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Beta Carotene

It might come as a surprise to most people that even beta carotene, perhaps the best known of the carotenes, doesn't have its own RDA, or Recommended Dietary Allowance. The only proven function for carotenes is as precursors - called pro-vitamins - to vitamin A.

If the only acknowledged role of carotenes, including beta carotene, is to serve as precursors of vitamin A, then, in theory at least, if you have enough vitamin A, you don't need the carotenes. Our bodies require vitamin A for good eyesight, proper growth and reproduction, and prevention of some diseases.

Evidence suggests that beta carotenes are required for optimal human health. You cannot underestimate how important it is to eat vegetables-even some of the less popular ones-that are good sources of carotenes. Those veggies include carrots, sweet potatoes, spinach, collards, parsley, kale, pumpkin, mustard greens, beet greens, and winter squash. Several fruits are also good sources, such as apricots, cantaloupe, and mangos.

Sources of Beta Carotene
Mangos	Carrots
Apricots	Sweet Potatoes
Cantaloupe	Butternut Squash
Peaches	Pumpkin

To find more about the interrelation of carotenes and vitamin A, ARS chemist Betty Burri conducted two experiments, each with about a dozen healthy women aged 18 to 42. She designed the tests to explore the question, "If people eat adequate amounts of vitamin A, do they need to eat carotenes?"

Both studies tracked many key indicators of general health. In each experiment, volunteers ate meals that featured familiar foods-but were low in carotenes and other carotenoids.

In one test, all volunteers ate only meals low in beta carotene. They followed this stint with a repletion phase in which they downed beta carotene supplements in addition to low-carotene meals.

In the other test, all volunteers ate low-carotene meals. Some took carotene supplements throughout the study; the others added supplements only during the repletion phase. Importantly, all meals provided an ample supply of preformed vitamin A from such sources as beef, chicken, turkey, pork, and fish.

Results from the carotene studies, says Burri, "suggest that we need carotenes-at least in small amounts-not only as vitamin A precursors but also as antioxidants."

We recommend eating deep orange and bright yellow vegetables and fruit. Vegetables such as sweet potatoes, carrots, and pumpkins all contain the phytonutrient beta carotene. Citrus fruits such as oranges, grapefruits, and tangerines contain another group of phytonutrients called bioflavonoids. Phytonutrients, substances found only in plants, may help your body fight disease and promote good health.

Beta carotene is a powerful antioxidant that is being studied along with vitamin C & E for the role it may play in reducing the risk of cancer, heart disease, maintaining good eyesight, boosting your immune system and slowing aging. Sunlight breaks down carotenoids so when you cut up vegetables don't leave them on the counter, use them quickly. Lightly cooking them makes their carotenoids more readily available.