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Protein myths: 8 claims checked against the research

Updated on 22.10.2026 8 min read11 sources

There are more legends about protein than about the right way to fold a banitsa (Bulgarian filo pie). "It wrecks your kidneys." "Your body only takes in 30 g at a time." "It's for bodybuilders." We took the eight most common claims and checked them against the research. Some are pure invention, some have a grain of truth, and for others the answer is "it depends".

In short

A 2018 meta-analysis found no decline in kidney function in healthy people who eat more protein. If you have kidney disease, things are different, and your doctor decides.
There's no 30 g ceiling per meal: a bigger serving of protein simply takes longer to digest.
Every adult needs protein, and the need goes up during pregnancy and breastfeeding.
More protein shows no harmful effects on bones (meta-analysis, 2017). Protein contributes to the maintenance of normal bones.
A cooked egg is absorbed much better than a raw one: 91% versus 51% in one study.

Myth 1: "Protein wrecks your kidneys"

This is the most stubborn myth, and it has its own logic. Protein really does make the kidneys filter more. EFSA describes this as a normal response: with more protein, the body makes more substances such as urea, which the kidneys clear out.

The question is whether that harms them. In 2018, Canadian scientists gathered all the controlled studies on the subject and ran a meta-analysis. Only adults without kidney disease were included. A high-protein diet in these studies meant at least 1.5 g of protein per kilogram, or at least 100 g a day.

28 / 1 358studies and participants: the change in kidney function was the same with more protein and with the usual amountDevries et al., The Journal of Nutrition, 2018

The authors' conclusion: in healthy adults, more protein does not worsen kidney function. EFSA also writes that the recommended intake is not a risk factor for the kidneys of healthy people.

The important caveat: with kidney disease, the rules for protein are different. If you have kidney disease, the amount of protein is something you decide with your doctor. Ask your doctor before you change anything.

Myth 2: "Your body can only absorb 30 g of protein at once"

This number has been doing the rounds in gyms for years. The trouble is, it mixes up two different things.

Absorption is the passage of nutrients from the gut into the blood. A 2018 review by Schoenfeld and Aragon puts it bluntly: the idea that there's a limit to how much protein can be absorbed is a long-standing misconception, and the amount that can be absorbed is practically unlimited. If you eat a big serving, it simply takes longer to digest.

The other question is how much of that protein the body uses for muscle. For a long time, the effect was thought to stop above 20 to 25 g. In a 2023 study in Maastricht, people were given 25 g or 100 g of protein after exercise. The larger amount produced a stronger and longer effect, lasting more than 12 hours, while the amount of amino acids burned off barely changed.

That doesn't mean it's best to eat all your protein for the day in one dinner. Spread across several meals, it's easier for most people. Read how in our article on spreading protein through the day.

Myth 3: "Protein is only for athletes"

Protein is a nutrient, like carbohydrates and fat. EFSA sets the recommended intake for every healthy adult: 0.83 g per kilogram of body weight a day, the same for women and men.

During pregnancy, EFSA adds 1, 9 and 28 g a day in the first, second and third trimester. In the first six months of breastfeeding the extra is 19 g a day, and 13 g after that. We work out what that means for you in our article on how much protein you need a day.

An older woman and a girl cutting vegetables for a salad in a bright kitchen — Protein comes from the ordinary food we cook at home. Photo: Vitaly Gariev / Pexels

And with age, the topic matters more, far from any gym. Protein contributes to the maintenance of muscle mass, and the PROT-AGE expert group recommends at least 1.0 to 1.2 g per kilogram a day for people over 65. The details are in our article on protein and aging.

Myth 4: "Protein leaches calcium from your bones"

The old theory sounds convincing. More protein means more calcium in the urine. The assumption was that the body takes this calcium from the bones to neutralize the acids from protein.

EFSA explains why the theory doesn't hold up. People who eat more protein often take in more calcium too. On top of that, more protein increases calcium absorption in the gut, which may explain the calcium in the urine. EFSA calls the very idea that bones are the body's main "buffer" against acids questionable, because it ignores the role of breathing and of the kidneys.

Hands pouring milk from a glass bottle into a glass next to a bowl of cut fruit — Protein and calcium are the two main building materials of bone. Photo: Thirdman / Pexels

In 2017, a meta-analysis from the US National Osteoporosis Foundation pooled 16 controlled trials and 20 observational studies of large groups of people. The conclusion: the data so far show no harmful effects of higher protein intake on bones.

Fact

This is one of the three claims about protein authorized in the EU: protein contributes to the maintenance of normal bones.

Myth 5: "The more protein, the better" (and the reverse: "lots of protein is dangerous")

Here the two myths meet in the middle. EFSA wasn't able to set an upper limit for protein, because there isn't enough data. Its panel concluded that an intake of twice the recommendation, about 1.7 g per kilogram, is safe for adults. Some active people in Europe regularly eat that much.

Intakes three to four times the recommendation have also been observed, with no visible harm, and also no visible benefit. Acute unpleasant effects show up at the extremes, when protein provides 45% or more of calories.

The takeaway is a calm one. Up to about twice the recommendation, protein is safe for a healthy adult, and beyond what you need, it doesn't work miracles. If you have kidney disease, are pregnant or follow a special diet, ask your doctor.

Myth 6: "Plant protein is no good"

All fresh foods, plant and animal, contain essential amino acids. Plant foods usually have less per gram of dry matter, especially lysine and methionine. A good combination of plant and animal foods, or of different plant foods, covers your needs.

A 2013 review in the Medical Journal of Australia says strict combining on the same plate isn't necessary if you eat enough, and a good variety, through the day. Bob chorba (bean soup) with a slice of bread and lentils with rice do the job just fine. The numbers for individual foods are in our article on animal and plant proteins.

Myth 7: "Raw eggs give you more protein"

The glass of raw eggs is a scene from the movies. Research shows the opposite. In a 1998 experiment in Leuven, Belgium, the body absorbed 90.9% of the protein from a cooked egg and only 51.3% from a raw one.

Hands cracking an egg, the yolk dropping into a white pot, with whole eggs and rosemary around it — A cooked egg is absorbed almost twice as well as a raw one. Photo: hello aesthe / Pexels

A 1999 experiment with healthy volunteers came to the same result. Of the cooked egg protein, 5.7% wasn't absorbed in the small intestine; of the raw, 35.1%. Heat unfolds the proteins and makes them easier to digest. There's more about eggs in our article on egg protein.

Myth 8: "Protein powder is just chemicals"

Protein powder is food with the water taken out, just like powdered milk, flour or instant coffee. We explain exactly how it's made, step by step, in our article on whether protein powder is just chemicals.

The ISSN's 2017 position stand offers a sensible order of priorities. First, aim for whole foods with complete protein. Protein powder is a safe and convenient way to add quality protein.

MEALUP is a protein powder made from egg white and milk protein concentrate, with no added sugar and no sweeteners. You sprinkle it over the food you're eating anyway.

Tip

When you read a label, look at the ingredients and the protein per serving. The shorter and clearer the list, the easier it is to judge what you're eating.

Frequently asked questions

How much protein is too much?

EFSA doesn't set an upper limit. Twice the recommendation, about 1.7 g per kilogram, is safe for healthy adults. With kidney disease, the amount is decided with your doctor.

Is more protein safe during pregnancy?

During pregnancy, your protein needs go up: an extra 1, 9 and 28 g a day in the three trimesters, according to EFSA. Talk to your doctor about any change to your diet during pregnancy.

If almost all protein gets absorbed, why spread it out?

Because it's more convenient and makes it easier to reach the amount you need without huge servings. The studies on an upper limit to the effect were done mainly after exercise and with powders, so an ordinary plate with protein at every meal is a safe bet.