Life Extension Magazine January 2007
By Will Brink
One of the greatest long-term threats to our ability to remain healthy and function independently with advancing age is a steady loss of lean muscle mass, a condition known as sarcopenia.
While doctors have long warned about the loss of bone mass (osteoporosis) that accompanies aging, scant attention has been paid to the equally debilitating loss of muscle mass commonly seen in older people.
Today, however, sarcopenia is increasingly recognized as a serious health problem that afflicts millions of aging adults and places an ever-greater strain on our health care system.1 Age-related loss of muscle mass and strength not only robs elderly people of the ability to perform even the most basic tasks of daily living, but also vastly heightens their risk of suffering devastating injuries and even death from sudden falls and other accidents. The good news is, all health-conscious adults can take immediate steps to implement a program that will greatly lessen their risk for sarcopenia.
In this article, we will review the nature of sarcopenia, its causes, and ways to both prevent and manage this condition. Since sarcopenia has no single cause, its prevention and treatment require an integrated approach that incorporates dietary strategies, hormone replacement, nutritional supplementation, and exercise.
Sarcopenia is the age-related loss of muscle mass, strength, and functionality. It generally appears after the age of 40 and accelerates after the age of approximately 75. Although most often seen in physically inactive people, sarcopenia is also common in those who remain physically active throughout their lives. Therefore, while engaging in regular physical activity is essential to avoiding sarcopenia, inactivity is not the only contributing factor to this condition. Like osteoporosis, sarcopenia is a multifactorial disease process that may result from sub-optimal hormone levels, inadequate dietary protein, other nutritional imbalances, lack of exercise, oxidative stress, and inflammation.2,3
Sarcopenia and osteoporosis are related conditions, and one often accompanies or follows the other. Muscles generate the mechanical stress required to keep our bones healthy. When this muscle activity is reduced, it increases our susceptibility to a loss of bone mass, often initiating a vicious circle of declining health and functionality.
Moreover, this loss of muscle mass can have additional far-ranging effects beyond an obvious loss of strength and functionality. Muscle acts as a metabolic reservoir.4 After a traumatic event, for example, muscle produces proteins and metabolites required for survival and recovery. In practical terms, this suggests that frail elderly people with decreased muscle mass may have poorer outcomes after major surgery or traumatic accidents, since they lack the metabolic reservoir of muscle mass to support the immune system and other bodily systems during the recovery process.
Protein and Other Dietary Factors
Major dietary factors that contribute to sarcopenia are inadequate protein intake, insufficient calorie intake, and chronic, low-level metabolic acidosis (or an abnormally increased acidity in the body’s fluids). Although it is generally believed that the average American consumes more protein than needed, inadequate protein in the diets of older adults is common. Further compounding this problem may be a diminished capacity to digest and absorb protein in the elderly. Several studies suggest that protein requirements for older adults are higher than for younger people, and should be higher than is often recommended.5-7 In short, many older adults may not consume enough high-quality protein to support and preserve their lean body mass.
While consuming an adequate amount of protein is important for older adults, consuming too much protein can result in a low-level, diet-induced metabolic acidosis, or abnormally increased acidity in the body. The typical American diet—which is high in animal proteins and cereal grains, and low in fruits and vegetables—can cause a low-grade metabolic acidosis that contributes to the decline in muscle and bone mass found in aging adults.8 One study found that adding a buffering agent (potassium bicarbonate) to the diet of postmenopausal women prevented the muscle-wasting effects of a “normal” diet.9 This led the researchers to conclude that the buffering agent may prevent continuing age-related loss of muscle mass and help restore lost muscle mass.
Therefore, older adults should strive to ensure an adequate intake of high-quality protein from a variety of sources, accompanied by an increase in fruits and vegetables, and a reduced intake of cereal grain foods. Buffering agents such as potassium bicarbonate can be incorporated in a supplement regimen, though they should not take the place of potassium-rich fruits and vegetables in the diet.
Importance of Optimal Hormone Levels
Aging is accompanied by declining levels of many essential hormones in the body, particularly tissue-building (anabolic) hormones such as growth hormone, DHEA (dehydroepiandrosterone), and testosterone.2
For example, circulating growth hormone levels in older adults are just one third of those in teenagers.3 Researchers have recently focused on insulin-like growth factor 1 (IGF-1) and mechano growth factor as critical hormones in maintaining muscle and bone mass.10 Without adequate levels of these hormones, it may be impossible for anyone to maintain lean body mass, regardless of how they eat or exercise.
Aging adults have a reduced output of mechano growth factor, a hormone that helps build muscle in response to exercise.11 This could help explain why older adults have a much more difficult time building muscle compared to their younger counterparts. However, when older people were given growth hormone before engaging in resistance exercise, their mechano growth factor response improved markedly, as did their muscle mass.11
Testosterone is also critical to maintaining lean body mass. Especially when given to testosterone-deficient men, this essential hormone can have a broad range of positive effects. One study noted that in healthy older men with low-normal to mildly decreased testosterone levels, testosterone supplementation increased lean body mass and decreased fat mass. Additionally, testosterone improved upper and lower body strength, functional performance, sexual function, and mood in some individuals.12 Although women produce less of this hormone than men do, adequate testosterone is just as essential to their health and well-being.
Because hormonal factors can significantly affect muscle mass, all adults over the age of 40 should undergo annual blood testing to track their hormone levels. If necessary, hormone deficiencies can be addressed using bioidentical hormone replacement therapy. Since hormone replacement therapy requires regular monitoring and is contraindicated in some individuals, you should consult a medical professional about your specific hormone replacement needs.