There is strong evidence from randomised controlled trials that high-dose beta-carotene supplements may increase the risk of lung cancer in some people. There is no strong evidence that dietary supplements, apart from calcium for colorectal cancer, can reduce cancer risk.
A dietary supplement is a product intended for ingestion that contains a ‘dietary ingredient’ intended to achieve levels of consumption of micronutrients or other food components beyond what is usually achievable through diet alone.
- High-dose dietary supplements are not recommended for cancer prevention – aim to meet nutritional needs through diet alone
Expert Panel conclusions
Randomised controlled trials of high-dose supplements have not consistently demonstrated the protective effects of micronutrients on cancer risk suggested by observational epidemiology. Furthermore, some trials have shown potential for unexpected adverse effects. The Panel is confident that for most people consumption of the right food and drink is more likely to protect against cancer than consumption of dietary supplements.
This Recommendation applies to all doses and formulations of supplements, unless supplements have been advised by a qualified health professional who can assess potential risks and benefits.
WHEN SUPPLEMENTS ARE ADVISABLE
The Panel recognises that dietary supplements, in addition to varied diets, may at times be beneficial for specific population groups:
- vitamin B12 for people over the age of 50 who have difficulty absorbing naturally occurring vitamin B12
- iron and folic acid supplements for women who may become or are pregnant
- vitamin D supplements for infants and young children and for pregnant and breastfeeding women, although specific recommendations for iron and vitamin D supplementation vary between countries
Public health and policy implications
In many parts of the world, nutritional inadequacy is endemic. In crisis situations it is necessary to supply supplements of nutrients to such populations or to fortify food to ensure at least minimum adequacy of nutritional status. The best approach is to protect or improve local food systems so that they are nutritionally adequate and promote healthy diets.
This also applies in high-income countries, where impoverished communities and families, and vulnerable people, including those living alone, the elderly, and the chronically ill or infirm, may also be consuming nutritionally inadequate diets. In such cases of immediate need, supplementation is necessary.
Policymakers should aim to maximise the proportion of the population achieving nutritional adequacy without dietary supplements by implementing policies that create a healthy food environment and food system. Policymakers are encouraged to frame specific goals and actions according to their national context. Find out more on policy action for cancer prevention.
Our Recommendations work together as an overall way of living healthily to prevent cancer.