From the Guidelines
The risk of developing cancer from using multivitamins is generally very low, and most research suggests that multivitamins neither significantly increase nor decrease cancer risk for the average person. The American Cancer Society guideline for diet and physical activity for cancer prevention, published in 2020 1, states that there is limited and inconsistent evidence that dietary supplements can reduce cancer risk. Some studies have found specific exceptions, such as high-dose beta-carotene supplements increasing lung cancer risk in smokers, and excessive selenium potentially raising prostate cancer risk in men with already high selenium levels. However, for most healthy individuals taking standard multivitamins at recommended doses, there's no strong evidence of cancer risk.
The key points to consider are:
- Multivitamins typically contain vitamins A, C, D, E, K, B vitamins, and minerals like zinc, selenium, and magnesium at levels close to recommended daily allowances.
- These supplements are most beneficial for those with nutritional gaps in their diet rather than as cancer prevention.
- If you're concerned about cancer risk, focus on established prevention strategies like:
- Maintaining a healthy weight
- Eating a balanced diet rich in fruits and vegetables
- Limiting alcohol
- Avoiding tobacco
- Getting regular exercise As stated in the USPSTF recommendation statement published in 2014 1, the evidence is insufficient to determine the balance of benefits and harms of supplementation with multivitamins for the prevention of cardiovascular disease or cancer. Therefore, it is essential to prioritize a healthy lifestyle and a balanced diet over reliance on supplements for cancer prevention.
From the Research
Cancer Risk from Multivitamin Use
- The relationship between multivitamin use and cancer risk is complex, with some studies suggesting a potential link between the two 2, 3.
- A study published in The Journal of Nutrition found that men who consumed one or more multivitamins daily had a slightly higher overall cancer risk compared to nonusers, with increased risks for prostate cancer, lung cancer, and leukemia 2.
- However, the same study found that daily multivitamin use was inversely associated with colon cancer risk in both men and women 2.
- Another study published in JAMA found that multivitamin use was significantly associated with a lower incidence of any cancer and lung cancer, but the evidence had important limitations 3.
- The US Preventive Services Task Force concludes that the evidence is insufficient to determine the balance of benefits and harms of supplementation with multivitamins for the prevention of cardiovascular disease or cancer 4.
Benefits and Harms of Multivitamin Supplementation
- Some studies suggest that multivitamin supplementation may have benefits, such as reducing the risk of cancer and cataracts, especially among men 5, 6.
- However, other studies have found that multivitamin use may be associated with higher risks of certain cancers, such as prostate cancer, lung cancer, and leukemia 2.
- The US Preventive Services Task Force recommends against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer, due to the potential harms outweighing the benefits 4.
- The task force also concludes that the evidence is insufficient to assess the balance of benefits and harms of the use of multivitamin supplements for the prevention of cardiovascular disease or cancer 4.
Overall Assessment
- The current evidence suggests that the relationship between multivitamin use and cancer risk is complex and may depend on various factors, such as the type of multivitamin, dosage, and individual characteristics 2, 3.
- While some studies suggest potential benefits of multivitamin supplementation, others have found associations with higher cancer risks 5, 2, 6, 3.
- The US Preventive Services Task Force concludes that the evidence is insufficient to determine the balance of benefits and harms of supplementation with multivitamins for the prevention of cardiovascular disease or cancer 4.