100 Evidence-Based Ways to Prevent Cancer (2025 Edition): Updated & Ranked

The article, titled "Dr. Oz is 100% Right: If You Want to Reduce the Cost of Medical Insurance, Make Yourself Healthier: 100 Ways to Prevent Cancer", was written by James Lyons-Weiler, PhD, and published on November 18, 2025, on the Substack newsletter Popular Rationalism. It appears to respond to a recent controversy involving Dr. Mehmet Oz (nominated or appointed to a health-related role under the incoming Trump administration as of late 2025), where social media critics accused him of "gaslighting" the public by suggesting personal health choices can prevent cancer and lower insurance costs. 

Lyons-Weiler defends Oz vehemently, framing the backlash as "medical malfeasance" driven by profit motives in the allopathic medical system. The core thesis—that cancer is largely preventable through lifestyle interventions—is presented as self-evident and evidence-based, with the bulk of the piece listing "100 ways" to reduce cancer risk.Strengths

• Empowering Message and Structure: The article effectively promotes personal agency in health, aligning with established public health principles that 30–50% of cancers are preventable via modifiable factors like diet, exercise, and avoiding toxins (per organizations like the American Cancer Society and World Health Organization). The list is well-organized into categories (e.g., eliminating carcinogens, optimizing nutrition, enhancing detoxification), making it accessible and actionable. Examples like avoiding tobacco, processed meats (classified as IARC Group 1 carcinogens), and radon exposure are uncontroversial and backed by decades of epidemiology.
• Focus on Mechanistic Plausibility: Lyons-Weiler emphasizes "evidence-backed, mechanistically plausible, and epidemiologically validated" items, such as sulforaphane in cruciferous vegetables activating detox pathways or high-fiber diets reducing colorectal cancer risk. This grounds the list in oncology basics, like reducing oxidative stress and inflammation.
• Call for Research: The piece thoughtfully critiques the lack of randomized controlled trials (RCTs) on interventions like intermittent fasting and ketogenic diets for primary cancer prevention, advocating for large-scale studies in high-risk groups (e.g., those with obesity or metabolic syndrome). This highlights a real gap in research priorities without dismissing observational data.
• Timeliness: Published shortly after Oz's comments (likely in November 2025 amid his HHS nomination discussions), it taps into a cultural debate on health autonomy vs. systemic blame, resonating with audiences skeptical of "Big Pharma."

Weaknesses

• Lack of Citations and Specificity: Despite claiming "evidence-backed" support, the list provides no direct references to studies, meta-analyses, or data sources. This undermines credibility—e.g., claims about green tea catechins or turmeric curcumin are plausible but vary in strength across cancers (stronger for prevention than treatment). Readers must take assertions on faith, which invites skepticism, especially for debated items like limiting red meat (epidemiology shows modest links to colorectal cancer, but causation is not ironclad).
• Overstatement and Polemics: Phrases like "gaslighting the public" and "social and medical malfeasance" veer into conspiracy-tinged rhetoric, portraying critics as profit-driven without evidence. This polarizes rather than persuades. The binary framing (prevention = empowerment; denial = sickness) ignores nuances, such as genetic predispositions (5–10% of cancers) or socioeconomic barriers to lifestyle changes.
• Potential Omissions and Inaccuracies: Some items feel repetitive or incomplete (e.g., multiple vegetable-focused tips without addressing bioavailability). Notably absent: vaccinations (e.g., HPV for cervical cancer) or screenings, which are proven preventives. One comment in the article notes overlooked acrylamide in coffee, highlighting selective focus. On seed oils (relevant to Oz's broader views), the list vaguely implies avoiding "industrial" or refined oils but doesn't specify, missing a chance to engage the 2025 controversy where Oz echoed misinformation about their toxicity.
• Evidence Gaps on Key Claims: Intermittent fasting and keto are highlighted for inducing autophagy and reducing IGF-1 signaling, but as the author admits, these lack RCTs for new-onset cancer incidence. Observational data is promising but confounded by overall healthy behaviors.

Overall, the article is motivational and structurally sound but suffers from unsubstantiated breadth, making it more inspirational pamphlet than rigorous guide. It earns a B- grade: Strong on intent and accessibility, weaker on scholarly rigor. (Grok 4.1)Ranking the 100 Ways to Prevent CancerThe original list isn't exhaustively detailed in the article summary (it's presented as a high-level enumeration), but we've ranked the top 20 based on strength of scientific consensus, drawing from epidemiological, mechanistic, and interventional evidence (e.g., from IARC, ACS, and meta-analyses up to 2025). Ranking prioritizes:

• High-impact, low-effort actions (e.g., broad risk reduction across multiple cancers).
• Strength of evidence (Tier 1: RCTs/meta-analyses; Tier 2: strong epidemiology; Tier 3: mechanistic/plausible).
• Feasibility (sustainable for most people).

We've grouped them into tiers for clarity and added brief substantiations. This is not exhaustive but represents a curated, evidence-prioritized subset.

 
Items are grouped by category and ranked within each category by strength of evidence + impact (Tier 1 = strongest, Tier 3 = promising but still emerging).

Tier 1 – Gold-Standard, Proven Prevention (Do these first)

1. Never use any form of tobacco (smoking, vaping, chewing) – causes ~22% of cancer deaths worldwide
2. Limit alcohol to 0–1 drink/day (no truly safe level)
3. Maintain BMI 18.5–24.9 (obesity causes 13 cancer types)
4. Stay up to date on cancer screenings (mammogram, colonoscopy, low-dose CT for smokers, Pap/HPV, etc.)
5. Avoid or strictly limit processed meat (IARC Group 1 carcinogen)
6. Test and remediate home radon (2nd leading cause of lung cancer)
7. Use sunscreen + protective clothing (prevents nearly all skin cancers)
8. Breastfeed for ≥12 months total (reduces maternal breast & ovarian cancer)

Tier 2 – Very Strong Epidemiological Evidence

11. Eat ≥30 g fiber daily (each 10 g reduces colorectal cancer ~10%) (1)
12. Exercise ≥150 min moderate or 75 min vigorous per week (cuts breast/colon risk 20–30%)
13. Eat cruciferous vegetables 4–5 times/week (broccoli, kale, Brussels sprouts) (1)
14. Limit processed or charred red meat to ≤18 oz (500 g) cooked weight per week
15. Get 7–9 hours of quality sleep nightly
16. Keep added sugar <10% of calories (ideally <5%) (BMJ 2023)
17. Consume ≥5 servings vegetables + fruit daily (especially non-starchy)
18. Maintain normal vitamin D levels (~50 ng/mL) (1)
19. Avoid ultra-processed foods (BMJ 2024 umbrella review: 10% increase in calories from UPFs → 20% higher cancer risk)
20. Limit sedentary time to <6–8 hrs/day

Tier 3 – Strong Mechanistic + Growing Human Evidence

21. Drink 2–4 cups green tea daily (EGCG) (1)
22. Use turmeric + black pepper regularly (curcumin + piperine) (1)
23. Eat 2–3 servings fatty fish or algae omega-3 weekly
24. Practice time-restricted eating or intermittent fasting (16:8 or 5:2) (3)
25. Use sauna 3–4×/week (Finnish studies: 40% lower all-cause mortality)
26. Optimize magnesium (400–500 mg/day from food or supplement)
27. Eat berries daily (anthocyanins, ellagic acid)
28. Include allium vegetables (garlic, onions, leeks) most days
29. Eat tomatoes & lycopene-rich foods (especially cooked with olive oil)
30. Consume fermented foods daily (sauerkraut, kimchi, yogurt, kefir)
31. Minimize exposure to BPA, phthalates, PFAS (glass/stainless containers)
32. Replace most seed oils in ultra-processed foods with extra-virgin olive oil, avocado oil, or butter/ghee in home cooking (seed oils themselves are not toxic when not overheated or in UPFs)
33. Strength train 2–3×/week
34. Walk ≥8,000–10,000 steps daily
35. Manage chronic stress (meditation, yoga, nature time, therapy)
36. Maintain strong social connections
37. Spend time in nature / forest bathing
38. Practice good oral hygiene (reduces head/neck and pancreatic cancer risk)
39. Coffee 3–4 cups/day (protective for liver & endometrial)
40. Cold exposure (cold showers, ice baths) – emerging hormesis data

Additional High-Impact Lifestyle Factors41–50. Limit high-heat cooking of meat (avoid charring; marinate with herbs/rosemary) 51. Filter tap water (reduces chlorine byproducts, arsenic, PFAS) 52. Use glass, stainless steel, or ceramic instead of plastic for food storage/heating 53. Choose organic when possible for the “Dirty Dozen” 54. Avoid unnecessary CT scans and diagnostic radiation 55. Quit or strictly limit vaping/e-cigarettes 56. Keep indoor air clean (HEPA filters, no indoor smoking, ventilate) 57. Test for and treat H. pylori if positive 58. Maintain healthy gut microbiome diversity 59. Optimize folate from food (leafy greens, legumes) 60. Get adequate selenium (Brazil nuts, fish)Emerging / Plausible but Needs More RCTs (Randomised Controlled Trials)61–70. NAC or glycine-rich foods for glutathione support
71. Ashwagandha or holy basil for cortisol control
72. Mushroom extracts (reishi, turkey tail, maitake) – immune modulation
73. Sulforaphane supplements (if you hate broccoli sprouts)
74. Berberine or metformin-like lifestyle for insulin sensitivity
75. Low-dose aspirin (only if high risk and doctor-approved)
76. Grounding/earthing
77. Red-light/near-infrared therapy
78. Hyperbaric oxygen (research phase)
79. Ketogenic diet in high-risk metabolic populations
80. Periodic prolonged fasting (48–96 h, medically supervised)Proactive Medical & Environmental Steps

81. Know your family history and consider genetic counseling if high risk
82. Annual physical + bloodwork (inflammation, metabolic markers)
83. Remove unnecessary hormone-disrupting cosmetics (parabens, phthalates)
84. Avoid unnecessary antibiotics (linked to microbiome disruption → higher risk)
85. Keep fasting insulin <8 µIU/mL and HbA1c <5.7%

86–100. Live by the top 50 items above consistently — modeling shows 40–60% of cancers are preventable with full adoption of Tier 1 + Tier 2 strategies.

Start with the first 20. Master those, then layer in the rest. Prevention compounds over decades.
References:

1. 2025–2026 Best Evidence-Based Supplements & Diet Strategies to Reduce Cancer Risk (Doctor-Reviewed Protocol)
2. I-PREVENT CANCER protocol: An Evidence-Based Guide to Cancer Prevention (2025 Edition)
3. Thomas Seyfried Cancer Treatment Protocol: Ketogenic Diet That Starves Cancer - A Comprehensive Guide (2025)
4. BMJ 2023 umbrella review, which recommends reducing free and added sugars to below 25 g/day and limiting sugar-sweetened beverages to less than one serving per week to reduce adverse health effects.
5. BMJ 2024 umbrella review: Adopt a whole-food diet and avoid ultra-processed foods.