November 22, 2010
Alpha Carotene Beneficial In Vegetables?

Since randomized trials of beta carotene supplementation did not appear to show a health benefit scientists have been trying to figure out what about vegetables make people healthier. One theory: alpha carotene might be a key beneficial substance in cancers.

High blood levels of the antioxidant alpha-carotene appear to be associated with a reduced risk of dying over a 14-year period, according to a report posted online today that will be published in the March 28 print issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

Oxygen-related damage to DNA, proteins and fats may play a role in the development of chronic diseases like heart disease and cancer, according to background information in the article. Carotenoids—including beta-carotene, alpha-carotene and lycopene—are produced by plants and microorganisms and act as antioxidants, counteracting this damage. Carotenoids in the human body are obtained mainly through eating fruits and vegetables rich in the nutrients, or through antioxidant supplements.

Paleo Diet expert Loren Cordain says the lower acidity of vegetables balances higher acidic foods. Vegetables also contain assorted flavonoids and other compounds. So is alpha carotene a real benefit or just a marker for whatever else in veggies is good for you?

People with higher blood alpha carotene had lower all-cause mortality.

Over the course of the study, 3,810 participants died; the risk for dying was lower with higher levels of alpha-carotene in the blood. Compared with individuals with blood alpha-carotene levels between 0 and 1 micrograms per deciliter, the risk of death during the study period was 23 percent lower among who had concentrations between 2 and 3 micrograms per deciliter, 27 percent lower with levels between 4 and 5 micrograms per deciliter, 34 percent lower with levels between 6 and 8 micrograms per deciliter and 39 percent lower with levels of 9 micrograms per deciliter or higher.

Higher alpha-carotene concentration also appeared to be associated with lower risk of dying from cardiovascular disease or cancer individually, and of all other causes. "The association between serum alpha-carotene concentrations and risk of death from all causes was significant in most subgroups stratified by demographic characteristics, lifestyle habits and health risk factors," the authors write.

It seems likely the vegetables really are good for your health. You do not have to know how they deliver their health benefits. You can just eat them. Go for the yellow-orange vegetables and deep greens. About to buy food for Thanksgiving Day? Go for sweet potatoes, pumpkin pie, and dark greens.

Alpha-carotene is chemically similar to beta-carotene but may be more effective at inhibiting the growth of cancer cells in the brain, liver and skin, they note. "Moreover, results from a population-based case-control study of the association between the consumption of fruits and vegetables and risk of lung cancer suggest that consumption of yellow-orange (carrots, sweet potatoes or pumpkin and winter squash) and dark-green (broccoli, green beans, green peas, spinach, turnips greens, collards and leaf lettuce) vegetables, which have a high alpha-carotene content, was more strongly associated with a decreased risk of lung cancer than was consumption of all other types of vegetables," the authors write.

Count me in the ranks of those who would rather pass on broccoli. Better winter squash or sweet potatoes. Yams too.

Share |      Randall Parker, 2010 November 22 10:53 PM  Aging Diet Studies

Morgan said at November 24, 2010 11:00 AM:

Just make broccoli soup! Nothing but broccoli, water, and salt. Oh and cheese.

Audacious Epigone said at November 24, 2010 12:58 PM:

Isn't yam another name for sweet potato?

Randall Parker said at November 24, 2010 9:20 PM:


No. Sweet potatoes are sometimes incorrectly called yams. But they are two different species, Ipomoea batatas (sweet potatoes) and Dioscorea Species (yams). See more here and here. The softer and firmer sweet potatoes are both sweet potatoes. But the softer varieties get labeled yams commercially to differentiate them from the firmer varieties. Yams are a different and sweeter plant and less widely sold.

Yams are lower in beta carotene. But it is not clear to me how they stack up for alpha carotene.

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