Print Digg


Lutein, Zeaxanthin and Acute Myocardial Infarction Risk

Friday, May 07, 2004

One of yesterday's headline read "Lutein, zeaxanthin could increase heart attack risk." Once again, an overly zealous health reporter has chosen to go for dramatic headlines instead of scientific accuracy by overstating the risk involved in a carotenoid study published in the July 2005 issue of The Journal of Nutrition.

The subjects in this study were Hispanic Americans of Mestizo background who lived in the central valley of Costa Rica between 1995 and 2004 and who were diagnosed survivors of a first acute MI by 2 independent cardiologists from the 6 recruiting hospitals in the catchment area. The control subjects came from the same population, but had no history of previous MI.

More study cases than controls were current smokers and more of the study cases had a previous history of diabetes and hypertension. Compared with controls, study cases also had greater waist-to-hip ratios (abdominal obesity); lower incomes; higher intakes of saturated fat, lutein and zeaxanthin; and lower intakes of polyunsaturated fat, and tocopherols. A lower proportion of study cases consumed alcohol at the time of the study compared with controls. Adipose tissue concentrations of the full-spectrum of carotenoids were initially lower in study cases than controls.

This interesting study found that beta carotene in adipose tissue, but not in the diet is associated with a decreased risk of nonfatal acute MI, whereas these researchers suggest lutein + zeaxanthin may be positively associated with a slightly increased risk of MI.

It's important to note that the major sources of dietary lutein and zeaxanthin were identified as celery; eggs, broccoli, salsa, peppers, spinach, oranges, yellow squash, avocado and cilantro; all of which are considered excellent sources of dietary carotenoids. Surprisingly, cooked spinach and yellow squash were associated with the highest risk of MI in this study. One possible explanation is that these two foods could be associated with undesirable chemical substances such as agricultural pesticides, which have been found in these two vegetables, as well as in sweet potatoes in the United States and Costa Rica, but why this is not the case in other dietary carotenoids is difficult to explain.

This particular study suggests that inverse associations between dietary antioxidants and intermediate cardiovascular end points, as well as markers of inflammation, may indicate that if dietary carotenoids and tocopherols are protective, their effect may be small and probably more important at the beginning of the disease process.

Ellen Troyer, MT, MA - Biosyntrx Chief Research Officer
Spencer Thornton, MD - Biosyntrx President