Chronic Intake of a Meal Including Alaska Pollack Protein Increases Skeletal Muscle Mass and Strength in Healthy Older Women: A Double-Blind Randomized Controlled Trial

BACKGROUND: In animal studies, a meal containing Alaska pollack protein (APP) induces fast-twitch muscle hypertrophy. To our knowledge, no interventional studies have examined the benefits of APP intake on muscle mass and muscle weakness and the prevention of sarcopenia in older individuals. OBJECTIVES: We evaluated the effects of APP intake on skeletal muscle mass, muscle strength, and physical performance among healthy community-dwelling older Japanese women. METHODS: In this double-blind randomized controlled trial, healthy women ≥ 65 y old were allocated to an APP or whey protein control (CON) group. Participants ingested test protein meals (5.0–5.1 g protein/serving) daily for 24 wk. Between-group differences in the change of skeletal muscle mass index (SMI) as the primary outcome and muscle strength as a secondary outcome were tested using multifrequency BIA and a handheld dynamometer, respectively, at baseline, and 4, 12, and 24 wk. The mean changes in the measured primary and secondary outcome variables from baseline to 4, 12, and 24 wk were compared using unpaired t tests. RESULTS: There were no between-group differences in nutritional status, food intake, or total energy and protein intakes at baseline, 12 wk, or 24 wk. The change in SMI was 0.12 kg/m(2) (95% CI: 0.01, 0.23 kg/m(2)) and 0.11 kg/m(2) (95% CI: 0.03, 0.19 kg/m(2)) greater in the APP group than in the CON group at 12 wk and 24 wk (P ≤ 0.03) and knee extension strength was 0.07 Nm/kg BW (95% CI: 0.02, 0.12 Nm/kg BW) and 0.05 Nm/kg BW (95% CI: 0.00, 0.09 Nm/kg BW) higher in the APP group than in the CON group at these times (P ≤ 0.015), respectively. The groups did not differ at 4 wk. CONCLUSIONS: Daily intake of a meal containing APP compared with whey protein increases skeletal muscle mass and lower-extremity muscle strength in healthy older women, suggesting that an APP-containing meal may be useful in the prevention of sarcopenia in this group. This trial was registered at as UMIN000035718.