Chanet A, et al. – This study was performed on healthy older adults to assess postprandial muscle protein synthesis and longer–term changes in muscle mass consequent to supplementing breakfast with a vitamin D and leucine–enriched whey protein medical nutrition drink. This “proof of principle” study revealed that this dietary intervention stimulated postprandial muscle protein synthesis and increased muscle mass after 6 wk of intervention and may, therefore, be a way to support muscle preservation in older people.

Methods

• Between September 2012 and October 2013, a randomized, placebo-controlled, double-blind study was performed in 24 healthy older men [mean ± SD: age 71 ± 4 y; body mass index (in kg/m²) 24.7 ± 2.8] at the Unit of Human Nutrition, University of Auvergne, Clermont-Ferrand, France.
• For 6 wk, researchers assigned participants to receive a medical nutrition drink [test group; 21 g leucine-enriched whey protein, 9 g carbohydrates, 3 g fat, 800 IU cholecalciferol (vitamin D3), and 628 kJ] or a noncaloric placebo (control group) before breakfast.
• They measured mixed muscle protein fractional synthesis rate (FSR) at week 0 in the basal and postprandial state, after study product intake with a standardized breakfast with the use of L-[2H5]-phenylalanine tracer methodology.
• They also assessed the longer-term impact of the medical nutrition drink by measurement of appendicular lean mass, representing skeletal muscle mass at weeks 0 and 6, by dual-energy X-ray absorptiometry.

Results

• Findings demonstrated that postprandial FSR (0–240 min) was higher in the test group than in the control group [estimate of difference (ED): 0.022%/h; 95% CI: 0.010%/h, 0.035%/h; ANCOVA, P = 0.001].
• Researchers found that the test group gained more appendicular lean mass than the control group after 6 wk (ED: 0.37 kg; 95% CI: 0.03, 0.72 kg; ANCOVA, P = 0.035), predominantly as leg lean mass (ED: 0.30 kg; 95% CI: 0.03, 0.57 kg; ANCOVA, P = 0.034).