Research Project: Intestinal Microbiome and Childhood Feeding

Location: Children's Nutrition Research Center

2022 Annual Report

Objectives
Objective 1: Compare the effects of inulin and fructo-oligosaccharides against a maltodextrin placebo in obese children, using a double-blind randomized controlled trial, to study weight loss, fecal microbiota and their functions. Objective 2: removed due to investigator departure. Objective 3: Conduct a clinical trial adding black-eyed peas to diets of young children at risk for stunting. Determine efficacy in reducing stunting and analyze fecal sample to understand potential mechanisms by which the food supplement ameliorates stunting. Assess dietary compliance in a novel, quantitative manner using a urinary biomarker for black eyed peas. Currently quercetin and ferulic acid are candidates for this biomarker.

Approach
A number of pressing nutritional issues face the US and other nations. Over 20% of children throughout the world are obese with even more children overweight; both associated with diabetes and heart disease. Given the importance of the gut bacteria in our general health and weight control, we will test via various sample analyses a dietary supplement (prebiotic) that selectively enhances the growth and activity of bacteria associated with leanness. We anticipate that this prebiotic will reduce the risk of overweight and obesity in children. There is a lack of molecular and metabolic biomarkers of existing nutritional therapy limiting the ability to appropriately and adequately assess the utility of dietary supplementation. We will perform serial measures of DNA methylation and tissue metabolites to identify suitable biomarkers of nutritional deficit and recovery. In addition, stunting affects about 23% of all children under 5 years of age globally. Most of these children are in Africa and south Asia and the consequences include lower economic productivity, decreased cognition and more diabetes and hypertension. Similar to obesity, the microbiome is implicated as a cause of stunting and new treatments are needed. We will determine using biomarker analysis if legume supplements can extend their benefits to children in West Africa.

Progress Report
In Objective 1, we continued investigating the relationship between the ability of gut bacteria to metabolize certain hormones generated by children and the development of obesity. This is important because diet dramatically affects the types of bacteria in the gut. In turn, the types of bacteria in the gut can increase or decrease the risk of obesity. We believe that one-way bacteria can influence obesity is by metabolizing certain hormones generated by humans. By metabolizing these hormones, the gut bacteria change the types and concentrations of these hormones in the gut. The hormones subsequently are absorbed into the body and can influence body metabolism which may relate to the risk of obesity. Using an advanced technique called metabolomics, we measured metabolites in the stool of children who identified as Hispanic and who were either obese or of normal weight. We found that androgens (hormones found in both girls and boys) were changed (sulfated) by the gut bacteria. The amount of these altered androgen hormones related to the likelihood that both boys and girls were obese versus normal weight and had evidence of resistance to the blood hormone insulin which is important in determining the level of blood sugar. Because the types of gut bacteria present also have been associated with the risk of having belly pain in both children and adults, we studied the relationship between the types of gut bacteria, the amount (abundance) of altered androgen hormones, and the risk of obesity. Some studies suggest that obese individuals are more likely to suffer from unexplained belly pain. We found that girls with belly pain had levels of altered androgens that were like that found in boys whereas girls without belly pain had much lower levels of altered androgens than boys with or without belly pain. These results suggest that the way gut bacteria metabolize androgens generated by children also may be important in determining whether an individual will suffer from unexplained belly pain. We and others have shown that 10-15% of children (and adults) worldwide suffer from unexplained belly pain, making this a major health concern. Going further, we found that the types of bacteria in the gut were associated with the risk of children developing belly pain after eating certain types of sugars. In the children who experienced pain after eating a type of sugar commonly found in the diet, the amount (abundance) of these altered androgens in stool were increased; these same children also were more likely to be heavier in weight. Our results highlight how diet can impact the types of bacteria in the gut; how these bacteria then can alter human-generated hormones; and taken together, the bacteria and altered hormones can influence the risk of obesity and belly pain. As we learn more about these relationships, we believe we can develop strategies to blunt the risk of obesity and belly pain by altering the types of gut bacteria and/or the impact of the gut bacteria on processing human-generated hormones. In Objective 3, the clinical trial in Sierra Leone, western Africa, is complete but the sample analyses remain to be done. In Sierra Leone many children are malnourished, and when these malnourished children are identified in a clinic, they receive a supplementary food. Common ingredients for these foods are milk, soy and other cereals. About 1,100 moderately malnourished children were enrolled in the trial. Each child was assigned to receive one of four distinct supplementary foods with different macronutrient ingredients; 1) milk, 2) milk protein + vegetable carbohydrate, 3) milk sugar + vegetable protein, or 4) vegetable ingredients. All malnourished children received about 500 calories daily for six weeks of their assigned food. After four weeks of receiving the supplementary food children were tested for their gut health, the bacteria in their gut and the small molecules in their stool. Children were also measured to see their growth response to the food. All the foods caused the children to grow similarly. All samples were collected and research analyses are ongoing.

Accomplishments
1. Dietary sugars and bacteria in the gut both contribute to abdominal pain and obesity. Sugars in the diet can impact the types and function of gut bacteria, which in turn, can modify the hormones secreted by the human body that may play a role in the development of obesity. To further study this impact of sugar, researchers at the Children's Nutrition Research Center in Houston, Texas, administered two types of sugars (one easily absorbed and another not easily absorbed) to children with irritable bowel syndrome, a condition found commonly in children and adults that causes abdominal pain and changes in stool habits. In the children who developed abdominal pain in response to the poorly absorbed sugar, there was a greater abundance of a hormone associated with obesity. These results highlight the way diet and gut bacteria interact to cause abdominal pain. In addition, the results show that the types and abundance of certain bacteria can affect hormones and potentially contribute to the development of obesity. Based on this research, future studies may help guide the development of diets and treatments that could modify the gut bacterial population to one that does not cause pain and does not increase the likelihood of obesity.