April 2015 Issue

Protein for Fitness: Age Demands Greater Protein Needs
By Densie Webb, PhD, RD
Today's Dietitian
Vol. 17 No. 4 P. 16

Studies suggest how much protein is needed for active older adults to build and maintain muscle for optimal health.

Older patients and clients need more protein than their younger counterparts. At one time, that would have been considered a controversial statement, but many experts now consider it a fact. Previously, it was believed that high protein intake resulted in bone loss and strained the kidneys, both especially risky for older people. Now it's been shown that more protein benefits bone health, and getting enough protein is as important as getting enough calcium and vitamin D.1,2 Higher protein intakes, of up to 35% of daily calories, pose a risk to older people only when they already suffer from some type of kidney function impairment.3

Though greater protein needs for older individuals aren't yet reflected in the Recommended Dietary Allowances (RDAs), it's clear that not only do older people progressively lose muscle as they age but also their physiology resists building new muscle. The muscle loss, known as sarcopenia, ranges anywhere from 0.5% to 2% of total muscle mass each year, starting around age 50.4,5,6

The good news is that after age 50, getting enough high-quality protein in the diet, coupled with physical activity, can help overcome that resistance. However, Douglas Paddon-Jones, PhD, a professor in the department of nutrition and metabolism at the University of Texas Medical Branch in Galveston, says his research shows that for people who are inactive, muscle loss can begin much earlier in middle age. Pair inactivity with low protein intake, and continued muscle loss with age is inevitable.

"The combination of resistance exercise, such as lifting weights or push-ups, and higher protein intakes appear to protect muscle and strength, even during weight loss," says Donald Layman, PhD, a protein researcher and professor emeritus in the department of food science and human nutrition at the University of Illinois. He believes that getting plenty of high-quality protein can help buffer the aging process.
Animal sources of protein are the highest quality protein in the diet and generally provide the most leucine, the essential amino acid that, Layman says, is the key threshold to the synthesis of muscle tissue. Pass this threshold, which likely is greater in older people (ie, get enough leucine), and muscle synthesis triggers. Whey protein has been found to be especially high in leucine.

Adequate vs Optimum
The RDA states that 0.8 g of protein/kg of body weight per day is adequate for all adults. But research indicates that protein requirements increase with age. Recommendations for how much protein is enough for older people vary, but current studies suggest that most people over age 65 should take in about 1 g to 1.2 g of protein/kg of body weight per day to both gain and maintain muscle mass and function.7 There are no separate recommendations for people between ages 50 and 65, but it stands to reason that getting enough protein during that time would make good nutrition sense. "No one has done an age-related curve of protein needs," Layman says, "but by age 65, you need the combination of exercise and high-quality protein. Older adults are less efficient in using amino acids for muscle protein synthesis than are young adults. Exercise increases the efficiency of muscle protein synthesis in older adults."

What about vegetarians? Older vegetarians can achieve the higher recommended protein intake, but it requires much more planning and forethought, Paddon-Jones says. Vegetarians should get protein from soy products, such as tofu, soymilk, and soy yogurt; lentils; beans; nuts; and seeds.

Getting adequate protein is important at any age, and national dietary surveys show that most Americans currently consume about 11/2 times the RDA for protein. That begs the question: Although protein needs increase with age, do we need to eat more protein if we're already consuming more than the RDA? Not according to Paddon-Jones, who says the danger of recommending that people eat more protein is that it easily can be interpreted as "eat more food." With overweight and obesity at epidemic levels, that isn't something RDs want to encourage.

However, Lauri Wright, PhD, RD, LD, an assistant professor of nutrition at the University of South Florida and a spokesperson for the Academy of Nutrition and Dietetics, says, "The average senior is consuming only 16% of daily calories as protein, compared with the current recommended range of 10% to 35% of daily calories for optimal health, so there's much room for improvement. We need to educate seniors, especially women, about the importance of protein in maintaining health and function."

Wright and Paddon-Jones agree, however, that it's best to focus on maintaining intake of high-quality proteins throughout life and not waiting until you're older. Eggs, low-fat milk, and Greek yogurt are examples of high-quality protein foods that easily can fit into the diet, especially at breakfast—even for elderly patients who have problems chewing or swallowing.

Protein at Every Meal
While not everyone agrees, some experts believe that equally distributing protein intake over three meals during the day is just as important as getting enough protein overall. The distribution is important for maximizing the utilization of amino acids for muscle tissue synthesis. Wright says that seniors should strive for 30 g at each meal and include protein in snacks as well. An example of a 30-g protein breakfast can include one scrambled egg and two Italian veggie sausage links. Paddon-Jones says that breakfast can be the most neglected meal when it comes to protein, and that a "tea and toast" breakfast isn't conducive to maintaining muscle health.

Senior Athletes
But what about people who stay physically active well into their 60s, 70s, and even 80s? Running, walking, cycling, hiking, even running marathons? Do they need even more protein than their less-active counterparts of the same age, and how much is enough? Again, Paddon-Jones says that obsessing over the right proportion of protein in the diet is unnecessary, unless you're going for the gold and training hard or working toward some personal best.

Results from the PROT-AGE Study Group suggested that physically active people over age 65 get at least 1.2 g of protein/kg of body weight. Wright recommends older weight lifters strive for 1.5 g of protein/kg of body weight per day.
Believe it or not, depending on the sport, some athletes are considered older once they reach age 21, according to the President's Council on Fitness, Sports & Nutrition, so who's considered an older athlete is relative. However, all older clients, but especially those who are physically active, require extra attention to their protein needs—the amount, the quality, and possibly the distribution throughout the day.

— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Texas.

References
1. Heaney RP, Layman DK. Amount and type of protein influences bone health. Am J Clin Nutr. 2008;87(5):1567S-1570S.

2. Verreijen AM, Verlaan S, Engberink MF, Swinkels S, de Vogel-van den Bosch J, Weijs PJ. A high whey protein-, leucine-, and vitamin D-enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. Am J Clin Nutr. 2015;101(2):279-286.

3. Paddon-Jones D, Short KR, Campbell WW, Volpi E, Wolfe RR. Role of dietary protein in the sarcopenia of aging. Am J Clin Nutr. 2008;87(5):1562S-1566S.

4. Buford TW, Anton SD, Judge AR, et al. Models of accelerated sarcopenia: critical pieces for solving the puzzle of age-related muscle atrophy. Ageing Res Rev. 2010;9(4):369-383.

5. Nair KS. Aging muscle. Am J Clin Nutr. 2005;81(5):953-963.

6. Mitchell WK, Williams J, Atherton P, Larvin M, Lund J, Narici M. Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front Physiol. 2012;(3):260.

7. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559.

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