Clean drinking water, sanitation, handwashing and nutrition interventions benefit the physiological stress system in early childhood, a new study has found.

A group of researchers, led by a global-health researcher at UC Santa Cruz, analysed 5,551 pregnant women and their children in rural Bangladesh.

The women were placed into one of seven groups. Four groups received nutrient supplements and then one of the following: clean drinking water, sanitation, handwashing stations or nutrition counselling. The fifth group received water, sanitation and handwashing interventions and the sixth received water, sanitation, handwashing and nutrition interventions. The final group received no interventions.

The results showed the children whose mothers received drinking water, sanitation, handwashing and nutrition had greater regulation of the physiological stress system in early childhood. These interventions enhanced the children’s physiological stress response, lowered their oxidative stress and reduced DNA methylation.

The study, ‘A cluster-randomized trial of water, sanitation, handwashing and nutritional interventions on stress and epigenetic programming,’ reported: “A regulated stress response is essential for healthy child growth and development trajectories.”

Oxidative stress is described by the researchers as “the accumulation of unstable free radicals that damage DNA and cellular structures.” It is linked to numerous paediatric disorders including asthma, protein-energy malnutrition and diarrhoeal diseases, and can lead to diseases such as diabetes, cancer and Alzheimer’s.

DNA methylation, a chemical change in DNA, is usually caused by environmental conditions that are present as cells divide and is associated with childhood maltreatment. Increased and abnormal DNA methylation has also been linked to diseases such as cancer, lupus, muscular dystrophy and birth defects.

Existing research provides a wide range of knowledge on the way early childhood development and health trajectory is affected by environmental factors. The researchers claim this new study, known as the WASH Benefits Bangladesh trial, provides the most accurate evidence on stress physiology and epigenetic programming as previous research lacked experimental interventions and control groups for comparison and were conducted in high-income countries with access to safe drinking water, sanitation and hygiene.

Audrie Lin, assistant professor of microbiology and environmental toxicology at UC Santa Cruz, said: “Here, we see differences in outcomes between an intervention group and a control group, both of significant size. When we began setting up the WASH Benefits trial in 2009, its scale was unprecedented in the health- and nutrition-research fields.

“This is really representative of the conditions that a majority of the world’s population contends with. When this type of research is done in high-income countries, you’re not really capturing all of these important stressors that could affect a child.”

The WASH Benefits trial was also the first to implement physical interventions rather than psychosocial interventions to improve stress physiology in children living in an area with limited access to resources. It demonstrated when and how interventions such as safe drinking water, nutrition, sanitation and hygiene change a child’s physiology.

Lin explained the improvements from physical interventions were similar to those from psychosocial measures.

She believes combining both forms of interventions will result in greater health benefits.

The researchers hope the trial, which began in 2012 and is still monitoring the participants, will continue to demonstrate the effects of interventions introduced within the first two years of a child’s life.

Lin added: “You often hear that what happens in the womb affects you for the rest of your life, especially in regards to your health and the development of certain diseases.

“The experimental design of this trial will serve as a powerful platform to find links between the interventions we introduced early on and the health trajectories of the participants in our study.”

The study was published in the journal Nature Communications.

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