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Alpha-Carotene in Yellow, Green Vegetables Extends Life


Move over, beta-carotene, and let alpha-carotene show us what it can do to extend your life. A team of researchers from the Centers for Disease Control and Prevention (CDC) report that high levels of alpha-carotene, found in yellow and green vegetables, appear to reduce the risk of dying over a 14-year period.

The antioxidant alpha-carotene trumps beta-carotene

Alpha-carotene belongs to a category of plant pigments and nutrients known as carotenoids, a group that also includes beta-carotene, lycopene, lutein, astaxanthin, and zeaxanthin. These antioxidants help fight oxygen-related damage to the body’s cells that can lead to the development of heart disease, cancer, neurodegenerative disorders, macular degeneration, and other serious conditions.

Convincing people to eat more carotenoid-rich fruits and vegetables to help lower their risk of chronic diseases has not proven to be very successful. Studies of beta-carotene supplements, however, have not provided convincing evidence that they can help with this goal.

This led the authors of the current study to remark that “Carotenoids other than beta-carotene may contribute to the reduction in disease risk, and their effects on risk of disease merit investigation.” They chose to evaluate alpha-carotene, drawing on data gathered from 15,318 participants in the Third National Health and Nutrition Examination Survey Follow-up Study.

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Study participants had provided blood samples between 1988 and 1994, and the subjects were followed-up through 2006. Chaoyang Li, MD, PhD, of the CDC, and his colleagues discovered that 3,810 participants had died, and that the risk of dying was lower with higher levels of alpha-carotene in the blood.

Specifically, compared with subjects who had blood alpha-carotene levels ranging from 0 to 1 micrograms per deciliter (mcg/dL), the risk of death during the study period was 23 percent lower among individuals with concentrations between 2 and 3 mcg/dL, 27 percent lower at 4 to 5 mcg/dL, 34 percent lower at 6 to 8 mcg/dL, and 39 percent lower at levels 9 mcg/dL or greater.

Higher levels of alpha-carotene were associated with a lower risk of dying from cardiovascular disease or cancer individually, and of all other causes. This lower risk held up when the authors considered factors such as lifestyle habits, demographic characteristics, and overall health risks.

Alpha-carotene, like beta-carotene and about 50 other carotenoids in the 600-plus carotenoid family, are called “provitamin A” compounds because the body can transform them into an active form of vitamin A. Therefore, foods that contain carotenoids can help prevent vitamin A deficiency.

The study’s authors note that although alpha-carotene is chemically similar to beta-carotene, it may be better at preventing cancer cell growth. They also point to research showing that eating foods high in alpha-carotene, such as yellow-orange (e.g., carrots, pumpkin, sweet potatoes) and dark-green (e.g., green peas, broccoli, spinach, green beans) vegetables is strongly associated with a reduced risk of lung cancer when compared with eating other types of vegetables.
Including more yellow and green vegetables rich in alpha-carotene in your daily menu could help extend your life. Just one more reason to eat more vegetables.

Archives of Internal Medicine, published online November 22, 2010; doi:10.1001/archinternmed.2010.440