Early child growth: how do nutrition and infection interact?

Abstract

It is well known that the relationship between child nutrition and infection is bidirectional, i.e. frequent illness can impair nutritional status and poor nutrition can increase the risk of infection. What is less clear is whether infection reduces the effectiveness of nutrition interventions or, vice versa, whether malnutrition lessens the impact of infection control strategies. The objective of this paper is to review the evidence regarding this interaction between nutrition and infection with respect to child growth in low-income populations. Even when there are no obvious symptoms, physiological conditions associated with infections can impair growth by suppressing appetite, impairing absorption of nutrients, increasing nutrient losses and diverting nutrients away from growth. However, there is little direct evidence that nutrition interventions are less effective when infection is common; more research is needed on this question. On the other hand, evidence from four intervention trials suggests that the adverse effects of certain infections (e.g. diarrhoea) on growth can be reduced or eliminated by improving nutrition. Interventions that combine improved nutrition with prevention and control of infections are likely to be most effective for enhancing child growth and development.

Figure 1

Episodes of diarrhoea per year among children under five (Margaret et al. 2003). Bars represent the 25th–75th percentiles across 20 countries (1990–2000).

Figure 2

Normal small intestine with healthy villi. http://duncanmarasanitation.blogspot.com/2009/09/tropical-enteropathy-3.html

Figure 3

Small intestine with environmental enteropathy characterized by unhealthy villi. http://duncanmarasanitation.blogspot.com/2009/09/tropical-enteropathy-3.html

Figure 4

Pathways by which fecal contamination leads to environmental enteropathy and child undernutrition (Adapted from Humphrey 2009).

Figure 5

Relationship between length at 36 months of age and number of days of diarrhoea during the first three years of life among supplemented and unsupplemented children in Colombia (Lutter et al. 1992).