What about supplements?

Many cancer survivors take supplements in the belief that it will prevent their cancer returning. Hundreds of web sites promote high-dose supplements with unsupported claims that they are cancer cures or can prevent recurrence. The difference between taking a supplement and eating food, is that a supplement contains specific isolated nutrients.

This means you miss out on all the other protective substances found naturally in food which are thought to work together. Although researchers are looking into the effect of specific components in food and their role in the prevention of cancer, at this stage there is no conclusive evidence that taking a particular food component can prevent cancer. In fact, high doses of some vitamins have been shown to increase the risk of certain cancers developing. For example, high doses of vitamin C have been shown to increase the risk of lung cancer in smokers.

Research into the effect of antioxidants, has shown that they are less effective when isolated from food and presented in tablet form. For instance, vitamin A (beta-carotene) supplements have been associated with a reduced risk of certain cancers but an increase in others, such as lung cancer in smokers. Research has also shown that vitamin E didn’t offer the same benefits when taken as a supplement. Antioxidant minerals or vitamins can also act as pro-oxidants or damaging ‘oxidants’ if they are consumed at levels well above the recommended amounts for dietary intake.

There are a few exceptions when supplements are advisable. Examples include B12 for people over 50 who have difficulty absorbing naturally occurring B12, folic acid supplements for women who may become pregnant, and vitamin D supplements for people who are not exposed to sufficient sunlight, or elderly people and people with dark skin who do not synthesise adequate vitamin D from sunlight. It is best to seek individual advice taking your circumstances into account. Some oncologists also recommended vitamin D supplements for women with breast cancer who have low levels when measured.

Another possible exception however, is omega-3 supplementation in the form of fish oil, as most people find it difficult to achieve the recommended intakes by consuming fish several times a week. However, because omega-3 supplements have the potential for side effects and interactions with medications, you should only take fish oil supplements under the supervision of your doctor and you should not exceed doses above 3 mg per day.

In summary, recommendations are to achieve recommended intakes of vitamins and minerals by diet alone, without the use of supplements. This can be achieved by following a well-balanced diet consisting of a variety of foods from within each food group. Supplements can be of assistance if you have or are at risk of nutrient deficiencies or not able to meet the recommended dietary intakes.  If you would like to take supplements, seek those that contain a broad spectrum of essential nutrients at their recommended daily levels, and check with your doctor or dietitian whether there are any interactions with any medications you may be taking.