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Malnutrition and Human Microbiome (gut bacteria)

In Latin, the word “mal” means bad, so malnutrition means bad nutrition. Under-nutrition (wasting, stunting, or deficiency of micronutrients), over-nutrition, obesity, and nutrition related non-communicable diseases (NCDs) are all different forms of malnutrition.

There are various drivers or causative factors that contribute to malnutrition. Some of those are as follows:

  • Socioeconomic disadvantage and poverty resulting in limited availability of quantity and quality (nutrient rich) of food

  • Unhealthy food habits lead the population towards undernutrition or over-nutrition. Two best examples of these are anorexia nervosa and obesity.

  • Biological factors such as epigenetics and early life nutrition influence the risk of NCDs, overweight, obesity and low birth weight.

  • Epigenetics: Maternal under-nutrition can result in restricted intrauterine growth and has effect on how infant’s body regulates the energy. And such changes are transferred to next generations through alternation in gene expression.

  • Early life nutrition : Nourishment of fetus and maternal nutrition prior to pregnancy affect the health of infant. Undernourished and low birth weight infant are predisposed to metabolic disease and obesity in later life.

  • Changes in food system: There is greater access to processed and unhealthy food because of changes in food production method. This replaces traditional diet and provides food which is lower in micronutrients and with added sugar, salt and fat. The result is overweight, obese population with micronutrients deficiency that increases risk of developing NCDs

Role of Microbiome in Malnutrition

Dietary habits, preferences and food choices are major factors affecting nutrition status as well as the microbiome of the individual. High calorie intake, lack of physical activity along with poor dietary choice such as high fat and low fiber diet can lead to imbalance of microbiomes. Same kind of microbiome alternation is seen with obesity. Change in diet and lifestyle helps in modulation of it and hence, in nutritional status of individual. It also contributes caloric value of the food. Short chain fatty acids produced by specific microbes by fermentation of undigested food provide nourishment to intestinal cells. Lower population of these bacteria’s decreases caloric value of food in undernourished and anorexic individuals. Thus microbiome plays role in severity of undernutrition by decreasing caloric value of food.

The nutritional transition can also present itself in an individual in their life course. Someone who is underweight, stunted, or wasted due to undernutrition in childhood may grow up into an obese adult. Malnutrition at the start of life negatively affects the microbial population of the gut for the rest of one’s life. Undernourished children’s microbiota remains immature and imbalanced into adulthood. This can compound the effects of switching from a nutrient-poor diet in childhood to an overabundance of energy-dense food later in life.

Method of delivery, antibiotic use during pregnancy and for the infant, and diet of mother during pregnancy and lactation period influences the microbiota of children. Breast fed babies have more beneficial bacteria such as bacteroids. Malnourishment in early life influences the maturation and diversity of microbiota. Bottle fed babies can develop imbalances in microbiome and contribute to malnutrition. Microbiome of malnourished children does not mature fully as compared to healthy children. Imbalanced and less diverse microbiota can lead to protein energy malnutrition in children. Diet, lifestyle and environment determine the diversity, abundance of microbiome in adults. Malnutrition (over-nutrition) leads to changes in microbiome causing over presence of firmicute and proteobacteria which harvest more energy from non-digestible food and increase calories value of the food. These reflect the obesity as well as cause of it. Low grade inflammation caused by gut flora also can increase the risk of obesity.

Microbiome modulation through diet and lifestyle can help population in multiple ways such as:

  • Maternal nutrition prior and during pregnancy to avoid under nutrition and its effect on infants health can be achieved through eating right.

  • Increase diversity, abundance and specificity in microbiota of children to reduce risk of malnutrition. Dietary changes including breast feeding, less use of antibiotic in early life reduces the imbalance in gut flora and has positive impact on health.

  • Use of prebiotic fiber FOS, GOS and inulin rich food help to establish beneficial flora (Bifidobacterium and lactobacillus species) in the intestine as well as ease in defecation, increase in stool bulk and water content influence the intestinal health of children.

  • To establish healthy gut flora probiotic supplements can be used. Probiotics strengthen immune system, provides health promoting bacteria (SCFA producing bacteria), and prevent infections with pathogens. Synbiotics, combination of pre and pro biotics, has greater effect than pre or pro biotic alone. Use of synbiotics ensures the growth of beneficial bacteria and promote overall gut health.

References [1]World Health Organization “The double burden of malnutrition Policy Brief” [2]World Health Organization statement . 15 January 2011. Exclusive Breastfeeding for six months is best for babies everywhere [3]Lectures from Edx course: WageningenX: NUTR104x Nutrition and Health: Human Microbiome

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