Acid Base Considerations in Stone-Age Farming Sweet Potato Eaters, Modern-Day Sweet Potato Eaters, and High-Protein Consumers

Thomas Remer*, Shoma Berkemeyer, Friedrich Manz
Research Institute of Child Nutrition, Dortmund, Germany.

© 2008 Remer et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Research Institute of Child Nutrition, Dortmund, Germany;


Net endogenous acid production (NEAP) can be estimated by a primarily anthropometry-dependent organic acid anion (OA) component and the particularly diet-dependent potential renal acid load (PRAL). However, there is evidence that certain foods may also impact on the OA component. Here, we discuss measurements of urinary 24-h OA excretion obtained in healthy subjects, against the background of relevant literature with a special focus on former Papuan New Guinea stone-age farmers eating predominantly highland sweet potatoes. Contrary to the reports in Papuans, we observed only modest increases of 5-12% in 24-h excretion rates of OAs (including the detoxification product of phenolic and benzoic acids, i.e., hippuric acid) in healthy adults consuming commonly available yellow-fleshed sweet potatoes. This and additional results on OA increases after higher protein intakes suggest that a specification of the NEAP=PRAL+OA model for estimating the diet-dependent acid load to the metabolic system might be useful regarding particular foods and their effects on the OA component.

Keywords: Acid-base balance, diet, hippuric acid, 24-h urine, net endogenous acid production.