Eating a lot of the pigment beta-carotene seems to increase the risk of cancer for current or past smokers, new research suggests. But it seems to cut the cancer risk among people who have never smoked.
The findings are based on a study of women, but researchers believe similar results
would be found in men.
"Based on the findings from our study and others, I would advise against beta-carotene supplements for current or past smokers," said senior author Dr Marie-Christine Boutron-Ruault.
"For beta-carotene-rich foods, the message is less clear, since they often contain other vitamins that may counteract the interaction of beta-carotene with smoking."
Beta-carotene is a yellow or orange pigment found in many plants, such as carrots and tomatoes.
The new study, which is reported in the Journal of the National Cancer Institute, involved 59,910 women who were followed for about seven years. During follow-up, 700 women developed tobacco-related cancers, such as lung cancer or head and neck cancer.
Among those who never smoked, consuming a diet containing moderate amounts of beta-carotene cut the risk of cancer by up to 28 per cent. Taking beta-carotene supplements reduced the risk by 56 per cent.
But among current or past smokers, eating moderate amounts of beta-carotene increased the cancer risk by up to 43 per cent. Beta-carotene supplements more than doubled the risk.
"We were surprised at the completely opposite effect high beta-carotene intake had on cancer risk depending on whether you had never smoked or ever smoked," Boutron-Ruault noted.
"We plan on doing a larger study with more cancer cases, a larger variety of doses of beta-carotene and tobacco, and both men and women."
- REUTERS
