Increasing intakes of beta-carotene in the diet were associated with a 22% reduction in diabetes risk, according to findings published in Nutrition, Metabolism and Cardiovascular Diseases.
Researchers from the University Medical Center Utrecht and the Dutch National Institute for Public Health and the Environment (RIVM) also report that the highest intakes of alpha-carotene were associated with a 15% reduction in diabetes risk.
“Carotenoids are known to have antioxidant functions, which may underlie the observed inverse associations with diabetes,” they wrote. “It has been suggested that antioxidants such as carotenoids might be effective in reducing diabetes by reducing oxidative stress. Of all carotenoids addressed in this study, beta-carotene is known to be a strong antioxidant, which may explain the observed association with diabetes in our study.
“We also found an inverse association with alpha-carotene, which could possibly be explained by the high correlation between beta-carotene and alpha-carotene.”
The study was limited to dietary intakes, and did not consider supplemental intakes of carotenoids. The study also only shows correlation and not causation.
The Dutch researchers analyzed data from 37,846 people participating in the European Prospective Investigation into Cancer and Nutrition- Netherlands study. The mean total carotenoid intake of the participants was 10 mg/day.
During the 10 years of follow-up, the researchers documented 915 new cases of type 2 diabetes.
After crunching the numbers, the researchers found that greater dietary intakes of alpha- and beta-carotene were both associated with significant reductions in the risk of diabetes. On the other hand, other carotenoids, including beta-cryptoxanthin, lycopene, lutein and zeaxanthin did not affect diabetes risk.
Commenting on the potential antioxidant mechanism and a lack of an association for other carotenoids, and lycopene in particular, the researchers stated: “Even though lycopene was a major contributor to total carotenoid intake, we did not find an association of lycopene with diabetes risk. It is unclear why lycopene shows no association with diabetes in the present study. Relative validity for lycopene was higher than for beta-carotene, the bioavailability for lycopene and beta-carotene are comparable, and the range of intake for lycopene was wider than for beta-carotene. Therefore this unlikely explains why we were unable to find an association of lycopene with diabetes. The higher completeness of the food database for beta-carotene values of foods (92% for vegetables; 98% for fruits) than for lycopene values of foods (79% for both vegetables and fruits) may partly explain these differences.”
The study’s findings were welcomed by Bryan See, regional product manager for ExcelVite Inc, which supplies natural mixed carotenoids complex to the market that contains high levels of both alpha- and beta-carotene.
“This study shows us that among the six common dietary carotenoids, consuming high levels of alpha-carotene and beta-carotene leads to reduction of type 2 diabetes risk in healthy men and women, at the same time, smoking status does not alter the benefit,” he said.
Source: Nutrition, Metabolism and Cardiovascular Diseases
Volume 25, Issue 4, 376-381, doi: 10.1016/j.numecd.2014.12.008
“Dietary intake of carotenoids and risk of type 2 diabetes”
Authors: I. Sluijs, E. Cadier, J.W.J. Beulens, D.L. van der A, A.M.W. Spijkerman, Y.T. van der Schouw