Too Many Supplements, Taken Too Long, May Raise Cancer Risk

It’s been recently shown that beta-carotene doesn’t protect people from getting lung cancer – quite the reverse, in fact. Now another study has appeared that has similar findings. It’s to be found in the American Journal of Epidemiology, and was conducted by University of North Carolina researchers.

The VITamins And Lifestyle (VITAL) study ran in Washington State. In 2000 to 2002 77,000 persons completed questionnaires about their supplement use during the previous 10 years; multivitamins and individual nutrients could be recorded, with details of duration, frequency, and dose. The participants were followed for the next 4 years, when data from cancer registries were used to search for associations between lung cancer and these individual supplements: beta-carotene, retinol, vitamin A, lutein, and lycopene.

Participants who smoked had a risk of developing lung cancer that increased with the length of time they had been taking supplements containing beta carotene, retinol, and lutein. The amount of time the person took supplements had a greater influence than the actual dose; even a modest dose, if taken for a long time, increased the risk of lung cancer among smokers. Thus taking lutein led to a doubling, and beta carotene a tripling of the risk of lung cancer after 4 years or more.

There were insufficient numbers of lung cancers in non-smokers to reveal any significant increased risks associated with the supplements. This suggests that you should: 1. not smoke; 2. if you must smoke, don’t take beta-carotene, retinol, or lutein supplements.