While soy protein's potential benefits for bone mass, cardiovascular health, and metabolism contribute to its popularity, don't forget another protein power player: whey. Put simply, whey offers high-quality protein derived from cow's milk.
Whey is the liquid that remains when the curd is removed from milk during the manufacturing of cheese. The most notable aspect of whey protein is that it has one of the highest biological values (a common measurement of protein quality) of any protein. This is due to the fact that whey protein contains an abundant amount of essential amino acids, particularly the branched-chain amino acids (BCAAs: leucine, isoleucine, and valine), considered to be important regulators of strength and body composition.
In addition, whey protein contains high amounts of cysteine, an amino acid that enhances the level of the powerful antioxidant glutathione. This, in addition to other components specific to whey protein (lactoglobulin, lactalbumin, lactoferrin, immunoglobulins, glycomacropeptides, and more), means that whey protein may also provide important benefits to overall health and immune function.
Concentrate v. Isolate
There are different types as well as different methods of processing whey. The two most popular types are whey concentrate and whey isolate. In general, whey concentrate is a cheaper form of whey that contains less protein, more lactose, and more milk fat than whey isolate. In contrast, whey isolate contains very little, if any, lactose and fat and, for that reason, is a top choice of many athletes and individuals who are lactose intolerant or following a low-fat diet.
Taking It Up a Notch
If gaining muscle and losing fat is your thing, read on. A recently published study compared the effects of whey protein hydrolysate (WPH) to casein (a slowly digested milk protein) during a 10-week weight-training program. WPH is a special type of whey protein isolate that has undergone enzymatic degradation to provide shorter, more rapidly absorbed chains of amino acids. Using a double-blind protocol, researchers reported that male weight trainers who supplemented their normal diet with WPH gained significantly more muscle and lost significantly more body fat compared to those who supplemented with straight casein. Improvements in strength were also greater in the WPH group. These dramatic results have made quite an impact within the exercise science and sports nutrition communities.
Time and more data will tell if the enthusiasm surrounding whey protein, and particularly WPH, is warranted. For now, one thing is certain: Whey protein's outstanding amino acid profile, superior biological value, and unique immuno-functional ingredients make it an excellent choice for promoting overall health and wellness.
The relationship between dietary protein intake and bone metabolism has been a subject of controversy. High protein intakes appear to increase urinary calcium excretion, primarily as the result of the metabolism of sulfur-containing amino acids present in certain proteins. This leads to a greater acid load and subsequent buffering response by the skeleton. However, many studies that reported this effect used high doses of purified forms of protein. This is important because protein from many foods, as well as the vast majority of high-quality, commercially available whey protein powders, contain added calcium, which would reduce any potential calcium loss.
A study of more than 1,000 women concluded that protein intakes above current recommendations may actually optimize bone mass in older women. Other research shows that high levels of dietary protein have a positive effect on bone health when compared to the recommended intake of 0.8 grams per kg bodyweight per day. For example, one study links higher total protein intake with a reduced risk of hip fracture in men and women 50 to 69 years of age.
One point that many researchers agree on is that low protein intakes appear to negatively affect bone formation. Considering all the available evidence, moderate levels of protein (approximately 20 to 40 percent of total daily caloric intake), along with supplemental calcium, phosphorus, and vitamin D appear necessary to optimize bone health. Considering their effects on bone health via lowering blood acidity, eating plenty of fruits and vegetables is also highly recommended.
"Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise" by E. Blomstrand et al., J Nutr, 1/06 "Branched-Chain Amino Acids as Fuels and Anabolic Signals in Human Muscle" by M. J. Rennie et al., J Nutr, 1/06 "The Effect of Whey Isolate and Resistance Training on Strength, Body Composition, and Plasma Glutamine" by P. J. Cribb et al., Int J Sport Nutr Exerc Metab, 10/06 "Protein Consumption Is an Important Predictor of Lower Limb Bone Mass in Elderly Women" by A. Devine et al., Am J Clin Nutr, 6/05 Whey Protein Institute, www.wheyoflife.org
With the advances in weight-lifting technology, the choice between free weights and weight machines comes down to a matter of comfort, preference and safety.