Indmedica Home | About Indmedica | Medical Jobs | Advertise On Indmedica
Search Indmedica Web
Indmedica - India's premier medical portal

Indian Journal of Community Medicine

Vol. 30, No. 3 (2005-07 - 2005-09)

Editorial

Zinc Deficiency: Public Health Perspective

Zinc is an essential micronutrient and plays an essential role in growth, immune functions, and resistance to infections in children. Zinc deficiency places children in many low-income countries at increased risk of illness and death from infectious diseases. Mild to moderate Zinc deficiency may be common in the developing world but the public health importance of this degree of zinc deficiency is not well defined as yet1 .

Association of maternal Zinc deficiency with adverse pregnancy outcome is still an unresolved issue2. Most studies in which pregnant women have been supplemented with zinc to examine effects on pregnancy outcome have been carried out in industrialized countries and the results have been inconclusive. Observational studies in human populations have produced strong associations between poor maternal zinc status and various indicators of poor pregnancy outcome but supplementation trials have not produced strong, or even consistent results3. Antenatal Zinc supplementation did not improve birth outcome in Bangladeshi urban poor. Positive results were observed only in subgroups of the pregnant population in some studies4.

Thus interventions with zinc supplementation alone are unlikely to reduce the incidence of low birth weight in developing countries. Full results of studies carried out need to be known and that more research in terms of supplementation trials are needed to determine the benefits of large-scale introduction of zinc supplementation to pregnant women in less-developed countries and to define the public health importance of maternal zinc. Prenatal zinc supplementation had some beneficial effect on infants. neuro-behavioural development and immune function1, but Zn supplementation alone in poor women did not seem to confer benefit on infants. mental development5.

Controlled trials of zinc supplementation during pregnancy in humans have not demonstrated consistent effects on weight at birth and/or duration of gestation.Those studies that have identified a positive effect of zinc on fetal growth were performed on low-socioeconomic or migrant groups in industrialized countries or in countries where diet and living conditions are improving. Early zinc supplementation in low birth weight or small-for-gestational-age infants led to improvement in growth6. In contrast, in studies conducted either on populations with minimal risk of zinc deficiency or those suffering from multiple and severe nutritional deficiencies, no effects have been found. In fact in some studies the positive growth response was attributed, in part, to a secondary impact of zinc on growth resulting from reductions in the incidence of anorexia, cough, diarrhea, fever, and vomiting in the stunted children.

There is strong evidence to support role of Zinc supplementation in diarrhoea morbidity and mortality reduction. A study from India identified a 68% reduction in mortality in

small-for-gestational-age term infants that were supplemented with zinc from 1 to 9 months of age7. Reduction of the health risks in Bangladeshi low birth-weight infants without any impact on birth-weight was noticed with antenatal Zn supplementation. It led to reduced risks for acute diarrhoea, dysentery, and impetigo among infants suggesting its potential to reduce infant mortality in regions with high rates of low birth weight8.

Six of nine randomized controlled trials of zinc supplementation demonstrated significantly lower incidence of diarrhea in the zinc group than in the controls. For the zinc-supplemented children the pooled ORs for diarrheal incidence and prevalence were 0.82 and 0.75 respectively9. Zinc was also found to have a therapeutic benefit in seven trials of acute diarrhea and five of persistent diarrhea. In studies of acute diarrhea, the illness duration has been found to be 9-23% shorter and severity was lesser in zinc-supplemented than in control children. Similar effects were not observed for persistent diarrhoea. Zinc supplementation to LBW full-term infants (mean birth weight 2,337 gm during the first 6 months of life was associated with a 28% reduction in diarrhea prevalence. Zinc- supplemented children had a 15% lower probability of continuing diarrhea on a given day in the acute-diarrhea trials and a 24% lower probability of continuing diarrhea and a 42% lower rate of treatment failure or death in the persistent-diarrhea trials10. There is thus strong evidence that Zinc supplementation reduces the duration and severity of acute and persistent diarrhea. Other community based studies in India have also shown lower incidence of diarrhoea, particularly persistent diarrhoea, lesser severity and duration of diarrhoea with Zinc supplementation particularly in children > 11 months old and in children with low plasma zinc concentrations11-13.

There is some evidence to suggest that Zinc supplementation can lead to reduced incidence of cough/ acute lower respiratory infection 14 and clinical attacks of malaria9. There was 45% reduction in the incidence of ARI in children with zinc supplementation in an Indian study. In five trials, a lower rate of pneumonia infection was found in the zinc-supplemented groups, and there was some indication of a preventive effect in three trials with a clinical malaria outcome7.

Results of community based prevalence studies on Zinc deficiency are still awaited.This would be required to workout the impact of mass Zinc supplementation programme in various age-groups. In the absence of prevalence data, potential beneficiaries of Zn Supplementation could be: Underweight and Stunted children , Low birth weight babies, and children with diarrhoea and/ or pneumonia. Improvement of zinc nutriture can become a priority intervention to reduce the high burden of serious infectious disease in children in developing countries in future.

To conclude,

  1. Zinc Supplementation has potential to improve child survival. Incorporation of Zn supplements in treatment schedules of diarrhoea and pneumonia should be promoted.
  2. Community based Supplementation should be undertaken in areas with multiple micronutrient deficiencies in high child mortality areas,
  3. Research to map-out prevalence of Zinc deficiency and other co-existing micronutrient deficiencies and study of micronutrient interactions should be encouraged further,
  4. Routine zinc supplementation can not be advocated to improve pregnancy outcome at this stage.

Dr. Arun Kumar Aggarwal
Assistant Professor
Community Medicine Department
PGIMER, Chandigarh
Email: [email protected]

References

  1. Shah D, Sachdev HP. Effect of gestational zinc deficiency on pregnancy outcomes: summary of observation studies and zinc supplementation trials. Br J Nutr 2001; 85: S101-8.
  2. Osendarp SJ, West CE, Black RE; Maternal Zinc Supplementation Study Group. The need for maternal zinc supplementation in developing countries: an unresolved issue. J Nutr 2003 ;133:817S-827S.
  3. Caulfield LE, Zavaleta N, Shankar AH, Merialdi M. Potential contribution of maternal zinc supplementation during pregnancy to maternal and child survival. Am J Clin Nutr 1998 ;68: 499S-508S
  4. Goldenberg RL, Tamura T, Neggers Y, Copper RL, Johnston KE, DuBard MB, Hauth JC.The effect of zinc supplementation on pregnancy outcome. JAMA 1995 ;274: 463-8.
  5. Hamadani JD, Fuchs GJ, Osendarp SJ, Huda SN, Grantham- McGregor SM. Zinc supplementation during pregnancy and effects on mental development and behaviour of infants: a follow-up study. Lancet 2002; 360:290-4.
  6. Castillo-Duran C, Weisstaub G. Zinc supplementation and growth of the fetus and low birth weight infant. J Nutr 2003; 133:1494S-7S.
  7. Black RE. Zinc deficiency, infectious disease and mortality in the developing world. : J Nutr 2003;133:1485S-9S.
  8. Black RE. Therapeutic and preventive effects of zinc on serious childhood infectious diseases in developing countries. Am J Clin Nutr 1998;68:476S-479S.
  9. Bhutta ZA, Black RE, Brown KH, Gardner JM, Gore S, and Hidayat A et al. Prevention of diarrhea and pneumonia by zinc supplementation in children in developing countries: pooled analysis of randomized controlled trials. Zinc Investigators. Collaborative Group. J Pediatr 1999;135:689 97.
  10. Bhutta ZA, Bird SM, Black RE, Brown KH, Gardner JM, Hidayat A, et al. Therapeutic effects of oral zinc in acute and persistent diarrhea in children in developing countries: pooled analysis of randomized controlled trials. Am J Clin Nutr 2000;72:1516-22.
  11. Sazawal S, Black RE, Bhan MK, Jalla S, Bhandari N, Sinha A etal. Zinc supplementation reduces the incidence of Persistent Diarrhoea and Dysentery among low socioeconomic children in India. J Nutrition 1996; 126: 443-50
  12. Sazawal S, Black RE, Bhan MK, Jalla S, Sinha A, Bhandari N. Efficacy of Zinc supplementation in reducing incidence and prevalence of acute diarrhoea- a community based, double-blind, controlled trial. Am J Clin Nutr 1997; 66: 413-8.
  13. Sazawal S, Black RE, Bhan MK, Bhandari N, Sinha A and Jalla S. Effect of Zinc supplementation during acute diarrhoea on duration and severity of the episode- a community based, double-blind controlled trail. N Eng J Med 1995; 333: 839 844.
  14. Sazawal S, Black RE, Jalla S, Mazumdar S, Sinha A and Bhan MK. Zinc supplementation reduces the incidence of acute lower respiratory infections in infants and preschool children: a double-blind controlled trial. Pediatrics 1998; 102:1-5.
Access free medical resources from Wiley-Blackwell now!

About Indmedica - Conditions of Usage - Advertise On Indmedica - Contact Us

Copyright © 2005 Indmedica