Causes of Cancer and Best Natural Ways to Reduce your Risk of getting Cancer? 1,000+ Studies Analyzed

Causes of Cancer and Best Natural Ways to Reduce your Risk of getting Cancer? 1,000+ Studies Analyzed - Part 2

By Dr. Frank Yap, MD - September 16, 2024

Can diet and lifestyle influence cancer risk? Dive into 1,000+ research studies to find out.

Most of us know Steve Jobs, Chadwick Boseman (Black Panther), Robin Gibb (Bee Gees), Donna Summer, Farrah Fawcett, Eartha Kitt, Peter Jennings, Paul Newman, Patrick Swayze, Sydney Pollack, Michael Crichton, Bob Denver, Ted Kennedy, Jerry Orbach, Anne Bancroft, William Rehnquist, and Tony Snow, just to name a few. What do they have in common? They all died from 'cancer'.

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.

Note: This is part 2 in Unveiling the Science Behind Cancer, Diet and Supplements series. Check out part 1: Top 10 Cancer Fighting Supplements? 1,000+ Studies Analyzed (2024)

That's where this article comes in. We've delved into the research to provide you with more than just basic advice. We've done the research, so that you don't have to. We'll not only share supporting evidence, but also explain our methodology for selecting the most valuable information.

Prevention holds greater value than both cure and early detection. Nonetheless, the incentive for profit often leans away from investing in preventive measures. This tendency is reflected in the limited coverage of preventative strategies within mainstream media channels.

The quest for cancer prevention and treatment has been shrouded in ambiguity when it comes to the world of dietary supplements. The bewildering array of options leaves us questioning their efficacy, for without robust scientific evidence, their true potential remains enigmatic.

Can foods and diet really influence your risk of getting cancer? What types of foods reduce your risk and types that might increase your risk? What about vitamin and mineral supplements? Can supplements reduce your cancer risk or do they actually increase your cancer risk? We have answers to all of these questions and more.

This article here is developed as a consumer guide and is not meant to share the various technical theories related to cancer but to share practical preventive strategies that we could put into action immediately.

The goal of this article is to summarize the relevant, updated and practical points so that you could have your personal blue-print to prevent and how to give yourself the best possible outcome if you get cancer. We have filtered out all those unproven ‘internet noise’ out there in the virtual world and have summarized the overwhelming information out there into the following list of ‘actionable’ strategies.

AACR Cancer Progress Report 2023

Safety considerations for nutrition, supplements and cancer
Fasting and Cancer
Achieve and maintain a healthy weight throughout life
Stay away from Carcinogens, environmental toxins and infections that contribute to cancer
Reduce Stress
Sleep Quality
Avoid risky behaviors
Avoid unnecessary exposure to radiation.
Key Takeaways

What is Cancer?

Cancer is the name given to a collection of related diseases. In all types of cancer, some of the body’s cells begin to divide without stopping and spread into surrounding tissues. (National Cancer Institute)

Genetic changes that cause cancer can be inherited from our parents. They can also arise during a person’s lifetime as a result of errors that occur as cells divide or because of damage to DNA caused by certain environmental exposures. Cancer-causing environmental exposures include substances, such as the chemicals in tobacco smoke, and radiation, such as ultraviolet rays from the sun. As shown from the image below, environmental factors contribute up to 95% of cancers.

There are many types of cancer treatment. The types of treatment that you receive will depend on the type of cancer you have and how advanced it is. Surgery, radiation, and chemotherapy are the standard types of treatment for cancer. While your cancer specialist is focusing on staging your disease, the type of surgery, radiotherapy or chemotherapy, many people tend to lose focus on their nutrition. There is also a lot of confusion due to the overwhelming mixing of credible scientific information and marketing hypes available on the internet.

There are also many phoney “cancer treatment” with amazing claims but devoid of any scientific data to back them up, typical of health scams. Cancer is a life threatening disease and therefore many consumers fell prey to these phoney cancer treatments.

Causes of Cancer

Cancer is daunting in the breadth and scope of its diversity, spanning genetics, cell and tissue biology, pathology, and response to therapy. Ever more powerful experimental and computational tools and technologies are providing an avalanche of “big data” about the myriad manifestations of the diseases that cancer encompasses.

The integrative concept embodied in the hallmarks of cancer (Cancer Discov 2022) is helping to distill this complexity into an increasingly logical science, and the provisional new dimensions presented in this perspective may add value to that endeavor, to more fully understand mechanisms of cancer development and malignant progression, and apply that knowledge to cancer medicine.

The Hallmarks of Cancer were proposed as a set of functional capabilities acquired by human cells as they make their way from normalcy to cancer states.

Biological Changes and Acquired Capabilities (Cell 2000):

sustaining proliferative signaling,
evading growth suppressors,
resisting cell death,
enabling replicative immortality,
inducing angiogenesis, and
activating invasion and metastasis.

Emerging Hallmarks (Cell 2011):

deregulating cellular energetics
avoiding immune destruction

Enabling characteristics (Cell 2011)::

Genome instability and mutation
Tumor promoting inflammation

Four new hallmarks (Cancer Discov 2022):

unlocking phenotypic plasticity,
non-mutational epigenetic reprogramming,
polymorphic microbiomes
senescent cells.

Cancer and Nutrition

When you’re healthy, eating enough food to get the nutrients and calories you need is not usually a problem. Most nutrition guidelines stress eating lots of vegetables, fruits, and whole-grain products; limiting the amount of red meat you eat, especially meats that are processed or high in fat; cutting back on fat, sugar, alcohol, and salt; and staying at a healthy weight. But when you’re being treated for cancer, these things can be hard to do, especially if you have side effects or just don’t feel well.

Good nutrition is especially important if you have cancer because both the illness and its treatments can change the way you eat. They can also affect the way your body tolerates certain foods and uses nutrients.

During cancer treatment you might need to change your diet to help build up your strength and withstand the effects of the cancer and its treatment. This may mean eating things that aren’t normally recommended when you are in good health. For instance, you might need high-fat, high-calorie foods to keep up your weight, or thick, cool foods like ice cream or milk shakes because sores in your mouth and throat are making it hard to eat anything. The type of cancer, your treatment, and any side effects you have must be considered when trying to figure out the best ways to get the nutrition your body needs.

Therefore, nutrition is not an option or a desire but rather a basic necessity. That makes it all the more important reason to make nutrition as part of your overall strategy to fight the cancer battle. Do not give up. Many people with cancer have been cured or survived longer than those without cancer.

The following are the essential things you should know about nutrition and cancer.

Diet and Cancer Prevention

Please remember that reducing your risk of getting cancer doesn’t simply depend on a single stand alone strategy or nutrient or supplement. Even if you zealously practise a healthy lifestyle and consume various supplements, you can still fall victim to this disease if you fail to address your other risk factors.

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.

Another 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 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.

**All-cause mortality: "Death from anything" may be a clearer term for the layperson as opposed to 'All-cause mortality'. This is one of the best measures for the factors that increase the risk of what eventually and most likely will take someone's life.

Carbohydrates (Macronutrient)

Carbohydrates are the body’s major source of energy. Carbohydrates give the body the fuel it needs for physical activity and proper organ function. The best sources of carbohydrates – fruits, vegetables and whole grains – also supply needed vitamins and minerals, fiber and phytonutrients to the body’s cells. (Phytonutrients are chemicals in plant-based foods that we don’t need to live, but that might promote health.)

Whole grains or foods made from them contain all the essential parts and naturally occurring nutrients of the entire grain seed. Whole grains are found in cereals, breads, flours, and crackers. Some whole grains, such as quinoa, brown rice, or barley, can be used as side dishes or part of an entree.

Fiber is the part of plant foods that the body cannot digest. There are 2 types of fiber. Insoluble fiber helps to move food waste out of the body quickly, and soluble fiber binds with water in the stool to help keep stool soft.

Other sources of carbohydrates include bread, potatoes, rice, spaghetti, pasta, cereals, corn, peas, and beans. Sweets (desserts, candy, and drinks with sugar) can supply carbohydrates, but provide very little in the way of vitamins, minerals, or phytonutrients.

As mentioned above, the BMJ 2024 umbrella review 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 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.

This harmful "ultra-processed" food, as the researchers called it, may include packaged sweet pastries and muffins, chips, candy, sodas, frozen dinners like meatballs and fish sticks, instant ramen noodles, sugary cereals, and pretty much anything else you can imagine that's cheap and comes in a ready-to-go packet or container at the store.

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

Fats (Macronutrient)

Fats play an important role in nutrition. Fats and oils are made of fatty acids and serve as a rich source of energy for the body. The body breaks down fats and uses them to store energy, insulate body tissues, and transport some types of vitamins through the blood.

You may have heard that some fats are better for you than others. Choose monounsaturated and polyunsaturated fats more often than saturated fats or trans fats.

Monounsaturated fats are found mainly in vegetable oils like olive, canola, and peanut oils. Polyunsaturated fats are found mainly in vegetable oils like safflower, sunflower, corn, and flaxseed. They are also the main fats found in seafood.

Saturated fats are mainly found in animal sources like meat and poultry, whole or reduced-fat milk, cheese, and butter. Some vegetable oils like coconut, palm kernel oil, and palm oil are saturated. Trans-fatty acids are formed when vegetable oils are processed into margarine or shortening. Sources of trans fats include snack foods and baked goods made with partially hydrogenated vegetable oil or vegetable shortening. Trans fats also are found naturally in some animal products, like dairy products. Trans fats can raise bad cholesterol and lower good cholesterol; try to eliminate them from your diet.

Researchers estimated that during the heyday of trans fats in the 1990s, they led to roughly 50,000 preventable deaths every year in the US. The US FDA rolled out a near-universal ban on trans fats in June 2015.

Proteins (Macronutrient)

We need protein for growth, to repair body tissue, and to keep our immune systems healthy. When your body doesn’t get enough protein, it might break down muscle for the fuel it needs. This makes it take longer to recover from illness and can lower resistance to infection. People with cancer often need more protein than usual. After surgery, chemotherapy, or radiation therapy, extra protein is usually needed to heal tissues and help fight infection.

Muscle mass optimizes you for longevity, and dietary protein, especially animal-based protein, is essential for muscle maintenance and muscle building. The greater your muscle mass, the higher your survivability against all diseases, including cancer. Cachexia, for example — the loss of muscle mass — accounts for 20% of all cancer deaths. (source)

One of the reasons for this is because muscle acts as a reservoir for amino acids, which are crucial during illness when your body’s demand for them increases.

Good sources of protein include fish, poultry, lean red meat, eggs, low-fat dairy products, nuts and nut butters, dried beans, peas and lentils, and soy foods.

Water

Water and liquids or fluids are vital to health. All body cells need water to function. If you do not take in enough fluids or if you lose fluids through vomiting or diarrhea, you can become dehydrated (your body doesn’t have as much fluid as it should). If this happens, the fluids and minerals that help keep your body working can become dangerously out of balance. You do get some water from the foods you eat, but a person should drink about eight 8-ounce glasses of liquid each day to be sure that all the body cells get the fluid they need. You may need extra fluids if you are vomiting or have diarrhea. Keep in mind that all liquids (soups, milk, even ice cream and gelatin) count toward your fluid goals.

Ashton Kutcher tried Steve Jobs’ all-fruit diet — and it didn’t go well

When Ashton Kutcher portrayed Steve Jobs in the 2013 movie “Jobs,” he intensely studied and implemented the Apple co-founder’s behaviors, including his unusual eating habits.

Kutcher opened up about how adopting Jobs’ idiosyncratic diet impacted his own health on an episode of the YouTube show “Hot Ones,” in September 2019.

It was “the craziest thing,” Kutcher said.

Famously, Jobs experimented on and off with a “fruitarian” diet, which is a strict vegetarian diet that emphasizes eating mostly fruit, as well as some nuts, seeds and grains. Jobs also would fast for periods of time, sometimes weeks or days, and he stuck to these eating patterns even while his health began to decline, according to Walter Isaacson’s biography, “Steve Jobs.”

Kutcher said Jobs was interested in the “healing properties” of fruit, and according to Isaacson’s book, the Apple co-founder was turned on to the fruit diet in college after reading the book “Mucusless Diet Healing System” by Arnold Ehret.

Sometimes, Jobs would stick to eating a few specific fruits at a time, such as apples and carrots, according to Isaacson’s book. Kutcher heard that Jobs drank a lot of Odwalla carrot juice, specifically, even to the point where his skin developed an orange hue. And Isaacson writes that Jobs stocked the Macintosh offices with Odwalla organic orange and carrot juices. (Odwalla did not respond to CNBC Make It’s request for comment.)

“So, I started just drinking carrot juice nonstop all day long,” Kutcher told “Hot Ones.”

Then one night, Kutcher felt a shooting pain in his back, and had to go to the hospital. He says he was diagnosed with pancreatitis, which is inflammation of the pancreas, and put on a pain killer medication.

“My pancreas was like crazy out of whack,” Kutcher said. (The pancreas is a gland that’s responsible for controlling blood glucose levels, plus releasing insulin and other enzymes that help with the digestion of food.)

“Then I’m getting freaked out like, ‘Oh my god I’ve become Steve Jobs.’” (Jobs died of pancreatic cancer in 2011, but eating excessive amounts of fruit does not cause pancreatic cancer.)

While fruit contains vitamins, nutrients and antioxidants that are beneficial for your health, experts warn against such restrictive diets — a diet of only fruit can put individuals at risk for nutrient deficiencies, such as essential fatty acids, as well as vitamin and minerals, Jeannine B. Mills, board-certified dietitian in oncology nutrition and member of the scientific and medical advisory board for the Pancreatic Cancer Action Network, tells CNBC Make It. This can lead to an array of health consequences, she adds. And an “overabundance of certain micronutrients from a concentrated intake of a select few foods” can lead to toxicity, she says.

It’s unclear why Kutcher got pancreatitis, and other important lifestyle factors beyond diet that can impact a person’s health, such as medications and underlying health conditions, Mills says. She advises against going on any sort of self-imposed diet without first discussing it with your doctor and a registered dietitian.

While it’s been years since Jobs died, and the biopic premiered, fruitarianism has maintained its popularity among people in the vegan community.

But Kutcher has some advice from his experience: “Don’t drink too much carrot juice,” Kutcher said. “That’s the moral of the story.”

Quit smoking

Cigarette smoking topped the charts as the leading risk factor, contributing to nearly 20 percent of all cancer cases and close to 30 percent of cancer deaths. Smoking comprised 56 percent of potentially preventable cancers in men and almost 40 percent of those in women. (Journal of the American Cancer Society 2024)

Journal of the American Cancer Society 2024

If you are a non smoker, then your risk of cancer will be reduced. Smoking is by far the leading risk factor for lung cancer. In the early 20th century, lung cancer was much less common than some other types of cancer. But this has changed once manufactured cigarette became readily available and more people began smoking.

Avoid tobacco products altogether, including cigarettes, cigars, and smokeless tobacco. About 80% of lung cancer deaths are thought to result from smoking. The risk for lung cancer among smokers is many times higher than among non-smokers. The longer you smoke and the more packs a day you smoke, the greater your risk.

On top of that, you should also try to cut down on your visits to places where people tend to smoke e.g. pubs etc. Passive smoking is just as bad.

Body Weight and Physical Activity

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)

Although our genes influence our risk of cancer, most of the difference in cancer risk between people is due to factors that are not inherited. Avoiding tobacco products, staying at a healthy weight, staying active throughout life, and eating a healthy diet may greatly reduce a person's lifetime risk of developing or dying from cancer. These same behaviors are also linked with a lower risk of developing heart disease and diabetes.

Many consumers are also unaware that grilling some popular food items can produce cancer-causing compounds called heterocyclic amines (HCAs). For more information on foods that contain the highest concentrations of HCAs: http://www.cancerproject.org/media/news/fiveworstfoodsreport.php. HCAs, a family of mutagenic and cancer-causing compounds, are produced during the cooking of many animal products, including chicken, beef, pork, and fish. In January of 2005, the federal government officially added HCAs to its list of known carcinogens.

These are the summary recommendations from the ACS Guidelines on Diet and Physical Activity for Cancer Prevention (2020):

Achieve and maintain a healthy weight throughout life.

Keep your weight within the healthy range, and avoid weight gain in adult life.

Follow a healthy eating pattern at all ages.

A healthy eating pattern includes:

Foods that are high in nutrients in amounts that help you get to and stay at a healthy body weight
A variety of vegetables – dark green, red and orange, fiber-rich legumes (beans and peas), and others
Fruits, especially whole fruits in a variety of colors
Whole grains

A healthy eating pattern limits or does not include:

Red and processed meats
Sugar-sweetened beverages
Highly processed foods and refined grain products

Be physically active.

Adults: Get 150-300 minutes of moderate intensity or 75-150 minutes of vigorous intensity activity each week (or a combination of these). Getting to or exceeding the upper limit of 300 minutes is ideal.
Children and teens: Get at least 1 hour of moderate or vigorous intensity activity each day.
Limit sedentary behavior such as sitting, lying down, watching TV, and other forms of screen-based entertainment.

It is best not to drink alcohol.

People who do choose to drink alcohol should have no more than 1 drink per day for women or 2 drinks per day for men.

In a 2020 review published in BMJ, key messages were:

Obesity and alcohol increase the risk of several types of cancer; these are the most important nutritional factors contributing to the total burden of cancer worldwide
For colorectal cancer, processed meat increases risk and red meat probably increases risk; dietary fibre, dairy products, and calcium probably reduce risk
Foods containing mutagens can cause cancer; certain types of salted fish cause nasopharyngeal cancer, and foods contaminated with aflatoxin cause liver cancer
Fruits and vegetables are not clearly linked to cancer risk, although very low intakes might increase the risk for aerodigestive (airway and digestive tracts) and some other cancers.

The Mediterranean-DASH diet

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

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.

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.

Olive Oil

Olive oil is loaded with health benefits, so it’s no wonder it’s one of the staples of the Mediterranean diet. There are more than 1,200 search results on olive oil and cancer on PubMed.

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.

Studies Confirm Importance of Strength Training in Moderation

Among them is 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.”

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.

Weight Loss: Achieve and maintain a healthy weight throughout life

Being at a healthy weight might lower the risk of some types of cancer. These include cancer of the breast, prostate, lung, colon and kidney.

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.

The American Cancer Society released guidelines in 2020 for reducing the risk of cancer.

The recommendations include the latest research on diet and physical activity, as well as policy and systems changes that reduce barriers to healthy living. The update focuses on increasing physical activity and developing healthy eating patterns at every age.

Avoid excess weight gain at all ages. For those who are overweight or obese, losing even a small amount of weight has health benefits and is a good place to start.

Get regular physical activity and limit intake of high-calorie foods and drinks as keys to help maintain a healthy weight.

Adults: Get at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity activity each week (or a combination of these), preferably spread throughout the week.

Children and teens: Get at least 1 hour of moderate or vigorous intensity activity each day, with vigorous activity on at least 3 days each week.

Limit sedentary behavior such as sitting, lying down, watching TV, and other forms of screen-based entertainment.

Fasting 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. Eating continuously can contribute to hyperinsulinemia.

That said, not every type of fasting is effective and safe. Intermittent fasting is the preferred option. Extended or extreme fasting can be counter-productive.

Related: Fasting as an Effective Anti-Cancer Strategy: Inspiring Success Stories

Alcohol and Cancer

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.

Best Cancer Fighting Foods

What are the most powerful cancer fighting foods? No single food can protect you against cancer by itself.

But research (American Institute of Cancer Research) shows that a diet filled with a variety of vegetables, fruits, whole grains, beans and other plant foods helps lower risk for many cancers. In laboratory studies, many individual minerals, vitamins and phytochemicals demonstrate anti-cancer effects. By including more foods that fight cancer into your diet, you will help reduce your risk of developing cancer.

The development of cancer, in particular, has been shown to be heavily influenced by your diet. The term “superfood” is a fairly new term referring to foods that offer maximum nutritional benefits for minimal calories.

Do take note that we are talking about foods to prevent your risk of cancer and not about treating cancer with foods. Cancer treatments will be something that you will need to discuss with your cancer specialist.

Many foods contain beneficial compounds that could help decrease the growth of cancer. There are also several studies showing that a higher intake of certain foods could be associated with a lower risk of the disease.

Some doctors and media channels argue that there is very little evidence to support the use of foods to prevent cancer.

We will delve into the research and look at a list of foods that may lower your risk of cancer.

1. Vegetables (Tomato, Broccoli, Carrot)

Observational studies have linked a higher consumption of vegetables with a lower risk of cancer (Trusted Source, Trusted Source, Trusted Source). 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 (Trusted Source, Trusted Source, Trusted Source, Trusted 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).

Another 2015 analysis looked at the results of five studies and concluded that eating carrots may reduce the risk of stomach cancer by up to 26% (Source).

Try incorporating carrots into your diet as a healthy snack or delicious side dish just a few times per week to increase your intake and potentially reduce your risk of cancer.

Carrot is also listed in the EWG's Clean 15. These 15 items had the lowest amounts of pesticide residues, according to EWG’s analysis of the most recent USDA data.

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.

2. Olive Oil

Olive oil is loaded with health benefits, so it’s no wonder it’s one of the staples of the Mediterranean diet. There are more than 1,200 search results on olive oil and cancer on PubMed.

Best Evidence: 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.

Swapping out other oils in your diet for olive oil is a simple way to take advantage of its health benefits. You can drizzle it over salads and cooked vegetables, or try using it in your marinades for meat, fish or poultry.

Though these studies show that there may be an association between olive oil intake and cancer, there are likely other factors involved as well. More human studies are needed to look at the direct effects of olive oil on cancer in people.

3. Dietary Fibers

Best evidence: A 2023 umbrella review (more than 100 studies analysed) 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.

4. Citrus Fruits

Eating citrus fruits such as lemons, limes, grapefruits and oranges has also been associated with a lower risk of cancer in some studies. There are more than 18,000 research studies on fruits and cancer.

One large study found that participants who ate a higher amount of citrus fruits had a lower risk of developing cancers of the digestive and upper respiratory tracts (Source).

A review looking at nine studies also found that a greater intake of citrus fruits was linked to a reduced risk of pancreatic cancer (Source).

Finally, another review of 14 studies showed that a high intake, or at least three servings per week, of citrus fruit reduced the risk of stomach cancer by 28% (Source).

These studies suggest that including a few servings of citrus fruits in your diet each week may lower your risk of developing certain types of cancer.

Keep in mind that these studies don’t account for other factors that may be involved. More studies are needed on how citrus fruits specifically affect cancer development.

5. 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)

6. Dairy products, milk, calcium and wholegrains

Best evidence: 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. Overall, 860 meta-analytic comparisons were included.

7. 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.

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.

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.

8. Berries

Berries are high in anthocyanins, plant pigments that have antioxidant properties and may be associated with a reduced risk of cancer.

There are more than 17,000 search results on berries and cancer on PubMed. Do take note that most of the research studies are pre-clinical, lab, animal and non-human studies.

In one human study, 25 people with colorectal cancer were treated with bilberry extract for seven days, which was found to reduce the growth of cancer cells by 7% (Source).

Another small study gave freeze-dried black raspberries to patients with oral cancer and showed that it decreased levels of certain markers associated with cancer progression (Source).

One animal study found that giving rats freeze-dried black raspberries reduced esophageal tumor incidence by up to 54% and decreased the number of tumors by up to 62% (Source).

Similarly, another animal study showed that giving rats a berry extract was found to inhibit several biomarkers of cancer (Source).

Based on these findings, including a serving or two of berries in your diet each day may help inhibit the development of cancer. Keep in mind that these are animal and observational studies looking at the effects of a concentrated dose of berry extract, and more human research is needed.

That said, strawberries have remained in the No. 1 slot for several years in EWG's Dirty Dozen List 2023. Blueberries is one of the newcomers on the Dirty Dozen list for 2023.

The Shopper’s Guide represents EWG’s analysis of the latest fruit and vegetable testing data from the Department of Agriculture and Food and Drug Administration. The 2023 shopper’s guide includes data from 46,569 samples of 46 fruits and vegetables, revealing the presence of 251 different pesticides in total, including some that have already been banned due to their potential health effects.

9. Beans

Beans are high in fiber, which some studies have found may help protect against colorectal cancer (Source, Source, Source).

One study followed 1,905 people with a history of colorectal tumors, and found that those who consumed more cooked, dried beans tended to have a decreased risk of tumor recurrence (Source).

According to these results, eating a few servings of beans each week may increase your fiber intake and help lower the risk of developing cancer.

Reduce Stress

While eliminating stress entirely might be unrealistic, understanding its impact on cancer progression is crucial. Chronic stress weakens our immune system, the body's natural defense against illness, including cancer.

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

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 (2010) shows that stress hormones, such as adrenaline, can directly support tumor growth and spread.

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.

Avoid risky behaviors

Another effective cancer prevention tactic is to avoid risky behaviors that can lead to infections that, in turn, might increase the risk of cancer. For example:

Practice safe sex. Limit the number of sexual partners and use a condom. The greater the number of sexual partners in a lifetime, the greater the chances of getting a sexually transmitted infection, such as HIV or HPV.

People who have HIV or AIDS have a higher risk of cancer of the anus, liver and lung. HPV is most often associated with cervical cancer, but it might also increase the risk of cancer of the anus, penis, throat, vulva and vagina.
Don't share needles. Injecting drugs with shared needles can lead to HIV, as well as hepatitis B and hepatitis C — which can increase the risk of liver cancer. If you're concerned about drug misuse or addiction, seek professional help.

Avoid exposure to environmental toxins, carcinogens and infections that contribute to cancer

Many people worry that substances or exposures in their environment may cause cancer. As part of the American Cancer Society's role in informing and educating people about cancer and its possible causes, this document provides lists of substances and exposures that are known or suspected to cause cancer. The lists below have been developed by two highly respected agencies – the International Agency for Research on Cancer (IARC) and the US National Toxicology Program (NTP). Some related information is included on how these and other agencies and groups test and classify possible carcinogens. Read more here: List of Human Carcinogens

Heavy exposure at work to certain pesticides, dyes, and chemicals may increase the risk of getting cancer of the pancreas. Steve Jobs passed away due to pancreatic cancer. Though this may not be directly related to his pancreatic cancer, Steve confirmed his drug use (marijuana and LSD) during college days. Read more here: FBI-reports-Steve-Jobs-did-LSD. Many researchers agree that marijuana smoke contains known carcinogens, or chemicals that can cause cancer much like those in tobacco smoke. Read more here: marijuana and cancer.

Avoid exposure to industrial and environmental toxins such as asbestos fibers, benzene, aromatic amines, and polychlorinated biphenyls (PCBs). (Harvard Health)

Avoid infections that contribute to cancer, including hepatitis viruses, HIV, and the human papillomavirus. Many are transmitted sexually or through contaminated needles. (Harvard Health)

Avoid unnecessary exposure to radiation.

Get medical imaging studies only when you need them. (Harvard Health)

Check your home for residential radon, which increases the risk of lung cancer. Protect yourself from ultraviolet radiation in sunlight, which increases the risk of melanomas and other skin cancers. But don't worry about electromagnetic radiation from high-voltage power lines or radiofrequency radiation from microwaves and cell phones. They do not cause cancer.

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.

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.

Cancer prevention should be part of a multi-modal approach in order to provide the best possible outcome. The above Diet and lifestyle recommendations are proven methods to reduce your cancer risk. That said, there is no miracle diet or treatment that can prevent all cancers.
You could also complement your research and read more from the American Cancer Society site. The site has comprehensive information on cancer. You could read more on cancer prevention by cancer type here: http://www.cancer.gov/cancertopics/prevention
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.

The FLCCC has provided a summary protocol of the key interventions (in order of priority) you can take in order to prevent cancer (Chapter 3: ROLE OF REPURPOSED DRUGS AND METABOLIC INTERVENTIONS IN TREATING CANCER):

Quit smoking.
Reduce or limit the use of alcohol.
Lose weight: adopt a healthy diet, manage insulin resistance, and follow a time-restricted eating plan. OneDayMD view: If you have cancer and you are under weight, this is not for you.
Avoid processed food and processed vegetable oils.
Avoid sugary beverages and pure fruit juices.
Limit consumption of red meat to no more than 3 portions/week.
Vitamin D3: 5000 u/day and adjusted according to vitamin D3 level.
Omega 3 fatty acids: 2-4 g/day.
Green tea catechins: 500-1000 mg/day. Green tea extract should be taken during/after a meal, rather than on an empty stomach.
Melatonin: 0.75–5 mg (extended/slow release) at night.
Metformin: Metformin should be considered in anyone at high risk of cancer, whether their risk extends from diabetes, pre-diabetes, insulin resistance, chronic viral infection, smoking, or genetics. Requires doctor’s evaluation, approval, and prescription. (Suggested dose ranges from 250-2000 mg daily.) OneDayMD view: If you are not at 'high risk', stick to intervention no. 3.
Regular aerobic exercise and resistance training 30 minutes/day (walking, home strength training, etc.).
Reduce stress (meditation, yoga, mindfulness exercises, etc.).
Get at least 8 hours of high-quality sleep (ensure adequate sleep hygiene).
Avoid known carcinogens.

Disclaimer

Although this is a comprehensive guide, please do not consider this guide as personal medical advice, but as a recommendation for use with professional providers. Consult with your doctor and discuss with her/him.
Our aim here isn't to replace your doctors' advice. It is intended as a sharing of knowledge and information. Do take note that most strategies are not 100% protective against cancer. It's a continuous struggle between the immune system and the cancer cells.

Note: This is part 2 in Unveiling the Science Behind Cancer, Diet and Supplements series. Check out part 1: Top 10 Cancer Fighting Supplements? 1,000+ Studies Analysed (2024)

Read More: This article is part of the Winning the War on Cancer series.

This article is also part of the diet and cancer series. Other diet and 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

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Cancer Care: The Role of Repurposed Drugs and Metabolic Interventions in Treating Cancer

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