Recovery from impaired dark adaptation in nightblind pregnant Nepali women who receive small daily doses of vitamin A as amaranth leaves, carrots, goat liver, vitamin A–fortified rice, or retinyl palmitate2

• Published in: The American journal of clinical nutrition 2005-02, Vol.81 (2), p.461-471
• Main Authors: Haskell, Marjorie J, Pandey, Pooja, Graham, Joanne M, Peerson, Janet M, Shrestha, Ram K, Brown, Kenneth H
• Format: Article
• Language: English
• Subjects: dark adaptation; food-based interventions; Nepal; Nightblindness; pregnancy; pupillary threshold; supplementation; vitamin A; vitamin A status; β-carotene
• ISSN: 0002-9165
• DOI: 10.1093/ajcn.81.2.461

Background: It is not known whether daily consumption of vitamin A–containing foods is efficacious for treating nightblindness. Objective: We assessed the effect of supplementation with vitamin A from food or synthetic sources on dark adaptation and plasma retinol concentrations in nightblind pregnant Nepali women. Design: Nightblind pregnant women were randomly assigned to 1 of 6 treatment groups to receive 6 d/wk for 6 wk either 850 μg retinol equivalents/d as retinyl palmitate, vitamin A–fortified rice, goat liver, amaranth leaves, or carrots or 2000 μg retinol equivalents/d as retinyl palmitate. Dark adaptation was assessed weekly by using the pupillary threshold (PT) test; plasma retinol concentrations were measured before and after the intervention. These outcomes were also assessed in a comparison group of nonnightblind pregnant women. Results: In the nightblind women, the mean PT improved significantly ( P < 0.0001) from −0.71 ± 0.04 to −1.42 ± 0.02 log cd/m2, and the final mean PT did not differ significantly from that in the nonnightblind women (−1.43 ± 0.04; P = 0.55). Improvement in dark adaptation was greater in the liver group than in the vitamin A–fortified rice group ( P < 0.02). Plasma retinol concentrations increased significantly ( P < 0.0001) from 0.95 ± 0.05 to 1.07 ± 0.05 μmol/L. The plasma retinol response was greater in the higher-dose capsule and liver groups than in the vegetable groups and significantly greater in the liver group than in the vitamin A–fortified rice group (both: P < 0.05). Conclusion: Improvement in dark adaptation did not differ significantly between women who received vitamin A as liver, amaranth leaves, carrots, or retinyl palmitate.