When Is Low Potential Renal Acid Load (PRAL) Beneficial for Bone?

  • Thomas RemerEmail author
  • Danika Krupp
  • Lijie Shi


Potential metabolic influences of dietary acid load on bone health have been discussed controversially. Here, we review the available findings in adults and healthy children regarding certain methodological aspects including (i) appropriate use of urinary biomarkers – potential renal acid load (PRAL) and net acid excretion (NAE), (ii) problems in the interpretation of results on calcium balance and bone turnover markers, and (iii) possible influences of selection bias regarding baseline diets of the population groups of randomized controlled trials. Based on the available evidence, it is concluded that calcium balance measurements and bone turnover markers are no adequate and sensitive tools to evaluate the modest but long-term prevailing influence of nutrition on bone status. Findings in children and adults exclusively conducted on the most reliable outcomes, that is, bone densitometric structure analyses, suggest that a low-PRAL diet may be especially relevant in certain population groups, for example, in children with higher dietary protein intakes, in postmenopausal women with impaired bone status, and probably in adults on a habitually acidifying nutrition. The mechanisms mediating detrimental bone effects of higher dietary acid loads under discussion include changes in endocrine–metabolic milieu, for example, impairment of GH/IGF-1 axis and higher glucocorticoid secretion as well as direct bone–cell-related changes by higher acid load. In conclusion, to identify moderate alterations in bone status exerted through nutritional influences, not only appropriate assessments of dietary proton load but also outcome measurements that are closely related to long-term bone structure are required.


Dietary acid load Biomarker Potential renal acid load Net acid excretion Bone Calcium balance 



Bone mineral density


Dual-energy X-ray absorptiometry


Net acid excretion


Net endogenous acid production


Organic acids


Peripheral quantitative computed tomography (pQCT)


Potential renal acid load


Randomized controlled trial


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Copyright information

© Springer-Verlag London 2013

Authors and Affiliations

  1. 1.DONALD Study at the Research Institute of Child Nutrition, Nutritional EpidemiologyUniversity of BonnDortmundGermany

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