Researchers from the Centers for Disease Control and Prevention (CDC) write in the Archives of Internal Medicine that if the results are replicated in future studies, than the the potential health benefits of elevated alpha-carotene levels should be studied in clinical trials.
“In this prospective study of a nationally representative sample of US adults over a mean follow-up period of 13.9 years, we found that serum alpha-carotene concentrations were inversely associated with risk of death from all causes, CVD, cancer, and all causes other than CVD and cancer,” wrote the researchers, led by Dr Chaoyang Li CDC in Atlanta.
“The negative association between serum alpha-carotene concentrations and overall risk of death was also significant in most subgroups stratified by demographic characteristics, lifestyle habits, and health risk factors,” they added.
Antioxidants
Carotenoids, including beta-carotene, alpha-carotene and lycopene, are vitamin A precursors that act as antioxidants – and may counteract oxidative damage to the body, which plays a role in the development of chronic diseases such as heart disease and cancer.
Li and colleagues said that in the past several decades, beta-carotene has received attention for its possible role in the prevention of several chronic diseases, including cancer and cardiovascular disease.
Although alpha-carotene is chemically similar to beta-carotene, the authors noted that studies have suggested that alpha-carotene is around ten times more effective than beta-carotene in inhibiting the development of cancer cells, and that it has more potent results in reducing the effects of liver cancer, and inhibiting the tumor-promoting actions of glycerol in lung carcinogenesis and skin tumors.
However, relatively few studies have directly examined the association between alpha-carotene concentrations and the risk of cancer or CVD, and findings from the number of limited number of studies on the association between serum or plasma alpha-carotene concentrations and risk of death have been inconsistent.
To assess the association between alpha-carotene levels in the body, and the risk of death from all causes, CVD, and cancer, the authors assessed the direct relationship between alpha-carotene concentrations and risk of death among 15,318 US adults in the Third National Health and Nutrition Examination Survey Follow-up Study (NHANES III).
Significant association
The authors reported significant associations between serum alpha-carotene concentrations and risk of death from CVD, cancer, and all other causes.
They reported the overall risk of death during the study to reduce by up to 39 percent for those individuals with a blood alpha-carotene levels of 9 micrograms per deciliter or higher, when compared with individuals with a blood alpha-carotene level of between 0 and 1 micrograms per deciliter.
The risk of death during the study period was reported to be 23 percent lower among those who had concentrations between 2 and 3 micrograms per deciliter, 27 percent lower with levels between 4 and 5 micrograms per deciliter, and 34 percent lower with levels between 6 and 8 micrograms per deciliter.
“Consistent with findings from previous studies our results showed an especially strong association between serum alpha-carotene concentrations and risk for death from some specific causes, including cancers of the aero digestive track, diabetes, and chronic lower respiratory disease,” stated the researchers.
Health benefits
Li and co workers concluded that their findings, based on data from a large representative sample of US adults, “showed that serum alpha-carotene concentrations were inversely associated with the risk of death from all causes and death from CVD, cancer, and all causes other than CVD and cancer.”
They added that the inverse association was independent of demographic characteristics, lifestyle habits, and traditional health risk factors, and indicated that the data supports increasing fruit and vegetable consumption as a means of preventing premature death and suggest a need for clinical research into the health benefits of alpha-carotene.
Source: Archives of Internal Medicine
Published online ahead of print, doi: 10.1001/archinternmed.2010.440
“Serum a-Carotene Concentrations and Risk of Death Among US Adults: The Third National Health and Nutrition Examination Survey Follow-up Study”
Authors: C. Li, E.S. Ford, G. Zhao, L.S. Balluz, W.H. Giles, S. Liu