A lpha-carotene, the often-overlooked cousin of more familiar beta-caro- tene, may help you live longer-and further explain the health benefts of eating vegetables and fruits. Researchers at the CDC, studying data on more than 15,000 adults from a national nutrition survey, report that people with the highest blood levels of alpha-carotene were 39% less likely to die from all causes over almost 14 years.
Carotenoids, a group of more than 600 compounds that includes alpha-car- otene, beta-carotene, lutein and lycopene (see page 8), are the red, orange and yel- low pigments that give fruits and vegeta- bles their colorful appearance. Alpha- and beta-carotene and beta-cryptoxanthin are called provitamin A carotenoids, or vitamin A precursors, because the body converts them into vitamin A. Although chemically similar to beta-carotene, alpha-carotene has been shown to be more effective at inhibiting certain cancer cells. Trials of beta-carotene in preventing cancer and heart disease have been disappointing, but the new fndings may spark interest in further research on alpha-carotene.
Chaoyang Li, MD, PhD, of the CDCs Division of Behavioral Surveillance, and colleagues looked at associations between blood levels of alpha-carotene and death rates in data from the Third National Health and Nutrition Examination Survey (NHANES) Follow-up Study. Of the 15,318 adults in their study, over an average follow-up of 13.9 years 3,810 died.
With higher blood levels of alpha- carotene, Dr. Li and colleagues saw a steady reduction in overall mortality risk compared to those with the lowest levels. The association between alpha-carotene and reduced mortality risk held for deaths from cardiovascular disease, cancer and all other causes, even after adjusting for other lifestyle and risk factors.
Consistent with fndings from previ- ous studies, Dr. Li and colleagues reported in Archives of Internal Medicine, our results showed an especially strong association between serum [blood] alpha-carotene concentrations and risk for death from some specifc causes, including cancers of the aero-digestive tract, diabetes and chronic lower respiratory dis- ease. (Cancers of the aero-di- gestive tract include those of lip, oral cavity and pharynx, larynx, esophagus, stomach, colon and rectum, liver and pancreas.)
The findings add further support to previous fndings that fruit and vegetable consumption is benefcial to peoples health, researchers added. Our results, if replicated in other studies and populations, suggest a need for clinical research into the health benefts of serum alpha- carotene.
As an observational study, the research was not designed to prove cause and effect. Clini-cal trials, which can correct for confound- ing factors, are often not as positive as such population studies-as was the case with previously encouraging fnd- ings about beta-carotene. But neither type of study is per- fect, and scientists evaluate the combination of evidence. In the meantime, given the proven health positives of consuming produce–including foods rich in alpha-carotene- these results provide another nutritional nudge to eat a rainbow of vegetables and fruits.
Alpha-carotene is found in yellow-orange produce as well as some green vegetables. Among foods highest in alpha-carotene, according to the USDA:
- Carrots and carrot juice
- Winter squash
- Vegetable juice cocktail
- Collard greens
- Snap beans
- Cornmeal and corn
- Sweet potatoes
- Bell peppers
Archives of Internal Medicine, online before print; abstract at <dx.doi.org/10.1001/archinternmed. 2010.440>