By Sheela Sinharoy

When people think of nutrition, they probably do not think immediately of toilets. However, there is growing interest within the global public health community in the relationship between sanitation and nutrition. A group of researchers led by Dr. Tom Clasen of Emory University and the London School of Hygiene and Tropical Medicine has been studying this topic. They recently published findings from a study examining the effectiveness of a rural sanitation program on several outcomes, including child malnutrition, in The Lancet.

The intervention took place in Odisha, India, in the context of the national Total Sanitation Campaign, through which the government of India promotes latrine construction. The campaign focuses on households below the poverty line; it provides them with a latrine but requires that they contribute materials and labor for construction. For this study, the researchers selected 100 rural villages and enrolled households with pregnant women or children under age four. The study took place between May 2010 and December 2013.

Malnutrition was measured in two ways, through height-for-age z-score (HAZ) in children under two and weight-for-age z-score (WAZ) in children under five. The intervention had no effect on mean HAZ. Intention-to-treat analysis also showed no effect on mean WAZ, but per-protocol analysis showed a modest effect size of 0.10 (95% CI: 0.003-0.20). In other words, among the households that were compliant with the intervention, the children had slightly better WAZ scores. The absence of a stronger effect was surprising enough to garner attention from The New York Times, which published an article titled, “Latrines May Not Improve Health of Poor Children.”

I wanted to learn more, so I spoke with Dr. Clasen about the findings. He explained that while latrine coverage increased through the intervention, latrine use remained sub-optimal. While it may seem counter-intuitive, many community members chose not to use their new latrines, preferring instead the culturally accepted practice of open defecation. In particular, the study found that “latrine use was nearly five times higher for women than for men or children.” The reasons behind these gender and age differences are not clear, but Dr. Clasen emphasized the need to increase latrine use, aiming for “everybody, all the time.”

Researchers are examining other potential factors influencing latrine compliance. For example, what role do women play in deciding whether a household invests the resources necessary to build a latrine? If this decision is in the hands of men, and men are less likely to use a latrine, what are the implications for sanitation coverage and compliance? The study team is carrying out analyses on these and many other questions.

Ultimately, Dr. Clasen explained, this was an isolated intervention that could not address the multitude of issues that might affect the study outcomes. Factors such as poor disposal of child feces, the close proximity of livestock, poor water quality, and other forms of contamination likely play an important role in determining child nutrition outcomes. As always, more research is needed to better understand the complicated relationship between sanitation and nutrition.

Clasen T, Boisson S, Routray P, Torondel B, Bell M, Cumming O, et al. Effectiveness of a rural sanitation programme on diarrhea, soil-transmitted helminth infection, and child malnutrition in Odisha, India: a cluster-randomised trial. Lancet. 2014 [cited 2014 Nov 3].