Study: Vitamin A (2000) and Night Blindness



Learn more about night blindness.

Researchers examined the effectiveness of treating Napali women with vitamin A and beta-carotene supplements to counter the effects of night blindness, known to researchers as "dark-adaptation threshold."

298 pregnant women aged 15-45 who experienced varying degrees of night blindness were tested in a placebo-controlled study examining the benefits of supplementation with vitamin A and beta-carotene. Almost half of them were also tested three months after they gave birth. The results were compared to 100 similarly aged American women who were not pregnant. The degree of night blindness was evaluated by looking at the amount of light needed for the pupils of the eyes to constrict after suddenly being exposed to light. The effectiveness was also evaluated by measuring blood retinol concentrations.

The researchers found that the women who were give vitamin A performed better than those receiving a placebo. The American women had better natural night vision than did the Nepali women.

The researchers concluded that successful adaption to changes in light were closely tied to serum (blood) retinol levels and markedly improved with vitamin A supplementation.

Researchers: Congdon NG, Dreyfuss ML, Christian P, Navitsky RC, Sanchez AM, Wu LS, Khatry SK, Thapa MD, Humphrey J, Hazelwood D, West KP Jr. Source Center for Human Nutrition, Department of International Health, The Johns Hopkins School of Hygiene and Public Health, Baltimore, MD, USA.

Published: Responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in pregnant and lactating women in Nepal, Am J Clin Nutr. 2000 Oct;72(4):1004-9.