The benefits and harms of protein for the body. Proteins: harm and benefit. Casein protein: benefits and harms
Sooner or later, many people involved in strength sports think about the need to take additional food supplements. On television, in magazines, and newspapers, debates about the dangers and benefits of sports nutrition do not stop. That anabolic steroids negatively affect the human body, probably everyone already knows. Is protein harmful or not? Is it really so necessary for athletes and will its use lead to health problems in the future? Let's try to figure it out.
What is protein
The English word protein is translated into Russian as “protein”. And protein is a necessary component of a healthy human diet, since it is involved in all life processes: 
- responsible for building bone and muscle tissues of the body;
- protects against bacteria and viruses;
- is a source of energy;
- regulates metabolism in the body;
- transports oxygen in the circulatory system;
- keeps skin, nails and hair in good condition.
In sports nutrition, protein is a powder with a high protein content. It is easily absorbed by the body and contains all the essential amino acids.
Protein powder is made from natural extracts of products containing protein of animal or plant origin:
- dairy products;
- meat;
- peas
The raw materials go through several stages of purification and drying, resulting in a completely natural protein concentrate, which is used in sports nutrition as an additional source of energy and material for the construction and regeneration of muscles.
How does protein affect your health?
According to doctors, consuming good quality protein powder in a reasonable dose does not have any negative effects on health. On the contrary, many scientific works have proven the beneficial effects of protein on the human body.
Protein is useful for both men who want to gain muscle mass and women who want to lose weight., get rid of skin problems and have strong healthy hair and nails.
All parents know the important role protein plays for a child’s growing body, so the question may arise: is protein ok for children? Experts agree that protein powder in an age-appropriate dosage affects the child’s body (from 3 years old) only in a positive way. Therefore, if it is difficult for a child to feed meat or cottage cheese, but he will be happy to drink a protein shake in an age-appropriate dose, there will be no harm in it.
Lack of protein in the human body leads to:
- sleep disturbance;
- depression and irritability;
- decreased immunity;
- frequent bowel movements;
- weight gain;
- slow wound healing;
- dry skin;
- brittle hair and nails;
- development of various diseases.
Poor nutrition and diseases of the gastrointestinal tract lead to symptoms of protein deficiency in the body, and it is simply unrealistic for people with increased physical activity and athletes to achieve daily protein intake from food. This is why consuming protein powder is essential.
It is important to understand that protein is an extract from products, and any product has properties, contraindications and daily intake. In accordance with this, the benefits of protein or the harm that can be caused to the body are determined.
Daily protein intake
The daily requirement for protein is individual and depends on the age, gender and physical activity of the person. In accordance with the recommendations of the World Health Organization The normal protein intake is considered to be 0.8 – 1 g/kg body weight. This is the average figure for an adult with moderate physical activity. For children under 18 years of age and pregnant women, the protein norm is 2 g/kg per day.
People engaged in heavy physical labor and athletes should take 2.5 g of pure protein, for girls and women whose task is to lose weight and maintain good physical shape - 1.5 g/kg body weight.
Exceeding the daily protein intake to 3 g/kg leads to side effects: digestive disorders and kidney diseases.
If it is almost impossible to exceed the protein norm with regular food, then it is easy when consuming protein powder. This is why it is very important to follow the exact dosage when preparing a protein shake and not exceed the recommended doses indicated on the can of protein powder.
Types of Protein Powder
Before you buy protein in a sports nutrition store, it is very important to figure out which powder is right for you. For this it is necessary to know the individual characteristics of the body(intolerance, allergies, chronic diseases) and take into account the purpose of use:
- gaining muscle mass;
- weight loss;
- recovery after strength training;
- maintaining general health;
- replenishment of the missing amount of protein from food (vegetarians, people with abdominal diseases).
To ensure that protein powder does not cause harm to the body, it is recommended that when choosing it, you should follow the advice of a trainer and your doctor, who will prescribe the type of protein that meets your needs in the necessary and sufficient dosage.
Animal based powders
Protein powder based on animal products is most popular among athletes: 
- Egg protein is an excellent source of protein, the standard among protein powders, containing all the essential amino acids. Has the highest amino acid digestibility coefficient - 1.00. It is egg white that is chosen by bodybuilders seeking to gain muscle mass. With its help, muscle fibers grow faster than with any other type of protein. Recent scientific studies have shown that eating egg whites strengthens the heart and blood vessels and helps increase good cholesterol levels. There is only one contraindication to taking egg whites – an allergic reaction to chicken eggs.
- Milk protein is another type of highly digestible protein powder with a full range of amino acids. Dairy proteins promote weight loss, lower blood pressure and restore muscle fibers after exhausting workouts. The main disadvantage is the lactose content, so milk protein is harmful for people who have lactose intolerance, which results in disruption of the gastrointestinal tract. Milk protein consists of two types of proteins: casein (“slow”) and whey (“fast”) proteins, which can be purchased separately.
- Casein protein is a protein found in cottage cheese. It is absorbed very slowly (up to 7 hours), thanks to which the muscles are fed with amino acids for a long time. It suppresses hunger for a long time, so casein is useful for weight loss.
- Whey protein is preferable to milk protein when building muscle mass. Absorbed by the body completely and in a short time (within 30-50 minutes).
- Beef protein is a rarity in sports nutrition stores and has a high price, so it is significantly inferior in popularity to egg and milk proteins, but its advantage is considered to be its creatine content, good tolerability (an option for athletes with allergies to lactose or chicken egg whites) and rapid digestibility .
Animal-based protein powders are completely natural, contain all essential amino acids, and are easily digestible. They are completely safe for women, men and even children. Only people with individual intolerance to animal proteins and with an increase in the recommended dose can cause harm.
Plant Based Protein Powders
Plant-based protein powders are vegetarian protein options, but they are completely complete and are good for overall health. In addition to amino acids, they contain fiber and polyunsaturated fatty acids.
There are proteins based on hemp, flaxseed, brown rice, and peas. These types of protein powders are rarely found on sale; most often they are included in a mixture with other proteins.
The most common type of plant-based protein powder is soy protein.. In terms of protein content, quality and digestibility, it is closest to animal protein powder (digestibility coefficient 0.95). It is able to quickly restore muscles after physical training and promotes their rapid growth.
But there is an opinion that soy protein is dangerous for men because it contains phytoestrogens, which are similar in action to female sex hormones. Is protein harmful to men's health? Let's look further.
Effect of soy protein on the body
Some side effects may indeed occur with long-term consumption of soy protein by men. Most often this is an allergic reaction to soy, less often – digestive disorders due to gluten intolerance.
Numerous studies have proven that phytoestrogens do not have a harmful effect on men's health and do not reduce potency if the recommended dose is not exceeded. With excessive consumption, it is possible to reduce the production of the lipase hormone responsible for the breakdown of fat, which will lead to a gain of fat mass rather than muscle mass.
For women (especially during menopause), soy protein is most preferable, since its consumption normalizes hormonal levels and prevents the development of breast cancer.
When choosing a soy protein product, you need to pay attention to the manufacturer and price, since you can purchase low-quality protein from genetically modified soybeans, which will cause more harm to health than benefit.
Negative effects of using protein powders
Protein powder has been proven to have a positive effect on the body. Protein is harmful to human health only when:
- individual protein intolerance;
- incorrectly selected sports diet(replacing main meals with protein shakes);
- non-compliance with dosage.
The following symptoms indicate obvious protein intolerance:
- protein rash, skin itching;
- redness of the sclera of the eyes, lacrimation;
- discomfort in the gastrointestinal tract;
- intoxication of the body (nausea, vomiting, increased body temperature).
How else can protein be harmful? It is quite rare to find good quality pure protein powder in sports nutrition stores. Basically, protein mixtures are fortified with various additives in order to increase the nutritional value and improve the taste of the protein.
Side effects from their use largely depend on the content of these additional substances. When purchasing a protein mixture, it is important to carefully study the qualitative and quantitative composition.
What ingredients in protein mixtures should you be wary of?
- Taurine is an amino acid added to all energy drinks. In small doses, it has a positive effect on health, but excess taurine makes the body work harder and increases the risk of diseases of the nervous and cardiovascular systems.
- Synthetic sweeteners (Sweeteners). Not absorbed by the body and cause irreparable harm to health in some diseases: for renal failure (cyclamate), phenylketonuria (aspartame), heart and vascular diseases (aspartic acid). Consumption of sweeteners in large doses has an extremely negative impact on health, especially in children and adolescents.
- Thickeners (Gum Blend): xanthan gum, carrageenan. They provide optimal consistency when preparing a protein shake, but regular use of these additives, according to the latest scientific data, can lead to stomach ulcers and cancer of the digestive tract.
- Synthetic sugars: dextrose and maltodextrin are important components of sports nutrition that affect the rate of recovery after physical activity, but excessive consumption of sugars increases the likelihood of developing diabetes, obesity, and heart disease. Often, high doses of dextrose cause digestive problems.
When adding various components to protein mixtures, manufacturers are not always guided only by the benefits they bring to the body and improvement of taste. More often this is done in order to reduce the cost of the product, because protein concentrate (60 - 85% protein) or hydrolyzed isolate (consists of 90% protein) will cost much more than a mixture for preparing a cocktail with nutritional supplements.
Protein bars
Another source of protein, in addition to high-protein mixtures, are protein bars. Their protein content should be higher than fat and carbohydrates. Unfortunately, many manufacturers, under the guise of protein bars, produce products containing a variety of ingredients.
Therefore, if the purpose of consuming a bar is to additionally obtain a high dose of protein, then you need to read the label very carefully about the composition and calorie content of the product. A high-quality protein bar, like protein powder, will only bring benefits, while a cheap fake will be harmful to your health and cause excess weight.
What to pay attention to when purchasing and consuming protein
It has been proven that taking high-quality protein in the appropriate dosage does not harm human health. But it is worth paying attention to the following points: 
- The consumption of high-protein foods should only be prescribed by a doctor or sports coach..
- You need to purchase protein powder or mixture only from well-known and trusted manufacturers.
- You cannot replace main meals with proteins and get part of the protein from meat and fish products, legumes and cereals, and nuts.
- With constant intake of high-protein mixtures throughout the year, an imbalance of hormones and electrolyte imbalance may occur in the body.
- With continuous consumption of protein mixtures for 5 years, irreversible degenerative processes begin in the liver tissues, and various diseases of the internal organs develop.
That is why it is necessary to take protein in courses under the strict supervision of a doctor. Uncontrolled long-term use is fraught with serious complications and health problems.
Protein is a healthy, completely natural biological food supplement, the correct use of which in sports and dietary nutrition does not harm the body, but helps to achieve your goals and improve health. Side effects occur only when consuming low-quality protein mixtures, in high doses or in case of individual intolerance.
consists of excessive load on the digestive organs and filtering of toxins, with excessive protein consumption. Protein can only cause harm if you eat more than 3 grams of protein per kilogram of your own weight, but this, naturally, is in a situation where you have a healthy liver and kidneys. You can minimize the risk of harm to an internal organ by passing a basic nitrogen balance test, which we recommend that all progressive athletes do. The point is that the nitrogen balance will help you find out your individual protein needs, so you can adjust your daily diet based on your individual needs. We have already said more than once that bodybuilding is a very individual sport in which there are no universal methods, so you need to try to adjust your training and nutrition to suit yourself.
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The harm of protein also lies in the excess amount of calcium, which in moderate quantities strengthens bone structures, and in excess amounts forms kidney stones. By the way, kidney stones are one of the main arguments of vegetarians. Of course, it is worth noting that plant foods also contain protein and calcium, so the argument is very unfounded, as is the whole idea of vegetarianism in general, in the sense of vegetarianism for the sake of health. You can be 100% sure that meat and animal products only bring benefits to the body, but only in moderation. What will happen if a person overeats protein? Boris Tsatsouline, author of the CMT blog, tried to figure this out.
Conclusion: The harm of protein, first of all, lies in the fact that stones form in the kidneys, including from excess calcium, but the formation of such side effects occurs only when a person significantly exceeds the recommended protein intake and, if he already has some then kidney disease. Unfortunately, many people overeat protein, especially in the first period of training, which is why we recommended in one of our articles to get tested for nitrogen balance. On the other hand, the situation when an athlete is malnourished with protein is even more deplorable, since the need for protein is increased, and he eats less protein than normal, then not only the muscles do not grow, but the proteins that make up the internal organs do not have time to renew themselves.
For vegetarians, vegans, and those who avoid or are allergic to dairy, soy protein often serves as the primary source of this important nutrient.
However, soy is a somewhat controversial product.
While some think of soy as a nutritious food, others consider it a health enemy.
In this article, we'll look at the science behind whether soy protein is good for your body or whether it can harm you.
Soy protein - benefits or harm for the body of women and men
Nutritional value and composition
Soy protein isolate is made from defatted soy flakes that have been washed with either alcohol or water to remove sugars and. They are then dehydrated and turned into powder.
This product is very low in fat and contains no cholesterol.
Soy protein powder is used to make soy formula for infants and to produce a variety of meat and milk alternative products.
28 grams of soy protein isolate contains (% of recommended daily intake) ():
- Calorie content: 95 kcal (5%).
- Carbohydrates: 2.1 g (1%).
- Fat: 0.9 g (1%).
- Fiber: 1.6 g (6%).
- Protein: 22.6 g (45%).
- Folate: 49.3 mcg (12%).
- Choline: 53.5 mg.
- Calcium: 49.8 mg (5%).
- Iron: 4.1 mg (23%).
- Phosphorus: 217 mg (22%).
- Sodium: 281 mg (12%).
- Zinc: 1.1 mg (8%).
- Copper: 0.4 mg (22%).
- Manganese: 0.4 mg (21%).
- Omega-3 fatty acids: 54.6 mg.
- Omega-6 fatty acids: 407 mg.
While soy protein isolate powder is a concentrated source of protein, it also contains phytates, which can reduce mineral absorption.
Summary:
Soy protein is a good source of plant protein and contains many different important nutrients. However, they also contain phytates, which reduce the absorption of minerals.
Helps build muscle
Unlike most other plant proteins, soy protein is a complete protein.
This means that it contains all the essential amino acids that the body cannot produce and must be obtained from food.
Although every amino acid plays a role in muscle protein synthesis, branched chain amino acids (BCAAs) are the most important when it comes to building muscle (,).
One study found that people who drank 5.6 grams of BCAAs after a resistance workout had a 22% increase in muscle protein synthesis, compared to people who received a placebo ().
Specifically, the BCAA leucine promotes muscle protein synthesis and helps build muscle (,).
Likewise, a review study found that whey protein supported muscle protein synthesis better than soy protein in young and older adults ().
Interestingly, soy may benefit you best when combined with other proteins.
Some research suggests that combining milk and soy proteins may result in greater muscle protein synthesis than whey, casein, or soy proteins alone ().
Summary:
Although soy protein contains the BCAA leucine and does increase muscle protein synthesis to some extent, it appears to be inferior to whey protein in terms of muscle building.
May help you lose weight
Research shows that high-protein diets can lead to weight loss, even without restricting the amount of calories or nutrients you consume (, ,).
However, evidence is mixed regarding the relationship between soy protein and weight loss.
Some studies show that soy protein may increase weight loss as effectively as animal proteins.
In one study, 20 obese men ate both a high soy protein diet and a high meat protein diet ().
Appetite control and weight loss were similar in both groups. The researchers concluded that diets high in soy protein were as effective in weight loss as diets high in animal protein.
Another 12-week study showed similar results using soy protein powder. Participants received either a soy-based or non-soy-based meal replacement. By the end of the study, both resulted in an average weight loss of 7.8 kg (7.8 kg).
In fact, one study of people with diabetes and obesity found that meal replacement with soy protein shakes may be more effective than standard diets for weight loss ().
Those who replaced meals with soy protein lost an average of 2 kg more than those who followed a standard diet.
However, although some studies have observed effects on reducing excess body weight, a review of 40 studies assessing the effects of soy protein on weight, waist circumference and fat mass found no significant beneficial effects ().
Overall, the evidence for soy protein intake for weight loss is not as strong as the evidence for other proteins such as whey and casein (,).
Summary:
Some research suggests that soy protein may be effective in losing weight, but the evidence is mixed and does not show it is more effective than other proteins.
Benefit for health
Some research suggests that including soy protein in your diet may provide a variety of health benefits.
For example, soy products have a positive effect on heart health. In a review of 35 studies, soy consumption lowered levels of "bad" LDL cholesterol and increased levels of "good" HDL cholesterol ().
Another review found that replacing animal protein with 25 grams or more of soy protein resulted in reductions in total cholesterol, LDL and (bad) cholesterol.
For cancer, the evidence appears mixed.
In many observational studies, a diet high in soy has been associated with a protective anticancer effect.
However, the scientists note that it remains unknown whether this refers to soy protein isolate powder or other plant protein derived from soybeans.
Some observational and case-controlled studies have linked soy consumption to a reduced risk of breast cancer ( , , ).
Others have found no effect in preventing the risk of developing breast cancer. In one study, soy consumption was even linked to stimulating rapid cell production in the breasts of premenopausal women, possibly increasing the potential risk of developing breast cancer (,).
Regarding the health effects of soy protein on men, some observational studies suggest that consuming soy products may reduce the risk of prostate cancer in older men (,).
Although results from observational studies are encouraging, human clinical studies regarding the potential protective anticancer effect of soy are currently inconclusive.
Additionally, many studies have been conducted using soy products rather than soy protein powder.
However, soy protein can be a good source of plant protein for people who do not consume animal proteins, including vegetarians and vegans, allowing them to benefit from consuming this nutrient ().
Summary:
Soy products may have potential health benefits, such as lowering cholesterol and possibly reducing the risk of cancer, but more research is needed.
Possible harm
Some people have problems with soy.
As mentioned, soy protein contains phytates, also known as anti-nutrients. They interfere with the absorption of minerals in your gastrointestinal tract (
Phytoestrogens are chemical compounds that occur naturally in plants and have estrogen-like properties. Soy is a significant source of phytoestrogens ().
However, soy protein powder is made from soybeans that have been washed with alcohol and water, which eliminates a significant portion of the phytoestrogens contained (,).
This is also why many men fear that soy protein may lower testosterone levels, but research does not support this claim.
A large observational study found that neither soy products nor soy isoflavone supplements altered testosterone levels in men ().
Many of the potential downsides of soy come from consuming soy in general, not just soy protein powder. More research is needed to see how soy protein affects health.
Summary:
Although there are some potential downsides to consuming soy protein, the evidence is fairly weak and suggests that most people can consume soy products without problems.
Summarize
- Soy protein is a complete source of protein. It can help build muscle, but is not as good as whey protein.
- In general, soy is safe for most people and may provide health benefits, including weight loss.
- If you like the taste or prefer plant-based foods, you might want to try soy protein.
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 essential 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 - 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.
It is difficult to say where protein is missing in the human body. It is found in bones, muscles, skin, tendons, ligaments, hair and, in general, in almost all tissues and organs. It is involved in the creation of hemoglobin, which supplies our blood with oxygen, as well as enzymes that drive many of the body's chemical reactions. It's amazing, but at least 10,000 different types of protein are involved in making us who we are.
This is why it is so important to understand the benefits and harm from proteins and have at least a general idea of how to eat so as not to harm yourself.
What do scientists say about protein?
The American Institute of Medicine (IOM) emphasizes that for an adult, the minimum intake of dietary or so-called dietary protein per day should be at least 0.8 g per 1 kg of body weight. However, in the United States, the recommended daily allowance for women and men over 19 years of age is 46 grams and 56 grams, respectively. A lack of this element in the body leads to loss of muscle mass, deterioration of immunity, slower growth, and also causes diseases of the respiratory and cardiovascular systems and can even lead to death.
Based on the results of various studies, the Institute of Medicine even established acceptable limits for protein consumption - daily from 10% to 35% of total calories. The basis for creating protein are amino acids, which our body synthesizes in the liver. However, some of them can only come from food. Moreover, these very important protein components are found only in products of animal origin - meat, fish, eggs, dairy products. First of all, those who follow a vegetarian diet should know about the benefits of this type of protein, since protein sources such as vegetables, grains, fruits, nuts, etc., lack some amino acids.
At the same time, the dangers of protein are also known. It is he who is responsible for the occurrence of food allergies, which are nothing more than a violent reaction of the body’s defense system. More and more studies are confirming that foods high in it play a significant role in human health. Although relatively little evidence has been collected on whether the amount of protein affects the development of chronic diseases, there is consistent evidence that consuming dietary protein found in fish, legumes, chicken and nuts instead of protein found in red meat can reduce the risk of some diseases and premature death.
The benefits of protein and harm
The question of the benefits and harms of protein has been clearly demonstrated by scientists from the Harvard College of Public Health in the field of cardiovascular disease. For over 20 years, as part of the large project The Nurses’ Health Study, 120 thousand men and women adherent to various dietary and lifestyle styles were monitored. It turned out that those who regularly included red meat in their diet, especially processed meat - that is, sausages, sausages, bacon and anything else that has undergone the processes of canning, smoking, pickling and others - are at higher risk of heart disease and heart attack. Replacing these products with foods with dietary protein - fish, poultry and legumes - helped reduce it. Moreover, every 85 g of regularly consumed red meat increased the risk of death from cardiovascular disease by 13%. And processed red meat, even in smaller quantities, about 40 grams daily - a serving equivalent to one hot dog - increased this danger to 20%. The harm to protein in this case is quite significant.
By the way, regarding the amount of dietary protein, evidence has been released that a diet high in protein is good for the heart if it comes from a healthy source.
How important is protein quality?
Protein quality plays an important role in the prevention of other diseases, such as diabetes.
Protein and diabetes
A recent study found that those who eat red meat, especially processed meat, are more likely to develop type 2 diabetes than those who eat less red meat, by an average of 12% and 32%, respectively. Replacing it in your daily diet with nuts, whole grain cereals or low-fat dairy products reduces the likelihood by 16-35%.
Another scientific observation in this area showed that if you increase your consumption of red meat, the harm of protein becomes even more obvious - namely, the risk of type 2 diabetes increases by 50% over the next 4 years. But reducing the proportion of red meat in the diet will lead to a reduction in risk by 14% over the next 10 years.
Protein and oncology
The observations of The Nurses’ Health Study project are also true in relation to cancer. Research regarding the relationship between cancer and the benefits and harms of protein is not yet conclusive. However, some evidence suggests that there is an increased risk of colon cancer when eating large amounts of red meat, including processed meat. Each additional portion increases the likelihood of cancer by 10% and 16%, respectively.
There are also certain recommendations regarding the consumption of red and processed meat. They were prepared by the American Institute for Cancer Research. According to them, in order to reduce the harm of protein, it is advisable to limit the total amount of meat in the diet. But if you have to make a choice, then first of all it must touch the grill. This is because high temperatures create compounds that can potentially cause cancer. This doesn't mean you have to give up grilling completely. You just need to carry out preliminary preparation - marinate the meat; partially cook it in the oven or microwave, which will reduce grilling time; and cook over low flame.
Protein and osteoporosis
The quality of protein and its quantity sometimes play a role in the occurrence of osteoporosis. Eating protein is associated with the release of certain acids into the bloodstream. The body usually neutralizes them using buffering agents and calcium. Eating too much protein can require too much calcium—and in some cases, the body supplies it from the bones.
In this case, the same study from The Nurses' Health Study demonstrated that a high-protein diet, followed for a long time, can weaken the skeletal system - that is, the harm of protein in this case is obvious. Women who consumed more than 95 grams of protein daily had a 20% higher risk of breaking a wrist than those who ate less than 68 grams per day. However, this area of research still contains certain contradictions.
Protein and Weight Control
The least indicative conclusions of scientists about benefits and harms of protein as far as weight is concerned. The difference here is quite minor. This 20-year study found that red meat eaters gained slightly more weight—by about half a kilogram every four years—compared to those who ate more nuts. The latter, on the contrary, lost about 250 grams every 4 years. 
It is important to know
The benefits of protein no doubt. However, here, as in everything related to health, there are subtleties and nuances. For example, protein-rich foods vary from one another and may be more or less healthy. It depends on what other substances are contained with the protein - the fiber necessary for the body or excess salts, healthy or harmful fats.
So, 170 g of beef fillet steak fried over an open fire is an excellent source of protein - it contains about 40 g. But at the same time, it contains about 12 g of saturated fat. For those whose daily calorie intake should not exceed 2,000, this is already a bit much, since it represents 60% of the daily recommended intake of this type of fat.
A ham of the same weight contains only 2.5 grams of saturated fat. But sodium is 500 milligrams higher than the permissible daily allowance. But salmon, like other fatty fish, is quite suitable - it has 34 g of protein, 1.7 g of saturated fat, fairly low sodium content, and also very healthy omega-3s.
In other words, the quality of the protein is just as important as its quantity. However, you should not rush to extremes. Therefore, remembering the unconditional benefits of protein, do not forget about the benefits of grains, fruits, vegetables, legumes and more.
Based on hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/
Almost every one of us loves to eat eggs for breakfast. We boil, fry them, make omelettes and other dishes. We need them both for baking and for preparing salads. But for some, the use of this product is beneficial, but for others it can be harmful.
The eggs of any bird are considered edible. But chicken eggs are still the most common, so they can be called one of the most popular products, eaten in almost all countries of the world. Let's consider what composition egg white has, what benefits it brings to our body, and what harm it can cause?
Features of egg white
Chicken eggs can be called a low-calorie product among other animal products. One egg weighs approximately 55-60 g. Moreover, for every 100 g of eggs there are 155 kcal. The main calorie content comes from the fatty yolk of the egg, while the white is its dietary part. Its calorie content is much lower. Chicken egg white contains water in the amount of 85% of the total mass. The rest are organic matter. Of all egg whites, 10% are proteins. These are ovalbumin, ovomucin and some others.
There is very little fat in the egg white. Their share in this part of the egg is only a third of a percent.
Carbohydrates – 0.75. Such a low content of these components allows egg white to rightfully be called a dietary product, so nutritionists advise people seeking weight loss to eat eggs without the yolk. This is a great way to get a lot of nutrients without harming your figure.
The cuisine of each country has its own recipes for preparing eggs, in which they can be either the main component of the dish or an auxiliary one. They are eaten boiled or fried. Some even prepare dishes using baked or pickled eggs. Many people believe that eating eggs raw is the most beneficial. It all depends on individual taste. They are also a necessary component of baking, added when preparing cutlets, salads, and used as a filling for pies. Therefore, it is very important to know what microelements are included in this product. What are its benefits and what are its harms for the human body.
Protein contains a number of elements necessary for the human body, such as amino acids and various minerals. Therefore, they must be included in the daily diet.
benefits and harms of boiled eggs
Benefits of egg white
Let's look at what is contained in chicken eggs and how they benefit us.
- Protein has a beneficial effect on the body, cleansing it. Scientific studies have shown that regular consumption of egg whites leads to a significant reduction in the amount of bad cholesterol in the blood, which causes serious heart and vascular diseases. Therefore, proteins are very useful for the prevention of these diseases.
- The advantage of protein is not only its low calorie content, but also its high protein content. This enzyme is necessary for the successful production of energy in the body's cells.
- In addition, it contains almost all amino acids that play a decisive role in many processes occurring in the body. This includes mental activity of the brain, cell restoration, and improvement in the condition of connective tissue.
- Egg whites contain B complex vitamins, as well as vitamins E and D.
Egg white in cosmetology
This product is useful not only when eaten. External use can also bring many benefits. Cosmetologists advise using it to care for oily skin. It helps dry it out and normalizes the functioning of the sebaceous glands. It is also perfect for combination skin.
A mask made from this component is very easy to prepare and is suitable for frequent use. To prepare such a mask, you just need to thoroughly beat the egg white and cool it. This mask is applied in three layers. First, apply the first one using a brush, which should dry a little. The second and third layers are applied in the same way. The product should be washed off with warm water after 15 minutes.
Chicken egg white is also often used in hair care. To speed up hair growth and provide intensive nutrition, you can prepare such a simple mask. Take 3 tablespoons of yogurt or other fermented milk product, combine with the white of one chicken egg. The product is applied to the hair for 25 minutes, distributing it over the entire length. Women who use this recipe regularly claim that their hair becomes silky and its structure is significantly improved. This method is not only effective, but also accessible to every woman who wants to maintain her beauty without special expenses or visiting salons.
fried eggs - benefits and harms
Can egg whites be harmful?
Many people believe that eating eggs and egg dishes every day can be harmful. The only justifiable concern about this is the cholesterol content. But this element is found only in the yolk of the egg. There is practically no protein in it. If 100 g of yolk contains about 250 mg of cholesterol, then in the protein its amount approaches zero. If you tend to be overweight and have high cholesterol levels in your blood, then to prevent the formation of plaques on your blood vessels, it is enough to exclude the yolk from your diet. You don't have to give up eggs completely.
If your body does not tolerate protein, then you should also avoid eating eggs. This is practically the only harm that this valuable product can cause. Allergies to yolk are much less common. If a person is allergic to protein, then most likely he will not be able to tolerate chicken meat either. This relationship is observed in 60% of cases.
If you suffer from this allergy, don't forget that they are present in many dishes. These include baked goods, salads, and some confectionery products.
how many eggs can adults and children eat per day?
Video: Is it possible to drink raw eggs for muscle growth?
Various sources of information constantly broadcast about the benefits of protein for the body. But few people know exactly why this element is useful. Protein is a very important compound because... acts as a carrier of life. More than twenty types of amino acids are the building blocks of protein. By binding in a variety of combinations, amino acids form protein, without which it is simply impossible to support the vital functions of the body. Below, you will find the main products containing protein and a table with their amount, and also find out what role it plays for our body.
Foods with the most protein
Some amino acids the human body cannot reproduce on its own. They are called irreplaceable. You need to replenish their supply with food. If a deficiency of these amino acids is created in the body, a sufficient amount of protein is no longer produced, and this leads to improper functioning of the body.
Protein (protein)- These are organic substances consisting of amino acids connected in a chain. It is an indispensable source of energy and cell structure for all systems of our body. 13 amino acids can be independently synthesized in our body, and 9 come from high protein foods.
The role of protein for the body:
- improves recovery, affects cell construction, increases muscle tissue growth;
- responsible for the synthesis of hormones;
- promotes blood clotting; without enough protein in the body, even a slight cut can lead to serious bleeding;
- stimulates the functioning of the nervous system, a deficiency leads to improper coordination and a difficult mental process;
- normalizes the functioning of the kidneys and liver, while perfectly rejuvenating the skin;
- is a source of energy for the body;
- ensures the delivery of nutrients to all systems;
- improves immunity, fights infections;
- significantly strengthens the structure of hair and nails;
- increases the speed of chemical processes occurring in the body.
Proteins of animal and plant origin
TO animals belong to that group proteins that enter the body with food of animal origin. These are dairy products, meat, fish, eggs. They are considered complete. The biological value of protein depends entirely on amino acid balance, the level of their digestion and absorption by the body. Proteins are identified as the most valuable milk, meat and eggs.
Less valuable squirrels vegetable origin. Their unbalanced state of essential amino acids is more difficult for the human body to absorb. They are quite difficult to digest because they have a dense fiber shell.
Important! Only a combination of animal and plant proteins can provide the body with a complete amount of amino acids.
According to doctors, the correct diet of an adult should include 55% animal proteins and 45% plant proteins. At the same time, you should know that the body’s absorption of the first type reaches 90%, and that of the plant variety ranges from 60 to 80%.
Daily protein intake
Most nutritionists adhere to the following protein intake per day:
1 - 1.5 grams per 1 kilogram human body weight, which is approximately
- women- 70 - 90 g per day,
- men- 90 - 130 g per day.
Children require slightly more protein per kilogram of body weight.
- for preschool children this figure is approximately 3 g per kg of body weight,
- for school age children- about 2 g per kg of body weight.
Much depends on the characteristics of not only lifestyle (mobility, mental stress, etc.), but also on the digestibility of the product by the body, some diseases, etc. This must be taken into account when calculating your norm.
Effect of heat treatment on protein
At temperatures 70° and above protein coagulation begins. In which the protein structure changes, transforming it into a linear chain of amino acids. In this form protein becomes more accessible to digestive enzymes and better absorbed by the digestive tract. But this happens only with the correct ratio of heat and time treatment. During long-term thermal processes, the loss of some important amino acids such as lysine occurs.
Products containing protein
To assess the quality of nutrition, it is very important to know the biological value of the protein consumed. This is especially important for building a balanced diet, for creating diets, for adequate nutrition for children and athletes.
Plant foods containing protein
Soybeans– 34.9 g. The high content of vegetable protein makes this product especially useful. The nutritional value is in no way inferior to animal protein. Soy is absorbed by the body even faster and easier than animal protein.
Peanut- 26.3 g. The content of a large amount of water-soluble fraction indicates the excellent completeness of the protein in the product, excellent digestibility and a high level of absorption by the body. Peanuts are simply necessary for the proper functioning of the heart, kidneys, and liver. It significantly increases blood clotting.
Peas- 23 g. Very tasty and healthy product. It is valued mainly for its high protein content. It should be noted that peas contain the same amount of protein as beef. But it is much easier to digest than meat protein.
Sunflower seeds– 20.8 g. This protein mainly consists of essential amino acids. Methionine is very important - a substance that stimulates fat metabolism, while normalizing cholesterol levels in the body.
Pistachios– 20.3 g These dried nuts are an excellent source of protein and protein. Thirty grams of pistachios contain 15% of your daily protein requirement. The product enriches the body with useful energy.
Lentils– 24.8 g. The vegetable protein contained in the product is well absorbed. The product enriches a person with tryptophan, an amino acid that is converted into serotonin in the body. The lack of this particular substance leads to depression and anxiety.
Dairy products and eggs containing protein
Hard cheese contains from 35 g to 25 g of protein, depending on the type. When cheese ripens, the protein in it becomes completely soluble. Therefore, it is perfectly absorbed by the body. And the protein content in such a large amount makes the product the most versatile source of protein consumption.
Cottage cheese- 17 g per 100 grams of product, which is about 21% of the daily value. A light and high-quality source of protein for our body. In addition to proteins, cottage cheese supplies our body with a significant amount of calcium and vitamins.
Chicken egg contains approximately 13 g (per 100 g of product) protein. This is a relatively low figure, but it is believed that eggs contain the most complete protein. And it comes first on the list of products for increasing muscle mass.
Egg sawed through- 12 years
Meat and fish products containing protein
Gelatin - 87 g. This product is a leader in animal protein content. It is obtained from the bones of cattle. But due to the fact that a small amount of it can be consumed in food, leadership can be considered relative.
Goose meat– 29 g. Goose meat is quite fatty and somewhat difficult to digest by the body. But the amino acids it contains stimulate the synthesis of most elements, which helps remove toxins and breakdown products from the body. Including ammonia.
Chum salmon caviar– 27 g. About 30 percent of the composition of red caviar is high-value proteins that are easily absorbed by the body. Caviar contains a complete list of amino acids, most of which the body cannot synthesize on its own, and must be enriched with them from the outside.
Salmon– 25.4 g. Red fish is an easily digestible source of protein, as well as essential amino acids. One hundred grams of the product enriches the body with half the daily requirement of protein. At the same time, red fish prevents the formation of uric and lactic acid salts in the body, which has a beneficial effect on kidney function.
Pork lean– 25 g. This product is recommended by doctors for the diet of pregnant women. The high protein content is excellent for breast milk production. Pork is easily digested by the body. This fact has been scientifically proven, and pork is ranked second in terms of digestibility by the stomach. This indicator makes the product very useful for the proper functioning of the gastrointestinal tract.
Chicken(without skin) – 25 g. Chicken is one of the best sources of protein. It has a positive effect on the treatment of many serious diseases, such as hypertension, ischemia, and stroke. Helps improve immunity and balance metabolism. Chicken protein contains 92% of essential amino acids. This indicator is second only to fish. The product is very easy to digest and contains little fat.
Beluga- 24 g. The benefits of beluga meat, which has proteins in a highly digestible form, lie in maintaining healthy intestinal microflora. The amino acids contained in the protein of this fish speed up metabolism and cleanse the intestines and liver of toxins and compounds of various heavy metals.
Cod liver– 24 g. The proteins included in the product perfectly normalize blood clotting and prevent the destruction of cartilage. Therefore, doctors advise consuming it in the diet of people who have suffered fractures, nursing mothers, pregnant women, and children.
Mutton– 24 g. An excellent source of easily digestible protein. One hundred grams of this meat replenishes 60.3% of the daily requirement of an adult. However, lamb is a difficult test for the digestive tract. Therefore, people with gastrointestinal problems need to limit the consumption of such meat.
Rabbit meat(hare) – 24 g. This is a dietary and very healthy product, similar in properties to chicken. This meat is valued for its high protein content with a very low fat content. Such proteins are absorbed by the body by almost 90%.
Turkey(low-fat) – 24 g. It is this tasty, healthy meat, used as a dietary meat in most diets, which, due to its high protein content, provides the body with vital energy.
Beef– 23 g. Excellent protein supplier. It is beef protein that improves oxygen saturation of cells. This is especially important for athletes and people involved in fitness. Beef also contains low-value proteins - collagen and elastin. It is a known fact that collagen is the main building material of interarticular ligaments.
High Protein Foods to Build Muscle
In order for the muscles to quickly acquire a beautiful athletic shape, as well as improve physical condition, there are a number of products that contribute to this:
- egg- sufficient amount of high quality protein
- chicken meat- protein product with low fat content
- fish- in addition to protein necessary for building muscle mass, it contains omega-3 fatty acids necessary for physical activity and proper functioning of the cardiovascular system.
- cottage cheese- not only rich in protein, but also calcium and vitamins.
- foods high in magnesium(dark chocolate, almonds) - this element is necessary for better protein absorption.
Table of foods containing large amounts of protein
| Products containing protein | Amount of protein per 100 g of product | % of the approximate daily value |
| Mutton | 24 | 30 |
| Lean lamb | 20 | 25 |
| Beef lean | 20 | 25 |
| Beef (minced meat) | 23 | 29 |
| Goose | 29 | 36 |
| Turkey (lean) | 24 | 30 |
| Rabbit, hare | 24 | 30 |
| Chicken (without skin) | 25 | 31 |
| Chickens (broilers) | 22,6 | 28 |
| Chicken liver (broil) | 18-21 | 25 |
| Chicken heart (broil) | 15-22 | 26 |
| Chicken stomachs | 20-22 | 27 |
| Beef brains | 11 | 14 |
| Lamb liver | 19 | 24 |
| Beef liver | 17 | 21 |
| Pork liver | 18 | 22 |
| Lamb kidneys | 12,5 | 16 |
| Beef kidneys | 12,5 | 16 |
| Pork kidneys | 14 | 18 |
| Pork is fatty | 19 | 24 |
| Pork lean | 25 | 31 |
| Fatty veal | 20 | 25 |
| Skinny veal | 22 | 28 |
| Duck | 17,6 | 22 |
| Lamb heart | 14 | 18 |
| Beef heart | 15 | 19 |
| Pig heart | 15 | 19 |
| Sausages | 10-20 | 19 |
| Beef tongue | 16 | 20 |
| Whole egg | 12 | 15 |
| Egg, yolk | 16 | 20 |
| Egg, white (1 pc.) | 11 | 13 |
| Beluga | 24 | 30 |
| Pink salmon | 21 | 26 |
| Chum salmon caviar | 27 | 34 |
| Squid (fillet) | 18 | 22,5 |
| Flounder | 18,2 | 23 |
| Carp | 19,9 | 25 |
| Mullet | 21,4 | 27 |
| Crabs | 18,7 | 23 |
| Shrimps | 20 | 25 |
| Icy | 17,4 | 22 |
| Bream | 21 | 26 |
| Macrurus | 15,3 | 19 |
| Pollock | 17 | 21 |
| Lamprey | 15 | 19 |
| Sea bass | 20 | 25 |
| Sturgeon | 16,5 | 21 |
| Cod liver | 24 | 30 |
| Blue whiting | 17,9 | 22 |
| Saber fish | 20 | 25 |
| Saira | 18,6 | 23 |
| Salaka | 18 | 22 |
| Sardine | 23,7 | 30 |
| Herring | 15,5 | 19 |
| Salmon | 16,3 | 20 |
| Smoked salmon | 25,4 | 32 |
| Whitefish | 19 | 24 |
| Mackerel | 18 | 23 |
| Horse mackerel | 18,5 | 23,5 |
| Sterlet | 17 | 21 |
| Som | 17 | 21 |
| Zander | 21 | 26 |
| Cod | 17 | 21 |
| Smoked cod | 23,5 | 29 |
| Tuna | 23 | 29 |
| coal fish | 14 | 17 |
| Acne | 17 | 21 |
| Oysters | 14 | 17 |
| Trout | 15,5 | 19 |
| Hake | 16,6 | 20 |
| Pike | 18 | 22 |
| Ide | 18,2 | 23 |
| Brynza | 18 | 22 |
| Hard cheeses (medium) | 25-35 | 38 |
| Dutch cheese | 26 | 33 |
| Kostromskaya cheese | 25,2 | 31 |
| Cheese Poshekhonsky | 26 | 32 |
| Cheese Lithuanian | 29 | 36 |
| Smoked sausage cheese | 23 | 29 |
| Processed cheese | 20 | 25 |
| Cottage cheese 0.6% | 16 | 20 |
| Cottage cheese 20% | 14 | 17 |
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 rationale 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).
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 monitor 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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