevent cancer.

In a nutshell, there are two conflicting recommendations from various professional groups. One for and the other against.

Therefore, it is wise to do your own research in consultation with your trusted doctor. Unfortunately, some of the references used by many media channels are based on outdated studies. That's where this article comes in again. We've delved into the research to provide you supporting evidence in order to reduce your confusion.

We have also organised and summarised relevant and salient research information in one place. Below, we look at the most published and studied categories.

Important Note: This information is for educational purposes only and should not be interpreted as medical advice.

Here is the list (listed in order of importance):

Vitamin D3 and K2

Is vitamin D the most powerful anti cancer supplement? Vitamin D can absorb calcium and help the immune, muscle, and nervous systems function properly. There are more than 11,000 search results on vitamin D and cancer on PubMed.

Prevention

A 2023 systematic review and meta-analysis of 14 RCTs (randomized controlled trials), published in Ageing Research Reviews (Kuznia 2023) found vitamin D3 supplementation reduced cancer mortality by 6%. This wasn’t considered statistically significant, but when only studies involving daily vitamin D intake were analyzed, cancer mortality dropped by a significant 12%.

The first randomized-controlled trial (DO-HEALTH) trial to investigate the combination of three complementary treatments for the prevention of cancer and suggest that the combination of daily vitamin D3, supplemental marine omega-3s, and a simple home exercise program may be effective in the prevention of invasive cancer among generally healthy and active adults aged 70 and older.

Findings from a 3 year Randomized Controlled Trial with more than 2,000 participants observed a 61% reduction in the risk of invasive cancer among patients who completed a home exercise program and took vitamin D3 and omega-3 fatty acids daily.

Dosage: Supplemental 2000 IU/day of vitamin D3, and/or 1 g/day of marine omega-3s, and/or a simple home strength exercise (SHEP) programme compared to placebo and control exercise.

These results, from the DO-HEALTH trial (ClinicalTrials.gov identifier NCT01745263), were published in Frontiers in Aging 2022.

A number of epidemiologic studies have also investigated whether people with higher vitamin D intakes or higher blood levels of vitamin D have lower risks of specific cancers. The results of these studies have been inconsistent, possibly because of the challenges in carrying out such studies. For example, dietary studies do not account for vitamin D made in the skin from sunlight exposure, and the level of vitamin D measured in the blood at a single point in time (as in most studies) may not reflect a person’s true vitamin D status. Also, it is possible that people with higher vitamin D intakes or blood levels are more likely to have other healthy behaviors. It may be one of these other behaviors, rather than vitamin D intake, that influences cancer risk.

A Secondary Analysis of the VITAL Randomized Clinical Trial studied the effect of Vitamin D3 Supplements on Development of Advanced Cancer. The Harvard research, published in the JAMA Network Open medical journal (2020), overturns the initial findings of a study of 25,000 people published in 2018.

Initially researchers believed there was no benefit from taking vitamin D, as they detected no reduced incidence of cancer diagnoses overall. But they were puzzled because cancer deaths went down among those taking the supplements. Meaning, there was no benefit in terms of prevention of cancer but a reduction in cancer deaths was observed.

A secondary analysis, found this anomaly can be explained by the fact that vitamin D seems to stop metastatic cancers - those aggressive types which spread to other parts of the body. That said, when stratified by BMI (body mass index), there was no significant reduction for the vitamin D arm in incident metastatic or fatal cancer among those with overweight or obesity (BMI 25-<30).

The cancers for which the most human data are available are colorectal, breast, prostate, and pancreatic cancer. Numerous epidemiologic studies have shown that higher intake or blood levels of vitamin D are associated with a reduced risk of colorectal cancer (R). In contrast, the Women’s Health Initiative randomized trial found that healthy women who took vitamin D and calcium supplements for an average of 7 years did not have a reduced incidence of colorectal cancer (NEJM 2006). Some scientists have pointed out that the relatively low level of vitamin D supplementation (10 μg, or 400 IU, once a day), the ability of participants to take additional vitamin D on their own, and the short duration of participant follow-up in this trial might explain why no reduction in colorectal cancer risk was found.

According to BreastCancer.org,

research suggestsTrusted Source

that certain cancers such as breast cancer, can have a higher risk of occurring when the body has low levels of vitamin D.

Studies also show a link between vitamin D deficiency and cardiovascular disease, diabetes, and cancer (Sizar, 2020).

In 2016, a landmark study published in PLOS ONE found that women over 55 with blood concentrations of vitamin D higher than 40 ng/ml, had a 67% lower risk of cancer compared women with levels lower than 20 ng/ml.

Many experts now recommend 800 to 1,000 IU a day, a goal that's nearly impossible to attain without taking a supplement. Although protection is far from proven, evidence suggests that vitamin D may help reduce the risk of prostate cancer, colon cancer, and other malignancies.

Although the role of vitamin D in cancer prevention remains an area of research interest and debate, avoiding deficient levels is recommended. (American Cancer Society 2020)

Vitamin D can also be absorbed through sunlight, or with the following diet such as fatty fish, egg yolks and fortified milk.

Make sure to take 500 mg to 1000 mg of magnesium and 150 mcg of vitamin K2, (not K1) which are important cofactors for optimizing vitamin D function. And, remember the only way you know what your vitamin D level is, is to test it. Vitamin D level should be in a therapeutic range of 50 to 70 ng/ml for treatment of rheumatoid arthritis. Most people are shocked how low their level is when they finally get around to testing it.

That said, as researchers explained in Nutrients (2022):

“Vitamin D supplementation is not the magic pill that miraculously solves the cancer burden or that can replace a healthy lifestyle. It is necessary to foster a good environment and invigorate a healthy lifestyle, including a high-quality diet and physical activity. Both have been proven to confer health benefits in many diseases, including cancer, and are the best preventive measures available.”

Related: Vitamin D Level and Cancer: Vitamin D Reduces Cancer Deaths

Treatment

A 2019 meta-analysis showed statistically significant reductions in cancer mortality.
A Secondary Analysis of the VITAL Randomized Clinical Trial (JAMA 2020) showed more significant reductions in cancer risk for those with normal BMI (<25).

Vitamin D and Chemotherapy

Multiple studies indicate that a significant proportion of cancer patients are vitamin D-deficient (level < 20 ng/mL) and that higher plasma 25-hydroxyvitamin D levels are associated with improved survival in colorectal, breast, gastric, and lymphoma cancer patients [Systematic Review 2014]. Meta-analyses and clinical trials demonstrate that vitamin D supplementation may reduce cancer mortality and improve survival in cancer patients, especially when used in combination with chemotherapy (Meta-analysis 2023). SUNSHINE (JAMA 2019), a clinical trial on metastatic colorectal cancer patients, showed that “high-dose” vitamin D3 (aiming for a level of >50 ng/mL) combined with standard chemotherapy resulted in improved progression-free survival compared to standard-dose vitamin D3.

Note: The dosage for vitamin D in prevention (1,000 to 2,000 IU daily) is very much different from the high dose treatment dosage i.e. 20,000 to 50,000 IU daily. Always consult your doctor first!

Vitamin C, E and Selenium

PubMed has indexed more than 3,000 research studies on vitamin C and cancer and more than 5,000 studies on vitamin E and cancer. United States Preventive Services Task Force has recommended the use of Vitamin C and E supplementation for cancer prevention (R).

Prevention

Best Evidence: An umbrella review* (Xu 2022) of more than 50 studies, to assess the existing systematic reviews and meta-analyses for the association between vitamin C intake and multiple health outcomes; showed that vitamin C intake was associated with reduced risk of all-cause mortality, cardiovascular disease (CVD), oesophageal cancer, gastric cancer, cervical cancer and lung cancer with an increment of 50–100 mg per day.

Beneficial associations were also identified for respiratory, neurological, ophthalmologic, musculoskeletal, renal and dental outcomes. A total of 76 meta-analyses (51 papers) of randomised controlled trials and observational studies with 63 unique health outcomes were identified. Harmful associations were found for breast cancer and kidney stones for vitamin C supplement intake.

2022 - Obese women who took vitamin C and B6 at amounts that exceeded the recommended daily intake levels were associated with a lower risk of breast cancer, according to a five-year long South Korean cohort study. 40,432 women without a history of cancer at baseline were included in this study.

2022 - A meta-analysis to review the association between vitamins and brain cancer showed that intake of vitamin C, β-carotene, and folate can reduce the risk of brain cancer, while high serum α-tocopherol (vitamin E) concentration also has a protective effect on brain cancer.

A 2017 meta-analysis of 11 studies concluded that patients with lower concentrations of serum vitamin E (the vitamin E level in your blood) had a higher risk for colorectal cancer.

Treatment

2023 - A systematic review to evaluate the existing literature on the safety and efficacy of vitamin C, E and selenium supplementation in oncology patients. Findings were generally favorable among the studies, and adverse effects of supplementation were limited. The review concluded that antioxidant supplements may provide benefits in reducing incidence or severity of treatment-induced side effects with limited risk for adverse effects.

2022 - A systematic review on the effect of vitamins C and E on cancer survival showed improvement of survival and progression rates of cancers by vitamins C and E. However, the authors concluded that more high quality trials with large sample sizes are required to confirm.

Vitamin C is known as an antioxidant, but at high concentrations, vitamin C can kill cancer cells through a pro-oxidant property (Transl Oncol. 2020). This study has also demonstrated that vitamin C treatment with magnesium supplementation provided more effective anticancer therapy than vitamin C treatment alone.

High-dose vitamin C cancer therapy was introduced by Linus Pauling and Ewan Cameron [R]. Clinical demonstration results by Pauling and Cameron showed that intravenous injection of 10 g/day of vitamin C extended the survival time of terminal cancer patients by about 4.2 times. However, results from the Mayo Clinic in 1979 showed that the survival time of vitamin C–treated patients was even shorter than that of the placebo group patients [R]. A significant difference between those two research groups was the route of AA administration: intravenous injection and oral administration, respectively.

When treating cancer, IV needs to be used because you simply cannot take the high dosages required orally. Doses over 10 to 20 grams of ascorbic acid will cause loose stools when taken orally, but IV administration bypasses the limitation of the gut. It also allows the vitamin C to get directly into the blood to the extracellular fluid, into the tumor microenvironment, to penetrate the tumor and saturate the entirety of the tumor.

To understand the mechanism of AA's anticancer activity, many research groups have treated colon, prostate, leukemia, lymphoma, brain, and stomach cancer cells and chemically or genetically transformed cancer cells with AA and showed cancer growth inhibition and even cancer cell death through hydrogen peroxide–mediated reactive oxygen species (ROS) generation [R]. In most cases, the pharmacological concentration of vitamin C required for anticancer effects (EC50 value of 1–10 mM) could only be achieved by intravenous administration. Thus, to apply vitamin C as an anticancer therapy, a high intracellular concentration in cancer cells is critically important (R).

According to the Mayo Clinic (2023):

"More recently, vitamin C given through a vein (intravenously) has been found to have different effects than vitamin C taken in pill form. This has prompted renewed interest in the use of vitamin C as a cancer treatment.

There's still no evidence that vitamin C alone can cure cancer, but researchers are studying whether it might boost the effectiveness of other cancer treatments, such as chemotherapy and radiation therapy, or reduce treatment side effects.

There are still no large, controlled clinical trials that have shown a substantial effect of vitamin C on cancer, but some preliminary studies do suggest there may be a benefit to combining standard treatments with high-dose IV vitamin C."

According to the concluding remarks from a 2020 article from the National Cancer Institute:

Vitamin C as a cancer therapy has had a controversial past. What has been intriguing are small clinical trials that suggest some responses, but with no clear rationale for why cancers should respond to vitamin C or a path forward for explaining which patients are most likely to respond. Now a growing number of preclinical studies are showing how high-dose vitamin C might benefit cancer patients. Importantly, these preclinical studies provide a clear rationale and potential biomarkers that may help personalize the therapeutic approach and identify patient populations that are likely to respond to high-dose vitamin C therapy. Since the mechanisms of action of vitamin C are becoming better defined, we can propose vitamin C combinations in a more rational, hypothesis-driven manner. In addition, given the current high financial cost of new cancer drugs, it seems rational to improve the effectiveness of current therapies by studying their clinical interactions with vitamin C. In our view, the implementation of this treatment paradigm could provide benefit to many cancer patients.

Ascorbic acid vs whole food vitamin C?

Synthetic Ascorbic acid is NOT the same as whole food vitamin C. If you were to compare the two to a car, vitamin C would be the whole car, fully functional, and the engine is an enzyme called tyrosinase, while ascorbic acid is the car frame, with no moving parts.

Whole food vitamin C can also boost your copper level, as vitamin C contains an enzyme called tyrosinase, which has 2 atoms of copper in it. Ascorbic acid is prooxidant, while vitamin C complex is actually an antioxidant. Anything that has copper is going to be antioxidant.

Caution: Those with cancer should avoid supplementing too heavily with vitamins A and E, as they act as antioxidants and can interfere with chemotherapy when taken in large doses.

Related: Benefits of Vitamin C in Cancer Treatment

Fish Oil (Omega-3 Fatty Acids)

PubMed has indexed more than 3,000 research studies on Omega-3 and cancer. Most people use fish oil supplements to enhance the amount of omega-3’s in their diet.

Best Evidence: A 2021 report (Nature Communications) suggest that higher levels of omega 3 fatty acids in circulation correlate with lower risk of premature death from age-associated diseases such as cardiovascular disease and cancer. The analysis was conducted with data from 17 prospective cohort studies examining the associations between blood omega-3 fatty acid levels and risk for all-cause mortality. Over a median of 16 years of follow-up, 15,720 deaths occurred among 42,466 individuals. The researchers found that, after adjustment for relevant risk factors, risk for death from all causes was significantly lower (by 15-18%, at least p < 0.003) in the highest vs the lowest quintile for circulating long chain (20-22 carbon) omega-3 fatty acids (eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids). Similar relationships were seen for death from cardiovascular disease, cancer and other causes.

The first randomized-controlled trial (DO-HEALTH trial) to investigate the combination of three complementary treatments for the prevention of cancer and suggest that the combination of daily vitamin D3, supplemental marine omega-3s, and a simple home exercise program may be effective in the prevention of invasive cancer among generally healthy and active adults aged 70 and older.

Findings from a 3 year Randomized Controlled Trial with more than 2,000 participants observed a 61% reduction in the risk of invasive cancer among patients who completed a home exercise program and took vitamin D3 and omega-3 fatty acids daily. These results, from the DO-HEALTH trial, were published in Frontiers in Aging 2022.

Many governments recommend eating omega-3 containing fatty fish, two times per week. But that is often not enough. Ideally, people would need to eat fatty fish four times per week, while also supplementing with omega-3 fatty acids, at least 1,000 mg of pure omega-3 (DHA and EPA) per day.

However, fish oil was shown in one study on mice (2015)Trusted Source to possibly reduce the effectiveness of chemotherapy, and for that reason ground flax seed is a worthy alternative.

Flax seed is rich in omega-3 fatty acids, which may reduce the risk of certain cancers. When supplementing, try to avoid flaxseed oil because it lacks the nutrients of ground flax seed. Ground flax seed can be purchased online or found in many larger grocery store chains. Simply sprinkle some ground flax seed on your food and enjoy.

Make sure you buy high-quality omega-3 fatty acid supplements, meaning that the omega-3 fatty acids are pure and have not oxidized much (having low “TOTOX” value).

TOTOX value stands for total oxidation value. The omega 3 fatty acids EPA and DHA from fish oil are highly sensitive to oxidation. This means that they are rapidly affected by contact with oxygen. Oxidised fatty acids are not beneficial to our health. For this reason, a good fish oil supplement has a low TOTOX value. The maximum TOTOX value is set at 26 by the Global Organization for EPA and DHA omega-3.

Magnesium and Molecular Hydrogen

PubMed has indexed more than 5,000 research studies on magnesium and cancer.

Colorectal Cancer

Several studies have demonstrated an association between high magnesium intake and reduced risk of colorectal cancer (CRC).

An analysis of the prospective, Swedish Mammography Cohort (JAMA 2005), evaluated 61,433 women aged 40 to 75 without a history of cancer for a mean follow-up of 14.8 years. The highest quintile of magnesium intake was associated with a significantly lower risk of CRC compared with the lowest quintile. This benefit was observed for both colon and rectal cancers.

A case-control study evaluated 2204 subjects from the Tennessee Colorectal Polyp Study (2007), which demonstrated that increasing total magnesium intake was significantly associated with decreasing risk of CR.. The highest tertile of dietary magnesium intake (>298 mg/day) was significantly associated with reduced risk of CRC in an age-adjusted model.

A study of 140,601 postmenopausal women from the Women’s Health Initiative (2015) with an mean follow-up of 13 years demonstrated a significant reduction in CRC risk with the highest quintile of total magnesium intake compared with the lowest quintile of magnesium intake. The benefit was driven by colon cancer, with a trend for rectal cancer.

Pancreatic Cancer

A study of 66,806 subjects aged 50 to 76 at baseline from the Vitamins and Lifestyle cohort (Nature 2015) evaluated magnesium intake and the incidence of pancreatic cancer during a mean follow-up of 6.8 years. Subjects with magnesium intake below the recommended dietary allowance were more likely to develop pancreatic cancer, particularly in those whose intake was less than 75% of the recommended dietary allowance. In this study, a 100 mg/day decrease in magnesium intake resulted in a 24% increase in risk of pancreatic cancer.

Molecular Hydrogen and Cancer

There is little evidence to show that molecular hydrogen can reduce the risk of cancer.

However, in terms of cancer management or treatment, studies involving the effects of H2 on cancer were systematically reviewed. More than 600 articles related to molecular hydrogen and cancer were retrieved from Cochrane, PubMed and Google Scholar, and 27 articles were included for this systematic review (2023).

Based on the authors' analysis, "H2 plays a promising therapeutic role as an independent therapy as well as an adjuvant in combination therapy, resulting in an overall improvement in survivability, quality of life, blood parameters, and tumour reduction."

Although H2 has demonstrated significant anti-cancer effects, the underlying mechanisms have not yet been elucidated. Many studies have shown that H2 therapy can reduce oxidative stress. This, however, contradicts radiation therapy and chemotherapy, in which ROS (Reactive Oxygen Species) are required to induce apoptosis and combat cancer.

Related: Best Molecular Hydrogen Tablets

Note: Most Molecular Hydrogen tablets uses pure elemental magnesium as its carrier and provides you with approximately 80 mg of magnesium per tablet. So, you receive also highly bioavailable magnesium for a healthy brain, muscles, cells, kidneys, and heart.

Melatonin

PubMed has indexed more than 3,300 research studies on melatonin and cancer.

Melatonin is one of the most important antioxidant molecules. In the human body — aside from having direct antioxidant effects — it also stimulates the synthesis of glutathione and other important antioxidants like superoxide dismutase and catalase.

Many people are not aware that only 5% of your body’s melatonin — which is also a potent anticancer agent — is produced in your pineal gland. The other 95% is produced inside your mitochondria — provided you get sufficient near infrared exposure which is typically from sun on your bare skin. This is why vitamin D is more than likely a biomarker for sun exposure, which is intricately involved in melatonin production. (R)

The Mediterranean Diet (MD) dietary pattern is also rich in antioxidants, such as melatonin. A systematic review published in Antioxidants (Elena 2023) showed high melatonin contents in MD-related foods, such as tomatoes, olive oil, red wine, beer, nuts, and vegetables. The consumption of specific MD foods increases melatonin levels and improves the antioxidant status in plasma.

Melatonin is also known to play a fundamental role in regulating the sleep-wake rhythm; however, in the last 10 years it has been discovered that it is actually involved in many other biological mechanisms, also playing an important role in the inflammatory, metabolic and neoplastic processes. In fact, the mechanisms by which melatonin performs an anti-tumor effect are many: it has an anti-oxidant effect that protects against DNA damage, acts as a scavenger of reactive oxygen species (which undermine genomic stability), stimulates DNA repair mechanisms, improves the functioning of the mitochondrial respiratory chain, and inhibits mitochondrial mitophagy and telomerase activity (Molecules 2018).

In addition, melatonin increases the expression of the p53 protein, induces its phosphorylation, inhibiting cell proliferation, promotes apoptosis, reduces the levels of the vascular endothelial growth factor and endothelin-1, fundamental for tumor growth and metastasis formation, reduces inflammatory processes and cell migration (Molecules 2018).

Reduction of melatonin production has also been seen in some types of cancer (breast and prostate) (Mogavero 2021).

Melatonin - Treatment

2022 - An umbrella review of meta-analyses based on randomized controlled trials (Pharmacological Research 2022):

"Survival at one year (P < 0.005) significantly increased with cancer patients."

2020 - A case series of 14 advanced cancer patients (Trends in Oncology 2020), treated with high dose (1,000 mg/day) of melatonin; achieved a disease control of 54% of the patients:

"Moreover, this preliminary study may also suggest that high dose melatonin has no toxicity in cancer patients with poor clinical status, as well as in healthy subjects."

2005 - A systematic review of 10 randomized controlled trials (J Pineal Res 2005):

"All trials included solid tumor cancers. All trials were conducted at the same hospital network, and were unblinded. Melatonin reduced the risk of death at 1 yr (relative risk: 0.66). Effects were consistent across melatonin dose, and type of cancer. No severe adverse events were reported. The substantial reduction in risk of death, low adverse events reported and low costs related to this intervention suggest great potential for melatonin in treating cancer."

Just be careful, though, as using high-dose melatonin long term could be a prescription for disaster. This is because doses of over 5 to 10 mg are likely to draw out heavy metals like mercury and unless you are on a good detoxification program and using sauna regularly these heavy metals could cause biological damage.

Related: What You Need to Know About Melatonin

Green Tea (EGCG)

PubMed has indexed more than 2,000 research studies on EGCG and cancer.

The Minnesota Green Tea Trial (MGTT. 2015) is the largest and longest double-blind, placebo-controlled, randomized intervention study that specifically evaluated the effects of oral GTE (green tea extract) containing defined quantities of EGCG on established biomarkers of breast cancer risk.

They randomized and stratified 1075 healthy postmenopausal women at high risk of breast cancer according to their breast tissue density and catechol-O-methyltransferase genotypes and divided them into two groups: 537 placebo and 538 green tea groups. Green tea group participants took 4 capsules that contained 843 mg EGCG, whereas the placebo group took capsules without green tea extracts.

Researchers measured changes in percent mammographic density, circulating endogenous sex hormones, and proteins of the insulin-like growth factor axis. Their results showed that supplementation with green tea extract could modify and reduce mammographic density (MD) and protect against breast cancer, even though it was only significant in younger women (50–55 years) and had no effect in older women (R), an age-dependent effect similar to those of tamoxifen.

According to a 2018 review, EGCG and green tea extracts may help prevent or delay cancer onset, cancer recurrence, and secondary growths from cancer.

However, the National Center for Complementary and Integrative Health (NCCIH) state that studies of green tea and cancer in humans have so far produced inconsistent results.

Several epidemiological studies (2011) have reported that the consumption of green tea may decrease cancer risk. Studies have also confirmed numerous health benefits of green tea including prevention of cancer (R, R) and cardiovascular disease, as well as anti-inflammatory, antioxidant, antiarthritic, antibacterial, and antiviral effects. (R, R, R, R).

Green tea also contains chemicals called polyphenols that have antioxidant, anti-inflammatory properties and anti-angiogenic properties, and the catechins in green tea polyphenols show very strong anti-angiogenic properties.

If you have cancer, consider drinking up to 3 cups of green tea per day to experience the benefits. Green tea pills are also available, but may be too concentrated.

Some studies show health benefits in people who drink as little as one cup per day, while other studies deem five or more cups per day to be optimal (Source, Source).

Zinc and Cancer

PubMed has indexed more than 20,000 research studies on zinc and cancer.

Given the important role of zinc in a wide range of enzymatic reactions and physiological processes, zinc deficiency has been identified in a variety of diseases, notably cancer. In recent years, multiple meta-analyses and reviews looking at zinc levels in individual cancer types have been published, as have a plethora of primary studies demonstrating a link between low zinc levels and specific types of cancer.

In a 2023 review, the authors summarize recent evidence implicating low zinc concentrations in serum or tissues as a characteristic in a wide range of cancers.

On the basis of the correlation between low zinc levels and poor cancer outcomes, many authors have speculated that zinc supplementation could be used to reduce the risk of developing cancer. A retrospective analysis published by Hosui et al. in 2018 reported that zinc supplementation appears to maintain liver function and decrease the risk of developing hepatocellular carcinoma. A more recent study by the same group found that oral zinc supplementation decreased the risk of hepatocellular carcinoma development in patients who received direct-acting antivirals to eradicate HCV [Hosui et al. 2021]. Valenzano et al. in 2021 also reported that in Barrett’s esophagus, administration of zinc gluconate resulted in the upregulation of several tumor-suppressive miRNAs and downregulation of inflammation-inducing proteins. Additionally, a 2022 mini-review by Iqbal et al. noted limited evidence for a correlation between high dietary intake of zinc and a reduced risk of breast cancer, suggesting that dietary supplementation could decrease the chance of developing this malignancy. These preliminary studies suggest that there could be potential for using zinc supplementation in the clinical setting to help prevent cancer development.

The extensive evidence demonstrating the prevalence of zinc deficiency in a wide range of cancer types suggests that zinc deficiency should be considered a relatively widespread feature of multiple cancers. While research regarding the potential clinical utility of testing zinc levels in patients with or at risk of developing cancer is still preliminary, the data suggest that zinc deficiency may be a potential biomarker for identifying patients at risk of developing cancer, predicting outcomes in patients with cancer, and even as a preventive or adjunctive treatment for cancer.

Quercetin and Cancer

PubMed has indexed more than 4,000 research studies on quercetin and cancer. The safety and potential usefulness of quercetin for the prevention and treatment of cancer have been documented in both animal experiments and a phase I clinical trial.

2022 - A paper published in August 2022 in Nutrition Research analyzed the pro-apoptotic effect that quercetin has on aging cells. The paper reviewed preclinical and early phase data using quercetin as a senolytic agent and found the data showed it was effective in “preventing or alleviating cancer formation.”

The authors reviewed the importance of cellular aging in the development of cancer cells and the effect that quercetin may have on the suppression of cancer cell proliferation.

Cellular senescence is a dynamic and multi-step process that is associated with alterations in metabolic activity and gene expression. This can compromise tissue regeneration and contribute to aging. On the other hand, by removing senescent cells, age-related dysfunction can be attenuated and potentially extend the lifespan.

According to Mount Sinai, quercetin should be used with caution as it may interact with certain antibiotics by reducing the effectiveness of the drug. It may also enhance the effect of some blood thinners, which can increase your risk of bleeding. In addition to these, it may interact with corticosteroids, digoxin, cyclosporine and fluoroquinolones.

Probiotics and Microbiome

Not only have gut bacteria been shown to influence gene expression (R, R), turning some genes on and others off, research (R) published in 2018 found gut microbes actually control antitumor immune responses in your liver, and that antibiotics can alter the composition of immune cells in your liver, triggering tumor growth.

Harvard Medical School researchers have identified the specific population of gut microbes that modulates both localized and systemic immune response to ward off viral invaders.

Certain gut bacteria also promote inflammation, which is an underlying factor in virtually all cancers, whereas other bacteria quell it. The presence of certain gut bacteria has even been shown to boost the patient's response to anticancer drugs. (Nature 2018)

One way in which gut bacteria improve the effectiveness of cancer treatment is by activating your immune system and allowing it to function more efficiently. Researchers have actually found that when these specific microbes are absent, certain anticancer drugs may not work at all.

Garlic (Allicin)

PubMed has indexed more than 1,200 research studies on garlic and cancer. Garlic and onions belong to the Allium genus of plants.

2023 - A randomized controlled trial (RCT) on garlic and gastric cancer (GC), published in January 2023, found a significant reduction in the risk of developing GC with increasing dietary intake of allium vegetables, particularly garlic vegetables. The study was conducted on the basis of the Shandong Intervention Trial, a randomized, placebo-controlled, factorial-designed trial (1995-2003) in a well-recognized high-risk area for GC in China. Participants were continuously followed up to December 2017 for 22.3 y (1995-2017). A total of 3,229 subjects were included.

2020 - A meta-analysis of 11 studies, published in January 2020, did find evidence that garlic could reduce the risk of ColoRectal Cancer.

Another study published in the Asia Pacific Journal of Clinical Oncology (2019) revealed the odds of getting ColoRectal Cancer were 79% lower in those who a diet high in allium vegetables, which include garlic, leeks and onions.

One study of 543,220 participants found that those who ate lots of Allium vegetables, such as garlic, onions, leeks and shallots, had a lower risk of stomach cancer than those who rarely consumed them (Source).

A study of 471 men showed that a higher intake of garlic was associated with a reduced risk of prostate cancer (Source).

Based on these findings, including 2–5 grams (approximately one clove) of fresh garlic into your diet per day can help you take advantage of its health-promoting properties.

Garlic is a great choice when it comes to giving your body a little extra protection. To reap the benefits of garlic, you should eat one clove per day, or 300 to 1,000 milligrams (mg)Trusted Source of garlic extract.

The active component in garlic is allicin, a compound that has been shown to kill off cancer cells in multiple test-tube studies (Source, Source, Source).

Several clinical studies have found an association between garlic intake and a lower risk of certain types of cancer.

Related: Garlic, the ‘King of Cancer Prevention’

5. Avoid tobacco and alcohol

Smoking and Tobacco

AACR Cancer Progress Report 2023

As depicted above, smoking is not only one of the risk factors but the no. 1 cancer risk factor. Avoid tobacco products altogether, including cigarettes, cigars, and smokeless tobacco (source).

Smoking has been linked to many types of cancer, including cancer of the lung, mouth, throat, voice box, pancreas, bladder, cervix and kidney. Even being around secondhand smoke might increase the risk of lung cancer.

But it's not only smoking that's harmful. Chewing tobacco has been linked to cancer of the mouth, throat and pancreas.

Staying away from tobacco — or deciding to stop using it — is an important way to help prevent cancer. For help quitting tobacco, ask a health care provider about stop-smoking products and other ways of quitting.

Alcohol

As shown in the image above, alcohol is ranked as the no. 3 risk factor.

Drink alcohol only in moderation, if at all. Alcohol increases the risk of various types of cancer, including cancer of the breast, colon, lung, kidney and liver. Drinking more increases the risk.

Best evidence: A 2021 umbrella review (Nature) of the literature concluded that Alcohol consumption is positively associated with risk of postmenopausal breast, colorectal, esophageal, head & neck and liver cancer.

6. Being Overweight or Obese Is Linked to Increased Cancer Risk

For those of you who do not use tobacco, one of the most important cancer risk factors that can be modified are body weight, diet, and physical activity. One-third of all cancer deaths in the United States each year are linked to diet and physical activity, including being overweight or obese, while another third is caused by tobacco products.

Next to cigarette smoke, excess body weight was the second main modifiable risk factor, contributing to 7.6 percent of potentially preventable cancers, followed by alcohol consumption at 5.4 percent, UV radiation exposure at 4.6 percent, and physical inactivity at 3.1 percent. (Journal of the American Cancer Society 2024)

Journal of the American Cancer Society 2024

Maintain a healthy weight is one of the recommendations according to both the WCRF/AICR (World Cancer Research Fund/American Institute for Cancer Research) recommendations (2018) and the American Cancer Society Guidelines on Diet and Physical Activity for Cancer Prevention (2020).

Obesity can increase cancer risk in three key ways:

Excess body fat can contribute to insulin resistance. As a result, your cells are unable to take up glucose properly, which encourages them to divide faster.
Obese people tend to have higher levels of inflammatory cytokines in their blood, which causes chronic inflammation and encourages cells to divide (Source).
Fat cells contribute to increased estrogen levels, which increases the risk of breast and ovarian cancer in postmenopausal women (Source).

The good news is that several studies have shown that weight loss among overweight and obese people is likely to reduce cancer risk (Source, Source, Source).

7. Be physically active

Physical activity counts too. Besides helping control weight, physical activity on its own might lower the risk of breast cancer and colon cancer.

Doing any amount of physical activity benefits health. But for the most benefit, strive for at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of hard aerobic activity.

You can combine moderate and hard activity. As a general goal, include at least 30 minutes of physical activity in your daily routine. More is better.

Studies Confirm Importance of Strength Training in Moderation

Best evidence: A systematic review and meta-analysis of 16 studies published in the British Journal of Sports Medicine in 2022.

Muscle-strengthening activities were associated with a 10% to 17% lower risk of cardiovascular disease (CVD), total cancer incidence, Type 2 diabetes and all-cause mortality. As in O’Keefe’s study, this review found a J-shaped association, with a maximum risk reduction of all-cause mortality, CVD and cancer (10 % to 20%) being observed at a dose of 30 to 60 minutes per week.

After 60 minutes, the benefits of strength training started to diminish, and above 140 minutes per week, it was associated with an increased risk of all-cause mortality.

Another 2022 systematic review published in the American Journal of Preventive Medicine (AJPM) found that:

“Compared with undertaking no resistance training, undertaking any amount of resistance training reduced the risk of all-cause mortality by 15% ... cardiovascular disease mortality by 19% ... and cancer mortality by 14% ...

A dose-response meta-analysis of 4 studies suggested a nonlinear relationship between resistance training and the risk of all-cause mortality. A maximum risk reduction of 27% was observed at around 60 minutes per week of resistance training ... Mortality risk reductions diminished at higher volumes.”

8. Sleep, Stress and Desk Job

Quality Sleep

Many studies, especially in the last 10 years, have evaluated the association between different types of cancer and different types of sleep disorders (Mogavero 2021). The majority of sleep disorders in patients with cancer are associated with activation of the inflammatory response (Mogavero 2021).

Circadian rhythm disorders seem to represent a risk factor for gastrointestinal and breast cancer, squamous cell carcinoma, thyroid and prostate cancer (albeit with dubious evidence), lymphomas and chronic myeloid leukemia, not for ovarian cancer. Insomnia represents a risk factor for a wide range of tumors, especially breast, nose, trachea, liver and oral cavity. (Mogavero 2021)

In a 2022 study, the detrimental associations of poor sleep with all-cause and cause-specific mortality risks are exacerbated by low PA (physical activity), suggesting likely synergistic effects. The study supports the need to target both behaviours in research and clinical practice.

A 2023 study indicated that insomnia and nap during the day may be risk factors of PLC (primary liver cancer) and adequate night sleep might keep us away from PLC (primary liver cancer).

A 2021 study, concluded that both unfavorable sleep duration and evening chronotype were associated with increased lung cancer incidence, especially for those with low to moderate genetic risk. These results indicate that sleep behaviors as modifiable risk factors may have potential implications for lung cancer risk.

Another similar study, the authors concluded that they have found robust evidence for effect of sleeplessness on lung cancer risk.

Stress reduction

High stress might be one of the most overlooked factors, especially concerning the long-term impact of being exposed to a stressful job environment.

However, it’s important to understand the role of stress on cancer progression. Scientists know that psychological stress can affect the immune system, the body’s defense against infection and disease (including cancer).

The body responds to stress by releasing stress hormones, such as epinephrine (also called adrenaline) and cortisol (also called hydrocortisone). The body produces these stress hormones to help a person react to a situation with more speed and strength. Stress hormones increase blood pressure, heart rate, and blood sugar levels. Small amounts of stress are believed to be beneficial, but chronic (persisting or progressing over a long period of time) high levels of stress are thought to be harmful.

Stress that is chronic can increase the risk of obesity, heart disease, depression, and various other illnesses. Stress also can lead to unhealthy behaviors, such as overeating, smoking, or abusing drugs or alcohol, that may affect cancer risk.

Some studies have indicated an indirect relationship between stress and certain types of virus-related growths. Evidence from both animal and human studies suggests that chronic stress weakens a person’s immune system, which in turn may affect the incidence of virus-associated cancers, such as Kaposi sarcoma and some lymphomas.

It is difficult to separate stress from other physical or emotional factors when examining cancer risk. For example, certain behaviors, such as smoking and using alcohol, and biological factors, such as growing older, becoming overweight, and having a family history of cancer, are common risk factors for cancer.

Studies have shown that stress might promote cancer indirectly by weakening the immune system's anti-tumor defense or by encouraging new tumor-feeding blood vessels to form. But a study published in The Journal of Clinical Investigation shows that stress hormones, such as adrenaline, can directly support tumor growth and spread.

Desk Job

One of the most important aspects of lifestyle is your job. If you're among the 86% of American workers who work at a desk all day, your job may have an adverse effect on your health.

Studies have found that those who sat for more than 8 hours a day with no physical activity had a risk of dying similar to the risk posed by obesity and smoking.

A 2009 study found that people who had increased sitting times had higher rates of cancer and overall mortality, even when they got some daily exercise.

The American Cancer Society has also found a link between long periods of inactivity and cancer. The group says that people who spend "prolonged leisure time sitting" — defined as more than 6 hours per day — have a 19% higher rate of death compared to people who sit an average of 3 hours per day. That number includes all causes of death, but it doesn't necessarily mean that sitting directly causes cancer or other diseases, since sick people are also likely to move around less.

9. Fasting, Keto Diet and Cancer

Fasting may help reduce obesity-associated cancers. “There’s a lot of obesity-associated cancers,” said Dr. Jason Fung, a nephrologist and fasting expert. “There’s about 13 cancers that are well accepted that they are associated with obesity; fasting might help decrease that.”

Fasting can potentially starve cancer cells. When fasting, the body uses fats and produces ketones for energy. Cancer cells rely heavily on glucose, making them less efficient at using ketones.

Additionally, fasting reduces insulin levels. Elevated insulin levels are linked to an increased risk of breast, prostate, and colorectal cancers.

Intermittent fasting may protect against liver inflammation and even liver cancer, a 2024 study has found. The study, conducted at the German Cancer Research Center and the University of Tübingen and published in the journal Cell Metabolism, aimed to understand more about how intermittent fasting can affect the liver. The researchers found that intermittent fasting can halt the progression of non-alcoholic fatty liver disease (NAFLD), a precursor to chronic liver inflammation and liver cancer.

Although the study is promising, the researchers acknowledge that because the study was conducted on mice, there is no way to know definitively whether the intermittent fasting regimen would produce the same results in humans.

Intermittent fasting refers to periods of restricted calorie intake or complete food avoidance. Like the Ketogenic diet, fasting triggers the use of ketones as the predominant energy source and may sensitize cancer cells to treatments and potentially slow down tumor growth. Fasting-induced metabolic changes may also favor the protection of normal tissues from therapy side effects and improve tolerance and quality of life impacts to care.

Additionally, fasting reduces insulin levels. Eating continuously can contribute to hyperinsulinemia. Elevated insulin levels are linked to an increased risk (2022) of breast, prostate, and colorectal cancers.

It is important to remember that intermittent fasting is not the best dietary choice for everyone and can even have dangerous consequences for people with certain health conditions.

The ketogenic diet is a low-carbohydrate, high-fat, and protein diet that forces the body to rely on ketones instead of glucose as a predominant energy source. It has shown potential in preclinical and early clinical studies for brain cancer treatment. By altering the metabolism of cancer cells, the ketogenic diet may inhibit tumor growth and enhance the effectiveness of other therapies.

10. People With Cancer: The Right Diet Can Have Beneficial Effects

After a cancer diagnosis, follow these recommendations if you can, according to the WCRF/AICR (World Cancer Research Fund/American Institute for Cancer Research).

Malnutrition and muscle loss are common in people with cancer and have a negative impact on health and survival (Source).

While no diet has been proven to cure cancer, proper nutrition is vital to complement traditional cancer treatments, aid in recovery, minimize unpleasant symptoms and improve quality of life.

Most people with cancer are urged to stick to a healthy, balanced diet that includes plenty of lean protein, healthy fats, fruits, vegetables and whole grains, as well as one that limits sugar, caffeine, salt, processed foods and alcohol.

A diet sufficient in high-quality protein and calories may help reduce muscle atrophy (Trusted Source).

Good protein sources include lean meat, chicken, fish, eggs, beans, nuts, seeds and dairy products.

Side effects of cancer and its treatment can sometimes make it difficult to eat. These include nausea, sickness, taste changes, loss of appetite, trouble swallowing, diarrhea and constipation.

If you experience any of these symptoms, it’s important to speak to a registered dietitian or other health professional who can recommend how to manage these symptoms and ensure optimal nutrition.

Additionally, those with cancer should avoid supplementing too heavily with vitamins, as they act as antioxidants and can interfere with chemotherapy when taken in large doses.

A Ketogenic Diet Shows Some Promise for Treating Cancer, but Evidence Is Weak

Animal studies and early research in humans suggest that a low-carb, high-fat ketogenic diet may help prevent and treat cancer.

High blood sugar and elevated insulin levels are risk factors for cancer development.

A ketogenic diet lowers blood sugar and insulin levels, potentially causing cancer cells to starve or grow at a slower rate (Trusted Source, Trusted Source, Trusted Source).

In fact, research has shown that a ketogenic diet can reduce tumor growth and improve survival rates in both animal and test-tube studies (Trusted Source, Trusted Source, Trusted Source, Trusted Source).

Several pilot and case studies in people have also indicated some benefits of a ketogenic diet, including no serious adverse side effects and, in some cases, improved quality of life (Trusted Source, Trusted Source, Trusted Source, Trusted Source).

There seems to be a trend in improved cancer outcomes as well.

For example, one 14-day study in 27 people with cancer compared the effects of a glucose-based diet to those of a fat-based ketogenic diet.

Tumor growth increased by 32% in people on the glucose-based diet but decreased by 24% in those on the ketogenic diet. However, the evidence is not strong enough to prove correlation (Trusted Source).

A recent review looking at the role of a ketogenic diet for managing brain tumors concluded that it could be effective in enhancing the effects of other treatments, such as chemotherapy and radiation (Trusted Source).

Yet no clinical studies currently show definitive advantages of a ketogenic diet in people with cancer.

It’s important to note that a ketogenic diet should never replace treatment advised by medical professionals.

If you decide to try a ketogenic diet alongside other treatment, be sure to speak to your doctor or a registered dietitian, as veering from strict dietary rules can lead to malnutrition and negatively influence health outcomes (Trusted Source).

Key Takeaways

The best way to prevent cancer is to utilise a menu of strategies by maintaining good health, like from eating a nutritious whole-food diet with lots of fruits and vegetables, avoid ultra processed foods and a healthy lifestyle.

Everyone’s situation is different, however, it is important to arm yourself with medical knowledge that cancer doctors (Oncologists) may simply not give you.

While supplements can be beneficial, they should complement, not replace, these fundamental preventive strategies. Taking supplements as a stand alone strategy cannot replace an unhealthy lifestyle i.e. heavy smoker, alcoholic, a very stressful and non-active lifestyle, overweight and obesity.

While there’s no silver bullet supplement, there are some anti-cancer supplements on the market that may help you keep the disease at bay or stop it from getting worse. Whether you’re living with cancer, a survivor, or just concerned for your health, talk to your doctor to determine the best treatment for you.

This article is part of the diet and cancer series. Other cancer related articles:

Top 10 Repurposed Drugs and Metabolic Interventions for Cancer Treatment: Evidence Based (2024)

Expert Explains Cancer May Be Metabolic Disease, and Shares a Cure

Gendicine, The First Approved p53 Gene Therapy Product for Cancer: 20 Years Track Record

Eat These Foods to Starve Cancer Cells to Death

Fighting Cancer with Food and Nutrition

Ivermectin for Colorectal Cancer?

How Vegetable Oil and Linoleic Acid Wrecks Your Health

Colon Cancer: New Study Shows Dietary Changes Can Shrink Tumors

For more information on treatment, causes and prevention, screening, and the latest research, check out this comprehensive resource page (by cancer type) from National Cancer Institute: https://www.cancer.gov/types.