Whey isolate builds the same muscle as hydrolyzed whey: in a 2019 double blind trial in the Journal of Nutrition, both raised muscle protein synthesis by about 43 percent. Hydrolyzed whey can reach your blood a little sooner. That head start has not turned into more muscle or strength in the trials that compared them.
So for most people, isolate is the better buy. Hydrolyzed whey earns its higher price in a few narrow cases, and this article shows you which ones.
Whey Isolate vs Hydrolyzed Whey at a Glance
If you are standing between two tubs, this table gives you the short version. Each row is explained further down, with the study behind it.
| Question | Whey isolate | Hydrolyzed whey |
|---|---|---|
| How it is made | Whey filtered to remove most of the fat and lactose | Isolate or concentrate, then broken into smaller pieces with enzymes |
| Protein by weight | 90 percent or more | Depends on the base: close to isolate if made from isolate, lower if made from concentrate |
| Lactose | About 0.5 percent | Depends on the base: very little from isolate, more from concentrate |
| Absorption speed | Fast; blood amino acids rise within the first hour | Faster in some trials, about the same in others |
| Muscle growth | Same as hydrolyzed whey in head to head trials | Same as intact whey in head to head trials |
| Taste | No bitterness added by processing | Can taste bitter, more so the more it is broken down |
| Price | Lower, with one fewer processing step | Usually higher, because of the extra enzyme step |
| Who it suits | Most people who lift, diet or want a low lactose shake | People chasing the fastest delivery or faster recovery from hard training |
How Each One Is Made
If the labels look like three versions of the same thing, that is because they are. All whey starts as the liquid left over when milk is made into cheese. What changes is how much it gets filtered, and whether it then gets broken down.
Whey concentrate
Concentrate is filtered the least. The International Society of Sports Nutrition (ISSN) notes that the concentrates used in sports products are usually 70 to 80 percent protein. The rest is mostly fat and lactose, the sugar in milk.
Whey isolate
Isolate goes through more filtering. The ISSN describes two common methods: microfiltration, which strains the protein through fine ceramic membranes, and ion exchange, which uses an electric charge to pull the protein away from the fat and lactose.
The result is 90 percent protein or more. A review in the Journal of Sports Science and Medicine puts isolate at about 0.5 percent lactose, against 10 to 55 percent in concentrate. You can compare the forms side by side in our guide to whey isolate vs whey protein.
Hydrolyzed whey
Hydrolyzed whey takes either of those and adds one more step. Enzymes cut the long protein chains into short pieces called peptides, chains of just two, three or four amino acids. That is the step your stomach and gut would otherwise do, which is why labels call it "predigested".
Hydrolysis does not change the protein percentage much. It changes the size of the pieces. A hydrolyzed product made from concentrate still carries the fat and lactose of a concentrate.
Absorption Speed
If you have read that hydrolyzed whey gets into your muscles faster, that is partly true. Smaller pieces can be absorbed with less digesting, so the amino acids can show up in your blood sooner.
Hydrolyzed whey is absorbed somewhat faster than intact whey in some trials, and in one small trial it brought back muscle strength faster after hard exercise. That is the real case for paying more for it.
In a 2010 study in the Journal of Agricultural and Food Chemistry, hydrolyzed whey raised blood amino acids more quickly than the same whey left whole. That trial was small, with five people on whey.
The recovery result comes from a 2010 trial in the Journal of Science and Medicine in Sport. After 100 hard leg contractions, strength dropped about 23 percent. People given 25 grams of hydrolyzed whey isolate had their strength back within six hours. People given regular isolate or flavored water did not. Only six people were in the hydrolyzed group.
Not every trial agrees. In a 2004 study in the European Journal of Nutrition, whole whey and hydrolyzed whey left the stomach at about the same speed, and their amino acids were absorbed at similar rates.
Muscle Growth and Strength
If you buy protein to build muscle, this is the section that decides it. Faster delivery only matters if it leads to more muscle, and so far it has not.
The 2019 Journal of Nutrition trial gave ten young men either hydrolyzed whey or intact whey, meaning whey that has not been broken down. Regular isolate is intact whey. Leucine, the amino acid that switches on muscle repair, reached the muscle to a similar extent with both.
Muscle protein synthesis rose about 43 percent with both. One marker stayed raised for three hours only after the hydrolyzed shake. The authors still concluded the two were similar for overall muscle building.
The longer test points the same way. In an eight week trial in the Journal of the American College of Nutrition, 56 trained men took 30 grams twice a day of hydrolyzed whey, regular whey concentrate or a carbohydrate placebo. Strength rose by similar amounts in every group.
The hydrolyzed group lost about 6 percent of its body fat, a significant difference from placebo. The authors wrote that it gave no other advantages alongside the training. Note that this trial used hydrolyzed concentrate, not hydrolyzed isolate.
What does move the needle is total protein. The ISSN puts the useful range for people who train at 1.4 to 2.0 grams per kilogram of body weight a day, spread across meals.
Taste, Stomach and Price
If you have tried a hydrolyzed shake and found it bitter, that is the chemistry, not your taste buds. A review of whey hydrolysates in food names bitter peptides as a major drawback of hydrolysis, and notes they grow as the protein is broken down further.
Bitterness has to be covered with more flavoring or sweetener. That extra enzyme step and flavor work are also why hydrolyzed whey usually costs more than isolate.
On your stomach, the gentler reputation is weaker than it sounds for healthy adults. In the 2004 trial, both forms left the stomach at the same pace. If milk sugar is what bothers you, isolate already removes most of it, which our article on whey isolate and lactose intolerance covers in detail.
Hydrolysis earns its gentle name in medicine. Doctors use extensively hydrolyzed milk formulas for some babies with cow's milk allergy, a use reviewed in the 2024 World Allergy Organization guideline update. Those are medical formulas used under a doctor's care, not sports shakes.
Safety and Who Should Avoid Both
If you have a milk allergy, neither one is safe for you. Both are milk protein, and hydrolysis does not change that. Milk is one of the nine major food allergens the FDA recognizes, and the FDA warns that severe reactions can be life threatening.
For healthy people who train, the ISSN position stand found no evidence that high protein intakes harm the kidneys or liver. Trials it cites ran as high as 4.4 grams per kilogram a day for eight weeks with no harmful effects reported.
People with kidney disease are different. The ISSN notes that people in kidney failure benefit from eating less protein, so ask your doctor before adding any protein powder. The same goes for choosing a protein for a child with a milk allergy. This article summarizes published research and is not medical advice.
Whey Isolate vs Hydrolyzed Whey FAQ
What is hydrolyzed whey protein isolate?
Hydrolyzed whey protein isolate is whey isolate that has been broken into short peptides with enzymes after filtering. It keeps the isolate's high protein and low lactose, and adds faster absorption in some trials. It can also taste more bitter, so it often needs more flavoring.
Is whey isolate easier to digest?
Whey isolate is easier to digest than concentrate for people who react to lactose, because filtering removes most of the milk sugar. Hydrolyzed whey is broken down further still. In one small trial, though, whole whey and hydrolyzed whey left the stomach at about the same speed.
How long does whey isolate take to digest?
Whey isolate raises blood amino acids fast, mostly within the first hour after you drink it. In a 2004 trial where the drink went straight into the stomach, half of it had left in about 20 minutes. A 2019 trial found blood leucine was already up one hour after a whey shake.
Should you take whey isolate before or after a workout?
Either works. The ISSN says benefits come from protein taken before or after training, and one trial it cites found similar muscle building from 20 grams of whey isolate taken just before or just after lifting. Hitting your daily protein total matters more than the clock.
Is whey isolate worth it?
Whey isolate is worth it if lactose bothers you, if you take several scoops a day, or if you count every gram of carbs and fat. If none of that applies, a concentrate builds muscle just as well. Over hydrolyzed whey, isolate is usually the better value.
Which One Should You Buy?
If you want to build muscle and keep your stomach happy, buy a whey isolate and spend the difference on hitting your daily protein total. If you train twice a day or need your strength back within hours, a hydrolyzed whey isolate is the one case where the extra cost has some evidence behind it.
BioHealth Nutrition makes Precision ISO, a whey protein isolate. Its ingredient list has four items: pasture fed whey protein isolate, natural flavors, stevia leaf extract and salt. Each scoop has 27 grams of protein and 1 to 2 grams of carbs, depending on the flavor.
Our pasture fed whey isolate has no added sugar, is sweetened with stevia leaf extract, and is third party tested for purity and potency. It is still milk protein, so it is not a fit for a milk allergy.
Precision ISO 100% Whey Protein Isolate Powder
27g of pasture fed whey protein isolate per scoop, with just 1 to 2g of carbs and no added sugar.
From $69.99
Shop Precision ISO 100% Whey Protein Isolate PowderCompare every whey protein isolate we make. If you are weighing where the whey comes from, read what pasture feeding changes in whey before you choose.
Sources. Moro T. et al., Whey protein hydrolysate increases amino acid uptake, mTORC1 signaling, and protein synthesis in skeletal muscle of healthy young men in a randomized crossover trial, Journal of Nutrition, 2019. Lockwood CM. et al., Effects of hydrolyzed whey versus other whey protein supplements on the physiological response to 8 weeks of resistance exercise in college aged males, Journal of the American College of Nutrition, 2017. Buckley JD. et al., Supplementation with a whey protein hydrolysate enhances recovery of muscle force generating capacity following eccentric exercise, Journal of Science and Medicine in Sport, 2010. Morifuji M. et al., Comparison of different sources and degrees of hydrolysis of dietary protein, Journal of Agricultural and Food Chemistry, 2010. Calbet JA. and Holst JJ., Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrolysates in humans, European Journal of Nutrition, 2004. Jäger R. et al., International Society of Sports Nutrition Position Stand: protein and exercise, Journal of the International Society of Sports Nutrition, 2017. Hoffman JR. and Falvo MJ., Protein: which is best?, Journal of Sports Science and Medicine, 2004. Jeewanthi RK. et al., Improved functional characteristics of whey protein hydrolysates in food industry, Korean Journal for Food Science of Animal Resources, 2015. Bognanni A. et al., WAO DRACMA guideline update XI: milk supplement and replacement formulas for infants and toddlers with cow's milk allergy, World Allergy Organization Journal, 2024. US Food and Drug Administration, Food Allergies: What You Need to Know.
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