Skeletal muscle is the tissue of action, movement, force, and function. Unfortunately, time takes a toll on bodies and on muscle mass. The combination of perceived energy decline, decreased physical activity, and a blunted response for muscle growth (“anabolic resistance”) forms the association between aging and a loss in muscle mass.
Sustaining this important tissue is a battle that Stuart Phillips, PhD, FACN, FACSM, professor at McMaster University in Ontario, Canada, has dedicated his career and his research to explore. On April 25, Dr. Phillips presented a comprehensive review of the research on dietary protein and aging at Experimental Biology 2012, in San Diego. The conference is an annual event where six scientific societies hold their joint scientific sessions and yearly meetings.
Deeming whey as the frontrunner in the race for the optimal protein supplement for aging adults, Dr. Phillips explained that whey’s muscle-retaining benefits are clearly beyond those offered by soy (and other protein sources). Whey protein, he said, is uniquely superior for muscle stimulus and retention. Concluding his inquiry into protein for healthy aging, Dr. Phillips explains that protein quality, quantity, and timing act synergistically to aid in the pursuit for long-term quality of life.
Isagenix caught up with Dr. Phillips at the event and afterward to gain more insight from his research. Taking a few moments to share the fruits of his pursuits, Dr. Philips tips his hat to whey protein:
Isagenix: What first interested you in studying the effects of protein on muscle?
Dr. Phillips: I was an athlete all my life playing hockey, football, rugby, and enjoying everything from swimming to triathlons. So muscle has always been near and dear to my heart (no pun) and my passion. I don’t compete in sports much anymore except with my wife and my three boys (13, 10, and 7), who are my stiffest competition yet! So now it’s about staying healthy, active, and maintaining my muscle mass, strength, and health. High-quality protein is a big part of that.
Isagenix: Can you explain anabolic resistance in aging? How does it relate to sarcopenia?
Dr. Phillips: Anabolic resistance is, as we define it, the inability of skeletal muscle in aged persons to mount a full protein synthetic response similar to that seen in the young. In other words, older people just don’t put the protein they eat into their muscles as efficiently as young people. That means as we age our muscles gradually begin to make less protein so our muscle mass declines, otherwise called sarcopenia.
Isagenix: Based on your research, how does whey compare to other proteins like soy for building muscle?
Dr. Phillips: Soy is an excellent high quality protein as its PDCAAS (protein-digestibility corrected amino acid score) would suggest. In fact, if you use the PDCAAS scoring system the way it’s used now, then isolated soy is the ‘same’ as whey and casein. In reality, however, whey is a superior protein for gaining muscle, which is something we’ve shown in several studies now (1-4). In fact, milk proteins in general are better than soy for promoting lean mass, or muscle, gain (2; 3).
Isagenix: Why does the evidence suggest whey protein is superior to soy (or other proteins) in aging adults for promoting muscle gains or holding on to muscle?
Dr. Phillips: Our work, and that of other research groups also, suggests that it’s the high leucine content of whey protein, which is an amino acid highly stimulatory for muscle protein synthesis and muscle growth. That along with all of the other ‘essential’ (i.e., we need to eat them because we cannot make them ourselves) amino acids are present in just the right quantities to support an optimal rate of protein accretion.
Isagenix: How do higher doses of whey protein help overcome anabolic resistance in aging to slow/reverse sarcopenia?
Dr. Phillips: We’re not entirely sure, but we’re proposing that as people age their muscles become desensitized to the effects of the amino acid leucine. However, if you consume higher quantities of protein or you consume proteins higher in leucine like whey, then you ‘overcome’ (or at least minimize) the anabolic resistance of aging and slow sarcopenia. I’d never say you could reverse sarcopenia, but good food choices and good high-quality proteins, along with physical activity, are a big part of slowing it down.
Isagenix: Why is it important to distribute large doses of protein throughout the day?
Dr. Phillips: We’ve conducted two dose-response studies in young men after resistance exercise (5), and recently in older men with their muscles at rest and also following resistance exercise (6). The young men require 20 grams of protein to maximally stimulate new muscle protein addition to their muscles whereas the older men needed more protein, double the dose in fact, or 40 grams, to achieve a maximal stimulation. (Editor’s note: Recently, Maastricht University researchers found that 35 grams of whey protein also showed significant increases in muscle protein synthesis compared to 20 grams or 10 grams in older men. See article here.)
Thus, if we think about getting this maximal stimulation throughout the day, then what we want to have happen is that we should eat, if we’re young, 20 grams of protein per meal and 40 grams per meal if we’re older. Currently, North Americans consume protein in a very imbalanced fashion with about 6 grams coming at breakfast, 12 grams at lunch, and 60 grams at dinner; that’s not the best way to hang onto your muscle mass.
Isagenix: How does exercise play a role in helping overcome anabolic resistance?
Dr. Phillips: Exercise brings back the sensitivity that is lost as we age. In a sense, exercise, for a short-time, ‘reverses’ aging. In fact, what it really does is reverse the effects of inactivity, but oftentimes aging and inactivity are one and the same. So even aged muscle, when exercised, becomes sensitive to leucine and other amino acids again.
Isagenix: What would you suggest to older people as a way for them to help hold on to muscle with age?
Dr. Phillips: 1) Exercise and get some form of physical activity every day; 2) Consume protein at levels higher than the current RDA; 3) Consume three equal protein-containing meals throughout the day with at least 20 to 40 grams of high-quality protein; 4) it should maybe go without saying, but fruits, vegetables, and dietary fiber are also important – I like the DASH [eating plan], for example, but with more protein.
References (as supplied by Dr. Phillips)
1. Burd NA, Yang Y, Moore DR, Tang JE, Tarnopolsky MA and Phillips SM. Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men. Br J Nutr 1-5, 2012.
2. Hartman JW, Tang JE, Wilkinson SB, Tarnopolsky MA, Lawrence RL, Fullerton AV and Phillips SM. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr 86: 373-381, 2007.
3. Josse AR, Tang JE, Tarnopolsky MA and Phillips SM. Body composition and strength changes in women with milk and resistance exercise. Med Sci Sports Exerc 42: 1122-1130, 2010.
4. Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA and Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol 107: 987-992, 2009.
5. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA and Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr 89: 161-168, 2009.
6. Yang Y, Breen L, Burd NA, Hector AJ, Churchward-Venne TA, Josse AR, Tarnopolsky MA and Phillips SM. Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men. Br J Nutr 1-9, 2012.