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Republished with permission from www.hsibaltimore.com, Health Sciences Institute e-Alert, July 21, 2004
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Only a very small percentage of older adults in the U.S. are doing enough to keep their muscles strong, according to a report from the Centers for Disease Control and Prevention (CDC).
This is a critical lapse for many reasons, but here are two good ones: 1) The moderate amount of exercise required to maintain muscles will yield other important health benefits. And 2) Keeping muscles strong is relatively easy.
And now it may be even easier. According to a new study that appears in a recent issue of the journal Nutrition, key nutrients have been shown to help develop muscle mass and support physical functioning as we age.
Getting a grip
Because age-related muscle loss is associated with osteoporosis and an increased risk of falls, researchers at the Vanderbilt University Medical Center wanted to find out if an intake of three nutrients might provide a simple way to help prevent muscle loss.
The Vanderbilt researchers recruited a group of 50 women whose average age was about 77. Over a 12-week period, a "treatment group" of 27 women received a daily supplement containing 1.5 grams of lysine, 2 grams of beta-hydroxy-beta-methylbutyrate, and 5 grams of arginine. (I'll tell you more about these three nutrients in a moment.) A second group of 23 women received a placebo.
Before and after the trial period, several measurements were taken to determine potential changes in muscle mass:
- Whole-body protein synthesis and loss (estimated with a specially designed blood test)
- Limb, hip and abdomen circumference
- Leg and handgrip strength
- Physical functionality
- Levels of hormones that affect proteins
- Percentage of lean body mass and body fat
The hormone levels of both groups remained the same, but the treatment group improved in all other categories compared to the placebo group. The treatment group also had a significant increase in the average circumference of limbs, and their protein synthesis increased approximately 20 percent, compared to placebo subjects.
Researchers concluded that a daily supplement of these three nutrients may play an important role in muscle health, while improving functionality, protein synthesis and strength in older women.
The multi-tasker
According to Healthnotes Newswire, the average person over the age of 70 may experience muscle loss as high as 15 percent per decade. So a 12-week trial can't begin to show an accurate picture of the long-term benefits of these nutrients. Nevertheless, the results of the Vanderbilt research provide a basis to consider supplementing with the nutrients studied, especially for older people who may be incapacitated in some way that prohibits exercise.
In the e-Alert "Five Stars" (8/26/03), I told you about arginine (also known as L-arginine), which is a remarkable amino acid, known to play a role in blood vessel dilation, reduction of inflammation, repair of skin and connective tissue, and thymus gland regulation. Arginine has also been shown to facilitate muscle metabolism by reducing body fat while increasing muscle mass.
Dietary sources of arginine include diary products, meat, poultry and fish, as well as nuts, rice, whole-wheat, soy and raisins.
Plus two...
In the Health e-Tips e-letter "Keeping Your Extra Parts" (5/13/04), Amanda Ross explained that lysine – an essential amino acid – has been used to increase calcium absorption and may help prevent osteoporosis. In supplement form, high doses of lysine may raise cholesterol levels and increase the risk of gallstones, so lysine supplementation should be monitored by a nutritionally oriented physician. Dietary sources of lysine include meat, fish, dairy products, legumes and brewer's yeast.
The third nutrient in the Vanderbilt study is beta-hydroxy-beta- methylbutyrate (HMB), a derivative of the amino acid leucine. HMB is not widely studied in humans, but animal tests show that it may improve the growth of lean muscle tissue by slowing protein breakdown. The dietary sources of HMB are limited to small amounts in citrus fruits, catfish and alfalfa.
Up off the duff
So... let's say you check with your doctor about these three nutrients, he gives you the green light to monitor supplementation, and in time they begin strengthening your muscles. That's great. But for older people who are able, exercise is still the most effective way to support muscle strength. And more specifically, exercise that incorporates weight training or resistance training will yield the best results, including:
- Reducing the risk of falls and fractures
- Increasing endurance
- Promoting healthy bone density
- Improving insulin sensitivity
The National Institute on Aging (NIA) has published a free guidebook for
starting an exercise program, which is available on their web site:
nia.nih.gov/exercisebook. The book provides a section on diet advice that offers the outdated and misguided USDA food pyramid as a dietary guideline, but other than that, you'll find useful tips for starting and staying with a strength exercise regimen.
Sources:
"Effect of Beta-Hydroxy-Beta-Methylbutyrate, Arginine, and Lysine Supplementation on Strength, Functionality, Body Composition, and Protein Metabolism in Elderly Women" Nutrition, Vol. 20, No. 5, May 2004, ncbi.nlm.nih.gov
"Battle Age-Related Muscle Loss with Amino Acid Combination" Kimberly Beauchamp, ND, Healthnotes Newswire, 6/24/04, pccnaturalmarkets.com
"Strength Training Among Adults Aged > 65 Years" Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention, Vol. 53, No. 2, 1/23/04, cdc.gov
"Strength Training Urged for Elderly" Merritt McKinney, Reuters Health, 1/23/04, story.news.yahoo.com
"Growing Older, Staying Strong: Preventing Sarcopenia Through Strength Training"
International Longevity Center - USA, Issue Brief, September-October, 2003,
ilcusa.org