title: Physiological effects beyond the significant gain in muscle mass in sarcopenic elderly men: evidence from a randomized clinical trial using a protein-rich food.
abstract: BACKGROUND
  Sarcopenia is strongly associated with an inadequate intake of dietary protein. Dietary protein supplementation boosts muscle-protein synthesis and increases muscle mass in the elderly. This study tested whether adding a protein-rich food, ricotta cheese, to the habitual diet increased total appendicular skeletal muscle mass and strength in elderly people.
  
  
  METHODS
  Participants (n = 40), were sarcopenic elderly men and women over 60 years of age. Two comparison groups were formed at random and followed for 3 months: the intervention group received 210 g/day of ricotta cheese plus the habitual diet, while the control group followed the habitual diet with no additional intervention. Total appendicular skeletal muscle (TASM) was assessed by dual-energy X-ray absorptiometry, while strength was measured using a handheld dynamometer at baseline and after the intervention period. The primary outcomes were the percentage of relative change in TASM and strength.
  
  
  RESULTS
  The percentage of relative change in TASM was not significant between the groups after the intervention period. Muscle strength improved in the intervention group, but showed only a tendency towards significance (P = 0.06). Secondary analysis showed that the men in the intervention group gained 270 g in TASM compared to those in the control group, and improved their fasting insulin levels (P = 0.05), muscle strength, lean body mass in the arms, and body weight variables.
  
  
  CONCLUSIONS
  The results of this study indicate that a nutritional intervention using a high-quality protein food, specifically ricotta cheese, in order to increase the amount of protein intake might not be regarded as fully promising in elderly men and women with sarcopenia. However, the gender effects on muscle strength, lean tissue in the arms, homeostatic assessment of insulin resistance, and body weight detected in this study suggest that additional research is needed on elderly male subjects with sarcopenia.
authors.affiliation: Coordinación de Nutrición, Centro de Investigación en Alimentación y Desarrollo, AC, Hermosillo, Sonora, México. helio@ciad.mx
authors.forename: Heliodoro
authors.initials: H
authors.lastname: Alemán-Mateo
authors.forename: Liliana
authors.initials: L
authors.lastname: Macías
authors.forename: Julián
authors.initials: J
authors.lastname: Esparza-Romero
authors.forename: Humberto
authors.initials: H
authors.lastname: Astiazaran-García
authors.forename: Ana Luz
authors.initials: AL
authors.lastname: Blancas
mesh_terms: D000368:Aged; D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism; D002611:Cheese; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D055948:Sarcopenia / Q000178:diet therapy* / Q000503:physiopathology; D012737:Sex Factors
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins