From the NY Times, Poor Sanitation in India May Afflict Well-Fed Children With Malnutrition:

[A]n emerging body of scientific studies suggest that … many of the 162 million … children under the age of 5 in the world who are malnourished are suffering less a lack of food than poor sanitation.

Like almost everyone else in their village, Vivek and his family have no toilet, and the district where they live has the highest concentration of people who defecate outdoors. As a result, children are exposed to a bacterial brew that often sickens them, leaving them unable to attain a healthy body weight no matter how much food they eat.

“These children’s bodies divert energy and nutrients away from growth and brain development to prioritize infection-fighting survival,” said Jean Humphrey, a professor of human nutrition at Johns Hopkins Bloomberg School of Public Health. “When this happens during the first two years of life, children become stunted. What’s particularly disturbing is that the lost height and intelligence are permanent.”