The gut microbiota—the collection of trillions of bacteria that populate the bowel in humans—goes through somewhat predictable developmental stages in infancy and early childhood. Some types of bacteria dominate right after birth, while others increase in number as the diet changes from milk to solid foods over the course of the first two years of life. The final profile is largely set by about age 3—what you’ve got in your gut at that point is basically what you’ll have into adulthood.
Many factors can affect the final profile—I’ve written about cesarean birth, antibiotic use, and the typical high-calorie, high-fat western diet as likely culprits. As you might suspect, these are problems of affluence. We can debate the effects of too many cesareans, too much antibiotics, and too many calories, but in developing countries there’s another potent shaper of the developing gut microbiota in childhood: starvation.
A recent study performed by Washington University in St. Louis and the International Center for Diarrheal Disease Research in Dhaka, Bangladesh, showed that children with severe acute malnutrition (SAM) have immature gut microbiota profiles—the types of bacteria in the bowel didn’t change over time as would be expected in well-nourished infants and children.
The study followed Bangladeshi infants and toddlers with SAM over the course of acute treatment and for several months afterwards. The malnourished children did gain weight rapidly with very high-calorie diets, but they were unable to achieve or maintain a normal weight once the treatment ended and they switched to a more typical diet. Signficantly, their gut microbiota remained immature—the bacteria present in the gut both before and after treatment were woefully inefficient at extracting calories from food.
So now we have evidence that the gut microbiota plays an important role in two very different nutritional diseases: obesity and malnutrition. Future SAM research will be aimed at supplementing probiotic bacteria as well as calories in hopes of promoting healthy, long-lasting changes to the microbiota.
The sooner the better, given the terrible toll malnutrition takes on children in many parts of the world.
Photo courtesy of Chris Turner