Rationale for multiple fortification

Nearly all fortified processed foods contain more than one added micronutrient. Milk products are often fortified with vitamins A and D only, whereas other beverages are often fortified with many minerals and vitamins. Multiple fortification of different types of beverages can be justified for a number of reasons. Virtually all broad-based nutrition surveys show that individual micronutrient deficiencies rarely occur in isolation. Since many major foods are excellent sources of several micronutrients, inappropriate food choices and economic constraints leading to unbalanced diets are unlikely to provide adequate levels of all micronutrients.

The existence and extent of the deficiencies of some micronutrients remain largely unknown, partly because of lack of adequate survey data, but also largely because of the absence of easily measurable, sensitive, and specific indicators of micronutrient status. Although the existence of such status indicators has allowed estimation of the dimension of deficiencies of iron, vitamin A, and iodine, this is not the case for other key micronutrients, such as zinc and calcium. Deficiencies of these two minerals maybe as widespread and as costly in terms of human health and well-being as the better-documented deficiencies of iron, vitamin A, and iodine.

Finally, multiple micronutrient supplementation has been shown to have a greater impact on nutritional status than administration of the supposed key deficient single micronutrient. For example, a 10-week, double-blind study on zinc and growth in six- and seven-year-old Chinese children showed that multiple micronutrient supplementation resulted in greater improvement in linear growth than zinc supplementation alone [3].