The effect of supplementation with alkaline potassium salts on bone metabolism: a meta-analysis
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The role of acid–base metabolism in bone health is controversial. In this meta-analysis, potassium bicarbonate and potassium citrate lowered urinary calcium and acid excretion and reduced the excretion of the bone resorption marker NTX. These salts may thus be beneficial to bone health by conserving bone mineral.
The role of acid–base homeostasis as a determinant of bone health and the contribution of supplemental alkali in promoting skeletal integrity remain a subject of debate. The objective of this study was, therefore, to conduct a meta-analysis to assess the effects of supplemental potassium bicarbonate (KHCO3) and potassium citrate (KCitr) on urinary calcium and acid excretion, markers of bone turnover and bone mineral density (BMD) and to compare their effects with that of potassium chloride (KCl).
A total of 14 studies of the effect of alkaline potassium salts on calcium metabolism and bone health, identified by a systematic literature search, were analysed with Review Manager (Version 5; The Cochrane Collaboration) using a random-effects model. Authors were contacted to provide missing data as required. Results are presented as the standardised (SMD) or unstandardized mean difference (MD) (95 % confidence intervals).
Urinary calcium excretion was lowered by intervention with both KHCO3 (P = 0.04) and KCitr (P = 0.01), as was net acid excretion (NAE) (P = 0.002 for KHCO3 and P = 0.0008 for KCitr). Both salts significantly lowered the bone resorption marker NTX (P < 0.00001). There was no effect on bone formation markers or BMD. KHCO3 and KCitr lowered calcium excretion to a greater extent than did KCl.
This meta-analysis confirms that supplementation with alkaline potassium salts leads to significant reduction in renal calcium excretion and acid excretion, compatible with the concept of increased buffering of hydrogen ions by raised circulating bicarbonate. The observed reduction in bone resorption indicates a potential benefit to bone health
KeywordsAlkali Bone mineral density Markers of bone turnover Potassium
Conflicts of interest
- 2.Berkemeyer S, Vormann J, Guenther ALB, Rylander R, Frassetto LA, Remer T (2008) Renal net acid excretion capacity is comparable in prepubescence, adolescence, and young adulthood but falls with aging. J Am Geriatr Soc 56(8):1442–1448. doi: 10.1111/j.1532-5415.2008.01799.x CrossRefPubMedGoogle Scholar
- 3.Frassetto LA, Morris RC, Sebastian A (1996) Effect of age on blood acid–base composition in adult humans: role of age-related renal functional decline. Am J Physiol Ren Physiol 271(6):F1114–F1122Google Scholar
- 8.Bushinsky DA (1995) Stimulated osteoclastic and suppressed osteoblastic activity in metabolic but not respiratory acidosis. Am J Physiol Cell Physiol 268(1):C80–C88Google Scholar
- 10.Higgins JPT AD, Stern JAC (2011) Chapter 8: assessing risk of bias in included studies. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. The Cochrane CollaborationGoogle Scholar
- 11.Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009) Preferred reporting times for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med 151(4):264–269Google Scholar
- 12.Buehlmeier J, Frings-Meuthen P, Remer T, Maser-Gluth C, Stehle P, Biolo G, Heer M (2012) Alkaline salts to counteract bone resorption and protein wasting induced by high salt intake: results of a randomized controlled trial. J Clin Endocrinol Metab 97(12):4789–4797. doi: 10.1210/jc.2012-2857 CrossRefPubMedGoogle Scholar
- 13.Ceglia L, Harris SS, Abrams SA, Rasmussen HM, Dallal GE, Dawson-Hughes B (2009) Potassium bicarbonate attenuates the urinary nitrogen excretion that accompanies an increase in dietary protein and may promote calcium absorption. J Clin Endocrinol Metab 94(2):645–653CrossRefPubMedCentralPubMedGoogle Scholar
- 16.He FJ, Marciniak M, Carney C, Markandu ND, Anand V, Fraser WD, Dalton RN, Kaski JC, MacGregor GA (2010) Effects of potassium chloride and potassium bicarbonate on endothelial function, cardiovascular risk factors, and bone turnover in mild hypertensives. Hypertension 55(3):681–688. doi: 10.1161/hypertensionaha.109.147488 CrossRefPubMedGoogle Scholar
- 19.Macdonald HM, Black AJ, Aucott L, Duthie G, Duthie S, Sandison R, Hardcastle AC, New SAL, Fraser WD, Reid DM (2008) Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial. Am J Clin Nutr 88(2):465–474PubMedGoogle Scholar
- 30.Maurer M, Muser J, Riesen WF, Hulter HN, Krapf R (2002) Alkali-induced neutralization of the acidogenic western diet inhibits bone resorption independent of potassium intake and reduces cortisol secretion in humans. J Am Soc Nephrol 13:387A–387AGoogle Scholar
- 31.Vezzoli G, Soldati L, Arcidiacono T, Terranegra A, Biasion R, Russo CR, Lauretani F, Bandinelli S, Bartali B, Cherubini A, Cusi D, Ferrucci L (2005) Urinary calcium is a determinant of bone mineral density in elderly men participating in the InCHIANTI study. Kidney Int 67(5):2006–2014. doi: 10.1111/j.1523-1755.2005.00302.x CrossRefPubMedGoogle Scholar
- 33.Shi L, Libuda L, Schoenau E, Frassetto L, Remer T (2012) Long term higher urinary calcium excretion within the normal physiologic range predicts impaired bone status of the proximal radius in healthy children with higher potential renal acid load. Bone 50(5):1026–1031. doi: 10.1016/j.bone.2012.01.026 CrossRefPubMedGoogle Scholar
- 34.Frassetto LA, Hardcastle AC, Sebastian A, Aucott L, Fraser WD, Reid DM, Macdonald HM (2012) No evidence that the skeletal non-response to potassium alkali supplements in healthy postmenopausal women depends on blood pressure or sodium chloride intake. Eur J Clin Nutr 66(12):1315–1322. doi: 10.1038/ejcn.2012.151 CrossRefPubMedGoogle Scholar