By 2014 over 300 zinc containing enzymes have been identified, as well as over 1000 zinc containing transcription factors.Phytate was recognized as removing zinc from nutrients given to chicken and swine in 1960. That it can cause human zinc deficiency however was not recognized until Reinholds work in Iran in the 1970s. This phenomenon is central to the high risk of zinc deficiency worldwide. Soils and crops
Soil zinc is an essential micronutrient for crops. Almost half of the worlds cereal crops are deficient in zinc, leading to poor crop yields. Many agricultural countries around the world are affected by zinc deficiency. In China, zinc deficiency occurs on around half of the agricultural soils, affecting mainly rice and maize. Areas with zinc deficient soils are often regions with widespread zinc deficiency in humans. A basic knowledge of the dynamics of zinc in soils, understanding of the uptake and transport of zinc in crops and characterizing the response of crops to zinc deficiency are essential steps in achieving sustainable solutions to the problem of zinc deficiency in crops and humans. Biofortification
Soil and foliar application of zinc fertilizer can effectively increase grain zinc and reduce the phytate:zinc ratio in grain. People who eat bread prepared from zinc enriched wheat have a significant increase in serum zinc.Zinc fertilization not only increases zinc content in zinc deficient crops, it also increases crop yields. Balanced crop nutrition supplying all essential nutrients, including zinc, is a cost effective management strategy.
Low maternal zinc status has been associated with less attention during the neonatal period and worse motor functioning. In some studies, supplementation has been associated with motor development in very low birth weight infants and more vigorous and functional activity in infants and toddlers. Testosterone production
Zinc is required to produce testosterone. Thus, zinc deficiency can lead to reduced circulating testosterone, which could lead to sexual immaturity (Ananda Parsad, et al.) hypogonadism, and delayed puberty. Causes
Dietary deficiency
Zinc deficiency can be caused by a diet high in phytate-containing whole grains, foods grown in zinc deficient soil, or processed foods containing little or no zinc. Conservative estimates suggest that 25% of the worlds population is at risk of zinc deficiency.In the U.S., the Recommended Dietary Allowance (RDA) is 8 mg/day for women and 11 mg/day for men. RDA for pregnancy is 11 mg/day. RDA for lactation is 12 mg/day. For infants up to 12 months the RDA is 3 mg/day. For children ages 1–13 years the RDA increases with age from 3 to 8 mg/day. The following table summarizes most of the foods with significant quantities of zinc, listed in order of quantity per serving, unfortified. Note that all of the top 10 entries are meat, beans, or nuts. Recent research findings suggest that increasing atmospheric carbon dioxide concentrations will exacerbate zinc deficiency problems in populations that consume grains and legumes as staple foods.