Serum levels of retinol, beta-carotene, and alpha-tocopherol in older adults.

Levels of retinol, beta-carotene, and alpha-tocopherol were determined in the serum of 415 adults over age 35 years who had volunteered in 1974 to donate blood for cancer research in Washington County, Maryland. Males had higher levels of serum retinol, lower levels of beta-carotene, and only slightly lower levels of alpha-tocopherol than did females. No clear-cut association was noted with age. Smokers had decreased serum levels of beta-carotene. Vitamin supplementation was associated with higher serum levels. Persons taking medication for high blood pressure had higher levels of retinol and alpha-tocopherol, but lower levels of beta-carotene.