All about fruitarianism with a long-term fruitarian, Lena

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:

  1. the validity of the preschool-age child amino acid requirement values (more than 4 times greater than the EAA requirement for an adult),
  2. the validity of correction for fecal instead of ileal digestibility,
  3. 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.

Albert Schweitzer

A man is ethical only when life, as such, is sacred to him, that of plants and animals as that of his fellow men, and when he devotes himself helpfully to all life that is in need of help. 

Enterotypes and Microflora

An enterotype is a classification of living organisms based on its bacteriological ecosystem in the gut microbiome. Humans can be roughly divided into three enterotypes depending on which genus of bacteria dominates their gut: Bacteroides, Ruminococcus, or Prevotella. 

  • People who eat a lot of meat and saturated fat tended to have more Bacteroides in their flora
  • Ruminococcus prevailed in people who consumed lots of alcohol and polyunsaturated fats. 
  • Prevotella favored a diet rich in carbohydrates.

Long-term diet is strongly associated with the gut microbiome composition. If switching gut enterotype is possible, it may take a long-term dietary intervention. 

Chimpanzees have enterotypes that are compositionally analogous to those found in humans. 

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