Protein fractions: what does the science say?
Protein fractions are one of the more mysterious aspects of whey protein. Manufacturers make big promises, but the reality is more complicated—these bioactive compounds may never reach the bloodstream.
Why are protein fractions so complicated?
Whey powder does contain interesting bioactive fractions. Scientists can identify and isolate them using sophisticated equipment. At high doses, these fractions have been observed to produce distinctive effects in the human body. But that is a long way from establishing that the fractions found in ordinary whey powder have the same effects.
The problem is that bioactive fractions are extremely sensitive. Processing, heating and even normal digestion can destroy them. What determines which fractions are released from long protein chains in the first place—and whether they are released in sufficient quantities to have any effect?
Protein fractions and digestion—uncharted territory
Frankly, no one knows exactly how whey protein breaks down in the stomach and intestines. This breakdown happens unpredictably and independently of other processes. Some studies have demonstrated changes in the immune system after whey consumption—but the actual causes of these changes remain virtually unknown.
There is one exception. The body has a particular transport mechanism for longer peptide chains, such as immunoglobulins: pinocytosis. In newborns and young children, long immunoglobulin chains are taken up intact from the digestive tract and transported into the bloodstream without being broken down, where they contribute to immune defense. The same mechanism sometimes also allows other long protein fractions into the bloodstream where they do not belong—this is what causes allergic reactions to food in young children.
This mechanism fades as a child grows. Food allergies are accordingly said to become less common as children grow older and may eventually disappear altogether. In adults, pinocytosis no longer works in the same way.
So what actually happens? Perhaps some fractions are transported in the same way in adulthood—otherwise, the entire debate about fractions would be pointless. But some protein fractions frequently discussed in sport consist of amino acid chains so long that their passage through the intestinal lining seems biologically unlikely.
What does this actually mean for you?
Just because the fractions we are interested in are present in the powder does not mean they reach the bloodstream in the same form and produce the desired effect. There is still a wide gap between manufacturers’ marketing and scientific research.
One positive exception is a whey peptide that lowers blood pressure, for which there is more evidence than for most other fractions. Beyond that, the field still needs a great deal more research.
The simple truth is that global demand for whey is growing faster than supply. This means prices will start rising in the near future—and the pressure to exaggerate the benefits of fractions in marketing will grow along with them.
Despite all this, whey protein may be the best sports supplement of all time. It is high in protein and mixes well. It contains plenty of branched-chain amino acids and glutamine, and the taste is perfectly tolerable. These facts matter a great deal—regardless of what else researchers discover about fractions.
FAQ—frequently asked questions
Do protein fractions actually reach the bloodstream?
Science has no definitive answer. Some fractions may survive digestion, but the evidence is weak for most. The effects of fractions isolated under laboratory conditions cannot be directly extrapolated to consuming ordinary whey powder.
Why are bioactive fractions destroyed?
Fractions are sensitive to heat, acidity and enzymes. Manufacturing processes and stomach acid destroy many of them before they even reach the intestines.
Is whey protein still worth taking?
Yes. Whey’s main benefits—its high protein content, abundance of BCAA, glutamine and good digestibility—are well documented and do not depend on the debate about fractions. Fractions are an added benefit that is still being researched; protein content is why the vast majority of people who train drink whey.
Translated from Body magazine; Author: Timo Kosonen
Author: Greta
Source: Protein
Come and train! ArtGym
