Vitamin A Plus Lutein Can Slow Vision Decline in Retinitis Pigmentosa
Vitamin A and its precursor beta-carotene, have long been known to have eye-related health benefits, hence the saying that carrots are good for the eyes. In a new study conducted at the Harvard Medical School in Boston, researchers have found that daily lutein supplements in addition to Vitamin A can help slow progressive vision loss in nonsmoking patients with retinitis pigmentosa (RP).
Eliot L. Berson MD and colleagues studied a group of 225 nonsmoking patients with retinitis pigmentosa, an eye disease in which there is damage to the retina which progresses over time. The participants, divided into two groups, were given 15,000 IU per day of vitamin A palmitate plus 12 milligrams of lutein daily or the vitamin A plus placebo. The groups were evaluated to disease progression over a study period of four years.
Those given lutein had a slower loss of vision in the mid-peripheral visual field. Peripheral vision is the area of sight that occurs outside of the very center of vision. In RP, sight is generally lost in this region first as symptoms progress. The researchers estimated that visual sensitivity could be preserved for an additional three to ten years with lutein supplementation.
There is no current effective treatment for retinitis pigmentosa. The condition, which is caused by a number of genetic defects, occurs in about 1 in 4,000 people in the United States. Signs and symptoms often first begin in childhood, but severe vision problems do not usually develop until early childhood. Most people with RP are legally blind by age 40.
Nutritional therapies have been studied as a treatment to slow the progression of vision loss, although none have been clinically proven to cure the disease. Lutein is a carotenoid found in dark green leafy vegetables such as kale and spinach, and egg yolks. In addition to RP, lutein has also been studied in the eye disease macular degeneration (AMD) because the compound is highly concentrated in the macula of the eye.
The average American consumes only 1 to 2 milligrams of lutein per day, less than the 6 to 10 milligrams thought to have the most nutritional and health benefits.