Can protein cause kidney pain? Excess protein: how harmful it is. Experiment: A lack of protein in the diet may also result in decreased bone strength

Protein is essential for the healthy functioning of the body, but people with kidney disease are often advised to limit their intake of protein foods and are strictly prohibited from going on protein diets. Why? How significant is the effect of protein on the kidneys of a healthy person and kidneys whose function is impaired? Are protein diets really a direct path to kidney disease?

The effect of protein on the kidneys: functions, protein intake and excretion

To understand the effects of protein on the kidneys, we must first briefly review the functions of proteins and their metabolism.

Proteins are an important component of the human body as they make up enzymes, tissues and organs. It is worth noting that proteins, unlike fats, are not stored by the body - accordingly, they must be constantly supplied with food.

Protein allows the body to recover from injury, stop bleeding, and fight infections. A protein molecule is made up of chains of amino acids, which are often called the “building blocks” of a living organism. The state of health is maintained by 20 amino acids, 11 of which are synthesized by the liver, and 8 come exclusively from food, which is why they are called essential:

• valine;
• isoleucine;
• leucine;
• lysine;
• methionine;
• threonine;
• tryptophan;
• phenylalanine.

If a protein contains all 8 essential amino acids in the required proportions, it is called complete; other proteins are incomplete. The highest biological value is found in animal proteins contained in:

• meat;
• eggs;
• fish;
• caviar;
• milk.

Proteins of plant origin contain incomplete proteins, since they do not contain all essential amino acids in sufficient quantities.

Proteins, unlike fats, do not accumulate in the body.

In the body, protein is broken down into amino acids, which enter the blood and are transported to cells for the synthesis of essential proteins used for:

• tissue restoration and healing;
• hormone production;
• production of antibodies and enzymes;
• maintaining acid-base and water-electrolyte balance;
• producing a certain amount of energy.

The breakdown of amino acids produces end products: ammonia, water and carbon dioxide. In this case, ammonia, being a toxic substance, is “neutralized” in the liver, turning into urea. Urea, in turn, is excreted by the kidneys along with urine.

The effect of protein on kidneys with normal and impaired function

Where did the myth that high-protein diets cause kidney disease come from? Indeed, high protein diets are contraindicated in patients with chronic kidney disease, but consuming protein foods in small to moderate quantities may improve the patient's condition.

Some believe that protein metabolites, which are excreted from the body in urine, place additional stress on the kidneys, resulting in diseases of the body's natural filters. However, the kidneys, like any other organ, work every day under the conditions for which they were created, namely, they filter about 180 liters of blood daily.

Healthy kidneys do an excellent job of removing protein breakdown products from the body.

Indeed, by increasing the amount of protein consumed, you force the kidneys to work a little more intensely, but this additional load is insignificant for them. Research shows that people whose kidneys function normally benefit from high-protein diets. The same applies to bodybuilders, who not only consume protein foods in large quantities, but also take various supplements for muscle growth. Moreover, consuming protein in large (but still reasonable) amounts helps lower blood pressure and improves the condition of diabetics.

Why are high-protein diets contraindicated for people with kidney disease?

Now you know that the main organ that removes the end products of protein breakdown is the kidneys. When they are affected by the disease, the glomeruli - the glomeruli of blood vessels that filter all the blood passing through them - begin to cope with their task worse. Therefore, in order not to overload already weakened kidneys, people with diseases of these organs are advised not to abuse protein foods. In addition, if the kidneys do not promptly remove toxic substances from the body, their accumulation can lead to problems with other organs and systems.

If you have kidney disease, you should not overuse protein foods.

It is important to understand that the amount of protein that can and should be consumed for kidney disease is determined based on the specific case. After conducting the necessary tests, the doctor will determine how much kidney function is reduced and recommend an adequate daily intake of protein and other products necessary for the normal operation of your small filters.

Thus, I would like to emphasize the site once again: the effect of protein on the kidneys depends on their condition. A healthy person, as studies show, should not worry about kidney damage due to a protein diet. However, patients with kidney diseases must definitely plan their diet with their doctor!

Protein is one of the main components of nutrition, which performs important functions for the human body. However, some doctors argue that for people with chronic kidney disease, protein may cause more harm than good because it has the ability to overload the organ, which can lead to complications and other kidney diseases.

Protein: finding a balance of benefits and harms

Positive properties

It is recommended to consume about 0.6-0.8 g of protein per 1 kg of human weight per day. But for renal pathologies in the acute stage or in an acute form, this indicator should be minimal, that is, recommended by the doctor. For example, for chronic deficiency - 20-50 g per day.

Protein is the main component of the human body:

• is part of tissues and organs, affects the development and growth of the body;
• contains a chain of 20 essential amino acids, 11 of which are produced by the liver, and 8 come from food.

During the process of assimilation, proteins are broken down into these amino acids, which enter different parts of our body through the blood, performing a transport function. In this way, vitamins, minerals and other beneficial substances are distributed throughout the body through the blood to all cells. The body uses it to heal wounds, produce antibodies and hormones, and maintain acid and water balance. Apart from these functions, protein is also a major source of energy.

Negative effects if abused

In addition to its beneficial effects, protein can also harm human health. Once in the body, protein is converted into energy. If this energy is not fully utilized, it is transformed into fat deposits, which in turn can harm the functioning of healthy organs, especially the kidneys and cardiovascular system. On the other hand, proteins are converted into ammonia, carbon dioxide and water during the actuation process. It is ammonia, entering the liver with blood, that forms uric acid, which poisons and dehydrates the liver. These metabolites are excreted through the kidneys in the urine, which is why renal function is impaired when consumption standards are exceeded.

The degree of effect of protein foods on kidney function

When the kidneys are healthy, eating protein foods will not affect the condition and functioning of the organ. On the contrary, a moderate amount of this component will only improve your health. But excessive protein consumption overloads the paired organ, as a result of which their filtration function is impaired. This statement is true for people with chronic diseases of the urinary system. For a healthy person, such a load is normal, if it is not part of the regime.

When a person has diseased kidneys, it is not recommended to abuse protein foods; it is strictly forbidden to use protein diets for weight loss. With excessive protein consumption, the filtration function of the kidneys works worse, toxic substances accumulate in the organ, and other organs are damaged. Loading the kidneys with protein is fraught with the formation of uric acid due to the accumulation of uric acid. And urolithiasis is fraught not only with constant renal colic, but also with severe inflammation.

The question of the dangers of consuming protein as a supplement is controversial. People with kidney disease or kidney failure are not recommended to take protein supplements. Excessive consumption leads to the accumulation of toxins in the blood and overload of the paired organ, and with insufficient physical activity, it also leads to obesity.

Professional bodybuilders consume 300-500 grams of protein per day for many months and even years. Does it harm their kidneys? Many publications often mention that high doses of protein are extremely dangerous for the kidneys. However, studies in animals kept on a high-protein diet for more than half their lives have shown no renal impairment. (Zaragoza R et al. Rats fed prolonged high protein diets show an increase in nitrogen metabolism and liver megamitochondria. Arch Biochem Biophys, 1987; 258:426-435.)

The most common problem with consuming large amounts of protein is dehydration. This is due to the fact that protein metabolism requires water, and if this is not replenished in sufficient quantities, problems may arise with both the kidneys and other organs. You should drink up to 8-10 glasses of liquid (1.5-2 l) per day.

In another study, 20 healthy, trained young men took high doses of protein (2.9 g/kg) for 28 days. Subsequently, numerous analyzes showed that high protein intake did not have any noticeable negative impact on health. (Kalman D et al. The effects of a high protein intake on markers of health in weight trained athletes. FASEB J 2000.)

It cannot be said that high protein intake over a longer period of time is also safe. However, it is clear that rumors about the harmful effects of protein on the kidneys are clearly exaggerated.

Beer and kidneys

Many people are interested in the question: is beer harmful to the kidneys? Opinions on this matter are quite varied. Beer increases the load on the organ when consumed. But some believe that the drink is not harmful because it has a low alcohol concentration. What negative effects does drinking beer have on a person or, conversely, can the drink be consumed in unlimited quantities?

Despite all the harmlessness of moderate beer consumption, this drink can deplete the kidneys of protein.

In addition to stimulating the elimination of harmful substances, beer drinks equally rid the body of beneficial ones.

Kidney disease from beer

• The dehydrating effect of beer leads to kidney dystrophy. They hurt, because the increased excretion of organic water, in an attempt to cleanse itself, provokes cell death and deformation of the organ. The process occurs because ethanol disrupts cellular structures when it enters the filtration channels.

The harmfulness of the habit of drinking beer can also be judged because its effect affects not only the kidneys. Patients are often diagnosed with alcoholic disease - a pathological condition of internal organs (liver, kidneys, pancreas, heart and others), which is formed under the influence of ethyl alcohol. First of all, beer harms the liver, because it directly takes part in filtering the blood. It is also useful to know that the disease is diagnosed not only in alcoholics, but also in people who tend to drink alcohol moderately.

Features of treatment and recovery

Many people may complain that their kidneys hurt. But treating symptoms alone for any disease would be extremely ineffective. What is the best thing to do then? Treatment depends directly on how much damage is caused. So you just need to contact a specialist. Only a doctor can examine and indicate the correct diagnosis. It is necessary to remember the dangers of alcohol and stop drinking drinks containing alcohol. Follow the diet prescribed by your doctor. If the kidneys are unable to cleanse the body, then hemodialysis and blood dialysis (artificial cleansing) are performed.

Products containing protein: lists, diets, benefits and harms

Protein is the most important building element for body cells.

It is known that it is involved in many human life processes, but its entire role has not been fully revealed.

Protein and its importance for the human body

A description of the number of functions of a protein could fit in a book with a hundred pages.

The following main purposes of this element for the human body are distinguished:

1. Construction.
2. Hormonal (many hormones are proteins or their compounds).
3. Transport (serves as a supplier of nutrients between other cells of the body).
4. Protective (for example, the protein fibrinogen thickens the blood, thereby preventing its loss).
5. Nutritional (casein and albumin are sources of nutrients for the intrauterine development of the fetus).
6. Stabilizing (maintains normal pressure levels in cells).
7. Contractile (serve as the main elements for the relaxing and contracting functions of muscles).

Proteins are delivered to the body along with food.

There are plant and animal sources of their intake.

It is not even the protein itself that is important, but the 22 amino acids that are synthesized during the breakdown of protein. It is believed that the body is able to obtain 13 of them on its own, but 9 amino acids must come from food.

How to calculate the daily protein intake for your diet

When a person consumes foods such as meat, milk, cheese, peas, the digestive system first breaks down food proteins into amino acids. They enter the blood, combine with enzymes and form proteins that serve the body. For example, to build muscles.

Nutritionists are not unanimous in their opinion about the daily intake of protein foods. The thing is that in the digestive tract some types of protein are not broken down due to the lack of appropriate enzymes.

Therefore, different protein products are absorbed differently. So, eggs are almost 95-100% broken down in the body, and peas are only 50-60%.

The first person to calculate the daily protein intake was Max Rubner. The scientist also introduced the concept of anabolism (the creation of new substances) and catabolism (the breakdown of substances). Calculated the wear rate (how much protein is lost by tissues per day).

A hundred years ago, he conducted research and found out that 0.3 grams of protein per 1 kg of body weight are needed per day. Translated into products, this is approximately a liter of milk for a person weighing 70 kg.

The research was carried out a long time ago, so it has lost its relevance.

In the modern world, other protein consumption standards have been developed:

8. for middle-aged people, the recommended daily intake is 1.5 grams per kilogram of weight;
9. for infants during a period of rapid growth, the norm is 2.2 grams per 1 kg;
10. for children aged 7-10 years, the daily norm is about 36 grams in total;
11. Pregnant women should receive an additional 30 grams of protein above the average for an adult. For example, if the expectant mother weighs 70 kg, then in addition to the norm of 105 grams, you need to add 30 grams of protein.

All these rules are valid under certain conditions:

12. additionally carbohydrates and fats must be supplied to the body;
13. the quality of the protein must be high, and its amino acid composition must be complete;
14. the ratio of animal and plant proteins must be maintained. The latter should be at least 30% of the total and no more than 35%.

So, an adult weighing 65 kg should consume about 98 grams of protein per day, provided that all the points above are met. At the same time, vegetable proteins should be about 29 grams of the total amount.

For athletes, norms are calculated individually and, as a rule, they are slightly higher than usual.

How does a lack of protein affect the body?

To determine protein deficiency in the body, a person just needs to look at himself in the mirror. Pay attention to your well-being.

If the following changes are observed, then it’s time to sound the alarm:

15. Loose skin, sagging muscles on the body (if the person is under 30).
16. There are wrinkles on the face and an uneven oval of the face.
17. Skin, nails, and hair are made of protein. Therefore, with a deficiency of this substance, their condition leaves much to be desired.
18. Obesity and muscle loss.
19. Decreased immunity.
20. Digestive problems: constipation, flatulence, etc.
21. Low resistance to stress.
22. Fast fatiguability.

If most of the points fit the description of a person’s appearance and behavior, then he urgently needs to change his eating habits.

The cause of protein deficiency can be not only its insufficient intake from food, but also somatic diseases (colds and flu).

When taking a blood test, a reduced content of hemoglobin and immunoglobulin is observed.

A balanced diet based on the consumption of both animal and plant sources of protein, supplemented with fats and carbohydrates, will help compensate for the lack of protein.

About the importance of proteins in the diet in the video.

Plant foods containing protein and their benefits

Animal products containing protein were mentioned above: meat, cheese, milk, fish. It is considered to be a quality source of protein.

Plant products contain protein, which does not contain all amino acids, but you must include two types of food in your diet. Especially when it comes to athletes or people on a diet.

Positive qualities of protein-containing products of plant origin:

23. no fat. This means that the dishes will be easily digestible and are perfect for losing excess weight;
24. Vitamins, minerals, and amino acids enter the body along with proteins;
25. controls the feeling of hunger due to long and partial digestibility;
26. fiber content, which is good for the digestive tract.

Protein is actually found in many plant foods. In the table we consider only those with the most protein.

The second column will show the amount of protein as a percentage per 100 g of product weight.

Harm and positive properties of soy protein

Many bodybuilders use soy protein to build muscle mass. But this product does not always live up to expectations, and sometimes it can cause harm.

Soy protein is a plant protein product, the harm and benefits of which are often discussed among both amateur and professional athletes. Soy contains a high level of complete protein, including essential amino acids that the body cannot produce on its own. Of all plant proteins, soy is the closest to similar animal products.

Soy protein is often used by people who want to achieve certain athletic performance and experience increased physical stress on their muscles. Soy itself causes a lot of controversy and discussion regarding the benefits and harm to the human body. Having understood all the arguments, you can understand that moderation in its use is necessary.

Let's talk about harm

Not everything is as good and useful as it is often presented. There is a whole set of significant disadvantages that soy protein has. They do not allow it to be used as a good source of amino acids for building useful muscle mass.

The negative aspects that are characteristic of soy protein include the low bioavailability and low efficiency of this product.

In other words, not all soy protein is absorbed by the body. Soy contains substances that inhibit (slow down) the action of internal enzymes that effectively break down protein molecules in the stomach and intestines. The presence of a special substance in soy protein that slows down the work of the enzyme trypsin, which breaks down protein molecules, leads to the fact that soy amino acids flow from the intestines into the blood slowly.

Therefore, when taking soy, the absorption of any proteins that come with food slows down.

Low degree and slow rate of absorption are the main disadvantages of soy protein. This problem can be successfully solved by industrial purification of the soy product. Manufacturers also enrich it with methionine and increase its value.

It is unwise to take such a product immediately after finishing a workout, to close the so-called protein window. But during a period of dietary fasting, it is ideal. The slow rate of breakdown and absorption allows the body to be supplied with amino acids for a long time. You don’t have to spend significant effort or large sums on this.

Another disadvantage of soy protein is its low biological activity.

Soy contains phytoestrogens - substances of plant origin, similar in structure to female sex hormones and having a similar effect. The harm from regular intake of food, which contains estrogens of plant origin, may include hormonal imbalance. Most often it manifests itself:

27. an increase in body fat reserves;
28. decreased testosterone levels in the blood;
29. decreased potency;
30. the appearance of neoplasms;
31. development of diseases of the cardiovascular system.

We must not forget that all soybeans from which sports nutrition is made are genetically modified. And this is a separate topic about the dangers of a popular product.

Let's talk about the benefits

Despite some harm, soy-based sports nutrition is successfully used and promoted throughout the world. The first thing that serves as an argument in favor of soy protein is its cost. The price of the product is significantly lower than other protein supplements.

There is no doubt that soy-based protein is beneficial for vegetarians and people with individual intolerance to animal protein. There are other positive aspects as well. Lecithin, which is contained in soy, helps in the restoration and renewal of brain cells, inhibits the aging process throughout the body.

The presence of phytoestrogens is not only harmful. Under the influence of these biologically active substances, cholesterol levels are reduced and the risk of blood clots is reduced. Some studies refute the negative effects of plant estrogens on the male body. To be absorbed into the body, phytoestrogens must be released under the influence of enzymes in the intestines. Less than half of the incoming plant estrogens are absorbed, so the harm to the male body is minimized.

There is evidence of the positive effect of soy on the thyroid gland.

Increasing the level of thyroid hormones promotes fat burning. And this is an undoubted benefit for those who are struggling with excess weight in the form of fat reserves.

The effect on the kidneys of soy protein is not as aggressive as that of animal proteins. This should be taken into account by people who have a predisposition to pathologies of the urinary system.

Female athletes often report feeling better after taking soy protein. For vegetarians who are involved in fitness or bodybuilding, it can be very useful. A slight increase in estrogen levels is not harmful. In addition, women, as a rule, do not strive to build large muscle mass. Men can be recommended to use soy protein not as the main source of protein, but as an additional one along with whey, meat or egg protein mixtures.

The benefits or harms of soy protein should always be assessed individually.

It must be remembered that fanaticism when taking only soy protein plays a negative role. It is recommended mainly for use by vegetarian athletes and women immediately after physical activity. Due to its slow and incomplete absorption, soy protein can supply the body with essential amino acids for a long time, but does not contribute well to gaining muscle mass.

In this case, it is better to consume proteins of animal and plant origin simultaneously. Moreover, nutritionists recommend a rational ratio of whey and soy protein as 2:1. Mixed protein increases the nutritional value of the product and reduces the risk of developing kidney pathologies.

Is beer good or bad?

32. Drinking beer is not dangerous - it has a lower percentage of alcohol. But it contains ethyl alcohol. And the kidneys, trying to get rid of alcohol toxins, work more actively. Drinking beer triples the load on the kidneys, accelerating the deterioration of organs. In addition, even if you drink drinks with a small percentage of alcohol, but constantly, alcoholism still occurs over time. The body gets used to the regular presence of alcohol in the blood. It is worth recalling that kidney disease also affects appearance - the face swells. This is one of the reasons why experts regard beer as a more dangerous drink than vodka or cognac. But you shouldn’t console yourself with the thought that strong alcohol is harmless.
33. It is useful to drink an intoxicating drink because it helps remove harmful substances from the body. But not only those who cause harm come out, but also those whose influence is undoubtedly useful. Organic water is removed (its benefit is that it helps dissolve organic substances), various elements, vitamins, potassium salts (their deficiency manifests itself in tachycardia, cramps, and calf muscles ache) and sodium (lack of it leads to worsening mood, sleep disturbances) , ascorbic acid (this is a natural antioxidant, its benefit is that it optimizes immunity against colds), phosphates (necessary in the construction of various tissue structures).

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What other negative effect does the drink have on the kidneys? Above we have listed many diseases that can arise from drinking beer. But the list doesn't end there. If you drink beer immoderately, it creates the following dangerous diseases:

34. Urolithiasis. Alcohol, clogging the body with poisons and toxins, accompanies the creation of kidney stones.

Dehydration, clogging of blood vessels, removal of useful substances - this is the result of beer addiction.

35. Nephritis. A decrease in the concentration of nutrients and dysfunction of filtration “paves the way” for infectious diseases.

Proteins in the human diet. The benefits and harms of proteins

Proteins play an integral role in the human diet. The human body is approximately 20% protein. To maintain your body in a healthy state, you must follow an optimal diet, which includes all vitamins, macro- and microelements in the right quantities. People who adhere to a vegetarian diet should be especially careful. For the most part, human muscles consist of protein, but its lack will also affect insensitive tissues, such as nails, hair, and teeth.

The human body needs large amounts of protein. This micronutrient is involved in the formation of tissues, the construction of cells, the transport of substances through the blood; the function of some proteins is to change the shape of cells. While other nutrients are used daily for energy, protein can be stored in the body for a long time. Let's take a closer look.

If the amount of protein consumed exceeds the norm, it is stored as fat. Excess carbohydrates are also transformed into fat deposits. Protein can be used as a source of energy. With intense exercise, muscle growth occurs due to protein. Proteins contained in the blood perform a protective function. When damaged, they promote blood clotting. If protein is not supplied in the required quantity, the body uses the one it already contains, which can cause hair to fall out, teeth to deteriorate, and nails to break.

Protein sources

Animal proteins:

Meat products. Traditionally the main source of protein. Fish. Possible in the diet of a pescetarian - a non-strict vegetarian. Eggs. Modern boiler eggs are of course different from home eggs, but this does not in any way affect the quality of the protein in them. Dairy products. Various nutritional supplements. Plant proteins:

Soybeans and other legumes. Richest in vegetable proteins. Nuts. Porridge. Seeds Some vegetables. Animal protein is necessary and healthy, but it's important to choose the right source. Fatty meat, such as pork, will do more harm than good. The optimal source of protein is fish. In addition, fish is a product often used in diets. In addition to protein, it contains valuable elements and all this with a fairly low calorie content of the product.

Most of plant proteins are incomplete; they do not contain all the necessary amino acids. For example, the amino acid tryptophan, from which the joy hormone serotonin is synthesized, is present only in animal products. If, for ideological reasons, you cannot consume animal products, you should include various plant sources of protein in your diet to compensate for the deficiency. The digestibility of proteins also varies. In first place according to this criterion are eggs and milk, then meat and fish, and the least digestible legume proteins.

Daily requirement

How much protein should you eat per day? It depends on body weight and lifestyle. There are 1.3-1.5 grams of protein per kilogram of weight. With intense physical activity, this amount increases. Also, active intellectual work requires more fuel; with an increased thought process, the body spends a lot of calories, although this is not obvious, therefore the protein norm for people in intellectual professions should be higher. Pregnant and lactating women need a higher dose of protein because... They share all the nutrients between the two of them with the child. On a diet, it is recommended to consume 2-3 grams of protein per kg of weight. A protein diet is built on this principle. And of course, athletes who want to increase body weight should supply this topic with a lot of building material.

In chicken breast there are 30 grams of protein per 100 grams of product, in fish - about 21 grams, in a boiled egg - 7. In one hundred grams of beef - 29. One glass of low-fat milk contains 7 grams, low-fat cottage cheese - 16.5. It turns out that consuming the required amount is not so difficult.

Excess protein. The benefits and harms of proteins

Everything useful is good in moderation. Despite all the positive properties of protein, it is not recommended to abuse it. It is generally accepted that such a diet leads to osteoporosis, kidney disease, digestive disorders, and diseases of the cardiovascular system. Let's analyze how fair this conclusion is.

Osteoporosis. This disease is characterized by decreased bone density. Excess protein leads to acidification of the blood. To cleanse the blood, the body uses calcium, as a result of which the supply of calcium is reduced and bones become brittle. However, it has been proven that athletes have very strong bones and exercise helps maintain bone density. So bodybuilders who consume more than 3 grams of protein per kilogram of body weight do not have to worry about the possibility of osteoporosis.

Kidney problems. Research confirms that eating too much protein has a negative effect on the kidneys. But these studies were conducted on people who already had kidney disease, so they cannot be reliable. The kidneys are involved in protein processing, but there is no reason to believe that this will have a bad effect on them if the person is healthy to begin with.

Digestion. Heartburn, disturbance of intestinal microflora, constipation, diarrhea - all this is wildly unpleasant. However, protein can only harm your digestive process if you don't have enough fiber in your body. You should eat more vegetables and fruits containing fiber, and this problem will not affect you. Also avoid consuming sodium, starch, artificial sweeteners, and drink more water. The digestive process can be harmed by excess salt and too high/low food temperature.

Cardiovascular system The heart is an irreplaceable organ; it carries out vital functions. There is an opinion that with increased consumption of protein foods, heart disease may occur. The problem is that people often choose the wrong source of protein by eating foods with saturated fat. Fats clog the body, cholesterol increases, and as a result, fats stick to the walls of blood vessels, which leads to diseases. If you choose the right diet, with a good ratio of saturated fat and protein, you don't have to worry about the consequences.

We can conclude that a large amount of protein does not harm a healthy body. But for some diseases, consumption should be limited. In case of acute nephritis, renal and liver failure, gout, protein reduction can be narrowed to its complete exclusion from the diet.

Protein is an amazing component that performs a number of different functions that enable our body to function. If you are a healthy person and regularly exercise, then you will not face any illnesses from excess protein. It is important to remember to eat protein-containing foods every day to replenish your strength and health.

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 diseased. 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 basis yet for why this should be done, but it may be a reasonable approach.

Observations of active male athletes and measurements of the levels of urea, creatinine and albumin in urine showed that in the range of protein intake from 1.28 to 2.8 g/kg body weight (that is, at the level of the recommendations described above), no no significant changes were observed (1). However, this experiment lasted only 7 days.

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 these studies primarily suggest that too much protein leads to too rapid changes, and the process of gradually 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. Shorter periods of fasting were 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 / alkaline content 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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