Food-based approaches for controlling vitamin A deficiency : studies in breastfeeding women in Indonesia

Micronutrient deficiencies seriously hinder mental and physical development and are still an important cause of death in developing countries. Therefore, goals have been set worldwide for the year 2000: to eliminate deficiencies of vitamin A and iodine and to reduce prevalence of iron deficiency anemia in women by onethird of 1990 levels. Food-based approaches for the control of micronutrient deficiencies, using foods naturally rich in micronutrients and/or fortified foods, are preferable, because a pharmaceutical approach can only reach a selective group and is less sustainable. This thesis describes research on the role of foods for improving vitamin A status of breastfeeding women in Indonesia.

In developing countries, people derive 80-85% of vitamin A from plant sources in the form of provitamin A carotenoids, which the body converts to vitamin A. Preformed vitamin A, retinol, exists only in animal foods and accounts for 15-20% of vitamin A intake. Our questionnaire confirmed that dark-green leafy vegetables are the most important source of vitamin A. However, feeding a portion of dark-green leafy vegetables daily for 12 weeks did not improve vitamin A status, while it improved after feeding a wafer enriched with the same amount of β-carotene. This, as well as results from other carefully controlled studies, contradicts the assumption that vegetables rich in provitamin A carotenoids can play an important role in the control of vitamin A deficiency. Causes of poor bioavailability of vegetable carotenoids could include: complex matrix of leaves; absorption inhibitors, such as fibre which entraps carotenoids, or other carotenoids which may compete for absorption; parasitic infestation; and genetic and/or dietary factors.

A very limited effect on vitamin A status should not lead to the conclusion that promoting the consumption of dark-green leafy vegetables is no longer necessary, but food approaches should be based on a variety of foods. Also, factors to calculate vitamin A activity of carotenoids should be reconsidered. In addition, we conclude that vitamin A intake questionnaires, which could be very simple, should only be used to estimate the risk of poor vitamin A status at community level. Vitamin A status and changes in status are best assessed by measuring serum retinol. The measurement of serum β-carotene is recommended for evaluating food-based interventions, because it is very responsive.