Efficacy of Vitamin A Fortified Rice in Lactating Thai Women

Vitamin A deficiency (VAD) remains a public health problem that occurs in children and women. WHO estimates that 190 million preschool age children (under five years of age) and 19.1 million pregnant women have inadequate concentrations of retinol . VAD may increase risk of morbidity and mortality during childhood, pregnancy and postpartum period . In developing countries, vitamin A status in lactating women is not optimal. Even in the United States, vitamin A status of low income pregnant women is marginal. Therefore, women of reproductive age are at risk of vitamin A depletion which compromises the vitamin A status of breastfed infants. Vitamin A is transferred to milk from both retinol binding protein bound and chylomicron associated vitamin A carriers. Because of teratogenicity of vitamin A, the transfer of vitamin A from pregnant mother to the fetus is carefully controlled. This results in all infants born with very low stores of vitamin A . Therefore human milk is still the best vitamin A source for infants. The concentration of vitamin A in breast milk is highest in the first 21 days postpartum (colostrum in the first 4-6 days and transitional milk in the next 7-21 days). Breast milk vitamin A concentrations and an infant's vitamin A status are based on maternal dietary intake. Breast milk retinol concentrations are a useful tool and a unique indicator for lactating women and represents extrapolations of vitamin A status of breastfed infant.

In high risk vitamin A deficiency areas, prior recommendation for lactating women was to give two doses of 200,000 IU vitamin A within 6 weeks post-delivery . However, the lack of impact evidence of this regimen led to the WHO's withdrawal of such recommendation as a public health policy .

Food-based intervention has been regarded as a sustainable approach to improve population vitamin A status. Most recently, vitamin A-depleted sows fed high-provitamin A carotenoid maize resulted in significant increase in liver stores in nursing piglets and significant higher milk retinol concentrations than sows fed white maize that given a high-dose vitamin A supplement .

Previous efforts to fortify staples or common vehicles with vitamin A offer promising solution to prevention of vitamin A deficiency in vulnerable population . Food fortified with vitamin A has potentials to improve women's vitamin A status and to increase the vitamin A concentrations of breast milk . Rice as the most important staple food in Thailand, represents the culture of consumption and lifestyle of Thai people . Recent study in Thai school children fed with extruded rice grains fortified with zinc, iron and vitamin A every weekday for 2 months, significantly increased liver stores of vitamin A, as assessed with a stable isotope technique . Likewise, fortification of rice with vitamin A may also benefit mothers during lactation.

The outcomes of this study will be useful to guide the promotion of food-based strategies to improve vitamin A status of mother and infant during lactation.