Health Information Center : Carotenoids

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Carotenoids, most of which are pro vitamin A, are a major topic in nutrition and health circles today. Why are they important? Because vitamin A, long known to be crucial for normal vision, has been discovered to have a whole host of diverse biological functions. Its role in controlling the way in which cells divide, develop, and mature has become an area of much interest among scientists.

Research Findings:

Cancer Protection
Diets rich in carotenoids have been associated with a lower risk of developing many kinds of cancer. Recent studies have also specifically targeted carotenoids other than beta-carotene (including alpha-carotene, cryptoxanthin, lutein, and lycopene) as having anti-cancer effects.

Cataract Protection
Research has shown that people who consumed fewer than 3.5 servings of fruits and vegetables daily had an increased risk of developing cataracts.

Immune System Enhancement
Studies suggest that carotenoids enhance both anti-microbial functions and immunity against tumors by increasing activity of natural killer cells.

Heart Disease Protection
Cardiovascular disease events dropped almost 50% in a group of heart disease prone men who took beta-carotene supplements every other day for five years.

Longevity
Dr. Richard Cutler from the National Institute on Aging, Gerontology Research Center supports a significant link between lifespan and plasma carotenoid levels. He states that “carotenoids may be biologically active not only as a protective agent, but also as a longevity determinant”.

Beta-carotene is the most well-known of the carotenoids and the predominate one in carrots, sweet potatoes, broccoli, and cantaloupe. Beta carotene, the molecule that contains two molecules of vitamin A, plays a major role as a contributor of vitamin A in our diets. In the last few years, food scientists have been able to measure not only beta-carotene in fruits and vegetables, but also numerous other carotenoids. Today we know that pro-vitamin A carotenoids include approximately 50 carotenoids which can be converted into at least one molecule of vitamin A. The other carotenoids (some 600 total in nature) may have important metabolic effects on the body independent of vitamin A. These as yet unidentified functions need to be considered when interpreting studies that claim health promotion properties from carotenoid rich vegetables.

Carotenoids are converted to vitamin A mainly in the intestine and liver. About 10% of dietary carotenoids are converted to vitamin A in the body and contribute 25% of our total vitamin A. We now know that many carotenoids also have antioxidant properties and studies are underway to determine other health benefits of carotenoid metabolites besides the long accepted role as precursors of vitamin A. Analytical data are available for five of the carotenoids found in foods and measurable in the blood. These include beta-carotene, alpha-carotene, lutein, lycopene, and beta-cryptoxanthin.