Whey: dangers for kidneys, liver, and digestion
"Is whey dangerous for the kidneys?" This is the most frequently asked question at the counter in this department, more so than the choice of flavor or price. It deserves a documented answer rather than a shrug, precisely because there is an opinion from a French agency on the subject. This article only deals with the risks: kidneys, liver, digestion, skin. For choosing between a concentrate, an isolate, and a native, that's elsewhere, and we will direct you to it.
What exactly is whey?
Whey, or lactoserum, is the liquid fraction of milk that separates from the curd during cheese making. Filtered, concentrated, and then dried, it produces a protein powder.
It is therefore neither a synthetic molecule nor an exotic extract: it is a food product derived from milk, and this already explains a good part of the answers that follow. The body digests it as it digests a dairy protein, with the same enzymes.
Three forms coexist on the shelves. Concentrate retains some lactose and fat. Isolate is more finely filtered, with much less lactose. Hydrolyzed is pre-cut into shorter peptides. These differences primarily affect digestive tolerance, a topic we cover below. For the actual choice, see our comparison of native, isolate, or concentrated whey.
IO.GENIX
IO Genix Whey 80 Professional - Whey 80 IO Genix, Whey Protein Lactomin® BCAA 8:1:1
IO Genix Whey 80 Professional is a powdered whey concentrate made by IO Genix, a Spanish brand. Its raw material is a whey protein concentrate obtained...
What does whey do, and what claims are authorized?
Three claims authorized by European Regulation 1924/2006 apply to proteins, and therefore to whey that meets the regulatory threshold for content:
- "Proteins contribute to the growth of muscle mass"
- "Proteins contribute to the maintenance of muscle mass"
- "Proteins contribute to the maintenance of normal bones"
These are claims about proteins in general, not about whey in particular. No authorized formulation distinguishes whey from egg protein, pea protein, or a steak. What differentiates whey from other sources lies in its absorption rate and its richness in leucine, two compositional facts, not two claims.
What not to expect from it
Protein powder alone does not build muscle: it supplements an intake. If your daily protein needs are already covered by your diet, adding whey provides no measurable benefit — the question of quantities is covered in our article on daily protein intake. It also does not cause weight loss, and it does not replace a meal in the nutritional sense: it lacks fiber, micronutrients, and pretty much everything else.
Does whey damage the kidneys?
This is the most common fear, and it is also the one on which we have the clearest formulation.
In its 2016 opinion on the risks associated with the consumption of food supplements for athletes, ANSES writes: "In subjects without a history of kidney function impairment, the possible harmful consequences for the kidney of excessive consumption of dietary proteins have not been demonstrated."
Read the sentence word for word, because every part matters. "Without a history of kidney function impairment": in an adult whose kidneys are healthy, there is no demonstration of a harmful effect. "Have not been demonstrated": this is not the same as "are excluded," and ANSES does not say that the question is closed.
The flip side exists and is explicit in the same document: excessive protein consumption can worsen pre-existing kidney disease. In other words, the issue is not whey, it is the state of your kidneys. If you have kidney failure, even in its early stages, the protein load should be discussed with a nephrologist — and this applies to chicken as much as to powder.
The practical point no one mentions
High protein intake increases blood concentrations of urea and creatinine. These are markers used to assess kidney function. As a result: a blood test performed on an individual who consumes a lot of protein may show high values without there being a kidney problem. Tell your doctor about this before the blood test. This avoids unnecessary worries and examinations, and we regularly repeat this in our shop.
IO.GENIX
IO Genix Isolate Professional - Whey Isolate Microfiltration PROMIKO CFM
IO Genix Isolate Professional is a powdered whey isolate, available in 1 kg and 2 kg, from intense chocolate to pistachio. It is produced by IO...
Is whey bad for the liver?
To our knowledge, there is no demonstration of liver toxicity from whey proteins in a healthy person at usual quantities.
What does exist, however, are reports. The 2016 ANSES opinion reports, among the adverse effects transmitted to the nutrivigilance system, liver damage — jaundice, elevated transaminases — including rare cases associated with combinations of proteins and creatine.
An honest reading of this data is as follows: reports most often concern multi-ingredient products, containing plant extracts, stimulants or undeclared substances, and the imputability to the protein itself is rarely established. A report is not proof of causality. But this outlines a clear practical rule: the longer and more exotic the ingredient list, the greater the risk. A whey whose ingredients fit in three lines is a safer product than an "anabolic" mix of twenty components.
As for the kidneys: if you have known liver pathology, ANSES advises against supplements for athletes, and your doctor makes the final decision.
Digestion and acne: what do we really know?
Digestive problems
This is the most common discomfort, by far. Three distinct causes, which must be distinguished because they do not call for the same response.
Lactose. A concentrated whey retains a significant portion; an isolate, much less. If bloating and gas appear within an hour of taking the shake and disappear when switching to an isolate, that's the cause. This is the number one reason for switching to isolate, well before protein content.
Sweeteners and thickeners. Sucralose, acesulfame K, polyols, xanthan gum, cellulose gum: in high doses or in sensitive individuals, they cause exactly the same symptoms as lactose. Two products with the same protein dosage can behave very differently for this reason alone. A simple test: try a natural version.
Cow's milk protein allergy. This is something else entirely and should not be confused with lactose intolerance. Allergy involves the immune system, manifests as skin, digestive, or respiratory symptoms, and constitutes an absolute contraindication — including to isolate, which is still a milk protein. In this case, vegetable proteins are the answer.
Digestive enzymes are sometimes proposed as a solution; they are only useful for lactose, and changing the form of whey resolves the problem more simply.
Acne
Frequent question, and honest answer: the link between dairy product or whey consumption and acne has been reported in observational studies and case series, with a hypothesis of a mechanism involving insulin and IGF-1. This remains a body of signals, not a demonstrated cause-and-effect relationship, and no French or European authority has published a conclusion on this point.
What we can tell you that is useful: this is feedback we regularly hear at the counter, usually from young men who have suddenly increased their consumption. If your skin has deteriorated since you started, the reasonable approach is empirical — stop for four to six weeks, or switch to a plant-based protein, and observe. This is not proof, it's a test that costs nothing. And persistent acne should be treated by a dermatologist, not by changing your powder.
Protéalpes
Protéalpes Whey Protein Sugar Free - Pure Isolate Without Additives
Protéalpes Whey Protéine is a whey isolate in a 750 g tub, whose distinctive feature has less to do with what it contains than with what...
Who should abstain, and how to read the label to limit problems?
The populations for whom ANSES advises against food supplements for athletes, in its 2016 opinion:
- Children and adolescents. An adolescent who trains meets their needs with food.
- Pregnant and breastfeeding women.
- People with cardiovascular risk factors or heart disease.
- People with kidney or liver failure.
- People with neuropsychiatric disorders.
In addition, specifically for whey, cow's milk protein allergy, which is an absolute contraindication.
The five lines to check on the pot
The protein content per 100g of powder, not per serving. This is the only comparable figure between two products, as the serving size varies from one brand to another.
The first ingredient on the list. If it's a concentrate when the pot advertises "isolate", you have a blend where the isolate is a minority. The order of the list is regulated and does not lie.
The presence of added amino acids at the end of the list. Glycine, taurine, alanine added to a protein powder artificially inflate the measured nitrogen content, and thus the declared protein content. This practice is known as protein spiking. Their presence is not proof, but it is a point to look at.
The "of which sugars" line and the lactose content. These directly inform you about the expected digestive tolerance.
The total length of the list. See the paragraph on the liver: this is the best safety indicator you have without a laboratory.
To go further on the comparison criteria between brands, our comparison of whey proteins details the method.
Frequently Asked Questions about the Dangers of Whey
Is whey dangerous for the kidneys?
ANSES indicates, in its 2016 opinion, that in subjects without a history of kidney function impairment, the possible harmful consequences of excessive dietary protein consumption have not been demonstrated. However, an excess of protein can worsen pre-existing kidney disease: if your kidneys are fragile, the question should be addressed with your doctor.
Does whey damage the liver?
No liver toxicity of whey proteins has been demonstrated in a healthy person. Liver damage has been reported to nutrivigilance, but most often with multi-ingredient products whose imputability is difficult to establish. A short ingredient list remains the best guide.
Why does whey give me stomach ache?
Three possible causes: the lactose in a concentrated whey, the sweeteners and thickeners in the formula, or an allergy to milk proteins. Switching to an isolate resolves the first two in most cases; the third requires abandoning all dairy protein.
Does whey cause acne?
A link has been reported in observational studies, without a cause-and-effect relationship being established and without any authority having made a statement. If your skin has deteriorated after starting, stopping for a few weeks or switching to a plant-based protein will give you a personal answer.
Does whey make you gain weight?
It provides calories, like all food. A typical dose provides little in terms of a day's intake. If your weight increases, the total caloric intake is the cause, not the powder itself.
Can you take whey every day?
For a healthy adult, there is no contraindication: it is a food. The real question is your total protein intake, not the frequency of consumption.
Can a teenager take whey?
ANSES advises against supplements for athletes for children and adolescents. At this age, protein intake can be easily met with common foods, and this is what we systematically advise parents who ask us.
Should you drink more water when taking whey?
The elimination of nitrogenous waste requires water, and good hydration is recommended for athletes anyway. There is no specific additional amount to recommend solely due to whey intake.
If you have any doubts about your tolerance or a condition that would contraindicate whey, the right conversation to have is with your doctor — and the conversation about the product itself, we are happy to have in our store in Vendargues, about ten minutes from Montpellier. Online, the protein section includes the alternatives mentioned in this article, including whey.
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