Estimation of the net acid load of the diet of ancestral preagricultural Homo sapiens and their hominid ancestors.
BACKGROUND
Natural selection has had < 1% of hominid evolutionary time to eliminate the inevitable maladaptations consequent to the profound transformation of the human diet resulting from the inventions of agriculture and animal husbandry.


OBJECTIVE
The objective was to estimate the net systemic load of acid (net endogenous acid production; NEAP) from retrojected ancestral preagricultural diets and to compare it with that of contemporary diets, which are characterized by an imbalance of nutrient precursors of hydrogen and bicarbonate ions that induces a lifelong, low-grade, pathogenically significant systemic metabolic acidosis.


METHODS
Using established computational methods, we computed NEAP for a large number of retrojected ancestral preagricultural diets and compared them with computed and measured values for typical American diets.


RESULTS
The mean (+/- SD) NEAP for 159 retrojected preagricultural diets was -88 +/- 82 mEq/d; 87% were net base-producing. The computational model predicted NEAP for the average American diet (as recorded in the third National Health and Nutrition Examination Survey) as 48 mEq/d, within a few percentage points of published measured values for free-living Americans; the model, therefore, was not biased toward generating negative NEAP values. The historical shift from negative to positive NEAP was accounted for by the displacement of high-bicarbonate-yielding plant foods in the ancestral diet by cereal grains and energy-dense, nutrient-poor foods in the contemporary diet-neither of which are net base-producing.


CONCLUSIONS
The findings suggest that diet-induced metabolic acidosis and its sequelae in humans eating contemporary diets reflect a mismatch between the nutrient composition of the diet and genetically determined nutritional requirements for optimal systemic acid-base status.
Sebastian
Anthony
A
Department of Medicine and the General Clinical Research Center, University of California, San Francisco, California 94143, USA. anthony_sebastian@msn.com
Frassetto
Lynda A
LA
Sellmeyer
Deborah E
DE
Merriam
Renée L
RL
Morris
R Curtis
RC
D000136:Acid-Base Equilibrium; D000138:Acidosis; D000143:Acids; D000383:Agriculture; D000822:Animal Husbandry; D000818:Animals; D005075:Biological Evolution; D004032:Diet; D002523:Edible Grain; D002149:Energy Intake; D015186:Hominidae; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D010945:Plants, Edible
D000143:Acids