Whey is one of the two major classes of protein in milk. (The other is casein, the “curds” of “curds and whey.”) Proteins are made of amino acids, and whey contains high levels of the amino acid cysteine. This is the basis for many of its proposed uses. It also contains branched chain amino acids (
). However, while there is no question that whey is a highly digestible and rich protein source, there is no meaningful supporting evidence that it provides any specific health benefits.
There are no well-documented medicinal uses of whey protein.
There is some evidence that whey can raise levels of
. Glutathione is an
that the body manufactures to defend itself against free radicals. In certain diseases, glutathione levels may fall to below-normal levels. These conditions include
, liver disease,
, and various types of cancer.
This reduction of glutathione might in turn contribute to the symptoms or progression of the disease. To solve this problem, glutathione supplements have been recommended, but glutathione is essentially not absorbed at all when it is taken by mouth.
Whey protein may be a better solution. The body uses cysteine to make glutathione, and whey is rich in cysteine. Meaningful preliminary evidence suggests that whey can raise glutathione levels in people with cancer,
However, while these are promising findings, one essential piece of evidence is lacking: there is no evidence as yet that this rise in glutathione produces any meaningful health benefits.
Whey protein has also been proposed as a
, based partly on its high content of
. However, there is no more than minimal evidence that whey protein helps accelerate muscle mass development.
Furthermore, there is little evidence that whey protein is more effective for this purpose than any other protein. For example, one small double-blind study found evidence that both casein and whey protein were more effective than placebo at promoting muscle growth after exercise, but whey was no more effective than the far less expensive casein.
However, a single small study did find ergogenic benefits with whey as compared to casein.
One study looked at whether whey protein could help women with HIV
build muscle mass
Participants were divided into three groups: those who undertook a course of resistance exercise (weight lifting), those who took whey, and those who did both. Resistance exercise alone was just as effective as resistance exercise plus whey, while whey alone was not effective.
Whey contains alpha-lactalbumin, a protein that in turn contains high levels of the amino acid tryptophan. Tryptophan is the body’s precursor to serotonin, and is thought to affect mental function. In a small double-blind study, use of alpha-lactalbumin in the evening
improved morning alertness
, perhaps by enhancing sleep quality.
Another small double-blind study found weak evidence that alpha-lactalbumin improved mental function in people sensitive to stress.
A third study failed to find that alpha-lactalbumin significantly improved memory in women experiencing
Very weak evidence hints that whey might help
or augment the effectiveness of
Infant formula based on pre-digested (hydrolyzed) whey protein is somewhat less allergenic than standard infant formula; this might reduce symptoms of
and possibly decrease the risk that the infant will later develop allergies.