Increasing dietary protein requirements in elderly people for optimal muscle and bone health.
ABSTRACT Osteoporosis and sarcopenia are degenerative diseases frequently associated with aging. The loss of bone and muscle results in significant morbidity, so preventing or attenuating osteoporosis and sarcopenia is an important public health goal. Dietary protein is crucial for development of bone and muscle, and recent evidence suggests that increasing dietary protein above the current Recommended Dietary Allowance (RDA) may help maintain bone and muscle mass in older individuals. Several epidemiological and clinical studies point to a salutary effect of protein intakes above the current RDA (0.8 g/kg per day) for adults aged 19 and older. There is evidence that the anabolic response of muscle to dietary protein is attenuated in elderly people, and as a result, the amount of protein needed to achieve anabolism is greater. Dietary protein also increases circulating insulin-like growth factor, which has anabolic effects on muscle and bone. Furthermore, increasing dietary protein increases calcium absorption, which could be anabolic for bone. Available evidence supports a beneficial effect of short-term protein intakes up to 1.6 to 1.8 g/kg per day, although long-term studies are needed to show safety and efficacy. Future studies should employ functional measures indicative of protein adequacy, as well as measures of muscle protein synthesis and maintenance of muscle and bone tissue, to determine the optimal level of dietary protein. Given the available data, increasing the RDA for older individuals to 1.0 to 1.2 g/kg per day would maintain normal calcium metabolism and nitrogen balance without affecting renal function and may represent a compromise while longer-term protein supplement trials are pending.
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ABSTRACT: We examined the incidence and the reversibility of sarcopenia and their associated factors over a 4-year period using the European Working Group on Sarcopenia in Older People (EWGSOP) criteria. A total of 4000 community-dwelling older adults aged ≥65 years were evaluated for which detailed information regarding demographics, socioeconomic, medical history, lifestyle, and clinical factors were documented at baseline, 2 years, and 4 years later. Sarcopenia was defined according to the EWGSOP algorithm. Incident sarcopenia and its reversibility were documented at each follow-up year, and related to possible factors. At baseline, of the 4000 participants, 361 (9.0%) had sarcopenia. Between baseline and 2-year follow-up, 6.0% of the participants without sarcopenia at baseline had developed sarcopenia, and 18.8% of the initially sarcopenic participants had reverted to normal. Between baseline and 4-year follow-up, the corresponding figures were 6.3% and 14.1%, respectively. The average annual incidence over 4 years was 3.1%. After multivariate adjustments, older age, female sex, presence of chronic obstructive pulmonary disease, presence of stroke, higher physical activity levels, presence of instrumental activities of daily living impairments, and lower body mass index were associated with incident sarcopenia, whereas younger age, female sex, higher body mass index and absence of instrumental activities of daily living impairments, but not physical activity, were associated with its reversibility. Protein and vitamin D intake were not significantly associated with sarcopenia incidence or its reversibility. Sarcopenia incidence increases with age, but is potentially reversible in a Chinese elderly population. High body mass index is protective against sarcopenia incidence and its reversibility. Increasing physical activity and maintaining a healthy weight could be beneficial in the prevention of sarcopenia. Geriatr Gerontol Int 2014; 14 (Suppl. 1): 15-28.Geriatrics & Gerontology International 02/2014; 14 Suppl 1:15-28.
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ABSTRACT: This study examined the effects of the dietary amount and source of protein on bone status in rats. 140 male Wistar rats aged 8 weeks were randomly allocated to 4 groups (n = 35) fed normal-protein (NP, 10% richness) or high-protein (HP, 45% richness) diets based on whey protein (WP) or soy protein (SP) sources for 12 weeks. Plasma urea was 46% higher for the HP compared to the NP diet (p < 0.001). Urinary calcium was 65% higher for the HP compared to the NP and 60% higher for the WP compared to the SP diets (all, p < 0.001). Urinary pH was 8% more acidic in the HP compared to the NP diet (p < 0.001) and 4% in the WP compared to the SP diet (p < 0.01). The plasma osteocalcin concentration was 19% higher for the NP compared to the HP (p < 0.05) and 25% for the SP compared to the WP diets (p < 0.01). Femur ash, metaphyseal and diaphyseal cross-sectional, trabecular and cortical areas were 3% higher in the HP compared to the NP diet (all, p < 0.05). Femur diaphyseal periosteal and endocortical perimeters were also 3% higher in the HP compared to the NP diet (both, p < 0.01). Groups fed the SP diet showed 2% higher femur ash percentage, 7% higher calcium content (both, p < 0.001), and 3% higher diaphyseal cortical area and thickness (both, p < 0.05) than those fed the WP diet. Some interactions were found, such as the greater effects of the SP diet on decreasing the higher plasma urea concentration promoted by the intake of the HP diet (p < 0.001). Under adequate Ca intake, HP diets could better maintain bone properties than NP diets, even with increasing some acidity markers, which could be reduced by the intake of SP sources.Food & Function 02/2014; · 2.69 Impact Factor
Dataset: JAMDA PROT-AGE paper - reprint