Dietary protein

Maintaining autonomy is an important aspect of ageing and dietary proteins have been proposed as factors that help maintain physical performance in older adults. Dietary protein intake is associated with increased muscle strength but not mobility in elderly men and women.


Unfortunately, aging often comes with a physical and cognitive decline that leads to a loss of independence. Elderly individuals often have difficulty with mobility and suffer from more health challenges than the rest of the population.

Several studies have attempted to demonstrate the association that exists between aging, dietary protein consumption, and physical performance; however, there has yet to be a consensus due to inconsistencies reported in prior cross sectional and longitudinal studies. In order to explore the subject in greater detail, Farsijani and colleagues studied the relationship between mealtime protein intake and physical performance over a 3 year period in elderly adults living independently. In an article recently published in the American Journal of Clinical Nutrition, researchers conducted a longitudinal study and analyzed 3-year follow-up data from 827 men and 914 women between the ages of 67-84 in Quebec, Canada. Participants, 98.5% of whom were Caucasian, were recruited between the years 2003 to 2008, and were generally healthy and living independently. The researchers computed measurements that reflected nutritional, functional, medical, biomedical, and social status at baseline and then annually over the duration of the study period. In order to adequately assess dietary protein intake the participants were interviewed and asked to give detailed descriptions of all foods and beverages (including brand names) and cooking recipes that were consumed in the previous day. There were a total of six non-consecutive 24-hour recall interviews and trained registered dieticians carefully conducted them.

There were also two functional composite scores used to measure physical performance: muscle strength (hand grip, arm, and leg strengths), and mobility (timed-up-and-go, chair stand, and fast walking speeds). As with the dietary assessments, each physical component was measured at baseline and then annually for the next 3 years. Farsijani and colleagues collected data for BMI, depression using the Geriatric Depression Scale (GDS), smoking, number of medications, physical activity using the Physical Activity Scale for the Elderly (PASE), and midupper arm muscle area (MAMA), and they considered depression and cognitive status as possible confounding variables in this study.

The researchers hypothesized that elderly people having a more evenly distributed protein intake during meals, regardless of the amount of protein consumed, would have a better physical performance and less decline over time. What they found was that, throughout the follow-up period, older men and women who had a more evenly distributed protein intake had greater muscle strength, but not mobility.  Protein-intake distribution was not associated with the rate of decline in physical function, which remained constant regardless of the total protein intake. They concluded that consuming a fair amount of protein at every meal, even if not reaching 30g, was better for muscle health than ingesting only one high protein meal.

This study may not be generalizable to more frail individuals who have chronic illnesses, as participants were those who were free-living and generally healthy. Also this observational study does not allow for a causal relationship to be established between protein intake at mealtime and physical performance. This study is important because it informs readers of the possible health benefits associated with increasing the protein content in each meal in elderly people. The ability to maintain physical strength and mobility for as long as possible will increase the independence and functionality of the aging population.


Written By: Kimberly Spencer B.Sc. (Hons)

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