Many dietary supplement manufacturers tout carotenoids as a "natural way to beat cancer." But just because carotenoids are extracted from fruits and vegetables doesn't mean they're completely safe, with some studies even showing that carotenoids may increase lung cancer risk. Although research is mixed regarding carotenoid supplements, adding a variety of healthy produce to your diet is a known way to help decrease your risks for cancer overall.
Identification
Carotenoids are a group of more than 600 naturally occurring molecules synthesized by plants, algae and bacteria, which give many plants like mangoes, red peppers, carrots, tomatoes and cayenne pepper their yellow, orange and red colors. The most common carotenoid is beta-carotene, which your body turns into vitamin A. Carotenoids are broadly classified into two types -- carotenes, including alpha-carotene, beta-carotene and lycopene, and xanthophylls, which include beta-cryptoxanthin, lutein and zeaxanthin.
Potential Cancer Link
A study in Finland on the use of beta-carotene and a form of vitamin E, published in the "New England Journal of Medicine" in 1994, looked at 29,000 male smokers over 14 years, who were randomly given beta-carotene, vitamin E, a combination or a placebo. Smokers in the beta-carotene group had an 8 percent higher mortality and an 18 percent higher rate of lung cancer than smokers receiving placebo.
Possible Benefits
In numerous studies, carotenoids have been linked with the prevention of several kinds of cancer. One such review, published in the October 2000 edition of "The American Journal of Clinical Nutrition," analyzed the diets of more than 124,000 men and women over a 10-year period in the Health Professionals Follow Up Study and the Nurses Health Study from 1984 to 1996. The researchers found that a diet featuring a variety of carotenoids was associated with a 32 percent drop in the incidence of lung cancer.
No Positive or Negative Associations
A review of 31 studies, published in 2008 in the "American Journal of Clinical Nutrition," determined that the risks or benefits of beta-carotene for lung cancer rates were generally small and not statistically significant. A followup look at the Health Professionals Study and the Nurses Health Study through 2006, published in March 2011 in "Nutrition Research," found that no carotenoids were significantly associated with cancer mortality one way or the other.
Recommendations
Although there are no established dietary intake levels for carotenoids, the National Academy of Sciences recommends you consume five or more servings of fruits and vegetables every day, which is equivalent to 3 to 6 mg of beta-carotene. Since few human studies have been conducted on the effects of the many types of carotenoids, and supplements can cause side effects when taken in large doses, the academy and other health experts advise against using carotenoid supplements.
References
- Intelihealth.com; A Natural Way To Beat Cancer?; March 2008
- "American Journal of Clinical Nutrition"; Intake of Specific Carotenoids and Risk of Lung Cancer in 2 Prospective U.S. Cohorts; D. Michaud, et al.; October 2000
- "New England Journal of Medicine"; The Effect of Vitamin E and Beta-Carotene on the Incidence of Lung Cancer and Other Cancers in Male Smokers; O. Heinonin, et al.; 1994
- "Nutrition Research"; Low-Serum Carotenoid Concentrations and Carotenoid Interactions Predict Mortality in U.S. Adults: The Third National Health and Nutrition Examination Survey; M.D. Shardell; March 2011
- "American Journal of Clinical Nutrition"; Carotenoids and the Risk of Developing Lung Cancer: A Systematic Review; L. Gallichio, et al.; August 2008
- Linus Pauling Institute; Carotenoids; Jane Higdon; December 2005
