The population of individuals over the age of 65 years, increased by 36 percent between 2006 and 2016 and is projected to double by 2060. While this population may technically constitute that which is termed the “elderly” population, many individuals are still quite active and healthy in their 60s. Many of us often think of the “elderly” as individuals in their 80s and beyond and according to the U.S. DHHS’s Association of Aging, it is expected that the number of individuals 85 years and older will increase by 129 percent between the years 2016 and 2040. Between these two age categories (65 and 85), mobility and physical functioning begin to rapidly decrease such that by the age of 75 years, nearly half of all individuals have difficulty with physical function.
Musculoskeletal deterioration in the elderly population (particularly osteoporosis and sarcopenia) is not only a major factor in declining mobility and physical functioning, but is also linked to many age-related chronic health conditions such as increased inflammation, loss of multiple physiological systems, hormone imbalance, psychological decline (depression, especially), mental/cognitive conditions, and increased vulnerability to infection, fever, falls, and surgery.
Nutritional deficits are important risk factors for diminished overall musculoskeletal performance and associated health risks in the elderly population. Muscle structure and function is dependent upon the availability of amino acids, provided primarily through dietary protein intake. Unfortunately, the elderly population has a reduced ability to digest and absorb protein, as well as decreased intake due to a reduced appetite, poor oral health and dysphagia, medication side effects, and social isolation, among other factors. Additionally, the elderly population experiences anabolic resistance and therefore, requires a greater intake of protein to achieve the same metabolic response (ie. muscle protein synthesis), compared to their younger counterparts. A declining immune system and increased degrees of chronic, systemic inflammation also contribute to a suppressed muscle protein turnover and homeostasis in the elderly population. Amino acids are the building blocks for immune cells and contribute to the health and function of this system.
A systematic review and meta-regression analysis of randomized trials, published in 2019, showed that mobility in elderly patients may be improved with a combination of protein supplementation and exercise therapy. When protein supplementation of up to 40 grams per day was combined with exercise therapy, lean body mass, length strength, and walk capability improved significantly. Often, increased physical activity is encouraged in elderly patients, but the synergistic effect of supplemental protein and exercise is rarely employed to improve muscle mass and hence, mobility.
In a randomized, placebo-controlled, double-blind study of 24 healthy men aged 67-75 years, the effects of protein supplementation during breakfast on postprandial muscle protein synthesis and longer-term effect on muscle mass were evaluated. The test group received 21 grams of leucine-enriched whey protein each morning as a medical nutrition drink for 1 year. Results showed that postprandial mixed muscle protein fractional synthesis rate was higher in the test group, which also gained more appendicular lean mass beginning in the 6th week. This study was also supported by a systematic review and meta-analysis of 391 elderly patients with an increased mixed muscle protein fractional synthesis rate following whey protein supplementation.
Protein-energy malnutrition is a major risk factor for the development of sarcopenia in older populations. Therefore, improving muscle mass and preventing its loss can be a crucial element in preventing or improving the mobility and health outcomes related to sarcopenia. We often focus on exercise as an important element in maintaining mobility in the elderly but rarely do we consider the impact of protein on the maintenance of muscle mass. Dietary protein is a foundational nutrient for maintaining muscle mass, mobility, and associated health outcomes throughout our later years of life.