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Recent Protein Research

Do older adults need more protein?

By Newsletter Editor  

When you ingest protein, the amino acids that are digested and absorbed into the bloodstream trigger a response in muscle to convert amino acids into protein. This anabolic response to the ingestion of protein is one of the main reasons whey and other protein supplements are popular as post-exercise supplements. However, research has shown that as you age you tend to become resistant to this positive effect of protein ingestion. The good news is that research indicates that this ‘anabolic resistance’ can be overcome by ingesting greater amounts of protein, especially leucine.

For example, in one recent study, elderly individuals had a 69% greater increase in muscle protein synthesis after exercise when they consumed 20 grams of whey (2.6 grams of leucine) compared to 20 grams of casein (1.6 grams of leucine). In an older group of active 70-year-olds, it was shown that 40 grams of whey consumed after resistance exercise produced a 32% greater increase in muscle protein synthesis compared to a 20 gram dose of whey. In contrast, 20 grams of protein appears to be enough to maximize muscle protein synthesis in younger individuals.

Recent results from training studies have demonstrated that greater amounts of protein are needed to overcome the blunted response to protein older adults experience. In one of these experiments, 80 adults 70 to 85 years of age participated in a resistance training program (3 days per week) for 6 months. One group was randomized to receive whey protein (20 grams two times per day) while another group received carbohydrate as a control. The whey group had greater increases in lean body mass (1.3 vs 0.7 pounds) than the carbohydrate group. This was confirmed by greater muscle mass in the thigh from computed tomography (4.6 vs 2.9%).

In summary, older adults need a higher protein dose than younger people. Older adults should consume at least 20-40 grams of whey after exercise to achieve a maximal increase in muscle protein synthesis. 

 

The best protein for post-workout: whey or blend? 

by Jeff Volek, Ph.D, R.D.

There has been great interest trying to figure out which protein source is best for active individuals, and new research indicates the answer may be a blend.

Whey protein gets a lot of attention because gram for gram it has more branched chain amino acids (especially leucine) than other proteins. It’s also digested quickly. These qualities result in a rapid and pronounced increased in muscle protein synthesis, but the effect is short-lived.

Casein and soy protein, on the other hand, have a different amino acid profile. They have a more moderate digestion rate and may have other antioxidant or anti-inflammatory effects. Therefore, it might be of value to combine both these high quality protein sources with whey, or at least that is what researchers hypothesized.

Researchers had young healthy participants perform a single bout of resistance exercise and then 1 hour later consume either whey protein alone or a blend of whey, casein, and soy. The supplements both contained 19 grams of protein. The blend consisted of 50% casein, 25% whey, and 25% soy.

Both supplements equally increased muscle protein synthesis during the first 2 hour post-exercise time period. During the 2 to 4 hour post-exercise time period, only the protein blend increased protein synthesis. Thus, the effects of whey protein alone were not sustained over a 4-hour time period after exercise.

Does this mean you should change your protein supplement? Results of this study are consistent with the large amount of research supporting the superiority of whey consumed right after exercise. However, it highlights the limitation of using whey as the only protein source when examined over a longer time frame. Based on these new findings, it would be prudent to either combine whey with a slower digesting protein source like casein or soy, or consume a meal containing protein during the first couple hours after exercise. The protein in milk is about 80% casein and 20% whey, so mixing whey with milk may also be a good option to help extend the muscle-building window. 

Whey vs. soy: gain 7.3 pounds of muscle

By Jeff Volek, Ph.D., R.D.

Many studies have shown that whey protein rapidly increases muscle protein synthesis, and the effect is amplified when consumed before and/or after resistance exercise. However, it’s not always appropriate to extrapolate short-term data to draw long-term conclusions. So the question of whether consistent supplementation with whey protein translates into greater gains in muscle mass from resistance training remains unclear.

My lab group at the University of Connecticut recently presented results of a large prospective study comparing whey protein to soy protein at the American College of Sports Medicine Annual Meeting. This study involved a 9-month resistance training and supplementation program with the main objective to examine changes in lean body mass determined by dual-energy X-ray absorptiometry (DXA).

A total of 147 healthy, untrained men and women completed baseline testing and then were randomly assigned in a double-blind manner to supplement daily with either whey protein, soy protein or carbs only (in individual packets of powder) while performing supervised resistance training. The supplements had similar caloric values. The whey and soy supplements contained equal amounts of protein. Subjects consumed the supplement in the morning with breakfast on non-training days and immediately after exercise on training days. The resistance training program consisted of supervised workouts 2-3 times per week.

The subjects were also prescribed a specific diet including a constant protein intake of 1g per kg of body weight (not including the additional supplementation). For the whey and soy protein groups, the addition of the daily protein supplement (22g per day) increased protein intake to 1.4g of protein per kg of body weight (about 95g of protein for a 150-pound person).

We are currently analyzing a large number of variables, but preliminary results indicated that regular consumption of whey protein significantly increased plasma levels of leucine and BCAAs. Despite consuming similar calories and protein during the program, gains in lean body mass were significantly greater in the whey protein group (7.3 pounds) than the soy protein group (3.9 pounds). This is the largest and longest resistance training study comparing the effects of protein sources on gains in lean body mass. The results give an edge to whey over soy protein in this group of young, healthy men and women.

 

Sipping casein protein doubles the muscle-building effect compared to whey protein

By Jeff Volek, Ph.D., R.D.

The milk proteins whey and casein are both excellent sources of all the essential amino acids. One distinguishing feature is their digestion rate. When consumed in a bolus, whey leaves the stomach quickly resulting in a rapid increase in blood amino acids. Casein on the other hand stays in the stomach longer and results in a much slower rate of absorption.

These differences in digestion rate have been shown in many studies to alter the effect on protein balance in the body. In most studies whey produces a slightly stronger effect than casein because of the rapid increase in essential amino acids that stimulate a robust increase in muscle protein synthesis. However, according to results of a recently published study the role of digestion rate may be altered if protein supplements are sipped rather than consumed in a single bolus.

Healthy subjects were studied over a 5 hour period during which time they consumed 30 grams of either whey or casein. The protein drinks were sipped every 20 min during the study period (14 ingestions). Subjects also performed cycle exercise for 20 min on two occasions during the five hour protocol. Blood levels of branched chain amino acids were approximately 10% higher curing casein than whey. Measures of net whole body protein synthesis were consistently about 2-fold higher during the casein than the whey.

These interesting results suggest that the way protein drinks are ingested may alter how they are processed. Specifically when sipping protein supplements, casein has a greater anabolic effect over whey. 


How much whey protein is needed after exercise to boost muscle building

By Jeff Volek, Ph.D., R.D.

Only one study has determined the dose response effect of protein provided after resistance exercise. Using egg protein, the study showed that muscle protein synthesis reached a plateau when 20 grams of protein was ingested. When 40 grams was ingested, there was no further increase in muscle protein synthesis. A similar study was recently conducted with whey protein isolate. Subjects consumed whey after a bout of single leg knee extensions, using the non-exercised leg as a control. The subjects were older, with an average age of 70 years.

After exercising one leg, they consumed a drink containing 0, 10, 20 or 40 grams of whey protein isolate. Measures of muscle protein synthesis were determined for 4 hours after exercise in the control (non-exercised) leg (to assess the effects of simply ingesting whey without exercise), and in the exercised leg (to assess the effects of whey plus resistance exercise). Rates of muscle protein synthesis were higher in the exercised leg compared to the control leg at all doses of whey, consistent with the synergistic effect of whey and exercise.

In the control (non-exercised) leg, there was a significant increase in muscle protein synthesis with the 20 gram dose, but no further increase with 40 grams. In the exercised leg, there was a significant increase in muscle protein synthesis with 20 grams of whey, and a further 32% increase with the 40 gram dose. This indicates that 20 grams of whey was necessary to significantly increase muscle protein synthesis at rest in elderly subjects, but after resistance exercise, a higher dose may be needed to achieve a maximal increase in muscle protein synthesis. 

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