Anti-Glare Effects of Lutein, Zeaxanthin;
Vitamin D for Artery Health

Scientists Examine Lutein's Effect on Glare

New research indicates that the carotenoids lutein and zeaxanthin may help our vision when we have difficulty seeing due to the glare encountered in very bright light (1).

These two carotenoids have been shown to slow down the progression of moderate to advanced age-related macular degeneration) in the AREDS trial. But in this new study, lutein and zeaxanthin appear to improve visual function even in healthy people with normal vision.

Researchers from the University of Georgia recruited 40 healthy young people (average age of about 24 years), and examined their reaction to glare. Glare is commonly encountered in bright sunlight, when staring at a computer monitor, and when facing the bright beams of oncoming headlights.

The investigators determined lutein and zeaxanthin's effects on glare by studying how the carotenoids affected macular pigment density. The eye's macula is made up of lutein and zeaxanthin, which help filter out certain damaging light waves. When the concentration of these carotenoids in the macula is higher, the macula is better able to absorb these light waves. Taking lutein and zeaxanthin increased the density of macular pigment significantly after six months of supplementation.

When the study volunteers performed visual tasks following exposure to glare, lutein and zeaxanthin supplements significantly reduced the damaging effects of the exposure for both of the visual performance tasks that were measured.

Improved Visual Performance under Glare

The researchers concluded, "Four to six months of 12 mg daily lutein plus zeaxanthin supplementation significantly increases macular pigment density and improves visual performance in glare for most subjects."

How can we achieve the level of lutein and zeaxanthin tested in this study? By consuming good sources of these carotenoids such as leafy green vegetables, corn, egg yolks, squash, broccoli and peas, and augmenting those foods with daily supplementation of lutein and zeaxanthin.

Vitamin D Status Linked to Artery Health

Increased levels of vitamin D may improve cardiovascular health and reduce the prevalence of peripheral arterial disease, or "PAD", suggests a new study (2). People who suffer from PAD often experience decreased blood flow in their legs. PAD occurs when arteries in the legs become narrowed or clogged with fatty deposits. According to 2008 statistics from the American Heart Association, PAD affects about 8 million Americans and is associated with significant disease and death.

In the new study, researchers looked at over 4,800 participants of the National Health and Nutrition Examination Survey (NHANES). They found that people with higher blood levels of vitamin D were far less likely to have PAD.

Blood samples from the NHANES participants were divided into 4 groups according to the concentration of vitamin D in the samples. The investigators found that the higher the level of vitamin D, the lower the risk for this artery disease. In fact, PAD was 64% more common in the group with the lowest compared with the highest blood levels of the vitamin.

How Might Vitamin D Lower Risk for PAD?

According to the study's lead author, vitamin D might directly affect blood vessels. We know that in laboratory animals vitamin D regulates one of the hormone systems that effects blood pressure. It may affect this same hormone system in humans too. The authors also point out that the study does not prove that increased levels of vitamin D protect against PAD directly. However, they called for large randomized clinical trials to test whether vitamin D supplementation offers protection against PAD.

References

1. Stringham JM, Hammond BR. Macular pigment and visual performance under glare conditions. Optometry Vision Science 85:82-8, 2008.
2. Melamed VL, et al. Serum 25-hydroxyvitami D levels and the prevalence of peripheral arterial disease. Results from NHANES 2001-2004. Arteriosclerosis, Thrombosis and Vascular Biology Epub April, 2008.