A Randomized Study on the Effect of Dried Fruit on Acid-Base Balance, Diet Quality, and Markers of Musculoskeletal Health in Community Dwelling Adults

Abstract

Objectives

We tested whether 100 g/day of dried fruit (vs. no supplemental fruit control) for 6 months alters 24-hr urinary net acid excretion (NAE), bone resorption, weight, body composition, muscle performance, and diet quality. We explored consistency of self-selected dietary composition and potential renal acid load (PRAL).

Methods

This randomized, single-blind, 2-armed study included 83 normal- and over-weight men and postmenopausal women (age ≥50 years) on self-reported low fruit diets. Endpoints included group differences in NAE (primary), 24-hr urinary N-telopeptide (NTX), weight, body composition, muscle performance, and diet quality.

Results

At baseline, mean (±SD) age was 69 ± 8 years; 86% were Caucasian; body mass index was 24.5 ± 2.8 kg/m²; 46% female, and NAE was 32.4 ± 23.1 mmol with no significant baseline group differences. No significant group differences were noted in NAE (primary), NTX, weight, body composition, muscle performance or diet quality at 6 months. In the cohort as a whole, 6-month change in NAE was positively associated with change in NTX, but no significant associations were noted in other outcomes. PRAL on the day of the urine collection was positively associated with NAE. Comparison of two consecutive baseline 24-hr diet recalls revealed wide intra-individual variability in PRAL in self-selected diets in our participants.

Conclusion

In this field study of older adults consuming self-selected diets, making one change to the diet by adding 100 g/day of dried fruit (equivalent to 4 servings per day) had no significant impact on NAE when compared to a no supplemental fruit control. This null finding may be attributable to the high day-to-day variability in consumption of foods affecting NAE. Added fruit also had no significant effect on weight, fat, muscle, or bone outcomes over a 6-month period.

Keywords:

• Dried fruit
• acid-base balance
• net acid excretion
• N-telopeptide
• body composition

Acknowledgments

We thank the staff in the Bone Metabolism Laboratory, the Metabolic Research Unit and the Nutritional Evaluation Laboratory for their contribution to the study. This material is based upon work supported by the U.S. Department of Agriculture, Agricultural 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 U.S. Dept of Agriculture.

Authors’ contributions

BDH designed research; HR and CHG conducted research; LC, KS analyzed data or performed statistical analysis; LC, KS, and BDH wrote paper; LC and BDH had primary responsibility for final content. All authors have read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This material is based upon work supported by the U.S. Department of Agriculture, Agricultural 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 U.S. Dept of Agriculture.