title: Food groups associated with measured net acid excretion in community-dwelling older adults.
abstract: 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.
authors.affiliation: Bone Metabolism Laboratory, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Shea
authors.affiliation: Bone Metabolism Laboratory, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Gilhooly
authors.affiliation: Bone Metabolism Laboratory, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
authors.forename: B
authors.initials: B
authors.lastname: Dawson-Hughes
mesh_terms: D000136:Acid-Base Equilibrium; D000143:Acids / Q000652:urine*; D000368:Aged; D003430:Cross-Sectional Studies; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D005638:Fruit; D006801:Humans; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D011795:Surveys and Questionnaires; D014675:Vegetables; D000067348:Whole Grains
chemical_list: D000143:Acids; D004044:Dietary Proteins