Do dietary supplements help reduce cancer risk?

The Bottom Line

  • Advertising and articles in the popular media continue to recommend dietary supplements for cancer prevention.

  • So far, there is little or no sound research evidence to support these claims.

  • Skip the supplements but follow evidence-based nutrition guidelines: more fruits, vegetables and fibre; less red and processed meats.

According to the latest research, if we want to age optimally and reduce our risk of cancer we need to exercise regularly and eat a nutritious, balanced diet that includes plenty of vegetables and fruit (1). That sounds sensible, and is what we're already striving to do. But what else?! For instance, all those supplements and "super foods" we hear about - should we be stocking up on those too?

In recent years there have been a flood of claims about the cancer prevention benefits of various vitamin and mineral supplements such as selenium, calcium, vitamins A, C and D, and various concentrated combinations of "natural ingredients". Apparently they'll help you drop weight effortlessly and reverse aging - in addition to preventing cancer!

No doubt the messages are exaggerated, but is it all just hype? Should we take supplements anyway, on the off chance there's some benefit? Is there any harm in taking them? Fortunately for us, scientific and medical research teams have been working to answer such questions.

What the research tells us

Vitamins, minerals and other nutrients are essential to good health and can help combat cancer and other diseases (1) - but don't plan on getting them in pill form. So far, the research conducted to date has shown little to no cancer fighting benefits from taking mineral, vitamin and other dietary supplements (2-6).

A few trials showed a slight benefit of certain nutritional combinations in helping prevent prostate cancer (7). But until further research proves otherwise, there is not enough evidence to justify spending money on supplements. In fact, there is evidence that dietary supplements can do more harm than good (3;6) - as in the case of beta carotene which has been shown to increase the risk of lung cancer in some people (3).

Instead, reduce your risk of cancer by focusing on evidence-based nutrition strategies: eating at least five servings/2.5 cups of vegetables and fruits a day, getting adequate fibre, and limiting red and processed meats (1). Ready to get started? Skip the drug store and stock up in the produce aisle of the grocery store or at your local farmers' market!

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Author Details


  1. Kushi LH, Doyle C, McCullough M, et al. American Cancer Society guidelines on nutrition and physical activity for cancer prevention: Reducing the risk of cancer with healthy food choices and physical activity. CA Cancer J Clin. 2012; 62(1):30-67. doi: 10.3322/caac.20140.

  2. Vinceti M, Filippini T, Del Giovane C, et al. Selenium for preventing cancer. Cochran Database Syst Rev. 2018; 1:CD005195. doi: 1002/14651858.CD005195. 

  3. Moyer VA. Vitamin, mineral and multivitamin supplements for the primary prevention of cardiovascular disease and cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014; 160(8):558-564. doi: 10.7326/M14-0198. 

  4. Bjelakovic G, Lotte Gluud L, Dimitrinka N, et al. Vitamin D supplementation for prevention of cancer in adults. Cochrane Database Syst Rev. 2014; 6:CD007469. doi: 10.1002/14651858.CD007469.pub2.

  5. Goulão B, Stewart S, Ford JA, et al. Cancer and vitamin D supplementation: A systematic review and meta-analysis. Am J Clin Nutr. 2018; 107(4):652-663. doi: 10.1093/ajcn/nqx047. 

  6. Cortés-Jofré, M, Rueda JR, Asenjo-Lobos C, et al. Drugs for preventing lung cancer in healthy people. Cochrane Database Syst Rev. 2020; 3:CD002141. doi: 10.1002/14651858.CD002141.pub3. 

  7. Hackshaw-McGeagh LE, Perry RE, Leach VA, et al. A systematic review of dietary, nutritional, and physical activity interventions for the prevention of prostate cancer progression and mortality. Cancer Causes Control. 2015; 26(11):1521-1550. doi: 10.1007/s10552-015-0659-4.

DISCLAIMER: These summaries are provided for informational purposes only. They are not a substitute for advice from your own health care professional. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the McMaster Optimal Aging Portal (

Many of our Blog Posts were written before the COVID-19 pandemic and thus do not necessarily reflect the latest public health recommendations. While the content of new and old blogs identify activities that support optimal aging, it is important to defer to the most current public health recommendations. Some of the activities suggested within these blogs may need to be modified or avoided altogether to comply with changing public health recommendations. To view the latest updates from the Public Health Agency of Canada, please visit their website.