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Eat your way to preventing age-related muscle loss Andrea N. Giancoli, M.P.H., R.D.
Not surprisingly, experts advise adequate protein intake as part of a balanced diet and exercise, with a focus on strength training, to manage or prevent sarcopenia. Is avoiding sarcopenia that simple? Let's explore the science behind muscle mass and function loss, and answer some common questions about how you can preserve your muscles as you age. How much muscle do you lose? We know from observing elite athletes as they age that they experience declines in performance, telling us that some muscle loss occurs in our 30s and 40s. Yet, how much we lose is unclear. Population studies reveal that at around age 50 muscle mass loss averages 1 to 2 percent per year. We may not notice acute losses, because "muscle is a dynamic tissue, and there's a tremendous reserve capacity," says Fielding. "If you simply lose muscle mass it may have very little impact on your body's ability to function. In your early 60s, we start to see that this loss may begin to affect physical ability." This makes sense, given muscle strength declines at an average rate of 3 percent per year after 60, and by our 70s we've lost an estimated 20 to 40 percent of our strength.
Activity and dietary patterns play important roles in muscle maintenance, but they don't paint the whole picture. Natural physiological shifts take place during aging that correlate to declines in muscle health, including the following:
Compelling research indicates that with age your ability to utilize protein to support and synthesize muscle may be blunted. Consequently, the adequacy of the recommended dietary allowance (RDA) for protein of 0.8 grams per kilogram per day (g/kg/d) for older people has come into question. But no scientific consensus has been reached. A new position paper on the nutritional needs for older adults (age 60 and older) published in the August 2012 Journal of the Academy of Nutrition and Dietetics suggests a range of protein intake between 1 to 1.6 g/kg/d. Fielding advises 1 to 1.2 g/kg/d for people over 60 (see example, below) to maintain and build muscle mass, as well as to ensure adequate intake of the essential amino acid leucine. Fielding explains: "Leucine has a potent effect on stimulating muscle protein synthesis. If you consume protein foods that are rich in leucine, they seem to stimulate muscle protein synthesis more than other comparable protein foods." Sources of leucine include milk, whey, tuna, beef, chicken, soy, peanuts and eggs. For a 70 kg man (around 154 pounds), 1 to 1.2 g/kg/d of protein equates to 70 to 84 g, compared to 56 g recommended at the current RDA level. With this kind of increase in protein, should you be concerned about kidney health? In the absence of kidney disease Fielding reports no safety concerns. He adds, "The effects of protein intake on renal function are largely overstated." The Academy of Nutrition and Dietetics position paper suggests an intake of about 25 to 30 g of protein at each meal for older adults. You can achieve this intake level by including protein-rich foods, such as lean meat, poultry, fish and seafood, eggs, dairy products, beans, lentils, soy foods, nuts, and seeds at each meal. In addition, servings of whole grains and vegetables can also help you meet your protein goals (see Protein Content in Common Foods.) The bottom line: There are no approved medications at this time to manage or prevent sarcopenia, although researchers are attempting to identify safe and effective treatments. In the meantime, balanced diets with adequate protein and strength training are the best and only tools we have to combat muscle mass and strength losses. Despite a lack of scientific consensus for an increased protein recommendation for older adults, it may be worth upping your intake slightly to support and build muscle, especially if you're engaging in strength training.
PROTEIN CONTENT IN COMMON FOODS
Chicken breast, 3 oz.: 25g protein Ground beef, extra lean (5 percent) 3 oz.: 22 g protein Tuna, canned, light 3 oz.: 22 g protein Yogurt, plain, non-fat, 1 cup: 14 g protein Cottage cheese, low-fat (1 percent) 1/2 cup: 14 g protein Tofu, firm 1/2 cup: 10 g protein Beans, pinto 1/2 cup: 9.5 g protein Milk, low-fat (1 percent) 1 cup: 8 g protein Peanut butter 2 tbsp.: 8 g protein Almonds, dry roasted 1 oz.: 6 g protein Egg, 1 large: 6 g protein Whole wheat bread, 1 slice: 4 g protein Source: USDA National Nutrient Database for Standard Reference Release 24 Score One for Fish, Fruits and Vegetables in the Battle against Sarcopenia Inflammation and oxidation in the body are also linked with poor muscle health. Diets that include fatty fish, rich in anti-inflammatory omega-3 fatty acids, and plenty of fruits and vegetables, chock full of antioxidants, are associated with greater muscle strength in older adults.
STRENGTH TRAINING: HOW MUCH AND HOW OFTEN
--For specific strength training exercises visit the NIA's Go4Life website at http://bit.ly/QJRdKn. Source: Go4Life from the NIA
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