Dietary acid load, kidney function, osteoporosis, and risk of fractures in elderly men and women
Because kidney dysfunction reduces the ability to excrete dietary acid excess, we hypothesized that underlying kidney function may have confounded the mixed studies linking dietary acid load with the risk of osteoporosis and fractures in the community. In a relatively large survey of elderly men and women, we report that dietary acid load did neither associate with DEXA-estimated bone mineral density nor with fracture risk. Underlying kidney function did not modify these null findings. Our results do not support the dietary acid-base hypothesis of bone loss.
Impaired renal function reduces the ability to excrete dietary acid excess. We here investigate the association between dietary acid load and bone mineral density (BMD), osteoporosis, and fracture risk by renal function status.
An observational study was conducted in 861 community-dwelling 70-year-old men and women (49 % men) with complete dietary data from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS). The exposure was dietary acid load as estimated from 7-day food records by the net endogenous acid production (NEAP) and potential renal acid load (PRAL) algorithms. Renal function assessed by cystatin C estimated glomerular filtration rate was reduced in 21 % of the individuals. Study outcomes were BMD and osteoporosis state (assessed by DEXA) and time to fracture (median follow-up of 9.2 years).
In cross-section, dietary acid load had no significant associations with BMD or with the diagnosis of osteoporosis. During follow-up, 131 fractures were validated. Neither NEAP (adjusted hazard ratios (HR) (95 % confidence interval (CI)), 1.01 (0.85–1.21), per 1 SD increment) nor PRAL (adjusted HR (95 % CI), 1.07 (0.88–1.30), per 1 SD increment) associated with fracture risk. Further multivariate adjustment for kidney function or stratification by the presence of kidney disease did not modify these null associations.
The hypothesis that dietary acid load associates with reduced BMD or increased fracture risk was not supported by this study in community-dwelling elderly individuals. Renal function did not influence on this null finding.
KeywordsBone mineral density Dietary acid load Fractures Osteoporosis Renal function
This work was supported by the grants from the Swedish Research Council. Baxter Novum is the result of a grant from Baxter Healthcare Corporation to Karolinska Institutet.
Conflicts of interest
BL is affiliated with Baxter Healthcare Corporation. TEL is an employee of Astellas. Ting Jia, Liisa Byberg, Lars Lind, Karl Michaëlsson, and Juan Jesus Carrero declare that they have no conflict of interest.
- 19.Macdonald HM, New SA, Fraser WD, Campbell MK, Reid DM (2005) Low dietary potassium intakes and high dietary estimates of net endogenous acid production are associated with low bone mineral density in premenopausal women and increased markers of bone resorption in postmenopausal women. Am J Clin Nutr 81:923–933PubMedGoogle Scholar
- 25.Lind L, Andersson J, Ronn M, Gustavsson T, Holdfelt P, Hulthe J, Elmgren A, Zilmer K, Zilmer M (2008) Brachial artery intima-media thickness and echogenicity in relation to lipids and markers of oxidative stress in elderly subjects:–the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Lipids 43:133–141PubMedCrossRefGoogle Scholar
- 33.McLean RR, McLennan CE, Qiao N, Broe KE, Tucker KL, Cupples LA, Hannan MT (2007) Net endogenous acid production (NEAP) and bone mineral density in men and women: the Framingham Offspring Study. J Bone Miner Res 22:S307Google Scholar
- 44.Schatzkin A, Kipnis V, Carroll RJ, Midthune D, Subar AF, Bingham S, Schoeller DA, Troiano RP, Freedman LS (2003) A comparison of a food frequency questionnaire with a 24-hour recall for use in an epidemiological cohort study: results from the biomarker-based Observing Protein and Energy Nutrition (OPEN) study. Int J Epidemiol 32:1054–1062PubMedCrossRefGoogle Scholar