The composition of intestinal microbiota depends on what food is ingested and has consequences on overall metabolism.
Intestinal microbiota starts developing at birth, and its composition is influenced by what we eat. Food intake can therefore play a role – good or bad – in the modulation of intestinal microbiota, in the very first weeks of life. As such, the composition of microbiota differs between babies who are breastfed and babies who receive infant formula1 : more specifically, the microbiota of breastfed babies has more lactic bacteria (Lactobacillus) and bifidobacteria (Bifidobacterium). The nutritional intake therefore has an influence on the composition of microbiota, first from a quantitative point of view, but also and especially from a qualitative point of view, bringing with it substantial metabolic changes.
It has been shown that an increase in fat in the diet increases the proportion of Gram-negative bacteria, with a rise in inflammatory lipopolysaccharides that ultimately favor insulin resistance, leading to type1 diabetes and obesity2. It has also been shown that certain amino acids found in red meat and eggs can be metabolized by intestinal microbiota and can affect how cholesterol is metabolized, increasing the risk of developing atherosclerosis3. Finally, the role of diet in microbiota imbalance in connection with obesity is being studied more and more4,5, as a notable difference has been observed between the microbiota of obese individuals and thin individuals.
The influence of diet
Given that fact, it is not hard to imagine the role that diet plays in modulating microbiota: studies have shown an impact of various dietary regimens or habits (vegetarianism, veganism) on the composition of microbiota6. Modifying that composition by introducing fiber (via vegetables, whole grains, and soluble fiber) can contribute to the restoration of a more diverse microbiota, proving that dietary balance is one of the cornerstones to a balanced microbiota.
1. Orrhage K et al. Factors controlling the bacterial colonization of the intestine in breastfed infants. Acta Paediat Suppl 1999 ; 430 : 47-57.
2. Julie Tomas et al. High-fat diet modifies the PPAR-γ pathway leading to disruption of microbial and physiological ecosystem in murine small intestine. PNAS 2016. 113 (40) : E5934-E5943.
3. Tuohy et al. The way to a man's heart is through his gut microbiota - dietary pro - and prebiotics for the management of cardiovascular risk. Proceedings of the Nutrition Society 2014 ; 73(2) : 172-85.
4. TurnbaughPJ et al. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature 2006 ; 444 : 1027-31.
5. Ojeda P et al. Nutritional modulation of gut microbiota - the impact on metabolic disease pathophysiology. J Nutr Biochem. 2016 ; 28 : 191-200.
6. Hayashi H et al. Fecal microbial diversity in a strict vegetarian as determined by molecular analysis and cultivation. Microbiol Immunol 2002 ; 46 : 819-31.
2016 Recommandations 2016 of the ICNM (International Conference on Nutrition in Medicine): http://www.pcrm.org/health/reports/seven-dietary-guidelines-healthy-microbiota