The Cancer Research Campaign is calling for warnings to be included on the labels of vitamin supplements containing beta-carotene. It says that beta-carotene may increase the risk of lung cancer in smokers. This point was made by Professor Gordon McVie (director general, CRC) during a programme on BBC Radio 4 (The ABC of vitamins) on July 25.
The charity's views are based on data from published trials which were designed to assess if beta-carotene supplements are effective in reducing the risk of lung cancer. However, the results showed the opposite effect in smokers. Professor McVie said: "My advice to smokers who cannot kick the habit is do not add to your risk of getting cancer by taking beta-carotene supplements. The research is cast iron in my view and I feel certain most smokers are not aware of this risk."
A spokesman for the vitamin manufacturer Solgar said during the programme that the source of beta-carotene used in the trials had been synthetic and that the adverse effect might not occur with natural sources of the supplement. However, Professor McVie said that proof was needed to confirm that people reacted differently to the two types. He suggested that the following warning should be included on products containing beta-carotene: "There is evidence to link beta-carotene in smokers with an increased incidence of lung cancer."
In 1998, the Government recommended that beta-carotene supplements should not be used to protect against lung cancer, but this warning had been largely overlooked or ignored, according to Professor McVie.
A spokesman for the Food Standards Agency told The Journal on July 25 that an expert group on vitamins and minerals was currently considering the safety of beta-carotene and that its results were expected to be published next summer. The agency's current advice was that vitamin supplements were not necessary in individuals who consumed a balanced diet and that "until definitive advice becomes available, smokers may wish to avoid taking dietary supplements containing beta-carotene."
The studies that support the charity's call include a Finnish study of 29,000 smokers which showed that taking beta-carotene supplements resulted in an 18 per cent increase in the risk of developing lung cancer (New England Journal of Medicine 1994;330:1029). A US study showed that beta-carotene increased the risk of developing lung cancer by 28 per cent in people who smoked or worked with asbestos (Journal of the National Cancer Institute 1996;88:1550).
The CRC says that beta-carotene is important for health as an antioxidant. However, it cautions that there is an apparent difference between the health benefits of beta-carotene in supplements and in food, although it is unknown why this is the case. There is no evidence that taking beta-carotene supplements poses a risk for non-smokers, the charity adds.

Beta-carotene should be avoided by smokers, according to Cancer Research Campaign