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

Am J Clin Nutr. 2005 Feb;81(2):461-71. doi: 10.1093/ajcn.81.2.461.

Abstract

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 microg retinol equivalents/d as retinyl palmitate, vitamin A-fortified rice, goat liver, amaranth leaves, or carrots or 2000 microg 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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Dark Adaptation / drug effects*
  • Diet*
  • Diterpenes
  • Female
  • Food, Fortified
  • Goats
  • Humans
  • Liver / chemistry
  • Meat
  • Nepal
  • Night Blindness / diet therapy*
  • Night Blindness / drug therapy
  • Pregnancy
  • Pregnancy Complications / diet therapy*
  • Pregnancy Complications / drug therapy
  • Treatment Outcome
  • 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

Substances

  • Diterpenes
  • Vitamin A
  • retinol palmitate