Protein is an important macronutrient in the diet of endurance exercise athletes. It promotes recovery, muscle growth and helps to increase strength. The amount and timing of protein intake is crucial to gaining muscle, but what about protein quality? Are all amino acids in food, as defined by common analytical procedures, available to the body as building blocks?

Protein is not just protein. The quality of a protein source can be determined by three characteristics: the amount of protein in the food, the amount of essential amino acids in the protein and the digestibility.

Protein is an essential nutrient in the diet that promotes growth and maintenance in the body, but different protein sources differ in quality. Over the years, several experts from FAO (United Nations Food and Agriculture Organization) / WHO (World Health Organization) / UNU (United Nations University) have estimated the specific protein needs of different age groups in terms of quantity and quality1. Since proteins from different sources have different qualities, this is an important issue to discuss when protein is used for health reasons.

As well as nutritional quality, microbiological quality is also an important theme in formulations aimed at specialized nutrition. Specialized nutrition is nutrition for vulnerable target groups, such as the young, elderly, pregnant, and immunodeficient population. For these groups it is important to minimize the risk of a product causing disease. To prevent disease due to microbiological infection, the microbiological quality of a product is extremely important. FrieslandCampina DMV caseinate is practically sterile and has a low presence of undesirable components such as lactose, residues and contaminants. This makes caseinate an ideal ingredient in the composition of a safe and healthy product.

Milk proteins such as casein and whey protein, as well as soy protein, have all the essential amino acids needed for the growth and maintenance of the body.

When you break a protein, you find a sequence of different amino acids, all together and linked together like a string of beads (see figure 1)

Figura 1: Estrutura primária da proteína

Figura 1: Primary protein structure

In total there are 20 different amino acids and each protein source has a different sequence and amount of amino acids available.

There are essential and non-essential amino acids. Essential or indispensable amino acids cannot be produced by the body and must be removed from food2. That’s why there is a focus on the amount of essential amino acids.

Quality of animal and vegetable proteins

Protein derived from vegetables such as grain products, leguminous vegetables and nuts are generally of lower quality than animal protein. Soy is a protein that stands out among vegetable solutions because, in addition to having excellent digestibility, as well as casein, whey protein and albumin, it also has all the essential amino acids in quantities that meet the needs of children aged 2 to 5 years of age, which is the age group where the needs of these amino acids are highest.

A complete source of protein is necessary for the growth and maintenance of the body.

The body is constantly forming new tissues and replacing old ones. The rate of this protein turnover varies from tissue to tissue. The complete intestinal mucosa is replaced every 4-5 days6, while muscle tissue is replaced every 3 months (based on 1.15% per day4). Bones renew even slower; the bone cell renewal rate is 10% per year5.

To form tissue and replace old tissue, the body needs building blocks. These blocks are the (indispensable) amino acids that must be obtained from food. To form new tissue all the essential amino acids are needed. When an amino acid is limiting or unavailable, it is not possible to complete new tissue formation. If the intake of a specific amino acid is too low, the body’s proteins will be broken down to supply that specific amino acid. This is the limiting amino acid and this determines the nutritional value (figure 2).

 Figura 3: Quando não há aminoácido limitante não é possível completar o recipiente. As abreviações com três letras na figura são os aminoácidos essenciais. Nos cereais a lisina é frequentemente o aminoácido limitante, enquanto que no feijão os aminoácidos sulfurados (metionina + cisteína) são frequentemente os limitantes.

Figure 2: When there is no limiting amino acid, it is not possible to complete the container. The three-letter abbreviations in the figure are the essential amino acids. In cereals lysine is often the limiting amino acid, while in beans the sulfur amino acids (methionine + cysteine) are often the limiting ones.

In casein and whey there is no amino acid that is really limiting.

Casein and whey protein are high quality proteins, just like soy protein, which means they contain all the essential amino acids that are well above the criteria defined internationally by the FAO (United Nations Food and Drug Administration). Agriculture) and there is no amino acid that is really a limiting factor in relation to quality.

Alguns aminoácidos têm um benefício bio-funcional específico.

Specific (essential) amino acids and their benefits:

– Leucine appears to be an important metabolic signaling molecule for protein synthesis. Leucine gives a signal for muscle to start muscle building. Whey protein is known for its high leucine content. A minimum dose of leucine is the threshold needed to stimulate an increase in muscle protein synthesis6, 7. Whey protein not only has the highest level of leucine, but studies show that ingestion results in the fastest onset. of leucine in the blood compared to the casein protein8.

– BCAA are branched chain amino acids and combine leucine, valine and isoleucine. These amino acids are not degraded by the liver and, therefore, their food intake directly influences plasma levels and availability to peripheral tissues such as muscle9.

In all internationally recognized protein definitions casein and whey protein and soy protein are high quality protein sources.

The nutritional quality of a protein can be expressed in several ways. The quality of the protein depends on the digestibility of the protein (and its amino acids) and the composition of the expendable and indispensable amino acids in the proteins2. Both PDCAAS (Protein Digestibility Corrected Amino Acid Index) and DIAAS (Digestible Indispensable Amino Acid Index) show that casein, whey protein and soy protein isolate are high quality proteins.


Protein quality is generally expressed by the PDCAAS (Protein Digestibility Corrected Amino Acid Index) which is adopted as the preferred method for measuring the value of protein in human nutrition.


In general, it appears that protein sources of vegetable origin, with the exception of isolated soy protein, may have lower digestibility than proteins of animal origin10.

Protein source digestibility has been defined as the proportion of food protein derived from amino acids that is effectively digested and absorbed, thus making it adequately available for the body’s protein synthesis11.

Animal protein sources, including dairy, eggs and meat, and isolated soy protein are highly digestible (>90%) (FAO, 2011). Depending on the processing method2 8 and the presence of various ‘anti-nutritional’ factors (components of the food source that interfere with the digestion and absorption of available protein, such as trypsin inhibitors, etc.)12. Vegetable sources, such as corn, oats, beans, peas and potatoes tend to have lower digestibility than animal sources, with values ​​ranging from 45% to 80%13.

At FrieslandCampina DMV

At FrieslandCampina we pride ourselves on 140 years of heritage in milk processing.

FrieslandCampina knows exactly which cows its milk comes from and this allows FrieslandCampina to control the quality of milk and its derivatives throughout the entire chain: from grass to cup. The entire chain is transparent and the entire process, from grass to cup, can be checked and guaranteed using an integrated quality control system. Our factories and farms are independently audited on various quality aspects. Milk can be traced within our chain. Quality standards are based on the highest standards in the world.

Along with our strong nutritional knowledge, we produce high nutritional quality proteins.

For more information: or


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1) Protein and amino acid requirements in human nutrition. Report of a joint FAO/WHO/UNU expert consultation (OMS Technical Report Series 935).

    Necessidades de proteína e aminoácido na nutrição humana. Relatório de uma consulta conjunta de especialistas FAO/OMS/UNU (OMS Séries de Relatório Técnico 935).


2) Scientific Opinion on Dietary Reference Values for protein. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). EFSA journal 2012;10(2):2557.
    Opinião Científica sobre os Valores Dietéticos de Referência para Proteína. EFSA Painel sobre Produtos Dietéticos, Nutrição e Alergias (NDA). EFSA jornal 2012;10(2):2557.
3) Van Vliet, S. Burd N.A., van Loon LJ, The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015 Jul 29. pii: jn204305.

    Van Vliet, S. Burd N.A., van Loon LJ. A Resposta Anabólica do Músculo Esquelético ao Consumo de Proteína de Origem Vegetal x Proteína de Origem Animal. J Nutr. 2015 Julho 29. pii: jn204305.
4) Wagenmakers AJM. Tracers to investigate protein and amino acid metabolism in human subjects. Proc Nutr Soc 1999;58:987-1000.

    Wagenmakers AJM. Marcadores para investigar o metabolismo das proteínas e aminoácidos em seres humanos. Proc Nutr Soc 1999;58:987-1000.
5) Manolagas SC. Birth and death of bone cells: basic regulatory mechanisms and implications for the pathogenesis and treatment of osteoporosis. Endocr Rev. 2000 Apr;21(2):115-37.

    Manolagas SC. Nascimento e morte de células ósseas: mecanismos reguladores básicos e implicações para a patogênese e tratamento da osteoporose. Endocr Rev. 2000 Abril;21(2):115-37.
6) Drummond MJ, Dreyer HC. Fry CS, Glynn EL, Rasmussen BB. Nutritional and contractile regulation of human skeletal muscle protein synthesis and mTORC1 signaling. J Appl Physiol. 2009 Apr;106(4):1374-84.


    Drummond MJ, Dreyer HC. Fry CS, Glynn EL, Rasmussen BB. Regulagem nutricional e contráctil da síntese de proteína do músculo esquelético humano e sinalização mTORC1. J Appl Physiol. 2009 Abril;106(4):1374-84.
7) Katsanos CS, Kobayashi H, Sheffield-Moore M, Aarsland A, Wolfe RR. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. Am J Physiol Endocrinol Metab. 2006 Aug;291(2):E381-7.

    Katsanos CS, Kobayashi H, Sheffield-Moore M, Aarsland A, Wolfe RR. É necessária uma elevada proporção de leucina para estimulação otimizada da taxa de síntese de proteína do músculo por aminoácidos essenciais em idosos. Am J Physiol Endocrinol Metab. 2006 Agosto;291(2):E381-7.

8) Tang, J.E., & Phillips, S.M. (2009). Maximizing muscle protein anabolism: The role of protein quality. Cur Opi Clin Nutr Met Car, 12(1), 66-71.

    Tang, J.E., & Phillips, S.M. (2009). Maximização do anabolismo da proteína do músculo. O papel da qualidade da proteína. Cur Opi Clin Nutr Met Car, 12(1), 66-71.

9) Layman DK. The role of leucine in weight loss diets and glucose homeostasis. J Nutr. 2003Jan;133(1):261S-267S.

    Layman DK. O papel da leucina nas dietas para perda de peso e homeostase da glucose. J Nutr. 2003 Janeiro;133(1):261S-267S.

10) FAO. Report of a sub-committee of the 2011 FAO Consultation on ‘‘Protein Quality Evaluation in Human Nutrition’’: the assessment of amino acid digestibility in foods for humans and including a collation of published ileal amino acid digestibility data for human foods. Rome (Italy): FAO; 2012.

      FAO. Relatório do sub-comitê da consulta FAO 2011 sobre a “Avaliação da Qualidade da Proteína na Nutrição Humana”: avaliação da digestibilidade dos aminoácidos em alimentos para humanos e incluindo a classificação dos dados publicados sobre digestibilidade ileal de aminoácidos em alimentos para humanos. Roma (Itália): FAO; 2012.


11) Rutherfurd SM, Moughan PJ. Available versus digestible dietary amino acids. Br J Nutr 108: S298–S305, 2012.

      Rutherfurd SM, Moughan PJ. Aminoácidos dietéticos digestíveis x disponíveis. Br J Nutr 108: S298–S305, 2012.


12) Sarwar Gilani G, Wu Xiao C, Cockell KA. Impact of anti-nutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality. Br J Nutr 2012;108: Suppl 2:S315–32.     

      Sarwar Gilani G, Wu Xiao C, Cockell KA. Impacto dos fatores anti-nutricionais nas proteínas alimentares na digestibilidade da proteína e biodisponibilidade dos aminoácidos e na qualidade da proteína. Br J Nutr 2012;108: Suppl 2:S315–32.


13) Van der Vlier, Clevers. Stem Cells, Self-Renewal, and Differentiation in the Intestinal Epithelium. Annual Review of Physiology. Vol. 71: 241-260.

      Van der Vlier, Clevers. Células-tronco, Auto-Renovação e Diferenciação no Epitélio Intestinal. Revisão Anual de Fisiologia. Vol. 71: 241-260.



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