By Dr. Nicola Sacchi - Author of the book: Drugs and doping in sport -
Proper protein intake is currently a very controversial topic. Often we talk about the possible risks that are taken to take too much protein, however at the present state of scientific knowledge on the subject, many of those problems that are attributed to the high protein intake are in reality only rumors without foundation.
Carefully analyzing the issue of excess protein, we must first define the concept of "too much": this term is not a precise measure and in fact there is no precise quantity that justifies the adjective "too much", which certainly varies from subject to subject but which is constantly mentioned, not to mention even abused, by phantom nutrition experts, who too superficially generalize the concept by saying that "too much protein is bad".
The reality is that analyzing all the main risks of which the excessive recruitment is accused, based on what the scientific literature shows, it turns out that none of the dangerous ailments generally mentioned has ever been really shown.
By scientifically analyzing these issues we can say that:
- According to some scholars, high protein consumption leads to a reduction in bone calcification. This effect is related to the fact that animal proteins contain many sulfur amino acids, which increase the release of calcium from the bones; however, there are studies showing that this theory must be revised, as several studies have shown that the bone density of protein consumers is similar to that of moderate consumers, and that the former are less prone to fractures than the latter.
- It is also believed that excessive consumption of proteins leads to kidney damage. What has been shown is that protein consumption modifies renal function, but this is considered by the most accredited experts in the field as a natural physiological adaptation. The hyperfiltration observed in patients and animals subjected to diets with high protein intake is only a natural adaptive process, which does not involve any additional risk. Some studies on athletes who habitually have a higher protein consumption, also associated with the use of amino acid and creatine supplements, do not show a greater incidence of renal pathologies than individuals subjected to diets with lower protein intake. One of these studies analyzed the effects of a daily intake of 2.8 grams of protein per kg of weight without showing any particular consequences in the kidney (Poortmans et al.).
For this reason, many scholars believe that the high protein intake does not involve greater risks of incidence of renal diseases. According to several research institutes, there is not enough data to state that protein consumption in healthy people should be limited to 15% of the total calorie intake, as is generally suggested by the media and some nutritionists. According to these institutions the protein intake can reach 35% of the quantity of calories ingested.
Some studies show that people with kidney diseases have difficulty eliminating nitrogen, therefore they must reduce protein consumption. In the case of overt diseases, there is a real risk that the excess of proteins will worsen the renal condition. However, this does not mean that proteins damage the kidneys, indeed the available data find little correlation between the two. In healthy people the increase in protein consumption simply requires an increase in water consumption to promote diuresis.
- Possible liver damage resulting from protein consumption was not found in any scientific study. Obviously those who suffer from liver diseases such as cirrhosis, liver failure, hepatitis, etc., must follow a particular diet and must reduce the consumption of proteins as the diseased liver is not able to metabolize them properly. People who do not have liver tissue damage do not have problems of this nature.
- The possible risk of gout is not in fact closely related to excessive protein intake but to excess meat, as the cause of this pathology is due to an accumulation of uric acid that is formed by the catabolism of nucleic acids (purines ), therefore from animal cells and not from proteins per se. Taking protides from milk, eggs or supplements prevents the accumulation of nucleic acid metabolites.
- Other alleged negative effects linked to excessive protein consumption are the risk of incidence of cardiovascular diseases identified in large consumers of red meat. In reality the problem is closely related to the presence in these meats of saturated fats and not to their protein intake, therefore also in this case it is not the proteins that entail health risks.
In practice, all the possible risks ascribed to the intake of high quantities of protein are not reflected in the scientific literature. Finally it is important to remember that many researches show that the increase in protein consumption at the expense of the intake of carbohydrates and fats promotes weight loss and how it is important to increase protein intake in the event of intense physical activity, as the body consumes and damages these molecules during activity.
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