Dietary acid load decreases with age and is associated with sagittal abdominal diameter: a nationally representative quantification study in US adults

BACKGROUND: Dietary acid load (DAL) has been associated with frailty and hip fractures in older adults, who often have a reduced kidney function and thus compromised buffering capacities. Studies to quantify DAL in older adults are scarce and controversies persist as to whether DAL in- or decreases with age. AIM: To enhance the understanding of DAL in older individuals, we examined its relationship with increasing age and selected anthropometric data in a well-characterized sample of US adults. METHODS: Secondary data analysis of nationally representative data from the National Health and Nutrition Examination Surveys data (NHANES 2011–2016). The sample included n = 3018 adults aged 60+, which may be extrapolated to represent n = 45,113,471 Americans. DAL was estimated using 4 formulas, including Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP). RESULTS: All employed DAL scores tended to decline with increasing age. Participants aged 80 years or older yielded the lowest DAL scores. The average US citizen aged 60+ consumed an acidifying diet, yet there were sex-specific differences in the adjusted means for some scores. NEAP was positively correlated with both body mass index (r = 0.26, p < 0.001) and the sagittal abdominal diameter (r = 0.31, p < 0.001) in this nationally representative sample. CONCLUSION: The previously reported phenomenon of increasing DAL values in older people in non-Western countries may not apply to the US. Our findings may constitute an important step towards a better understanding of DAL in older US adults, and highlight the need for additional population-specific research in the field. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40520-023-02508-6.