The rich yellow of a mango or deep orange of a carrot are the work of nutrients called carotenes. Our bodies can convert some carotenes--namely, alpha-carotene, beta-carotene, and beta-cryptoxanthin--into vitamin A, a nutrient essential for proper growth and reproduction as well as for good eyesight. What's more, new evidence further supports the value of carotenes as antioxidants that may reduce our risk of cancer, stroke, arteriosclerosis, and cataracts.
Dozens of familiar, brightly colored, yellow, orange, or dark-green vegetables and fruits provide carotenes. Perhaps most studied to date is beta-carotene. Scientists have long suspected that individuals differ in their ability to absorb beta-carotene and convert it to vitamin A. Early beta-carotene studies with humans gave researchers a glimpse of this variability. But a series of investigations over the past 5 years, led by ARS chemist Betty J. Burri, offers new, more detailed proof of this diversity.
These findings are important for people who are cutting back on the amount of meat and dairy products they eat. "Meat, eggs, cheese, and whole milk are rich in vitamin A," says Burri, "so people who eat little if any of these foods need to be sure they are getting an adequate supply of this nutrient from other sources."
Burri is with the ARS Western Human Nutrition Research Center in Davis, California. She did the work with Terry J. Neidlinger, also at the center; Andrew J. Clifford, Stephen R. Dueker, Sabrina J. Hickenbottom, and Yumei Lin of the University of California, Davis, Department of Nutrition; and Jin-Young K. Park, formerly with ARS and now with the Food and Drug Administration.
Special Compounds Used As Trackers
The researchers studied 45 male and female volunteers, aged 18 to 42. For some of...
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