How Diet and Fiber Influence Cancer Risk

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Cancer is the second leading cause of death, and while it sparks fear for good reason, 40% of cases are preventable. In this episode, I outline six practical, evidence-based steps that can help reduce your risk.

We begin by understanding which cancers are most common based on gender—breast, colon, and lung in women; prostate, colon, and lung in men. While some rare cancers (like pancreatic or ovarian) evoke greater fear, the focus here is on the ones we’re more likely to face and can meaningfully act on.

Next, I break down risk factors into two categories. Some are unavoidable—your sex, age, or family history. For example, if a close relative had breast or colon cancer, early screening or genetic testing may be warranted. However, only about 5–10% of cancers are directly linked to inherited genetic mutations (American Cancer Society
).

The more empowering list? Avoidable risk factors—where our actions matter most. Smoking remains the leading modifiable cause of cancer, responsible for about 19% of all cases. Excess weight and obesity account for another 8% and are especially tied to hard-to-treat cancers like pancreatic and ovarian (ScienceDirect
) and PubMed
). Visceral fat appears more predictive than BMI alone. Alcohol, especially in large quantities, is also linked to liver, GI, and breast cancers.

Some risks are cancer-specific. HPV causes nearly all cervical cancers, and melanoma is largely driven by UV exposure. Air pollution, especially particulate matter, may slightly increase lung cancer risk (ASCO Global Oncology
).

Step three is to act on what you can. Quit smoking, aim for a healthy weight, wear sun protection, and ensure your kids get their routine HPV and Hepatitis B vaccines
. Exercise plays a major role too—high activity levels correlate with 10–20% lower risk of several major cancers (JAMA
). In colon cancer survivors, regular exercise reduced recurrence by 30% (PubMed
).

Step four is awareness: don’t ignore new symptoms like unexplained bleeding or lumps. Early detection can be life-saving.

Step five is screening. If you're 45 or older, colonoscopy is now recommended. Women should get regular mammograms and PAP smears, and individuals with smoking history may benefit from lung CT scans. For rarer cancers with family history, targeted screenings may apply. I also address why whole-body MRIs
 and liquid biopsies
 aren’t ready for routine use.

Step six? Don’t put your hope in supplements. Large trials show omega-3s, vitamin D, beta carotene, and vitamin C offer no real protective benefit (NEJM VITAL Study
, Meta-analysis on Vitamin C
, JNCI on aspirin
).

Takeaways:
You can reduce your cancer risk by modifying lifestyle factors like smoking, weight, and activity. Don’t delay screenings—they catch cancers early when treatment is most effective. And remember: no supplement replaces proven preventive strategies.

Visit drbobbylivelongandwell.com
 for more evidence-based tools, and listen to the full episode for actionable steps to help you live long and well.