FAQ

Eighteen questions, answered properly

The questions people actually ask before buying whey, with the answers that a supplement brand’s own FAQ tends to skip. Where the evidence is thin, we say so.

The basics

Is whey protein isolate lactose free?

Cross-flow micro-filtration removes most of the lactose along with the fat, which is why a true isolate can carry a lactose free claim while a concentrate cannot. Trace amounts can remain, so people with a diagnosed milk allergy, which is a reaction to the protein rather than the sugar, should avoid whey entirely. Whey isolate is a milk product and every label will say so.

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

Concentrate runs anywhere from 29% to 89% protein by weight and retails nearer 70 to 80%, with the remainder made up of lactose, fat, and moisture. Isolate is filtered further to 90% or more, which strips the lactose and the fat. Hydrolysate is isolate that has been partially broken down before you drink it, which speeds absorption and usually costs more and tastes bitter.

What does undenatured mean?

Denaturing is the unfolding of a protein’s three-dimensional structure, usually by heat or acid. Undenatured means the manufacturer used a low temperature process that leaves those structures intact. Note that your stomach acid denatures protein anyway, so the practical argument is about the fragile immunoglobulin and lactoferrin fractions rather than about the amino acids, which survive either way.

What does cross-flow micro-filtration remove?

It pushes liquid whey across a ceramic membrane rather than through it, so the membrane does not clog. The membrane pore size lets lactose, minerals, and fat pass while holding back the larger protein fractions. What is left behind on the membrane side is the concentrated protein, at a higher purity than the starting liquid and without the heat or chemical solvents that other separation methods use.

What is the difference between BV and PDCAAS?

Biological value measures how much of the absorbed nitrogen your body retains, on a scale where whole egg was originally set at 100. Whey scores around 104 and soy around 74. PDCAAS scores a protein against human amino acid requirements and caps at 1.0, which puts whey, casein, soy, and egg all at the ceiling and makes the measure less useful for telling them apart. BV discriminates more at the top of the range, which is why the whey literature tends to quote it.

Health and safety

Can I take whey protein every day?

Daily protein intake is what determines whether you meet your requirement, because the body has no dedicated store for amino acids the way it has glycogen for carbohydrate and adipose for fat. Whey is a food, not a drug, and there is no evidence of harm from ordinary daily use in healthy adults. If you have kidney disease or any condition that requires you to manage protein intake, that is a conversation with your doctor and not with a website.

Is stevia safe?

Steviol glycosides purified from the stevia leaf hold GRAS status with the FDA and carry an established acceptable daily intake set by JECFA that is far above what a scoop of protein powder contributes. Whole stevia leaf and crude extracts do not have that status. The common complaint is not safety but taste: a proportion of people register a lingering bitter or liquorice note, and no amount of formulation makes that go away for them.

Can teenagers take whey protein?

Whey is a dairy food in powdered form, so the question is really whether a teenager should drink milk, and the answer is generally yes. The more useful point is that most adolescents can meet their protein needs from food, and a shake is a convenience rather than a requirement. For a young athlete training hard, discuss it with a paediatrician or a registered dietitian first.

Does whey protein cause acne?

There is observational research associating dairy intake, and whey supplementation specifically, with acne in some individuals, with insulin and IGF-1 signalling proposed as the mechanism. The evidence is not strong enough to say whey causes acne, and plenty of people use it with no skin change at all. If your skin changes after starting a whey product, stopping for four weeks is a cheap way to test it on yourself.

Is whey protein safe for people who are lactose intolerant?

Most people who tolerate lactose poorly do fine with an isolate, because the filtration has already removed the great majority of the lactose. Concentrate is a different matter and is a common cause of the bloating people blame on protein powder in general. Start with a half scoop if you are unsure.

Choosing a product

Is whey better than plant protein?

On amino acid completeness and leucine content, whey has the edge: soy’s biological value sits near 74 against whey’s 104, and its limiting amino acid is methionine. A well-formulated blend of pea and rice closes much of that gap. If you avoid dairy for ethical or digestive reasons, plant protein is a perfectly reasonable choice, you just need slightly more of it.

How do I tell an isolate from a concentrate without reading the marketing?

Divide the grams of protein by the gram weight of the scoop. Both numbers are on the panel. Above 90% and you are almost certainly holding an isolate. Below 80% and you are holding a concentrate or a blend, whatever the front of the jar says. This one calculation tells you more than the entire label design.

How much sugar should a protein powder have?

Aim for 1g or less per serving, with total carbohydrate under 3 to 4g. Sugar appears on ingredient lists under a long list of names, including sucrose, high fructose corn syrup, fructose, dextrose, glucose, and lactose. A product can carry several of them and still look modest on any single line.

Is gluten free worth looking for on a whey label?

Gluten is not one of the major allergens the FDA requires to be declared, so its absence from an allergen statement tells you nothing. The claim has to be explicit. Whey itself contains no gluten, but flavouring systems and added ingredients can introduce it, which is why the explicit claim matters.

How much protein do I actually need each day?

Somewhere between 0.8 and 1.5 grams per pound of bodyweight, depending on how much you train and whether you are trying to lose fat while holding muscle. Sedentary adults sit at the bottom of that range, people in a calorie deficit and older adults defending muscle mass sit nearer the top. Our buyer’s guide has a calculator that does the arithmetic.

Using it

Does protein timing matter?

Far less than the supplement industry spent two decades suggesting. Total daily intake is the dominant variable, and the anabolic window is measured in hours, not minutes. Spreading protein across three or four feedings is a reasonable habit, mostly because it makes hitting the daily total easier.

Can I bake with whey protein?

Yes, with two caveats. Heat denatures the protein, which does not reduce its amino acid content but does change texture, and whey holds far less moisture than flour so baked goods turn dry and rubbery if you swap too much. Replace no more than a third of the flour by weight, and use the unflavored version unless the recipe wants vanilla.

How long does an opened jar last?

Follow the best-before date on the jar, which is typically 12 to 24 months from manufacture, and once opened treat moisture as the enemy. Keep the scoop dry, close the lid properly, and store the jar somewhere cool and dark rather than next to the kettle. Clumping is a moisture problem. A sour or cardboard smell means the fat fraction has oxidised and the jar should go.

Still deciding?

The isolate we ranked first carries a money-back guarantee on the unused portion, so a first jar costs you nothing but the trying.