Spotlight on Lutein, Part II

The last issue of Staying Healthy discussed the role of lutein in protecting vision as we age. Lutein is the antioxidant carotenoid found in green leafy vegetables. Now, a study published in this month's journal of the American Heart Association, Circulation, suggests that lutein also plays a key role in helping protect against atherosclerosis.

In atherosclerosis, fatty material accumulates under the inner lining of artery walls causing them to become thicker and less elastic. The disease develops slowly, until arteries become narrow and obstructed. When it develops in the carotid arteries, atherosclerosis can lead to stroke. In the coronary arteries, it can result in heart attack. Atherosclerosis is the leading cause of illness and death in the United States and most other Western countries.

Carotenoids are believed to be responsible for some of the cardiovascular protective effects of a diet high in fruits and vegetables. In The Los Angeles Atherosclerosis Study, researchers from USC and UCLA measured the levels of lutein in the plasma of 460 healthy men and women. They also used ultrasound to determine the thickness of their carotid arteries. When these measurements were repeated 1 1/2 years later, thickening of the carotid artery lining had increased significantly in those with the lowest plasma levels of lutein. In contrast, progression of this thickening was blocked in people with the highest lutein concentrations.

Further studies were conducted to understand how lutein might be working. In a cell study, they found that lutein reduced the inflammatory response of cells called monocytes to LDL cholesterol trapped in the artery wall. This inflammatory response is part of the process leading to plaque formation and artery narrowing. In the second experiment, lesions in the aorta's of mice with the genetic predisposition to deposit fat in artery walls were reduced by 44% only in those that had lutein added to their food.

According to the lead investigator, Dr. James Dwyer, "Our findings in epidemiological, in vitro, and in vivo investigations suggest that lutein may be a potent protective factor against the progression of atherosclerosis in humans and animals."

Reference
Dwyer JH, Navab M, Dwyer KM, et al. Oxygenated carotenoid lutein and progression of early atherosclerosis: the Los Angeles Atherosclerosis Study. Circulation. 2001;103:2922-2927.