Routing compounds to body's tissues.

Carotenoids are pigmented compounds found in fruits and vegetables that help the body take in nutrients such as vitamin A. They also appear to enhance activity of the immune system.

While there has been much research on the potential health-promoting effects of carotenoids and several other classes of phytochemicals from plant foods, relatively little is known about either the digestive processes necessary to prepare these compounds for uptake into the cells that line the intestine or their absorption and transfer to various tissues in the body, Mark L. Failla, professor of nutrition, University of North Carolina at Greensboro, points out. "Since the details about the digestive process remain relatively unknown, current recommendations about which carotenoid-rich fruit or vegetable to eat are usually based on the amount of the compounds that are present."

However, results from a number of studies suggest that the food with the highest level of a particular carotenoid may not be the optimal source for its delivery to target tissues. "Just because it's in the food doesn't mean your body is capable of absorbing it," he indicates. "There are literally thousands of compounds that we consume when we eat a balanced diet that includes the recommended five servings of fruits and vegetables each day. Many of the...