Alternative Names: Pro-vitamin A.
Beta-carotene is a member of a class of compounds called carotenoids. Carotenoids, in general, are responsible for the yellow/orange pigmentation of many fruits and vegetables such as carrots, sweet potatoes, pumpkins and apricots. As a precursor to vitamin A, beta-carotene can be taken in high doses without the toxicity associated with vitamin A.
While beta-carotene can be made synthetically, it can also be harvested naturally from carotene-rich plant material, such as the sea algae Dunaliella salina. Isolated with beta-carotene are the carotenoids alpha-carotene, zeaxanthin, cryptoxanthin, and lutein. Beta-carotene is a common ingredient in multi-vitamin, immune enhancing, as well as antioxidant formulations.
There have been many reports in recent years telling of the benefits of beta-carotene supplements. As an antioxidant it has been studied for its ability to lower the risk for certain cancers, protect against cataracts, enhance the immune system, and reduce the risk of heart disease. While these studies are not conclusive, many are very promising. Of course, as a precursor to vitamin A, beta-carotene has all the benefits associated with vitamin A, without the risk of toxicity.
Recent studies have associated an increased risk of lung cancer among smokers taking beta-carotene. While these studies are somewhat inconclusive, caution should be taken by smokers when taking beta-carotene.
A 1999 study showed that supplemental beta-carotene has different effects in smokers and nonsmokers. Beta-carotene supplementation has been linked to an increase in lung cancer in smokers, but does not appear to increase risk in nonsmokers. [Nutr Cancer 1999; 34: pp.167-72]
One study showed a slightly increased risk of vascular surgery among people with intermittent claudication who took beta-carotene supplements. [Törnwall ME, Virtamo J, Haukka JK, et al. The effect of alpha-tocopherol and beta-carotene supplementation on symptoms and progression of intermittent claudication in a controlled trial. Atherosclerosis 1999;147: pp.193-7]
Until more is known, people with intermittent claudication wishing to use beta-carotene supplements should first consult with their doctor.
A study published in 1992 by the State University of New York compared 310 women having breast cancer to 316 women without the disease. The study found that the cancer-free group ate many more beta carotene-containing fruits and vegetables than he women with breast cancer. In addition, the National Cancer Institute studied 83 women with breast cancer and found that they had lower blood levels of beta carotene.
The diets of 358 white men and women with NHL and 1432 controls living in Nebraska were compared. Dietary carotene intake was inversely related to NHL risk in men but not in women. [Ward MH, Hoar ZS, Weisenburger DD, et al. Dietary factors and non-Hodgkin's lymphoma in Nebraska]
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