Whey protein

Short answer

Whey is a milk-derived, fast-digesting protein. The basic difference between concentrate, isolate, and hydrolysate is protein content and degree of filtration. In single-meal studies, whey stimulated muscle protein synthesis more than casein and soy; however, in long-term training studies, no difference in strength and lean mass was found between soy and animal protein. The protein amount on the label did not always match in measurements. ^{[1] [4] [6]}

What is whey protein and how is it produced?

Milk contains two main protein groups: casein and whey (the protein of the liquid left after cheese-making). According to the ISSN’s description, in making milk protein products, proteins are first separated from lactose and fat in milk; when acid is added to milk, casein precipitates, whey stays in the liquid, and it is then purified by filtration. ^[1]

What is the difference between concentrate, isolate, and hydrolysate?

The ISSN also touches on the cost–quality balance of filtration methods: ion exchange is relatively cheap and gives the highest protein concentration, but according to the ISSN it generally denatures some valuable immune peptides; microfiltration and ultrafiltration preserve these peptides and are more expensive. ^[1] This is the logic behind price differences: more or finer filtration raises cost. This information does not mean that a price is proof of quality; quality is measured by label and content accuracy (below).

The ISSN says that filtration serves to separate protein from lactose and fat and that purity increases as filtration steps increase; the difference in tolerance between concentrate and isolate in people with lactose intolerance is not addressed in the ISSN text. For those diagnosed with milk allergy, milk-derived products are discussed with an allergy physician. Digestive and skin complaints are covered on the harms page.

Why is whey the most studied powder protein?

The ISSN states that whey proteins (hydrolysate and isolate) are the most comprehensively researched protein for pre- and post-resistance exercise supplementation, probably because of their high essential amino acid (EAA) and leucine content, solubility, and digestion speed. The same document targets a leucine content of 700–3000 mg for a single protein dose and a balanced EAA mixture. ^[1]

The study by Tang and colleagues shows this assumption with a short-term measurement: young men (6 in each group) were given a whey hydrolysate, casein, or soy drink containing 10 g of EAA. Whey raised blood EAA and leucine levels more than casein and soy; after resistance exercise, muscle protein synthesis was about 122% higher after whey than after casein and about 31% higher than after soy. The authors attribute the difference to digestion speed and perhaps small differences in leucine content. ^[2] This is the short-term effect of a single dose in three groups of 6 people each; it does not directly measure muscle gain over weeks.

What is the difference between whey and casein?

Boirie and colleagues gave casein and whey protein labeled with 13C-leucine as a single meal to 16 young, healthy adults. Whey produced a “striking but brief” rise in blood amino acids, while casein produced a longer-lasting moderate plateau. Whey increased whole-body protein synthesis by 68% and casein by 31%; casein reduced whole-body protein breakdown by 34%, while whey did not reduce it. Over 7 hours, net leucine balance was more positive with casein than with whey. ^[3]

These findings show that “fast” and “slow” proteins give different metabolic responses; they do not show that one protein is superior to the other in the long term. Studies on night use of casein are described on the timing page.

Does plant protein replace whey?

There are two separate kinds of evidence, and they should be read together.

The meta-analysis by Messina and colleagues collected resistance training studies lasting at least 6 weeks: 9 studies, 266 participants; whey was compared with soy in 5 of them, and soy was compared with other proteins (beef, milk, dairy) in 4. Whey or soy supplementation increased strength; there was no difference between groups in strength and lean mass. The first author’s address is a nutrition consulting company. ^[4]

Hevia-Larraín and colleagues compared 19 young men whose habitual diet was vegan with 19 omnivorous young men in 12 weeks of supervised resistance training; total protein was brought to about 1.6 g/kg/day with supplemental protein (soy in vegans, whey in omnivores). No difference between groups emerged in gains in lean mass and strength. Participants were not randomly assigned to the protein source and were untrained young men. ^[5]

The ISSN 2017, on the other hand, states that animal and dairy proteins carry the highest EAA proportion, whereas vegetarian proteins may lack one or more EAAs; soy is the most researched plant protein, and according to the ISSN, exercise studies are limited for sources such as pea, rice, and hemp. ^[1] For this reason, saying “the same as whey” for plant blends is not supported by evidence outside soy.

What to look at on a whey protein label?

Three questions are separate in label reading.

1. How much of the product is protein? A scoop or 100 g of product is not entirely protein. The mean protein content measured by González-Weller and colleagues in isolate and concentrate whey supplements representing the European market was 70.9% (range 18–92.3%), and there was a statistically significant difference between the declared and actual protein percentage. The authors report that they found high label non-conformity. ^[6] Arithmetically, 70% protein in a 30 g scoop means about 21 g of protein; this is not a recommendation, it is how the proportion reads.

2. Is protein alone, or with added amino acids? In the analysis of popular protein supplements in the Indian market, most products did not meet the declared protein amount, while some showed more protein than declared, which raised suspicion of “protein/amino acid spiking”; heavy metals were also reported in many formulations. ^[7] The Turkish Food Codex Communiqué on Sports Foods (Türk Gıda Kodeksi Sporcu Gıdaları Tebliği) says that amino acids, amino acid mixtures, and amino acid compounds may be added to protein concentrates; amino acids seen as a separate item in the ingredient list therefore suggest that part of the grams of protein may come from free amino acids. ^[8]

3. Protein source and proportion. According to the same communiqué, in protein concentrates the proportion of egg-, milk-, meat-, or soy-derived protein in dry matter must be at least 70%; in addition, substances on the IOC–WADA prohibited list cannot be present in products within this scope. ^[8] What protein proportion the “whey” statement on the label actually corresponds to can be verified only by laboratory analysis.

This guide does not recommend brands or products. Label accuracy, contamination, and doping topics are described with their sources on the harms page; needs calculation and the logic of use are on the how to use page.

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