How Well Do You Convert Beta-Carotene into Vitamin A?
ARS News Service, USDA, March 23, 2001

Beta-carotene adds attractive colors and nutritional value to many familiar fruits and vegetables. Studies led by Agricultural Research Service chemist Betty J. Burri during the past five years provide new information on the ability of our bodies to absorb beta-carotene and convert it into an essential nutrient, vitamin A. Vitamin A is essential for proper growth and reproduction, as well as for good eyesight.

Burri's findings are important for people who are cutting back on the amount of meat or dairy products—foods that are rich in vitamin A—that they eat. These individuals need to be sure they are getting an adequate supply of vitamin A from other sources.

Burri found new extremes in the amount of time it takes for beta-carotene to be absorbed and converted and in the amount that is converted. Among the most unexpected results was a statistically significant difference in beta-carotene uptake and conversion by physically similar volunteers. About half of Burri's 45 volunteers—male and female—didn't take up much beta-carotene. And, about half of the volunteers didn't form much vitamin A from the beta-carotene they did absorb.

according to Burri, variation in the way our bodies respond to beta-carotene is likely gene-based. Nutrition scientists might soon be able to use new information from human genome researchers to develop customized dietary guidelines that take into account an individual's ability to convert beta-carotene into vitamin A.

More information is given in the ARS monthly journal, Agricultural Research, which can be viewed online at http://www.ars.usda.gov/is/AR/archive/mar01/clues0301.htm.

ARS News Service contact: Marcia Wood, phone 510/559-6070, e-mail MarciaWood@ars.usda.gov

Scientific contact: Betty J. Burri, ARS Western Human Nutrition Research Center, Davis, CA; phone and fax 530/752-4748, e-mail bburri@ars.usda.gov.