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 palmitate

• Published in: The American journal of clinical nutrition 2005-02, Vol.81 (2), p.461-471
• Main Authors: Haskell, M.J, Pandey, P, Graham, J.M, Peerson, J.M, Shrestha, R.K, Brown, K.H
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; amaranth grain; Animals; beta-carotene; Biological and medical sciences; carrots; dark adaptation; Dark Adaptation - drug effects; Diet; dietary nutrient sources; Diterpenes; Female; Food, Fortified; fortified foods; goat meat; Goats; Humans; leaves; Liver - chemistry; livers as food; maternal nutrition; Meat; Medical sciences; Nepal; night blindness; Night Blindness - diet therapy; Night Blindness - drug therapy; nutritional intervention; Ophthalmology; Pregnancy; Pregnancy Complications - diet therapy; Pregnancy Complications - drug therapy; pregnant women; Retinyl Esters; retinyl palmitate; rice; Treatment Outcome; Vision disorders; vitamin A; Vitamin A - administration & dosage; Vitamin A - analogs & derivatives; Vitamin A - blood; Vitamin A - therapeutic use; Vitamin A Deficiency - diet therapy; Vitamin A Deficiency - drug therapy; vitamin supplements
• ISSN: 0002-9165; 1938-3207
• 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 microgram retinol equivalents/d as retinyl palmitate, vitamin A-fortified rice, goat liver, amaranth leaves, or carrots or 2000 microgram 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 micromol/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.