Dairy and Dairy Alternative Supplementation Increase Integrated Myofibrillar Protein Synthesis Rates, and are Further Increased when Combined with Walking in Healthy Older Women.

doi:10.1093/jn/nxab358

Paper

Dairy and Dairy Alternative Supplementation Increase Integrated Myofibrillar Protein Synthesis Rates, and are Further Increased when Combined with Walking in Healthy Older Women.

Published Oct 5, 2021 · Tanner Stokes, Yixue Mei, Freddie Seo

The Journal of nutrition

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Abstract

BACKGROUND The stimulation of muscle protein synthesis (MPS) by dietary protein is reduced with age. We hypothesized that twice-daily milk consumption would increase daily rates of MPS in older women relative to a non-dairy milk alternative and that MPS would be enhanced by increased physical activity (PA). METHODS Twenty-two older women were randomly assigned to one of three experimental groups: whole milk (WM; n = 7, 69 ± 3 y), skim milk (SM; n = 7, 68 ± 3 y) or an almond beverage (AB; n = 8, 63 ± 3 y). From days 1 to 3, participants consumed a standardized diet (0.8 g protein⋅kg-1 ⋅d-1) and performed their habitual PA (Phase 1, Baseline). From days 4 to 6, participants continued to perform habitual PA, but consumed an intervention diet consisting of the standardized diet plus twice daily beverages (250 mL each) of either WM, SM, or AB (Phase 2, Diet Intervention). Finally, from days 7 to 9, the intervention diet was consumed, and PA via daily steps was increased to ∼150% of habitual daily steps (Phase 3, Intervention Diet + PA). Deuterated water was ingested throughout the study, and muscle biopsies were taken on days 1, 4, 7 and 10 to measure MPS. RESULTS Daily MPS rates were not differentially affected by the addition of WM, SM or AB to a standardized diet. There was, however, a significant effect of study phase such that, when collapsed across conditions, MPS was significantly increased from Phase 1 to Phase 2 (+0.133%⋅d-1; 95% C.I., 0.035 - 0.231; P < 0.01) and further increased from Phase 2 to Phase 3 (+0.289%⋅d-1; 95% C.I., 0.063 - 0.250; P < 0.01). CONCLUSIONS Increasing physical activity through walking was sufficient to increase daily MPS rates in older women, irrespective of whether dietary protein intake is increased beyond the recommended intake of 0.8 g⋅kg-1 ⋅d-1. The trial was registered at clinicaltrials.gov as NCT04981652.

Study Snapshot

Key takeawayIncreasing daily physical activity through walking is sufficient to increase muscle protein synthesis rates in older women, regardless of dietary protein intake.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Dairy and Dairy Alternative Supplementation Increase Integrated Myofibrillar Protein Synthesis Rates, and are Further Increased when Combined with Walking in Healthy Older Women.

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