COOL NEW DATA RE PH

Am J Clin Nutr 2002 Dec;76(6):1308-16

Estimation of the net acid load of the diet of ancestral preagricultural Homo
sapiens and their hominid ancestors.

Sebastian A, Frassetto LA, Sellmeyer DE, Merriam RL, Morris RC Jr.

Department of Medicine and the General Clinical Research Center, University
of California, San Francisco, California 94143, USA.
[log in to unmask]

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. DESIGN: 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.

-----------------------------------------------------------------
To unsubscribe from the list send an email to [log in to unmask] with the words SIGNOFF EVOLUTIONARY-FITNESS in the _body_ of the email.

To get a copy of the old archives or the FAQ, look in the EvFit folder at http://briefcase.yahoo.com/dryeraser