The Difference Between Hydrolyzed Whey Protein and Regular Whey Protein

Whey protein powder is used in supplement drink mixes and meal replacements aimed at reducing body fat and increasing lean muscle mass. All whey powders are processed to some degree, but hydrolyzed whey undergoes additional processing to break the protein into smaller fragments that may be easier for people with allergies to digest safely.

In many cases, you can tell how much processing your whey powder has undergone by the percentage of protein it contains. Unprocessed whey protein is simply the clear liquid left over from cheese-making, and dehydrating the liquid turns it into whey powder. Undenatured whey powder is left mostly in that form and contains about 25 percent to 40 percent protein. Whey concentrate powder is filtered further to remove some fats and lactose compounds and has a final protein percentage of 50 percent to 89 percent. Whey isolate, an even more processed form of powder, has the majority of lactose and fat removed and is at least 90 percent protein by weight. Hydrolyzed whey powder undergoes additional processing; it may sometimes be called predigested whey.

Because whey is derived from cow's milk, people with difficulty digesting lactose or with cow's milk allergies typically avoid it. Whey concentrate powders contain less lactose than milk and are often easier for people with mild lactose intolerance to digest, but they may not be suitable for those with severe lactose intolerance. Extensively hydrolyzed whey, on the other hand, is less likely to cause allergic reactions and may also be lactose-hydrolyzed. Highly hydrolyzed whey was found to produce no ill effects for more than 90 percent of child subjects with a cow's milk allergy, according to a clinical trial published in the journal "Pediatric Allergy and Immunology" in 2001.

Another key difference between hydrolyzed whey and regular whey is that the body is more easily and rapidly able to digest hydrolyzed whey. Regular whey powder is considered a "fast-acting" protein, meaning the body is able to digest it within 30 minutes of consumption, but hydrolyzed whey acts even more quickly. All whey powders may improve muscle size, strength gains and recovery if you drink them after participating in strength training, but hydrolyzed whey increases amino acid availability to stimulate muscle protein synthesis more effectively.

If you're lactose-intolerant or have a cow's milk allergy and still want to use whey protein, lactose-hydrolyzed powder is likely to be a healthier choice for you than regular whey concentrate. If lactose doesn't bother you, it's a matter of preference. Hydrolyzed whey may seem superior because of its rapid effects, but it also contains denatured proteins that have become less effective during the manufacturing process, so it's not always the "best" choice. Because both whey concentrates and isolates are quickly digested, hydrolyzed whey doesn't hold a clear advantage over them. To get the best product while taking into account price, nutrient quality and health benefits, nutritionist and personal trainer Monica Mollica recommends choosing a partially hydrolyzed whey concentrate that contains at least 80 percent protein.