Gut microbial composition depends on different dietary habits just as health depends on microbial metabolism, but the association of microbiota with different diets in human populations has not yet been shown.
Significant differences were found in gut microbiota between European children (EU) and that of children from a rural African village of Burkina Faso, , where the diet is high in fiber content, and is similar to that of early human settlements at the time of the birth of agriculture.
Burkina Faso children showed a significant enrichment in Bacteroidetes and depletion in Firmicutes, and a unique abundance of bacteria from the genus Prevotella and Xylanibacter, completely lacking in the EU children. Enterobacteriaceae (Shigella and Escherichia) were significantly underrepresented in Burkina Faso children.
In addition, we found significantly more short-chain fatty acids in Burkina Faso children.
Gut microbiota might have coevolved with the polysaccharide-rich diet, allowing to maximize energy intake from fibers while also protecting from inflammations and noninfectious colonic diseases.
The protein digestibility-corrected amino acid score (PDCAAS) has been adopted by FAO/WHO as the preferred method for the measurement of the protein value in human nutrition.
PDCAAS = Amino Acid Score x Digestibility
The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern. This scoring pattern is derived from the essential amino acid requirements of the preschool-age child.
Although the principle of the PDCAAS method has been widely accepted, critical questions have been raised in the scientific community:
- the validity of the preschool-age child amino acid requirement values (more than 4 times greater than the EAA requirement for an adult),
- the validity of correction for fecal instead of ileal digestibility,
- the truncation of PDCAAS values to 100%.
The reference scoring pattern was based on studies performed more than 25 years ago on a limited number of 2-year-old children recovering from malnutrition.
According to the current official recommendations, a 2-year old child needs ~ 3x higher essential-to-non-essential amino acid ratio, and needs essential amino acids in different proportions than adult. Methionine/cysteine is the limiting essential amino acids for adults, and for children it is lysine or tryptophan.
The use of fecal digestibility overestimates the nutritional value of a protein because amino acid nitrogen entering the colon is lost for protein synthesis in the body and is, at least in part, excreted in urine as ammonia.