Coming to Terms with Carotenoids

• Xanthophylls are carotenoid molecules that contain oxygen, such as lutein and zeaxanthin.
• Carotenes are unoxygenated (oxygen-free), such as alpha-carotene, beta-carotene and lycopene. In most cases, carotenes contain only carbon and hydrogen.

Carotenoids are known to be vital for "plant metabolism, growth and photosynthesis, and are a main dietary source of vitamin A in humans," explained Aaron G. Wheadon, distribution manager for North America and Asia, Kalsec Inc. "They are thought to be associated with reduced risk of several chronic health disorders, including some forms of cancer, heart disease and eye degeneration."

Leong added there are several specific types of cancer that carotenoids can help protect against: "Besides the well-known provitamin A activity of carotenoids, especially beta-carotene, consumption of carotenoids-rich fruits and vegetables has been associated with a reduction in risk of colorectal, lung, ovarian and other cancers.”

Jeane Vinson, sales and marketing manager, Cyanotech Corp., agreed, adding, "People consuming diets rich in carotenoids from natural foods, such as fruits and vegetables, are healthier and have lower mortality from a number of chronic illnesses."

However, carotenoids have also been shown to be effective in topical applications as well, specifically for their sun-protecting capabilities. "They are becoming increasingly popular for use in creams and lotions for their ability to naturally protect our skin externally from the harmful ultraviolet (UV) rays of the sun," Wheadon said. "Carotenoids play a critical role as protective agents. They function as quenchers of peroxyl and oxy radicals, as well as a photoprotective role by screening harmful light wavelengths. Through these mechanisms, they guard cellular structures and DNA against electron-scavenging free radicals."

Leong agreed, noting, "[there is evidence] that carotenoids and tocopherols prevent UV light–induced skin lesions and protect against skin cancer, and that skin carotenoid concentrations decrease with UV irradiation."

This useful protection is due to the antioxidant properties that carotenoids possess. "All carotenoids have antioxidant properties derived from the 'electron rich' polyunsaturated polyene chain," DePrince said.

Beta- and Alpha-Carotene

According to Leong, palm oil contains "the highest known concentration of naturally derived carotenoids [specifically beta-carotene]. In fact, crude palm oil is the world's richest natural plant source of carotenes in terms of retinol (provitamin A) equivalent." Leong stated it contains about 15 to 300 times as many retinol equivalents as carrots, leafy green vegetables and tomatoes, which are considered to have significant quantities of provitamin A activity. Researchers from Oleochemistry Research Center of Lion Corporation, Tokyo, studied the antioxidant effect of palm fruit carotene on skin lipid peroxidation.(1) Guinea pigs were orally fed ad libitum palm fruit carotene, beta-carotene or vehicle emulsions, in which carotene was suspended in drinking water. After treatment of carotene for 12 weeks, animals were exposed to UV, and squalene monohydroperoxide (the initial products of UV-peroxidated squalene; SqOOH)/squalene [Sq]) ratios in the skin lipid were analyzed. Carotene accumulation was found in the skin of guinea pigs that were orally administered palm fruit carotene or beta-carotene. After UV irradiation, especially immediately after, the rise in the SqOOH/Sq ratio was effectively suppressed in both carotene-drinking groups in contrast with the control (carotene-untreated) group. The results suggested palm fruit carotene intake prevents skin lipid peroxidation caused by UV irradiation.

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