Supplementation with iron and riboflavin enhances dark adaptation response to vitamin A-fortified rice in iron-deficient, pregnant, nightblind Nepali women.

BACKGROUND: Nightblindness affects 16-52% of pregnant women in areas of Nepal and in some cases persists after vitamin A treatment. Iron and riboflavin affect vitamin A utilization and photoreceptor function, respectively, and pilot data in the study population showed a high prevalence of iron and riboflavin deficiencies. OBJECTIVE: The objective was to assess the effect of supplemental iron and riboflavin on pupillary threshold (PT) and plasma retinol in nightblind, pregnant Nepali women given vitamin A-fortified rice. DESIGN: Nightblind pregnant women were randomly assigned to receive, 6 d/wk under supervision for 6 wk, a vitamin A-fortified rice curry dish providing 850 microg retinal activity equivalents/d with either a 30-mg Fe and 6-mg riboflavin (FeR + VA) capsule or a placebo control (VA only) capsule. Hemoglobin, erythrocyte riboflavin, and plasma ferritin and retinol were measured before and after the intervention. Dark adaptation was assessed by PT score. RESULTS: Women who were iron deficient at baseline (n=38) had significantly greater improvement in PT score with iron and riboflavin supplementation than without (P=0.05). Iron and riboflavin supplements significantly reduced the prevalences of riboflavin deficiency (from 60% to 6%; P<0.0001), iron deficiency anemia (from 35% to 15%; P<0.007), and abnormal PT (from 87% to 30%; P<0.05) from baseline. Mean increases in erythrocyte riboflavin (P<0.0001) and plasma ferritin (P=0.01) were greater in the FeR + VA group than in the VA only group. CONCLUSIONS: Iron deficiency may limit the efficacy of vitamin A to normalize dark adaptation in pregnant Nepali women. Further studies are needed to assess the effect of simultaneous delivery of iron and vitamin A for the treatment of nightblindness.

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.

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.