Zinc and copper: proposed fortification levels and recommended zinc compounds

Micronutrient fortification of foods is now a highly relevant tool worldwide for overcoming micronutrient deficiency. Recent data show that subclinical zinc deficiency is widespread; in Mexico a national survey showed that 25% of children less than age 11 y had plasma zinc concentrations below 10.0 micromol/L (65 microg/dL). Copper deficiency in populations is unknown but copper supplementation is recommended to accompany zinc supplementation. Of the foods available for fortification, staple cereals are very good candidates for reducing micronutrient deficiencies. Because of its higher stability and lower cost, we recommend fortification of cereal flours with zinc oxide, which is absorbed as well as the less stable and more expensive forms of zinc. Depending on the amount of the food that is expected to be eaten, zinc fortification of staple foods could be 20-50 mg/kg of flour. For copper fortification the safer compound is copper gluconate. Copper sulfate is significantly less expensive, but an evaluation of potential physicochemical reactions that affect the final food product is recommended. The suggested amount of copper added to staple foods is 1.2-3.0 mg/kg of flour. For food supplements designed as part of supplementation programs to reduce micronutrient deficiency in children less than age 3 y, a dose of the final product (usually approximately 40-50 g) should contain approximately 4-5 mg of zinc and approximately 0.2-0.4 mg of copper depending on the habitual diet, magnitude of deficiencies and period of supplementation.