What defines sarcopenia from a clinical perspective? Sarcopenia is defined as the age-related loss of muscle mass, strength and functionality. Sarcopenia generally appears after age 40 and accelerates after the age of approximately 75. Although sarcopenia is mostly seen in physically inactive individuals, it is also commonly found in individuals who remain physically active throughout their lives. Thus, it’s clear that although physical activity is essential, physical inactivity is not the only contributing factor. Just as with osteoporosis, sarcopenia is a multifactorial process that may involve decreased hormone levels (in particular, GH, IGF-1, MGF, and testosterone), a lack of adequate protein and calories in the diet, oxidative stress, inflammatory processes, chronic, low level, diet-induced metabolic acidosis, as well as a loss of motor nerve cells
A loss of muscle mass also has far ranging effects beyond the obvious loss of strength and functionality. Muscle is a metabolic reservoir. In times of emergency it produces the proteins and metabolites required for survival after a traumatic event. In practical terms, frail elderly people with decreased muscle mass often do not survive major surgeries or traumatic accidents, as they lack the metabolic reserves to supply their immune systems and other systems critical for recovery.
There is no single cause of sarcopenia, as there is no single cause for many human afflictions. To prevent and/or treat it, a multi-faceted approach must be taken, which involve hormonal factors, dietary factors, supplemental nutrients, and exercise.
Dietary considerations
The major dietary considerations that increase the risk of sarcopenia are: a lack of adequate protein, inadequate calorie intake, and low level, chronic, metabolic acidosis.
Although it’s generally believed the “average” American gets more protein then they require, the diets of older adults are often deficient. Compounding that are possible reductions in digestion and absorption of protein, with several studies concluding protein requirements for older adults are higher than for their younger counterparts (Young, 1990; Campbell et al., 1994; Campbell et al., 1996). These studies indicate that most older adults don’t get enough high quality protein to support and preserve their lean body mass.
There is an important caveat on increasing protein, which brings us to the topic of low level, diet-induced, metabolic acidosis. Typical Western diets are high in animal proteins and cereal grains, and low in fruits and vegetables. It’s been shown that such diets cause a low grade metabolic acidosis, which contributes to the decline in muscle and bone mass found in aging adults (Frassetto et al., 2001). One study found that by adding a buffering agent (potassium bicarbonate) to the diet of post-menopausal women the muscle wasting effects of a “normal” diet were prevented (Frassetto et al., 1997). The researchers concluded the use of the buffering agent was “… potentially sufficient to both prevent continuing age-related loss of muscle mass and restore previously accrued deficits.”
The take home lesson from this study is that - although older adults require adequate intakes of high quality proteins to maintain their muscle mass (as well as bone mass), it should come from a variety of sources and be accompanied by an increase in fruits and vegetables as well as a reduction of cereal grain-based foods. The use of supplemental buffering agents such as potassium bicarbonate, although effective, does not replace fruits and vegetables for obvious reasons, but may be incorporated into a supplement regimen.
Hormonal considerations
As most are aware, with aging comes a general decline in many hormones, in particular, anabolic hormones such as Growth Hormone (GH), DHEA, and testosterone. In addition, researchers are looking at Insulin-like Growth factor one (IGF-1) and Mechano Growth factor (MGF) which are essential players in the hormonal milieu responsible for maintaining muscle mass as well as bone mass. Without adequate levels of these hormones, it’s essentially impossible to maintain lean body mass, regardless of diet or exercise.
It’s been shown, for example, that circulating GH declines dramatically with age. In old age, GH levels are only one-third of that in our teenage years. In addition, aging adults have a blunted GH response to exercise as well as reduced output of MGF (Hameed et al., 2003), which explains why older adults have a much more difficult time building muscle compared to their younger counterparts. However, when older adults are given GH, and then exposed to resistance exercise, their MGF response is markedly improved, as is their muscle mass (Hameed et al., 2004).
Another hormone essential for maintaining lean body mass is testosterone. Testosterone, especially when given to men low in this essential hormone, has a wide range of positive effects. One review looking at the use of testosterone in older men (Gruenewald et al., 2003) concluded:
“In healthy older men with low-normal to mildly decreased testosterone levels, testosterone supplementation increased lean body mass and decreased fat mass. Upper and lower body strength, functional performance, sexual functioning, and mood were improved or unchanged with testosterone replacement”
Contrary to popular belief, women also need testosterone! Although women produce less testosterone, it’s as essential to the health and well being of women as it is for men.
The above is a highly generalized summary and only the tip of the proverbial iceberg regarding various hormonal influences on sarcopenia. A full discussion on the role of hormones in sarcopenia is well beyond the scope of this article. Needless to state, yearly blood work after the age of 40 is essential to track your hormone levels, and if needed, to treat deficiencies via Hormone Replacement Therapy (HRT). Private organizations like the Life Extension Foundation offer comprehensive hormone testing packages, or your doctor can order the tests. However, HRT is not for everyone and may be contraindicated in some cases. Regular monitoring is required, so it’s essential to consult with a medical professional versed in the use of HRT, such as an endocrinologist.
Nutrient considerations
There are several supplemental nutrients that should be especially helpful for combating sarcopenia, both directly and indirectly. Supplements that have shown promise for combating sarcopenia are creatine, vitamin D, whey protein, acetyl-L-carnitine, glutamine, and buffering agents such as potassium bicarbonate.
Creatine
The muscle atrophy found in older adults comes predominantly from a loss of fast twitch (FT) type II fibers which are recruited during high-intensity, anaerobic movements (e.g., weight lifting, sprinting, etc.). Interestingly, these are exactly the fibers creatine has the most profound effects on. Various studies find creatine given to older adults increases strength and lean body mass (Chrusch et al., 2001; Gotshalk et al., 2002; Brose et al., 2003). One group concluded:
“Creatine supplementation may be a useful therapeutic strategy for older adults to attenuate loss in muscle strength and performance of functional living tasks.”
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Vitamin D
It’s well established that vitamin D plays an essential role in bone health. However, recent studies suggest it’s also essential for maintaining muscle mass in aging populations. In muscle, vitamin D is essential for preserving type II muscle fibers, which, as mentioned above, are the very muscle fibers that atrophy most in aging people. Adequate vitamin D intakes could help reduce the rates of both osteoporosis and sarcopenia found in aging people (Montero-Odasso et al., 2005) leading the author of one recent review on the topic of vitamin D’s effects on bone and muscle to conclude:
“In both cases (muscle and bone tissue) vitamin D plays an important role since the low levels of this vitamin seen in senior people may be associated to a deficit in bone formation and muscle function”
and
“We expect that these new considerations about the importance of vitamin D in the elderly will stimulate an innovative approach to the problem of falls and fractures which constitutes a significant burden to public health budgets worldwide.”
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Whey protein
As previously mentioned, many older adults fail to get enough high quality protein in their diets. Whey has an exceptionally high biological value (BV), with anti-cancer and immune enhancing properties among its many uses. As a rule, higher biological value proteins are superior for maintaining muscle mass compared to lower quality proteins, which may be of particular importance to older individuals. Finally, data suggests “fast” digesting proteins such as whey may be superior to other proteins for preserving lean body mass in older individuals (Dangin et al., 2002).
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Additional Nutrients of interest
There are several additional nutrients worth considering when developing a comprehensive supplement regimen designed to prevent and or treat sarcopenia. In no particular order, they are: fish oils (EPA/DHA), acetyl-l-carnitine, glutamine, and buffering agents such as potassium bicarbonate. There is good scientific reason to believe they would be beneficial for combating sarcopenia, but data specific to sarcopenia is lacking. For example, EPA/DHA has been found to preserve muscle mass (e.g. is anti-catabolic) under a wide range of physiological conditions. The anti-inflammatory effects of fish oils would also lead one to believe they should be of value in the prevention or treatment of sarcopenia. In general, fish oils have so many health benefits, it makes sense to recommend them here.
Acetyl-l-carnitine also offers many health benefits to aging people, and data suggests it should be useful in combating this condition. More research specific to sarcopenia is needed however.
Glutamine is another nutrient that should be useful in an overall plan to combat sarcopenia. Finally, data does suggest strongly that bicarbonate and citrate buffering agents containing minerals such as potassium, magnesium, and calcium can reverse the metabolic acidosis caused by unbalanced western diets. However, I hesitate to recommend this particular strategy as it does not address the root cause, which is the diet itself. Much greater health benefits will result from improving the diet over simply adding in this supplement. In addition, there are potential problems that could result from excessive intake of buffer salts, such as hyperkalemia and formation of kidney stones.
Exercise Considerations
Exercise is the lynchpin to the previous sections. Without it, none of the above will be an effective method of preventing/treating sarcopenia. Exercise is the essential stimulus for systemwide release of various hormones such as GH, as well as local growth factors in tissue, such as MGF. Exercise is the stimulus that increases protein and bone synthesis, and exerts other effects that combat the loss of essential muscle and bone as we age. Exercise optimizes the effects of HRT, diet and supplements, so if you think you can sit on the couch and follow the above recommendations…think again.
Although any exercise is generally better then no exercise, all forms of exercise are not created equal. You will note, for example, many of the studies listed at the end of this article have titles like: “GH and resistance exercise” or “creatine effects combined with resistance exercise” and so on. Aerobic exercise is great for the cardiovascular system and helps keep body fat low, but when scientists or athletes want to increase lean mass, resistance training is always the method. Aerobics does not build muscle and is only mildly effective at preserving the lean body mass you already have. Thus, some form of resistance training (via weights, machines, bands, etc.) is essential for preserving or increasing muscle mass. The CDC report on resistance exercise for older adults summarizes it as:
“In addition to building muscles, strength training can promote mobility, improve health-related fitness, and strengthen bones.”
Combined with HRT (if indicated), dietary modifications, and the supplements listed above, dramatic improvements in lean body mass can be achieved at virtually any age, with improvements in strength, functionality into advanced age, and improvements in overall health and general well being.
Conclusion
Hopefully, the reader will appreciate that I have attempted to cover a huge amount of territory with this topic. Each sub-section (nutrition, hormones, etc.) could easily be its own article if not its own book. This means each section is a general overview vs. anything close to an exhaustive discussion. Below is guide to web sites that offer additional information regarding the topics covered in this article and should (hopefully!) help fill in any gaps. To summarize, to prevent or treat sarcopenia:
• Get adequate high quality proteins from a variety of sources as well as adequate calories. Avoid excessive animal protein and cereal grain intakes while increasing the intake of fruits and vegetables.
• Get regular blood work on all major hormones after the age of 40 and discuss with a medical professional if HRT is indicated.
• Add supplements such as: creatine, vitamin D, whey protein, acetyl-l-carnitine, glutamine, and buffering agents such as potassium bicarbonate.
• Exercise regularly, with an emphasis on resistance training, a minimum of 3 times per week.
I’m going to conclude this article the way most people would start it, with the good news and the bad news. The bad news is, millions of people will suffer from a mostly avoidable loss of functionality and will become weak and frail as they age from a severe loss of muscle mass. The good news is that you don’t have to be one of those people. One thing is very clear: it’s far easier, cheaper, and more effective to prevent sarcopenia - or at least greatly slow its progression - than it is to treat it later in life. Studies have found, however, that it’s never too late to start - so don’t be discouraged if you are starting your sarcopenia fighting program later in life.
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