Acid-producing diets have been associated with adverse health conditions. Dietary acid load can be estimated from dietary intake data, but the available methods require a full dietary assessment. We sought to identify a simpler means to estimate 24-h urinary net acid excretion (NAE), a robust measure of net endogenous acid production, using self-reported intakes of fruits, vegetables (acid-neutralizing foods), grain and/or protein (acid-producing foods) acquired by two different methods in community-dwelling older adults. Identifying food groups associated with NAE by using a method not requiring a full diet assessment could have a broad clinical application.
Fruit, vegetable, protein and grain servings/day were estimated with a widely used food frequency questionnaire (study A, n=162, 63±8 years). Differences in their intakes across NAE categories (<5, ⩾5 to <15, ⩾15 to <50, ⩾50 milliequivalents (mEq)/day) were analyzed using analysis of variance. The findings were verified in a second study, which estimated dietary intakes, using a more detailed record-assisted 24-h recall (study B, n=232, 67±6 years).
Fruit intake was significantly associated with NAE in both studies. In study A, fruit intake was 9% lower with each categorical NAE increase (unstandardized beta=−0.21, P=0.01) and 7% lower with each categorical NAE increase in study B (unstandardized beta=−0.18; P=0.02). Grain intake was positively associated with NAE in study B only (unstandardized beta=+0.14; P=0.01). Vegetable and protein intake were not associated with NAE in either study.
The inverse association between fruit intake and NAE suggests low self-reported fruit intake may be an indicator of acid-producing diets in older adults.
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This study was funded by NIH/NIAMS grant numbers R01AR060261 and R01AR052322 and also received support from the US Department of Agriculture, Agricultural (USDA) Research Service, under agreement No. 58-1950-7-707. Any opinions, findings, conclusion or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the USDA.
The authors declare no conflict of interest.
Supplementary Information accompanies this paper on European Journal of Clinical Nutrition website
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Shea, M., Gilhooly, C. & Dawson-Hughes, B. Food groups associated with measured net acid excretion in community-dwelling older adults. Eur J Clin Nutr 71, 420–424 (2017). https://doi.org/10.1038/ejcn.2016.195