The contribution of plant foods to the vitamin A supply of lactating women in Vietnam: a randomized controlled trial

Abstract

Background:More information is needed on the efficacy of carotenoids from plant foods in improving vitamin A status.Objective:We aimed to quantify the efficacy of provitamin A–rich vegetables and fruit in improving vitamin A status.Design:Breastfeeding women in 9 rural communes in Vietnam were randomly allocated to 1 of 4 groups: the vegetable group (n= 73), which ingested 5.6 mg β-carotene/d from green leafy vegetables; the fruit group (n= 69), which ingested 4.8 mg β-carotene/d from orange or yellow fruit; the retinol-rich group (n= 70), which ingested 610 μg retinol/d from animal foods and 0.6 mg β-carotene/d; and the control group (n= 68), which ingested 0.4 mg β-carotene/d. Meals of groups 1, 2, and 4 contained <30 μg retinol/d. Lunch and dinner were provided 6 d/wk for 10 wk.Results:Mean (95% CI) changes in serum retinol concentrations of the vegetable, fruit, retinol-rich, and control groups were 0.09 (0.03, 0.16), 0.13 (0.07, 0.19), 0.25 (0.17, 0.33), and 0.00 (−0.06, 0.06) μmol/L, respectively. Mean (95% CI) changes in breast-milk retinol concentrations were 0.15 (0.04, 0.27), 0.15 (0.02, 0.28), 0.48 (0.32, 0.64), and −0.06 (−0.21, 0.09) μmol/L, respectively. According to these findings, the equivalent of 1 μg retinol would be 12 μg β-carotene (95% CI: 8, 22 μg) for fruit and 28 μg β-carotene (17, 84 μg) for green leafy vegetables. Thus, apparent mean vitamin A activity of carotenoids in fruit and in leafy vegetables was 50% (95% CI: 27%, 75%) and 21% (7%, 35%), respectively, of that assumed.Conclusion:The bioavailability of carotenoids from vegetables and fruit is less than previously assumed.