Children in poor regions of the world tend to grow slightly taller than their counterparts in other impoverished areas who lack clean water, hygiene, and sanitation.
British researchers found in a recent study that kids four-years-old or younger had grown on average 0.2 inches taller than others. The effect appeared among those children who washed their hands, drank clean water, or used functional toilets -- or some combination of the three.
However, the minute but statistically significant trend was not seen in all 14 studies included in a review led by Alan Dangour of the London School of Hygiene & Tropical Medicine. Anna Bowen, a medical epidemiologist at the U.S. Centers for Disease Control and Prevention, told Reuters the effect was nevertheless significant. "The absolute difference in height is not large, but stunting is associated with many negative health and economic outcomes," she said. "Therefore increasing the median height of the population even slightly could have benefits," added Bowen, who was not involved in the research.
The investigators sought to test the impact of water, sanitation, and hygiene improvements on the prevention of diarrhea and infectious disease among children in poor countries, receiving funding in 2011 from the U.S. and United Kingdom for a total of $626 million. Dangour and his colleagues then measured whether hygiene conditions affected height and weight in children, finding no difference in weight from the interventions, according to results published by The Cochrane Collaboration, an international medical research group.
Yet, the researchers also failed to find a height difference when analyzing randomized controlled trials, but noted the short duration of the trials. Nine to 12 months was too short of a period to notice significant differences in height from interventions in these areas, they noted.
Around the world, nearly one in four children below the age of five experiences stunted growth from malnutrition and other factors, according to the World Health Organization. The researchers in the group of studies did not seek to assess whether hygiene and sanitation waged the biggest influence over children’s height, however. "The whole package is important," Dangour told Reuters Health. "So we didn't want to separate them out."
However, other researchers continue to study children’s height as a metric of population health.
Source: Dangour, Alan, D., Watson, Louise, Cumming, Oliver, Boisson, Sophie, Che, Yan. Interventions To Improve Water Quality And Supply, Sanitation And Hygiene Practices, And Their Effects On The Nutritional Status Of Children. The Cochrane Collaboration. 2013.