This article is an excerpt from Sports Nutrition for Endurance Athletes by Monique Ryan MS, RD, LDN, CSSD. In her comprehensive guide to sports nutrition, Ryan uses her 30 years of experience coaching professional and age-group athletes to simplify this complex subject into proven, real world guidelines. Sports Nutrition for Endurance Athletes shows runners, cyclists, and triathletes how to address specific nutritional needs for short- and long-course racing and busts dozens of myths and misconceptions along the way.
Which of the protein sources currently used in supplements is best? Basically, there are several sources that provide high-quality protein.
Whey protein is the component of milk that is separated out when making cheese and other dairy products. It is a high-quality protein that contains all the essential amino acids and is an especially rich source of the branched chain amino acids (BCAAs), which are especially important for muscle building—particularly leucine. Whey protein isolate is the highest form, at 90 percent protein, and is lactose-free. Whey protein is soluble and easy to digest and is often referred to as “fast” protein as it gets to the muscles quickly and is one of the most potent stimulators of protein building.
Casein, also found in milk, is a “slow” digesting protein. It helps prevent muscle protein breakdown, ultimately preserving muscle mass. Whey and casein work well together to prevent muscle breakdown. Because protein synthesis is dynamic, consuming milk sources of protein regularly at meals and snacks is recommended. Because casein provides benefits as a slow protein, do not use the hydrolyzed form, which is more rapidly broken down.
Soy protein is an excellent source of protein—especially soy protein isolate, which is 90 percent protein. It is a high-quality protein choice for vegetarians and is lactose-free. Soy protein concentrate is only 70 percent protein. Like whey protein, it is considered a “fast” protein and can promote increases in lean body mass. When soy protein has been compared with milk protein, studies have shown that the milk protein leads to greater gains in muscle mass. Soy protein, however, is still an effective protein for muscle mass increases.
Albumen, the high-quality protein found in eggs, is easily digested and high in the BCAAs, especially leucine. Egg protein is absorbed more slowly than whey and faster than casein. It supports muscle building and can be obtained from real food sources or is often incorporated into high-protein energy bars. Egg protein is obtained from egg whites and is considered the standard against which to compare other proteins—though real eggs may not be as convenient a protein source as supplements, depending on the timing and location of your training.
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See what to eat and when with Sports Nutrition for Endurance Athletes. Ryan demystifies optimum daily nutrition and shows simple steps to make the best decisions about what you eat and drink.