Sporting Attitude -- July 2007
To satisfy that demand, manufacturers are developing sports foods and beverages designed to increase energy, enhance performance and build muscle. As they do, they are finding that whey protein is a perfect fit for everything from clear beverages to nutrition bars. One reason is whey protein’s nutritional quality and the health benefits emerging from research funded by America’s dairy farmers. Another reason is whey protein’s expanding functionality, which makes it ideal for use in varied sports nutrition products.
Science is confirming what body-builders have told one another for years—namely, that consuming whey protein appears to positively affect muscle synthesis, body composition and physical performance. What follows is the latest research and thinking on whey protein and nutrition.
Muscle GrowthWhey protein contains all of the essential amino acids in the proportions that the body requires for building muscle. In addition, its amino acid composition is not unlike that of skeletal muscle, providing essential amino acids for building and maintaining muscle. Whey protein also offers more of the muscle-building branched chain amino acids (BCAAs) than other proteins (26g of BCAAs leucine, isoleucine and valine per 100g whey protein). Leucine is a unique amino acid that has been shown to independently stimulate muscle protein synthesis.
Recent clinical studies have shown that whey protein delivers key nutritional benefits such as independently stimulating muscle protein synthesis; stimulating protein synthesis better than carbohydrates alone; and augmenting new muscle protein synthesis after resistance exercise. For example, Stuart Phillips, Ph.D., McMaster University, Ontario, looked at the short-term effect of dairy and soy proteins on muscle accretion in conjunction with exercise. Eight healthy young men consumed 18g of either milk protein or soy protein (in liquid form, as either skim milk or a soy beverage) after lifting weights. Muscle accretion was greater following milk consumption (Phillips, SM, et al. 2005. J Am Coll Nutr. 24:134S-139S).
This short-term benefit may carry over into muscle mass gains over the long term. In the same published research, Phillips also studied 54 novice male weightlifters over 12 weeks of a weight-training program during which they doubled their strength. After each of their workouts, the young men consumed two beverages containing either milk protein (skim milk), soy protein or an energy-matched amount of carbohydrate after exercise. “The milk group saw greater lean mass accretion and greater fat mass loss than either the soy or carbohydrate groups,” Phillips says.
The most recent research by Phillips and his team found that young men who drank a glass of skim milk after weightlifting built more muscle mass than those who drank a glass of a soy beverage, experiencing 34% more muscle protein synthesis with milk than with soy (Wilkinson, SB, et al. 2007. Am. J. Clinical Nutrition, 85:1031-1040). Findings from previous long-term studies of adults (10 weeks) conducted in 2003 and 2004 suggested a trend toward greater gains in lean body mass with dairy protein (whey, milk) intake after a resistance exercise training program, as compared to consumption of a carbohydrate beverage alone. (Chromiak, et al. 2004. Nutrition, 20:420-7) and (Rankin, JW, et al. 2004. J Am Coll Nutr. 23:322-30).
Whey protein supports muscle synthesis, whether it is ingested before or after training, according to Matt Pikosky, Ph.D., R.D., director of research transfer, Dairy Management Inc.™ (DMI). “High-intensity exercise, such as resistance training, increases the breakdown of muscle. Ingesting protein or amino acids as close to the exercise bout as possible will cause an increase in muscle protein synthesis that is greater than this increase in breakdown, which, if repeated over time, can lead to an increase in muscle mass,” notes Pikosky. Simple proximity to exercise time may be the key, as research has shown no difference in effect whether the whey protein was ingested before training or immediately after.
Body CompositionBody composition is the relative proportion of body fat to fat-free mass (organs, bone and muscle tissue) in the human body. Scientific evidence is growing to suggest that whey protein helps promote better body composition, particularly when combined with resistance exercise. That is because—thanks in part to its BCAAs—whey protein not only promotes muscle growth but also limits muscle loss.
High levels of amino acids must be present in the blood to stimulate muscle protein synthesis and maximize the stimulus of resistance training. Consuming whey protein appears to provide the significant increase in blood amino acid concentrations that encourage muscle protein synthesis. At the same time, whey is a rich source of cysteine. Supplementation with cysteine-rich compounds has been shown to increase glutathione production (which governs changes in body composition), halting muscle protein breakdown and improving muscle strength and body composition during exercise training. Because whey is rapidly absorbed by the body, its amino acids and cysteine are easily assimilated.
In one study, four groups of resistance-trained men were given whey isolate, carbohydrate, creatine or a combination of creatine and whey supplement. After 11 weeks of resistance training, the whey-supplemented groups experienced double the gain in fat-free mass than males who were given the carbohydrate supplement. Muscle biopsies taken before and after training revealed that whey supplementation increased the size of some muscle fiber types by up to 543%, compared to carbohydrate supplementation (Cribb, PJ, et al. 2007. Med Sci Sports Exerc. 39:298-307).
Enhanced Physical PerformanceThe BCAAs in whey protein also provide fuel for exercising muscles, help maintain blood glucose levels during exercise and assist in muscle repair and post-exercise recovery. These amino acids provide an energy source during endurance exercise that allows athletes to train more intensively for longer periods.
Whey protein is rich in arginine and lysine, amino acids that may increase the release of growth hormone, which is a stimulator of muscle development. In addition, bioactive compounds isolated from whey protein (e.g., lactoferrin, lactoferricin) may improve immune function and gastrointestinal health as well as reduce excess free radical production in athletes when intensive training compromises these systems.
Other emerging benefits of whey protein include blood pressure control, glycemic control, satiety and weight management, says Peter Huth, Ph.D., director of regulatory and research transfer, DMI. “Research suggests that intact whey protein at high levels may have some blood pressure-lowering effects,” he notes. In addition, “Some preliminary epidemiological evidence shows that dairy protein appears to be involved in helping increase glucose control in individuals who are insulin resistant.”
Whey protein’s effects on food intake and satiety were reported by University of Toronto professor G. Harvey Anderson. He and his team gave healthy young men 200-calorie beverages containing about 45g of sweet whey protein an hour before a pizza meal. The whey protein beverage more effectively reduced the amount of pizza they consumed, compared to an equal amount of carbohydrates, egg protein or water control (Anderson, GH, et al. 2004. The Journal of Nutrition, 134:3011-15).
Functional FitFunctionally, whey protein offers sports foods and beverages a clean flavor and solubility as well as emulsifying and gelling properties. DMI-funded research is focusing on whey ingredients with enhanced functionality. A national expert panel coordinated by DMI’s National Dairy Foods Research Center Program is exploring the enhancement of whey protein’s properties such as heat stability and optical clarity. All of these properties are important for functionality in clear sports beverages.
At North Carolina State University, for example, researchers are looking at the factors that can influence the perception of astringency in high-acid beverages that contain whey protein. “It appears that salivary proteins and whey proteins aggregate and precipitate to varying degrees when combined, and the degrees of aggregation and precipitation are tied to the potential for astringency,” explains Allen Foegeding, Ph.D., William Neal Reynolds distinguished professor, Department of Food Science, North Carolina State University. “Interestingly, astringency decreases as pH is lowered below pH 3.4, due to the decrease in attractive charge between the whey proteins and saliva proteins. Decreasing the net positive charge on whey proteins via modifications may help reduce astringency in acidic whey protein-fortified drinks,” he says.
Researchers at the University of Wisconsin-Madison are focusing on whey protein isolates that have enhanced functionality such as high optical clarity, no-sediment formation and increased thermal stability. These functionalities will increase their usage in shelf-stable and refrigerated beverages.
“The advantage that whey proteins have is that they are one of the few proteins that stay clear in solution at an acidic pH,” says Mark Etzel, Ph.D., professor of food science at the University of Wisconsin-Madison. “We are trying to understand how to incorporate whey protein isolates in acid beverages (pH 4.6 and below) while maintaining clear solutions without precipitates or sediment formation.” Whey protein, if not denatured, is clear in solution at pH 4.6 and below. Once heated, the protein may become cloudy and precipitate out of solution if the pH is too close to pH 4.6 and heat treatment is too harsh. “The heat treatment we are targeting is for hot fill conditions—190°F for a few minutes. This type of beverage would be stable at room temperature,” explains Etzel.
His research group is looking at whey protein isolates that provide 10% of the daily value for protein, focusing on pH and the addition of sugars and salts to beverages. “What we have found is that for whey protein isolate at a pH of 3.7 and below, it is relatively easy to obtain clear solutions. When we worked at a pH range of 3.8-4.0, we found this to be a critical range where we had to be more careful.”
In the critical range of 3.8-4.0, Etzel found that there was an impact depending on what type of ingredient was added. The type of sugar, such as glucose, sucrose and high-fructose corn syrup was important, with sugar alcohols resulting in the clearest solutions. Addition of sodium, potassium and calcium salts decreased clarity, while addition of amino acids such as asparagine, proline and glutamine increased clarity. Thus, the selection of ingredients in the formulation of clear beverages containing whey protein isolate may be an important factor, especially in the pH range of 3.8-4.0.
For active adults looking for foods to sustain them, energy bars can also be an appealing source of replenishment. To ensure product quality during shelflife, researchers at the University of Minnesota are investigating ways to preserve the soft texture of nutrition bars made with whey protein. “During storage, proteins interact with each other, creating disulfide bonds that reduce protein quality,” explains Ted Labuza, Ph.D., professor of food science and engineering. His group is conducting research on using whey hydrolysates to slow the hardening of nutrition bars.
In addition, Labuza’s group is studying the effect of the Maillard reaction when high-fructose corn syrup is used as a sweetener in sports nutrition bars. The glucose and fructose in high-fructose corn syrup react with protein, resulting in the Maillard reaction, which contributes to bar hardening. He found that switching to sucrose prevents this from occurring.
To learn more about whey protein from the dairy industry’s leading source of product, ingredient and nutrition research and information, find prototype sports nutrition bar and beverage formulations or locate a dairy ingredient supplier, visit www.innovatewithdairy.com.