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Am J Clin Nutr. 2000 Oct;72(4):1004-9.

Responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in pregnant and lactating women in Nepal.

Author information

1
Center for Human Nutrition, Department of International Health, The Johns Hopkins School of Hygiene and Public Health, Baltimore, MD, USA.

Abstract

BACKGROUND:

Impaired dark adaptation occurs commonly in vitamin A deficiency.

OBJECTIVE:

We sought to examine the responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in Nepali women.

DESIGN:

The dark-adapted pupillary response was tested in 298 pregnant women aged 15-45 y in a placebo-controlled trial of vitamin A and beta-carotene; 131 of these women were also tested at 3 mo postpartum. Results were compared with those for 100 nonpregnant US women of similar age. The amount of light required for pupillary constriction was recorded after bleaching and dark adaptation.

RESULTS:

Pregnant women receiving vitamin A had better dark-adaptation thresholds (-1.24 log cd/m(2)) than did those receiving placebo (-1.11 log cd/m(2); P: = 0. 03) or beta-carotene (-1.13 log cd/m(2); P: = 0.05) (t tests with Bonferroni correction). Dark-adaptation threshold was associated with serum retinol concentration in pregnant women receiving placebo (P: = 0.001) and in those receiving beta-carotene (P: = 0.003) but not in those receiving vitamin A. Among women receiving placebo, mean dark-adaptation thresholds were better during the first trimester (-1.23 log cd/m(2)) than during the second and third trimesters (-1.03 log cd/m(2); P: = 0.02, t test). The mean threshold of nonpregnant US women (-1.35 log cd/m(2)) was better than that of all 3 Nepali groups (P: < 0.001, t test, for all 3 groups).

CONCLUSIONS:

During pregnancy, pupillary dark adaptation was strongly associated with serum retinol concentration and improved significantly in response to vitamin A supplementation. This noninvasive testing technique is a valid indicator of population vitamin A status in women of reproductive age.

PMID:
11010944
[Indexed for MEDLINE]
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