More than half a million deaths each year in infants and children under the age of 5 years is estimated due to deficiency of zinc. This review article will describe mild-to-moderate zinc deficiency that would include growth vacillating, discrepancies in immune function and changed integrity and function of the gastro-intestinal tract. It will also discuss sub-clinical features, which includes oxidative stress and a pro-inflammatory state. The homeostatic response due to low dietary zinc intake by increasing its absorption is limited, particularly if the zinc source is of poor bioavailability, and management of endogenous intestinal losses is an essential component of adaptation. Due to low zinc intakes, older breastfed infants, specifically those infants of low birthweight, are predicted to be at risk of zinc deficiency if complementary food selections are unfortified or low in zinc. Various host factors such as early age, poor intrauterine zinc absorption due to poor maternal status and/or prematurity, and gastro-intestinal dysfunction are strongly predisposing to zinc deficiency. Environmental enteropathy is predominant in low-resource settings and might considerably impair zinc absorption and/or increase endogenous losses, and can lead to relatively high zinc requirements. Developing evidence mentions common features between chronic inflammation and deficiency of zinc, and each may aggravate the other. Additional investigations of zinc homeostasis in low-resource settings in populations are required to quantify absorption capacity of zinc and losses. Effective preventive strategies can potentially address the higher zinc requirements along with the underlying setting that continues a vicious cycle of zinc deficiency and multiple adverse consequences.

Source: Krebs NF, Miller LV, Hambidge KM. Zinc deficiency in infants and children: a review of its complex and synergistic interactions. Paediatr Int Child Health. 2014;34(4):279-288. doi:10.1179/2046905514Y.0000000151