Low blood levels of vitamin E could lead to a greater risk of physical decline in old age, a new study says.

Benedetta Bartali, a nutritionist and a Brown-Coxe postdoctoral fellow at Yale University’s School of Medicine, and her team randomly selected 700 people over the age of 65 who were already participating in a longitudinal study in Tuscany, Italy. After analyzing blood samples and the results of physical function tests, researchers discovered that the only factors that affected physical decline were age and vitamin E levels. Vitamin E acts as an antioxidant that may help to reduce the development of atherosclerosis and other conditions, Bartali said.

According to the U.S. National Institutes of Health, the recommended daily dose of vitamin E is 15 milligrams, or 22.5 International Units. Excessive amounts of vitamin E can be harmful, however, so researchers warn against taking more than 400 International Units. Results of the study are published in the Jan. 23 issue of the Journal of the American Medical Association.