NEWSLETTER #25

Colorful Carotenoids

For Prevention And Optimal Health

By Marcia Zimmerman, MEd, Cn

From alpha carotene all the way through to zeaxanthin, fat-soluble carotenoids serve a variety of functions that enhance good health and help prevent disease. Hundreds of studies have shown that carotenes have diverse nutritional benefits including antioxidant protection against certain cancers, cardiovascular disease, cataracts, and macular degeneration. Carotenes also boost immune function, enhance intercellular communication--essential for proper cell functioning--and help regulate normal cellular growth and reproduction.

Provitamin A

Thirty-four carotenoids have been identified in humans. However, only four of them--alpha, beta, and gamma carotenes, plus beta cryptoxanthin--can be converted into vitamin A, or retinol, in the body. Unlike vitamin A, they do not build up to toxic levels in the body, so their conversion into A is a safe way to meet our vitamin A requirements.

Some experts believe this is a major consideration for pregnant women. During the rapid embryonic development in the second to fifth weeks of pregnancy, at least one study links high intakes of vitamin A (more than the RDA of 4,000 IU) with fetal abnormalities. Fortunately, there has been no evidence of teratogenic (birth defects), mutagenic (DNA damage), or carcinogenic (cancer) effects from carotene supplements in animal studies. Paradoxically, vitamin A deficiency can become a problem in the last trimester of pregnancy, when too little of this vitamin can cause preterm delivery.

Furthermore, long-term supplementation of beta carotene, even among people with adequate vitamin A levels, has not led to increased vitmain A stores. As nature intended, the provitamin carotenes are converted into vitamin A only on an as-needed basis.

Other Important Functions

A growing body of scientific evidence shows that taking a number of carotenoids offers numerous protective benefits. They are powerful free radical quenchers and enhance the effects of other antioxidants including vitamin C and vitamin E. Because each works a different way, the water-soluble antioxidants seem to be more effective in combination with several of the fat-soluble carotenoids.

Immune Enhancement

Activating immunity without stimulating increases in one kind of immune cell over another is the safest way to prevent disease. Carotenes boost immunity by stimulating a variety of immune cells. In one study, scientists showed that long-term beta carotene supplementation enhanced immune activity in men, with the effect most pronounced among older individuals. Other research finds that several kinds of immune cells become more aggressive with beta carotene supplementation.

Antiaging and Cancer Prevention

High blood levels of carotenes are repeatedly linked with longevity. Damage to DNA and poor DNA repair are the ultimate aging factors. DNA strand breaks that occur in lymphocytes (white blood cells) significantly compromise immune response, leading to several age-related conditions. Carotenes help prevent aging by reducing the number of DNA strand breaks that would otherwise lead to mutations, the formation of premalignant lesions, and their eventual progression into cancer. Taking beta carotene supplements (30 mg/day, or 30,000 IU) has been shown to protect chromosomes (DNA), even when they are exposed to radiation.

A failure in signaling between cells may be another cause of cell overgrowth and cancer. By stimulating intercellular communication, carotenoids protect normal biological functions.

They may even prevent cancers. A study of 826 New Yorkers found that those non-smokers with the greatest intake of beta carotene-rich foods were significantly less likely to get lung cancer. Scientists have also found that carotenoids protect against cancers of the mouth.

A growing body of research links lycopene, a carotenoid found in cooked tomatoes, with lower incidence of several cancers, including those of the breast, cervix, colon, endometrium, lung, prostate, and stomach. "Lycopene is one of the most potent free-radical scavengers in nature," says Paul LaChance, PhD, professor of food science and nutrition at Rutgers University.

The lungs are particularly susceptible to oxidative stress from free radicals. Research at the University of North Carolina, Chapel Hill, recently found that daily tomato juice or spaghetti sauce combined with vitamins C and E mitigated DNA damage and loss of lung function in people exposed to high ozone levels.

Cardiovascular Health

Several large, long-term studies show that carotenoids protect against heart disease. A 14-year study of 123 men and women found that the risk of heart attack in smokers was significantly increased as blood levels of carotenoids decrease. Another long-term study discovered that those with the highest blood levels of carotenoids had the lowest risk of coronary heart disease. Scientists at the Centers for Disease Control in Atlanta found that, among 11,327 men and women, those with the highest levels of alpha and beta carotene and beta cryptoxanthin were significantly less likely to suffer the pains of angina pectoris, a serious symptom of coronary artery blockage.

For Eyes And Skin

Although beta carotene is more popularly used as a sun-protective supplement, a combination of beta carotene and vitamin E appears to protect better against sunburn, according to nutritional biochemist Dr. Wilhelm Stahl and colleagues at Heinrich Heine University in Dusseldorf, Germany. And mixed carotenoid supplements produce higher tissue levels of carotenoids in the areas of the body most likely to get sun-burned: the back, forehead, and arms.

Particularly effective in protecting the eyes from photosensitization at the water's surface, astaxanthin

(a carotenoid apparent in the red color of crab, salmon, and shrimp) is absorbed into the light-sensitive eye tissues. Astaxanthin appears 10 times as effective against oxygen free radicals as other carotenoids--and 100 times more effective at trapping free radicals than vitamin E. No wonder this newly discovered carotenoid is considered the "find" of the 21^st century.

Available in dark green, leafy vegetables, zeaxanthin and a closely related carotenoid lutein can reduce the risk of macular degeneration by as much as 43 percent, finds Johanna Seddon, MD, at the Massachusetts Eye and Ear Infirmary, who studied the connection between diets high in dark green, leafy vegetables and development of this vision disorder. These carotenoids are concentrated in the macula, a tiny yellow spot in the back of the eye that's damaged in macular degeneration.

"Lutein and zeaxanthin are the only carotenoids in the lens, just they are the only carotenoids in the macula," says Billy Hammond, PhD, professor of vision science at the University of Georgia. Elderly people with high levels of these two carotenoids have "very youthful vision," he adds.

Analyzing 10 years' worth of data gathered from 492 nurses, Allen Taylor, PhD, and colleagues at Tufts University in Boston find that both carotenoids and vitamin C protect against cataract formation. The greatest reduction in cataract formation (60 percent) was afforded nonsmokers who took supplements of vitamin C (at least 362 mg/day), while consuming a high intake of carotenoid-rich foods.

Right To The Souce

Since eating a wide variety of whole foods will provide all the carotenoids, a diet of brightly colored fruits and vegetables is wise. Cooking or juicing helps release the carotenoids in foods, making them more available as nutrients.

Supplements often provide carotenoids in a more bioavailable form. Consider a natural mix of carotenoids in supplements, rather than simply beta carotene, for the greatest protection. For dosage, studies on the antioxidant benefits of carotene supplement use anywhere from 20,000 to 35,000 IU of carotenes.

Author of The ADD Nutrition Solution, Eat Your Colors, and Reverse Aging (the latter with Ronald Pero, PhD), contributing editor Marcia Zimmerman is a respected nutrition expert.

Selected Sources

*Biochemical and Physiological Aspects of Human Nutrition by Martha Stipanuk, PhD

*"Carotenoids and Carotenoids plus Vitamin E Protect against Ultraviolet Light-Induced Erythema in

Humans" by Wilhelm Stahl

*The Color Code by James A. Joseph, PhD

*Dietary Reference Intakes for Vitamin C, Vitamin E, Slenium, and Carotenoids by Norman Krinsky

*"Identification, Quantification, and Relative Concentrations of Carotenoids and Their Metabolites in

Human Milk and Serum" by Frederick Khachik

*"Serum Vitamins, Carotenoids, and Angina Pectoris: Findings from the National Health and Nutrition

Examination Survey III" by E.S. Ford and W.H. Giles