Low Protein Intake Irrespective of Source is Associated with Higher Mortality Among Older Community-dwelling Men.

OBJECTIVES: Our aim was to determine the association between protein intake (overall and by source) and all-cause and cause-specific mortality among older men. DESIGN: Prospective cohort study. SETTING: 5790 ambulatory community-dwelling older men from multicenter Osteoporotic Fractures in Men (MrOS) study. MEASUREMENTS: Total energy and protein intake, and protein intake by source (dairy, non-dairy animal, plant) were assessed using a 69-item food frequency questionnaire. We included up to 10-year follow-up with adjudicated cardiovascular, cancer and other mortality outcomes. We used time-to-event analysis with protein exposures, mortality outcome, and adjusted for possible confounders including age, center, education, race, smoking, alcohol use, physical activity, weight, total energy intake (TEI), and comorbidities. Hazard ratios were expressed per each unit=2.9% TEI decrement for all protein intake variables. RESULTS: The mean (SD) baseline age of 5790 men was 73.6 (5.8) y. There were 1611 deaths and 211 drop-outs prior to 10 years, and 3868 men who were alive at the 10-year follow-up. The mean (SD) total protein intake was 64.7 (25.8) g/d, while the mean (SD) intake expressed as percent of total energy intake (%TEI) was 16.1 (2.9) %TEI. Lower protein intake was associated with an increased risk of death, with unadjusted HR=1.11 (95% CI: 1.06, 1.17) and adjusted HR=1.09 (95% CI: 1.04, 1.14) and the associations for protein intake by source were similar. The adjusted HR for cancer mortality was HR=1.13 (95% CI: 1.03, 1.25) while the association for CVD mortality was HR=1.08 (95% CI: 0.99, 1.18). CONCLUSIONS: Low protein intake, irrespective of source, was associated with a modest increase in risk of all-cause and cause-specific mortality among older men. Special consideration should be given to level of protein intake among older adults.

Transition to a More even Distribution of Daily Protein intake Is Associated with Enhanced Fat Loss during a Hypocaloric and Physical Activity Intervention in Obese Older Adults.

BACKGROUND: Optimization of intentional weight loss in obese older adults, through preferential fat mass reduction, is challenging, as the concomitant lean mass loss may exacerbate sarcopenia. Recent studies have suggested within-day distribution of protein intake plays a role in determining body composition remodeling. Here, we assessed whether changes in within-day protein intake distribution are related to improvements in body composition in overweight/obese older adults during a hypocaloric and exercise intervention. METHODS: Thirty-six community-dwelling, overweight-to-obese (BMI 28.0-39.9 kg/m2), sedentary older adults (aged 70.6±6.1 years) were randomized into either physical activity plus successful aging health education (PA+SA; n=15) or physical activity plus weight loss (PA+WL; n=21) programs. Body composition (by CT and DXA) and dietary intake (by three-day food records) were determined at baseline, 6-month, and 12-month follow-up visits. Within-day protein distribution was calculated as the coefficient of variation (CV) of protein ingested per defined time periods (breakfast [5:00-10:59], lunch [11:00-16:59] and dinner [17:00-1:00]). Secondary analysis was performed to determine associations between changes in protein intake distribution and body composition. RESULTS: In both groups, baseline protein intake was skewed towards dinner (PA+SA: 49.1%; PA+WL: 54.1%). The pattern of protein intake changed towards a more even within-day distribution in PA+WL during the intervention period, but it remained unchanged in PA+SA. Transition towards a more even pattern of protein intake was independently associated with a greater decline in BMI (P<0.05) and abdominal subcutaneous fat (P<0.05) in PA+WL. However, changes in protein CV were not associated with changes in body weight in PA+SA. CONCLUSION: Our results show that mealtime distribution of protein intake throughout the day was associated with improved weight and fat loss under hypocaloric diet combined with physical activity. This finding provides a novel insight into the potential role of within-day protein intake on weight management in obese older people.