Nutrient-rich dairy proteins improve appendicular skeletal muscle mass and physical performance, and attenuate the loss of muscle strength in older men and women subjects: a single-blind randomized clinical trial

Heliodoro Alemán-Mateo,1 Virginia Ramírez Carreón,1 Liliana Macías,1 Humberto Astiazaran-García,1 Ana Cristina Gallegos-Aguilar,1 José Rogelio Ramos Enríquez2 1Coordinación de Nutrición, Centro de Investigación en Alimentación y Desarrollo, A.C., 2Laboratorio de Análisis Clínicos e Investigación, Departamento de Ciencias Químico Biológicas, Universidad de Sonora, Hermosillo, Mexico Background: At present, it is unknown whether the use of nutrient-rich dairy proteins improves the markers of sarcopenia syndrome. Therefore, our proposal was to investigate whether ­adding 210 g of ricotta cheese daily would improve skeletal muscle mass, handgrip strength, and ­physical performance in non-sarcopenic older subjects.Subjects and methods: This was a single-blind randomized clinical trial that included two homogeneous, randomized groups of men and women over 60 years of age. Participants in the intervention group were asked to consume their habitual diet but add 210 g of ricotta cheese (IG/HD + RCH), while the control group was instructed to consume only their habitual diet (CG/HD). Basal and 12-week follow-up measurements included appendicular skeletal muscle mass (ASMM) by dual-energy X-ray absorptiometry, handgrip strength by a handheld dynamometer, and physical performance using the short physical performance battery (SPPB) and the stair-climb power test (SCPT). The main outcomes were relative changes in ASMM, strength, SPPB, and SCPT.Results: ASMM increased in the IG/HD + RCH (0.6±3.5 kg), but decreased in the CG/HD (–1.0±2.6). The relative change between groups was statistically significant (P=0.009). The relative change in strength in both groups was negative, but the loss of muscle strength was more pronounced in CG/HD, though in this regard statistical analysis found only a tendency (P=0.07). The relative change in the balance-test scores was positive for the IG/HD + RCH, while in the CG/HD it was negative, as those individuals had poorer balance. In this case, the relative change between groups did reach statistical significance.Conclusion: The addition of 210 g of ricotta cheese improves ASMM and balance-test scores, while attenuating the loss of muscle strength. These results suggest that adding ricotta cheese to the habitual diet is a promising dietetic strategy that may improve the markers of sarcopenia in subjects without a pronounced loss of ASMM or sarcopenia. Keywords: nutritional intervention, nutrient-rich dairy proteins, ricotta cheese, markers of sarcopenia, elderly