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  • Writer's pictureDr Ferraro

Amino acids. Part III

Updated: Feb 10, 2019

In this last chapter dedicated to amino acids and protein supplements I will talk about those that are definitely among the most used supplements in the world of gyms: protein powder. These are, like the BCAA, a subset of the largest family of food supplements; Please remember that for no supplement overdosing is synonymous with the better results and indeed with an abuse of supplements can easily cause unpleasant side effects. There is no supplement able to provide food that “normal” foods are not able to provide and the use of aids must not ignore the consultation of an expert nutritionist or dietician.

The Recommended Daily Allowance (RDA) and the Estimated Average Requirement (EAR) are indexes estimated by the World Organization of Health that ​​refer to the average daily consumption of a nutrient. Based on these indexes, the daily proteins requirement varies according to age, sex, body weight and type of activity. For people with a normal metabolic processes it is advised not to go below 0.8 g x kg of body weight in a day. Example, a person of 100kg will have to take about 80g of protein per day. For sedentary people, this need is guaranteed by normal and healthy eating.

In athletes, the protein requirement tends to increase differently by the sports disciplines carried out. Some of the most used indications in sports emphasise the importance of taking about 15% of total calories from proteins. To do ,it, you have to multiply the total daily calories by the value of 0.15 to calculate the amount needed. For example, if the requirement is 3000 calories, 450 calories should come from proteins. When calculating protein requirements do not forget to also consider the duration and intensity of the activity, the athletes who train for several hours a day can lose muscles mass because they burn a higher percentage of proteins as fuel. To preserve muscle mass, these athletes can consume up to 3.5 g of protein per kg of body weight! Other examples are endurance sports, such as alpine skiing and football for which a requirement of 1.2 - 1.4 g protein x kg of body weight o swimming 1.6 g protein x kg of body weight or gymnasts for 1.9g protein x kg body weight.

Foods of animal origin such as meat, eggs and fish provide all the amino acids needed to build and develop muscles, but these foods can contain an excessive amount of fat. Athletes need to take a sufficient amount of protein, to replace part of those that are catabolized for energy during exercise and to preserve muscle mass, but it is not always easy. Indeed, it is not unusual for certain types of athletes, such as resistance or weightlifters, to have difficulty consuming enough protein to meet their daily needs. For athletes who need large amounts of protein every day eat them with regular food can be harmful to their health, imagine an athlete who after an intense workout should eat a grilled steak, which is why in some cases a protein supplement can represent the solution to the problem. However, it is essential to know that the proteins consumed in excess are not conserved in the muscles but their carbon skeleton can be reused to form stocks of fat, and therefore we must be careful to integrate the appropriate amount to body weight and the type of sport that followed.

There are plenty of products on the market but how do we understand what they are for?

To better understand these products we can use another index: the biological value (BV).

Biological value is among the most important indices for the evaluation of protein quality. It is a parameter of food evaluation based on the quality of the proteins contained in them, depends on the amino-acid composition of a food and its digestibility, and is defined as the ratio between the retained nitrogen and the absorbed nitrogen. The equation to measured it established the amount of nitrogen that is absorbed and used and of all the losses that occur through urinary and faecal excretions. Figure 1.

Figure 1. Formula for the biological value

Using this value we can therefore summarise the protein as follow

  • Whey protein: VB> 100

  • Egg protein: VB = 100

  • Milk protein: VB> 90

  • Casein proteins: VB <80

  • Soy protein: VB <75

  • Wheat proteins: VB <55

What could be the side effects caused by excess intake of protein supplements?

The most important side effects are kidney disease, liver disease, bone demineralisation, acidosis and increased adipose tissue. Keep in mind that protein supplements are contraindicated in cases of renal or hepatic disease, cardiovascular disease, hypertension, pregnancy, during lactation and if under 12 years; in case of prolonged use (more than three consecutive months), the doctor's opinion must be sought.

So it's OK to use such supplements, but consciously and carefully. Shortcuts or miraculous products do NOT exist; we must always train seriously, eat healthy, if necessary, integrating smartly.

To mention that to understand the protein qualities other values ​​such as the protein efficiency ratio (PER), the digestive utilisation coefficient (DUC), the Protein Digestibility Corrected Amino Acid Score (PDCAAS), the index or chemical score (ICS) and the Net Protein Utilization (NPU) can be used.


Burke E. R. Alimentazione da campioni. Recupero, salute e rendimento muscolare. Edizioni Mediterranee, 2002.

Campbell T. C. The China Study. Macro edizioni, 2013.

Racaniello D, Ferraresi G. Mercolini I. Integratori Alimentari, a cura di Laboratori BioLine s.r.l, 2011.

Pascalis P.D. A scuola di fitness. Calzetti Mariucci, 2010.

Institute of Medicine (Trumbo et al.) Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. J Am Diet Assoc, 2002.

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University of Derby Kedleston Rd, Derby DE22 1GB,

Lecturer in Sport Therapy and Rehabilitation

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