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/m2 (95% CI: 0.01, 0.23 kg/m2) and 0.11 kg/m2 (95% CI: 0.03, 0.19 kg/m2) 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.

Acute elevation of free fatty acids impairs hepatic glucose uptake in conscious rats.

To investigate the dose-dependent effect of free fatty acid (FFA) on the hepatic glucose uptake (HGU), we determined hepatic glucose fluxes by a dual tracer technique during the basal state and euglycemic hyperinsulinemic clamp combined with a portal glucose load in three groups of rats given saline (saline), low-dose lipid (lipid-L), or high-dose lipid infusion (lipid-H). In the basal state, lipid infusion dose-dependently increased plasma FFA (saline, 400 +/- 50; lipid-L, 550 +/- 30; lipid-H, 1700 +/- 270 micromol l(-1); mean +/- S.E). Endogenous glucose production (EGP) in lipid-H was 63.5 +/- 5.5 micromol kg(-1) min(-1) and significantly higher than in the saline and lipid-L (40.2 +/- 2.9, 47.6 +/- 3.1 micromol kg(-1) min(-1), respectively). During euglycemic hyperinsulinemic clamp, plasma FFA decreased to 130 +/- 30 micromol l(-1) in saline, but remained at basal levels in lipid-L and lipid-H (470 +/- 30 and 1110 +/- 180 micromol l(-1), respectively). Insulin-suppressed EGP was complete in saline and lipid-L, but impaired in lipid-H (38.0 +/- 6.4 micromol kg(-1) min(-1)). Elevated FFA dose-dependently reduced HGU (saline, 12.2 +/- 0.9; lipid-L, 8.6 +/- 0.6; lipid-H, 4.7 +/- 1.4 micromol kg(-1) min(-1)). In conclusion, acutely elevated FFA impairs HGU as well as insulin-mediated suppression of EGP during hyperinsulinemic clamp with portal glucose loading. Impaired hepatic glucose uptake associated with elevated FFA may contribute to the development of insulin resistance in obesity and type 2 diabetes.