Aging after middle age is associated with changes in body composition, including increases in fat mass and decreases in muscle mass. After the age of 30 years, per decade 3–8% reduction in lean muscle mass occurs.
Muscle protein synthesis declines with age. Muscle deposition occurs in response to a complex interplay between physical activity and hormonal signaling and protein intake. Although a number of underlying mechanisms contribute to age-related decrease in muscle mass, inadequate dietary protein intake may accelerate this process.
Dietary surveys suggest that many adults and older adults consume insufficient dietary protein, which may contribute to the age-related loss of muscle mass. Recent studies have shown that older adults need more dietary protein than do younger adults to support good health, promote recovery from illness, and maintain functionality. Older people need to make up for age-related changes in protein metabolism, thus higher intake of protein may be beneficial in older adults.
Guidelines for dietary protein intake have traditionally advised similar intake for all adults, regardless of age or sex is 1.0 grams of protein per kilogram of body weight each day. Western data suggests that older people may require higher amount of protein to maintain and regain muscle mass on daily basis compared to younger people. However, one should consult a dietitian to understand their protein needs.
In addition to consuming inadequate amounts of total dietary protein, older adults may be at risk of consuming inadequate animal protein, a source of high-biological-value protein. Not only the overall protein intake is important but also the amount of protein intake with each meal matters. Meals should contain a moderate amount of high quality protein. Milk and milk products, egg, poultry, meat, fish, etc., provide high quality proteins. These protein sources provide all the essential amino acids in the right proportion which are capable of stimulating muscle protein synthesis even in ageing population. Thus, ingestion of adequate amount of high-quality protein at each meal could be a useful strategy to maintain muscle mass especially in the aging population.
In Indian diets, 60% of proteins come from cereals and grains which are not high quality proteins. Intake of milk and other animal protein is low in India, largely due to vegetarianism, misbeliefs and high price of these foods. Including smaller quantities of milk, milk products and other animal foods along with staples can improve the protein quality of a meal.
Protein also contributes to the maintenance of normal bones.In addition to adequate supply of calcium and vitamin D, dietary proteins represent key nutrients for bone health and play important role in preventing of osteoporosis in the aging population.
Besides ensuring adequatequantity and quality of proteins in the diet, incorporating exercise or moderate physical activity is important to maintain muscle mass. The loss of lean body mass is dramatically increased during inactivity. Of particular concern is the age-related loss of skeletal muscle (sarcopenia), which may lead to greater risk of functional impairment and mortality.