- Provitamin A (PVA) maize: Effect on dark adaptation and breast milk retinol in rural Zambia
In separate randomized trials, we assessed whether regular consumption of PVAmaize would increase 1) pupillary responsiveness (PR), a functional indicator of VA status, in children, and 2) breast milk retinol concentration (BMRC) in lactating women.
Children (4-8 y; n=542) received either PVA-maize or white-maize (2 meals/d, 6 d/wk for 6 m). PR, an objective measure of dark adaptation, was assessed pre- and post-intervention using a portable dark adaptometer. Lactating women (18-35 y; n=149) received either PVAmaize (600 µg retinol equivalents (RE)/d) plus placebo, white-maize plus retinyl-palmitate (600 µg RE/d), or white-maize plus placebo, (2 meals/d, 6 d/wk for 3 wk). BMRC was measured pre- and post-intervention.
Mean (± SD) PR was significantly poorer at baseline in the PVA-maize vs white-maize group (16.1% ± 6.6 vs 18.1% ± 6.4; p=0.02), but did not differ at follow-up (17.6% ± 6.5 vs 18.3% ± 6.5; p=0.99). PR increased [2.2% (95% CI: 0.1, 4.3) vs 0.2% (95% CI: -1.1, 1.5) in the PVA-maize vs white-maize group; p=0.01] among children with baseline serum retinol <1.05 μmol/L. Mean baseline BMRC was 0.95 µmol/L (95% CI: 0.86, 1.05); 56% of women had BMRC <1.05 μmol/L. Endline BMRC did not differ by group (p=0.13); the proportion of women with low milk retinol (<28 nmol/g fat) was 51.1%, 43.8%, and 26.1% in the white-maize, PVA-maize, and retinylpalmitate groups, respectively (p for trend=0.03).
Regular consumption of PVA-maize increased PR among children with marginal VA status, and tended to reduce the risk of low BMRC among women.
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