Abstract
Chinese (CH) lose approximately 2/3 as much nitrogen (N) as Caucasians (CA) on a high fat, high carbohydrate, zero protein intake. The justification theory of hereditary non-essential amino acid (NEA) deficiency states that deficiencies in NEA can occur on marginal protein intake by heterozygotes for any of the 32 enzymes required to synthesize all the NEA. N loss during starvation depends on the ability to resynthesize protein which is turning over. If an essential amino acid is lost then all of the NEA lost by that molecule of protein cannot be reutilized. Efficiency of reutilization depends upon the available constellation of NEA. The low protein intake of the CH, who have subsisted for 50 centuries on cereals, would make it difficult for a heterozygote for NEA synthesis to survive. The CA, a hunter and fisherman, would not lack for protein. Though total caloric nutrition might be poor there would be no selection against mutations in the NEA pathways. This interpretation is supported by data which show that the essential amino acids in the plasma of CH and CA after a 2-week fast are equal whereas the plasma of CH contains 50% more of the NEA. This is associated with a mean loss of 1.8 mgs. of nitrogen per basal calorie in the CA and 1.2 mgs. per basal calorie in the CH. The justification hypothesis may not only supply an explanation of differential response to the same diet, but might even provide dietary suggestions for prevention of many problems of protein synthesis.
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Bessman, S., Huang, PC. 398 THE GREATER NITROGEN SPARING EFFICIENCY OF CHINESE THAN CAUCASIANS REINTERPRETED ACCORDING TO THE JUSTIFICATION THEORY. Pediatr Res 12 (Suppl 4), 430 (1978). https://doi.org/10.1203/00006450-197804001-00403
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DOI: https://doi.org/10.1203/00006450-197804001-00403