What is the effect of a high protein diet on the body?

Protein is the latest scathing topic, either due to the ever-popular popular protein diets or the increased intake of protein supplements on a daily basis.

Benefits of a high protein diet: 

• Increases the feeling of satiety;
• Promotes fat loss;
• Helps increase muscle mass;
• Improves cardiovascular markers.

The effect of increased protein intake on the human body has been scientifically proven to achieve the above effects [1, 2, 3, 4, 5, 6]. However, this raises concerns about excessive protein intake, as some researchers believe that excessive protein intake can contribute to a variety of health problems, such as kidney, liver and heart disease, or osteoporosis. Are these concerns justified?

What are the effects of excessive protein intake on your health and well-being? 

What are the effects of protein intake on the liver? 

Excessive protein intake or cause an increase in the levels of ammonia (a toxic substance) in the blood. A healthy liver will process the ammonia that has been formed as a result of protein catabolism into non-toxic urea, which will then be removed from the body by the kidneys. However, the liver's ability to convert ammonia to urea is limited, so excessive protein intake is not recommended [7].

What are the effects of excessive protein intake on the kidneys? 

Excessive intake of animal protein increases the urinary excretion of calcium, which increases the risk of calcium oxalate kidney stones in the long term [10]. However, there is an opportunity to reduce this risk by increasing the intake of water, fruits, vegetables and foods high in calcium. 

Concerns about excessive protein intake include kidney function. The claim that moderate protein intake in people with or at risk of kidney failure is true. However, this does not mean that high protein intake will increase the risk of kidney failure in healthy people [7, 8]. Studies investigating an excessive protein diet, regardless of whether the respondent is an athlete or not, indicate that there is no evidence of adverse effects on renal function [6, 7, 8, 9].

Relationship between high protein diets and weight gain 

Although 1 g of protein and 1 g of carbohydrates are worth 4 k cal, maintaining a high-protein diet requires more energy than a high-carbohydrate diet. Several studies indicate that a high-protein diet helps control weight [1, 2, 3, 4, 5, 6, 7]. Even a minimal increase in dietary protein intake (to values above 3 g / kg body weight) in the study indicated a decrease in the dynamics of fat percentage growth. The same observations were analyzed by increasing caloric intake [10, 11]. This does not mean that you can increase your protein intake without limits without gaining weight. Among other factors, many protein-rich products are also high in fat. The most important thing in wanting to eat more protein without gaining weight is diet planning and regular exercise.

Is Excessive Protein Intake Harmful To Heart Health?

Contrary to what people might think, a high-protein diet does not increase the risk of heart disease [7]. Several studies indicate improvement of cardiovascular markers [1, 3, 12], such as low levels of lipoproteins, triglycerides, and cholesterol by adhering to diets high in protein and low in carbohydrates [1, 7]. The only problem is that protein sources often have a high content of saturated fats, which is harmful to the health of the cardiovascular system. It must also be remembered that it is not just an increase in protein intake, nor should we forget the groups of foods that are important for the health of the cardiovascular system, such as fruits and vegetables.

How does a high protein diet affect your body's pH?

Unlike fruits and vegetables (naturally alkaline), the metabolism of proteins and cereals increases the level of organic acids in the blood plasma, thus lowering the pH level. Changes in acid-base homeostasis have a negative effect on your health, but the body has physiological mechanisms that ensure a constant pH level. However, we recommend compensating for the increase in protein intake by reducing cereal intake and increasing fruit and vegetable consumption. Thus, your body does not need to activate compensation mechanisms.

Protein intake and malignancies: are there risks? 

There is no link between increased protein intake and the development of malignancies. Some studies show that high meat consumption (red meat) increases the risk of some malignancies. This particular risk, in turn, is not related to protein, but to the fat content of meat [7, 13]. Therefore, most of the protein you eat should be from fish and lean meat. 

Is It Safe To Use High Protein Supplements? 

Protein supplements, such as whey protein, do not have a negative effect on your health unless you take the supplement in excess of the recommended daily allowance (portions). Society of Sports Nutrition In your opinion, dietary supplements are a safe way to absorb high-quality protein in the amount you need [12,14].

As mentioned above, high-protein diets have several advantages, mostly related to weight loss, weight control, increased muscle mass, and improved cardiovascular health markers [1, 2, 3, 4, 5, 6].

Studies conducted among healthy respondents indicate that this type of diet did not pose a threat to human health during the study period [6, 15]. In specific cases, however, protein intake can have negative effects: when there is a pre-existing health condition that may be worsened by a high protein diet, or when increased protein intake is not commensurate with fruit, vegetable intake, water intake and / or excessive protein intake. due to admission.

Contrary to many beliefs, the potential negative effects associated with protein intake are usually due to excessive intake, an unbalanced diet, and not to the origin of the protein (animal, plant or food supplement).

How much protein should I take? 

The recommended daily dose of protein is the same for women and men and is 0.8 g per kilogram body weight per day [7]. This is the minimum amount of protein that should be taken in to prevent nitrogen loss in the body [16, 17]. However, this amount has not been restored for decades and several studies suggest revising the recommended values based on the positive health benefits of high protein diets [16].

For those who exercise regularly, International Society of Sports Nutrition recommends a daily intake of 1.4-2.0 g of protein per kilogram of body weight per day to maintain or increase muscle mass. Higher protein intake would be necessary if you want to increase muscle mass by reducing calories. However, it is recommended to absorb up to 35% of the daily energy from protein [7, 12, 14].

The acceptable range of protein macronutrient distribution is 10-35% of total daily calories [7,12,14]. With this range in mind, each person should adjust their protein intake to their daily needs based on weight, physical activity and goals.

Conclusions

Only a few studies show the health effects of excessive protein intake. This is due to the fact that even people who eat only meat very rarely manage to reach 35% of the daily energy intake due to the fat present in protein. However, there have been some cases of excessive protein intake associated with exclusive lean meat intake, usually among freight forwarders. They developed headaches, nausea, diarrhea, and symptoms that resolved with reduced protein intake fairly rapidly [7].

References:

1. Wycherley, T. et al. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. The American Journal of Clinical Nutrition, 2012. 96: 1281-1298.

2. Krieger, J.K. et al. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. The American Journal of Clinical Nutrition, 2006. 83: 260–274.

3. Leidy, H. J. et al. The role of protein in weight loss and maintenance. The American Journal of Clinical Nutrition, 2015. 101 (Suppl): 1320S – 9S.

4. Cuenca-Sánchez, M., et al. Controversies Surrounding High-Protein Diet Intake: Satiating Effect and Kidney and Bone Health. Advances in Nutrition, 2015. 6: 260–266.

5. Aragon, A.A. et al. International society of sports nutrition position stand: diets and body composition. Journal of the International Society of Sports Nutrition, 2017. 14:16.

6. Antonio, J. et al. The effects of a high protein diet on indices of health and body composition - a crossover trial in resistance-trained men. Journal of the International Society of Sports Nutrition, 2016. 13: 3.

7. Institute of Medicine, Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (Macronutrients). 2005, Washington, DC: The National Academies Press.

8. Martin, W. F. et al. Dietary protein intake and renal function. Nutrition & Metabolism, 2005. 2:25.

9. Antonio, J. et al. A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Male. Journal of Nutrition and Metabolism, 2016. 2016: 9104792.

10. Antonio, J. et al. The effects of consuming a high protein diet (4.4 g / kg / d) are body composition in resistance-trained individuals. Journal of the International Society of Sports Nutrition, 2014. 11:19.

11. Antonio, J. et al. A high protein diet (3.4 g / kg / d) combined with a heavy resistance training program improves body composition in healthy trained men and women - a follow-up investigation. Journal of the International Society of Sports Nutrition, 2015. 12:39.

12. Jäger, R. et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017. 14:20.

13. Nilsson, L. et al. Low-carbohydrate, high-protein diet score and risk of cancer incident; a prospective cohort study. Nutrition Journal, 2013. 12:58.

14. Thomas, D.T. et al. Nutrition and Athletic Performance. Medicine and Science in Sports and Exercise, 2016. 48 (3): 543-568.

15. Nilsson, L. et al. Low-carbohydrate, high-protein diet score and risk of cancer incident; a prospective cohort study. Nutrition Journal, 2013. 12:58.

16. Wolfe, R. et al. Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range. Advances in Nutrition, 2017. 8: 266–75.

17. Scientific Opinion on Dietary Reference Values for protein. EFSA Journal, 2012. 10 (2): 2557.