Good nutrition requires more than access to nutritious foods: it requires the body to be able to absorb the nutrients in the food a person consumes. Harmful germs, often found on the hands, can prevent the body’s ability absorb nutrients.
The World Health Organization (WHO) estimates that 50% of child undernutrition cases are due to repeated diarrhea and intestinal infections caused by poor sanitation and hygiene conditions or lack of safe water.[i] Handwashing with soap is a critical determinant for achieving and maintaining good nutrition, and this healthy behavior plays an important part in preventing micronutrient deficiencies, stunting, wasting, and deaths.
If disease-causing bacteria, viruses, or parasites on a person’s hands enter their mouth, they can travel down to the gut. There, they may damage the body’s ability to absorb and use nutrients from food. Germs may directly consume nutrients before the body can use them and damage the intestinal lining; this is referred to as environmental enteropathy.[ii] Environmental enteropathy includes flattening out parts of the intestine (villus blunting), which reduces places where nutrients can be absorbed into the body. This means that nutrients can that pass through the gut but fail to be absorbed, and then be lost in diarrhea.[iii] These pathogens can also irritate the gut, and can damage its barrier functions, making it easier for toxins to enter the body and cause chronic inflammation. This, in turn, can further damage the gut and use up nutrients in the process.[iv]
Stunting, or low height for age, is caused by long-term insufficient nutrient intake and frequent infections in early childhood, resulting in delayed motor development, impaired cognitive function, and reduced school performance. WHO estimates each year that undernutrition in all its forms accounts for 45% of all deaths of children under 5 years of age, and that 44 countries have a significant proportion (at least 30%) of children younger than 5 who are stunted.[v]
Similarly, wasting, or low weight for height, is caused by acute insufficient nutrient intake and/or disease, and is a strong predictor of mortality among children under the age of 5. WHO also estimates that as of 2014, 50 million children were wasted or are too thin for their height.[vi]
Handwashing breaks the vicious cycle of diarrhea and undernutrition.
Children are susceptible to infection by bacteria and viruses, found in fecal matter, that cause diarrhea. When children get diarrhea, they (a) often eat less food, and (b) have a reduced ability to absorb and benefit from nutrients in the food they do eat. As a result, this can contribute to undernutrition. When children are undernourished, they become far more susceptible to developing diarrhea when they come into contact with the bacteria and viruses in fecal matter. And so the cycle goes repeats itself.
Good handwashing with soap can prevent nearly half of all cases of childhood diarrhea. It is also estimated that drinking clean water and handwashing with soap can reduce the loss of nutrients through diarrhea and reducing stunting in children under the age of 5 by up to 15%, giving children a better chance of maintaining good nutrition and growing up to thrive.[vii][viii]
Given the important role of handwashing in nutrition, the Global Handwashing Partnership helped co-found the Clean, Fed & Nurtured Community of Practice which works to explore and promote the integration of WASH, nutrition, and early childhood development in the 0-3 age range. The GHP also provides a number of resources relating to the integration of nutrition and handwashing in our resources section.
[ii] Sharp TM, Estes MK. An inside job: subversion of the host secretory pathway by intestinal pathogens. Curr Opin Infect Dis, 2010; 23: 464-69.
[iii] Fenn B, et al. An evaluation of an operations research project to reduce childhood stunting in a food-insecure area in Ethiopia. Public Health Nutrition, 2012; 15(9), 1746-54.
[iv] Dangour AD, et al. Interventions to improve water quality and supply, sanitation and hygiene practices, and their effects on the nutritional status of children. The Cochrane Library, 2013.
[v] WHO, UNICEF, USAID (2015). Improving Nutrition Outcomes with Better Water, Sanitation and Hygiene: Practical solutions for policies and programs.
[vii] Solomons NW. Pathways to the impairment of human nutritional status by gastrointestinal pathogens. Parasitology, 1993; 107: S19-35.