People with chronic kidney disease are contraindicated in diets that are dominated by protein food, because the effect of protein on the kidneys can be negative. But this does not mean that it is completely prohibited; in small quantities it can improve health. Proteins are an essential component in the daily diet. They serve to form muscle cells.

The effect of protein foods on the kidneys

It is important to consume complete protein, which is found in meat, eggs, fish, milk, and caviar. But if consumed in excess, it can do more harm than good, especially to the kidneys. If the filtering internal organs are healthy, then they will be perfectly able to remove protein breakdown products. Another thing is diseased organs that need to work harder to do the same job. If the kidneys cannot cope, then toxic substances will begin to accumulate in the body, a large accumulation of which will lead to problems with other internal organs.

What are the dangers of such a diet?

This diet is a fairly popular method of losing weight. Is this so, and does it have a negative effect on the body, in particular on the kidneys? The basic rule of such a diet is to increase the consumption of protein foods, but it is necessary to reduce the amount of carbohydrates.

A person first loses weight due to water loss. With a limited amount of carbohydrates, the body begins to take glycogen (complex carbohydrate) from the muscles and liver to get the necessary energy. If a person has an insufficient supply of carbohydrates, then the weight will still return over time. During a protein diet, a lot of calcium is removed from the body, which can lead to the formation of kidney stones. Due to the predominance of protein in the daily diet (protein products), an excess of uric acid is formed in the blood, which, turning into crystals, injures the internal organ. You should not experiment with such a diet if you have a diseased kidney, gout, or impaired renal function. This may lead to an exacerbation of the disease and. And if there are no contraindications, and you still want to try this method of losing weight, then it is important to remember the simple formula for calculating the daily protein requirement. You need to divide your actual weight by 2, the resulting figure will be the required amount of protein in grams. If your weight is 60 kilograms, then the daily requirement of pure protein will be 30 grams.

The main building material for muscle cells are proteins. Protein compounds contained in meat, fish or plant products include fats and carbohydrates, which is determined by the vital activity of the organism from which the food was obtained.

Protein used in sports nutrition, unlike plant and animal protein, is protein molecules purified from foreign impurities.

Because people are aware of changes in a familiar substance by chemical means, there is a belief that protein is harmful to the male body. Public opinion was also influenced by the fact that purified protein can cause digestive disorders and allergic reactions.

Is the information about the dangers of protein true?

Technologies for the production of protein purified from impurities make it possible to include more essential protein in the diet without increasing the calorie content of a serving of food. High-protein mixtures are necessary for bodybuilding, weight loss and for healthy eating with reduced fat and sugar content.

Among the most common negative consequences for the body are:

1. Allergic reactions.
2. Digestive disorders (diarrhea, constipation, flatulence).
3. Kidney pathologies.

Digestive disorders and protein allergies are a common natural reaction of the human body to foreign substances that enter it through food. The occurrence of these unpleasant phenomena is due only to the characteristics of each person; they cannot be called the consequences of taking purified protein. Almost everyone can encounter them even when consuming ordinary foods containing protein.

1. Allergies are based on individual intolerance to a substance. When it is contained in regular healthy foods, the body's reaction may be almost unnoticeable due to the presence of many other substances. They mask, reduce or even neutralize the effect of the allergen. But when it enters the body in concentrated form, this substance causes a characteristic reaction in the form of a rash, indigestion, and other things. Protein is a substance purified from carbohydrates and fats. Therefore, protein intolerance, unnoticeable during a normal diet, may well unexpectedly appear when taking a concentrated diet. This is how the myth about the allergic consequences of protein intake was born.
2. Digestive disorders can occur as a special case of allergies. In some cases, they can be caused by dysbiosis or deficiency of enzymes that are needed for the digestion and absorption of protein. In both cases, excess undigested protein accumulates in the intestines, which causes active activity of putrefactive bacteria. The process is accompanied by the release of a large amount of gases (indole, skatole, etc.). A similar situation occurs when the dose of protein concentrate is too high (250-300 g/day).

In order to prevent the unpleasant consequences of taking protein, it is enough to follow the recommended intake of the drug (15-20 g per dose) and take probiotics and digestive enzymes. Using enzymes will allow the body to digest protein faster and better absorb it. Increased intake of fluids and foods containing fiber will help avoid constipation.

How does protein affect the kidneys and potency?

Among the myths about the harmful effects of protein on the male body, the main place is occupied by concerns about decreased potency. These rumors stem from the fact that the nutrition previously produced for bodybuilders and athletes contained steroid additives. These substances are also capable of increasing muscle mass, but they are not related to the protein concentrates used in our time. To avoid intimate male problems, it is enough to buy high-quality sports nutrition, since cheap analogues may contain unwanted components in the form of steroids.

But even high-quality nutrition can have an impact on potency when consuming soy protein, which is usually used by vegetarians. Its effect lies in the high content of phytoestrogens in soy. These substances are plant analogues of female sex hormones. But, thanks to their relatively low content in ready-made food, we can talk about its practical safety for the male genital area. Those who still fear for their health should prefer whey or egg protein.

The truly dangerous consequences of consuming sports nutrition in a diet can only become if a man has undiagnosed kidney pathologies. Therefore, before including a protein drug in your diet, you should consult your doctor and undergo a medical examination. If kidney failure is detected, you will have to stop eating protein.

Due to the fact that the body spends a lot of liquid on protein processing, when using sports nutrition for weight loss or muscle growth, it is recommended to ensure that the amount of liquid you drink per day is at least 2 liters.

Essential nutrients must be obtained from natural foods. Protein is no exception, and for a complete healthy diet, you should remember that protein concentrates should only be a food supplement.

A certain part of people are particularly distrustful of sports nutrition, believing that all products in this category, without exception, cause great damage to health. In fact, in addition to steroids and anabolic steroids, there are quite safe and officially recognized means - for example, proteins.

They do not have a destructive effect on the body, and at the same time allow a person to achieve rapid muscle growth. At the same time, it is worth saying that there are also certain disadvantages in using these products, for example the negative effect of protein on the kidneys.

What is whey protein?

In sports nutrition, whey protein is mostly used, since it is as close as possible to natural protein, which the human body itself breaks down due to metabolic processes. Whey protein, like egg and meat protein, is a protein obtained through the use of a special technology for isolating it from ordinary products.

Products made in this way undergo the necessary purification, and a person involved in sports receives a completely finished dietary supplement that does not require additional effort from the body to process it. It only needs to break down proteins into amino acids and use them directly to form and maintain muscle mass.

Reference! It should be remembered that with an excessive intake of whey protein, the body reduces the function of producing enzymes necessary for the breakdown of protein compounds that are part of regular food (meat, fish, etc.).

Whey protein is natural to the human body. Its addition to the diet is considered advisable only when you need to quickly gain muscle mass and achieve this in the fastest and relatively safe way.

At the same time, it cannot be said that such a protein can be taken by everyone, without exception, who wants to bring their body into a sporty shape. If a person has an individual intolerance to protein, which manifests itself in the form of allergies or dysfunction of the digestive system, then its intake can be adjusted or supplemented with the necessary enzymes.

If there is no effect from the measures taken, you will have to stop taking whey protein. From the above it follows that this remedy does not pose potential harm on a large scale, the consequences of which may become irreversible. But if a person has any kidney diseases, the use of this dietary supplement is strictly prohibited.

Protein production stages

What kidney functions does it affect?

The main idea about the harmful effects of protein on the kidneys during a high-protein diet is based on the fact that they, like the liver, are the main organs that perform a recycling function. Therefore, with an increase in its intake into the body, the load on the kidneys increases significantly, and the only question is how ready they are to carry out their activities uninterruptedly.

The possible negative side effects of excessive protein intake on the kidneys are directly related to the functions they perform in the body. The issue under consideration concerns the following two:

• Filtering function. The kidneys ensure the excretion of residual products of protein metabolism (and not only it), toxic and foreign substances from the body. In addition, they regulate the concentration level of vital substances for the human body. chemical elements(sodium, calcium, potassium, etc.), returning them back through reabsorption or excreting them in the urine.
• Maintaining acid-base balance. The kidneys are responsible for the balance of alkalis and acids, because frequent changes in the body’s environment towards acidification can lead to dangerous consequences. Often, as a result of this imbalance, kidney stones form, bones become thinner, and cancerous tumors etc.

Reference! The daily protein intake for physically inactive people is 0.8 g per 1 kg of body weight, for children 1.5 g, adolescents - 1 g, and for athletes 1.6–2.2 g.

The effect of protein on filtering function

When consuming more protein, the kidneys have to filter out the increased content of its metabolic products, but the organs of a healthy person are able to quickly adapt to such loads. This occurs due to an increase in renal filtration rate. However, in certain pathologies, this ability is lost, which leads to the need for strict control of the intake of proteins into the body in order to prevent the development of relapse of the disease.

To study such deviations, several diverse scientific studies have been conducted and the condition of athletes taking high amounts of protein has been studied.

The results of the experiment showed that bodybuilders, despite high levels of calcium and uric acid in their blood serum, had normal concentrations of creatinine, albumin and urea, so-called markers of kidney health.

At the same time, for the sample under study, the nitrogen balance was determined to be positive, and the daily dose of protein was 1.26 g/kg. These values ​​indicate a sufficient amount of protein for intensive muscle building. Based on the results of this experiment, scientists concluded that protein doses up to 2.8 g/kg are not harmful to kidney function in people who regularly exercise.

The next experiment was to study the effect of protein on the kidneys in women - healthy and suffering from mild renal failure (RF). Protein content of their diet was assessed by dietary questionnaire, and filtration function was determined by urinary creatinine concentration.

The results of the experiment were similar to the first: significant doses of protein are absolutely harmless for women with healthy kidneys. It was noted that animal proteins (non-dairy) in large doses can lead to a decrease in renal function in women with moderate renal failure.

With healthy kidneys and physical activity, protein intake is absolutely harmless

Link between protein and kidney stones

Kidney stones (calculi) are often a kind of “reward” for a long time of neglecting one’s body. As a rule, they are formed when urine is overly concentrated, which contributes to the crystallization of the mineral salts and other particles of microscopic sediment contained in it.

According to scientifically confirmed data, risk factors for stone formation are considered to be insufficient fluid intake and excess protein in the diet. This leads to an increase in the content of oxalates, uric acid and calcium in the urine. And it is also known that animal protein is more harmful to the kidneys than vegetable protein, since its consumption increases the risk of stone formation.

This statement has several explanations. Excessive intake of animal protein increases acidity, and this, in turn, reduces the ability of the kidneys to reabsorb calcium. As a result, the calcium content in the urine increases, which is considered favorable conditions for the formation of kidney stones.

On the other hand, animal protein is the main source of purine substances, from which uric acid (UA) is synthesized during the metabolic process. And it rightfully belongs to no less a determining factor in increasing the risk of stone formation. That is, the higher the level of uric acid, the greater the danger.

The solubility of UA is directly related to the acid-base balance of urine. When the pH decreases to 5.5–6.0, which is caused by excessive consumption of protein products, the solubility of uric acid decreases, while the process of stone formation is facilitated and accelerated. Several experiments were conducted to confirm these statements.

In one of them, scientists studied the effect of a popular low-carbohydrate diet (Dukan diet) on kidney function. To do this, the subjects took large doses of protein for 6 weeks. As a result, the acidity increased (pH dropped), the concentration of insoluble UA increased by 2 times, and the calcium content increased by 60%. From which the conclusion was not difficult to draw.

Important! A high-protein diet significantly increases the risk of kidney stone formation.

The next experiment was to evaluate the effect of animal protein on stone formation. This experiment involved people with a history of kidney stones. One control group was fed high-protein food for 2 weeks, and the other, on the contrary, low-protein food.

As a result, it was found that high consumption of animal proteins and purines leads to an increase in the level of uric acid salts by 90%, uric acid itself by 200–250%, and reduces pH, which ultimately causes the formation of ammonium salts and uric acid crystals.

The following experiment confirmed that the content of insoluble UA was highest in a high-protein diet consisting of animal proteins. In the process, scientists concluded that crystallization of urine occurs much faster with a diet based on animal proteins.

Excessive consumption of animal proteins can lead to kidney stones

In addition, it has been proven that an excess of animal proteins in the diet leads to the rapid formation of calcium oxalate crystals in the urine, which is considered another explanation side effects protein of this plan.

Harm from long-term use

With prolonged inclusion of high-protein products in the diet, structural changes in the kidney parenchyma were noted, which allowed them to cope with excessive loads. The so-called adaptation occurs. With a sharp increase in protein doses (from 1.2 to 2.4 g/kg), damage to kidney tissue is observed.

In the blood there is an increase in the amount of its breakdown products, which normally should not be detected. This is also explained by the body’s adaptive abilities, but they already occur in parallel with pathological changes. A sharp increase in protein doses is dangerous for the functioning of the kidneys, whereas with a gradual increase, the filtration system adapts.

It should be noted that if a sharp increase in protein is accompanied by intense physical activity, then the negative changes in the kidneys are expressed quite insignificantly. Therefore, when combining protein intake in moderation and exercise, people with healthy kidneys are not in danger.

Whereas patients with a history of kidney disease should try to minimize the consumption of animal proteins. This will allow them to avoid relapses and keep their health under control.

Recommendations . From all of the above, it follows that consuming protein for the purpose of building muscle mass for people who play sports and do not suffer from kidney disease does not pose any danger. At the same time, others need to consult a doctor before taking protein sports nutrition and periodically undergo urine tests so as not to miss the onset of various diseases.

Among builders of their own muscles, there is a widespread opinion - “the more protein, the better” and often such people, without making calculations, consume the maximum possible amount of protein products and supplements. What do scientists say about excessive amounts of protein in the body – can it be harmful?

Protein intake rate

To begin with, we should recall the official recommendations for protein consumption. For example, the NSCA sports nutrition guide for gaining lean muscle mass recommends, in addition to a moderate excess of calories (10-15% above normal), to consume 1.3-2 g/kg body weight per day.

And during the active phase of reducing the percentage of fat, scientists even recommend increasing the rate of protein consumption - up to 1.8-2 grams / kg of body weight per day. Moreover, the lower the percentage of fat (for example, when preparing for competitions), the higher the requirements for protein consumption. If the goal is to reduce the percentage of fat to very low values, it is recommended to increase protein intake to 2.3-3.1 g of protein per 1 kg of body weight per day.

Let's now find out what happens to our body when we consume large amounts of protein.

Excess protein and kidneys

Don't ask this question if you have healthy kidneys, and control your protein intake if they are sick.

The smartest approach is to gradually increase protein intake to a higher level in the diet, rather than jumping in with both feet at the same time. Usually, With increased protein intake, it is recommended to drink more water . One of the reasons is to reduce the risk of kidney stones. However, there is no clear scientific justification

why this should be done, but perhaps it is a reasonable approach.

Another study (2) also found no association between protein intake and kidney health (in postmenopausal women).

A study involving nurses (3) confirms these findings. But it does suggest that the protein safety data does not apply to cases of kidney failure and other kidney diseases, and that non-dairy animal proteins may be more harmful to the body than other proteins.

It has been suggested that protein intake leads to functional changes in the kidneys (4). Protein may affect kidney function (5,6), therefore, when using it, there is a possibility of damage to them. The most pronounced results were obtained in experiments on mice (protein ranged from 10-15% to 35-45% of the daily diet at a time) (7,8).

Also, one study (9) of healthy people found that doubling the amount of protein consumed (from 1.2 to 2.4 g/kg body weight) led to higher than normal levels of protein metabolism in the blood. There was a tendency for the body to adapt - an increase in the glomerular filtration rate, but this was not enough to bring uric acid and blood urea levels to normal within 7 days (9).

All of these studies primarily suggest that too much protein results in too rapid a change, and the gradual process of increasing volumes does not worsen renal function (10). This means that it makes more sense to gradually change your protein intake over a relatively long period of time.

People with kidney disease are advised to use protein-restricted diets, as this will slow down the seemingly inevitable deterioration of the condition (11,12). Failure to control protein intake in patients with kidney disease accelerates (or at least does not slow down) the decline in kidney function (3).

Excess protein and liver

There is no reason to believe that normal levels of protein intake as part of a normal diet would be harmful to the liver of healthy rats or humans. However, there is preliminary research suggesting that very large amounts of protein after a sufficiently long fast (more than 48 hours) can lead to acute liver injury.

During treatment liver diseases (cirrhosis) it is recommended to reduce protein intake, since it causes the accumulation of ammonia in the blood (13,14), which makes a negative contribution to the development of hepatic encephalopathy (15).

It has been shown in at least one animal model that liver injury occurs during cycling between 5-day periods of sufficient protein intake and periods of protein deficiency (16). A similar effect was observed when consuming a meal containing 40-50% casein after a 48-hour fast.(17). Animal studies (18,19) have provided preliminary evidence that increased protein intake (35–50%) at the time of refeeding after a 48-hour fast may cause liver harm. More short periods fasting was not considered.

Amino acids are acids, right?

We remind you that proteins are complex organic compounds consisting of smaller “building blocks” - amino acids. Actually, proteins consumed in food are broken down into amino acids.

Theoretically, it is possible to prove the harm of amino acids due to their excess acidity. But this is not a clinical problem: their acidity is too low to cause any trouble.

Read how our body regulates the balance of acidity / alkalinity in the text “ “.

Excess Protein and Bone Mineral Density

Analysis of a large observational study shows no link between protein intake and the risk of bone fractures (an indicator of bone health). The exception is when, with increased dietary protein, total calcium intake falls below 400 mg/1000 kcal daily (although the hazard ratio was quite weak at 1.51 when compared with the highest quartile) (26). Other studies have failed to find a similar correlation, although this would logically be expected (27,28).

Soy protein itself appears to have an additional protective effect on bone tissue in postmenopausal women, which may be related to the isoflavone content of soy (30).

The Role of Strength Training

As funny as it may seem, there is a study on this topic in rats. The rodents were acutely exposed to large amounts of protein in their diet, causing their kidney function to deteriorate.

But “resistance training” (apparently, one of the groups of rats was “loaded” physically) reduced the negative effect in some of them and had a protective effect (8).

Research mentioned:

1. Poortmans JR, Dellalieux O Do regular high protein diets have potential health risks on kidney function in athletes. Int J Sport Nutr Exerc Metab. (2000)
2. Beasley JM, et al Higher biomarker-calibrated protein intake is not associated with impaired renal function in postmenopausal women. J Nutr. (2011)
3. Knight EL, et al The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency. Ann Intern Med. (2003)
4. Brändle E, Sieberth HG, Hautmann RE Effect of chronic dietary protein intake on the renal function in healthy subjects. Eur J Clin Nutr. (1996)
5. King AJ, Levey AS Dietary protein and renal function. J Am Soc Nephrol. (1993)
6. Dietary protein intake and renal function
7. Wakefield AP, et al A diet with 35% of energy from protein leads to kidney damage in female Sprague-Dawley rats. Br J Nutr. (2011)
8. Aparicio VA, et al Effects of high-whey-protein intake and resistance training on renal, bone and metabolic parameters in rats. Br J Nutr. (2011)
9. Frank H, et al Effect of short-term high-protein compared with normal-protein diets on renal hemodynamics and associated variables in healthy young men. Am J Clin Nutr. (2009)
10. Wiegmann TB, et al Controlled changes in chronic dietary protein intake do not change glomerular filtration rate. Am J Kidney Dis. (1990)
11. Levey AS, et al Effects of dietary protein restriction on the progression of advanced renal disease in the Modification of Diet in Renal Disease Study. Am J Kidney Dis. (1996)
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