What are they and what is their role?
Amino acids are referred to as the building blocks of proteins, crucial for various biological functions, including tissue repair, enzyme production, and nutrient absorption[1]. They are organic compounds composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur. Each protein is built in a specific sequence of amino acids and so a deficiency in only one amino acids can prevent the use of all other amino acids until that deficiency is corrected. So not all proteins are equal and we need to be conscious of the quality of the protein as well as the total amount. Milk protein is one of the very best proteins and so with 100% more protein than standard cow’s milk, SuperNutrio really does pack a punch.
Amino acids can be described in one of three ways:
Essential Amino Acids: These amino acids cannot be synthesised by the human body and must be obtained through diet. There are nine essential amino acids. Each plays a vital role in maintaining health and supporting bodily functions. For example, leucine is critical for muscle protein synthesis, while tryptophan is a precursor for serotonin, a neurotransmitter involved in mood regulation.
Conditionally Essential Amino Acids: Conditionally essential amino acids are amino acids that the body can typically synthesise under normal circumstances, but under certain conditions, such as illness, stress, or during stages of rapid growth and development, the body may not be able to produce them in sufficient quantities. Therefore, these amino acids must be obtained through the diet or supplements during these times to meet the increased demand.
Non Essential Amino Acids: These can be synthesised by the body, so they do not necessarily need to be consumed through the diet. There are eleven non essential amino acids. Although termed “non essential,” these amino acids are still crucial for various physiological processes. For instance, glutamine supports immune function and gut health.
Table 1.
Each amino acid plays an important role in the maintenance of health and cell function. Differing food sources present differing levels and combinations of amino acids. For a protein to be considered complete all essential amino acids most be present.
Table 2.
Recommended Intakes of Amino Acids: The recommended intake of amino acids varies based on age, sex, physical activity level, and overall health. The recommended intakes provide guidelines for essential amino acid consumption which aim to ensure adequate protein synthesis and maintenance of bodily functions. Providing the daily intake of protein is met from a high biological value source, the needs should be met.
The daily requirements of amino acids vary across different stages of human life due to factors such as growth, development, and maintenance needs. Table X below provides a general overview of the essential amino acids and their daily requirements for different life stages.
Table 3. Daily amino acid requirements for life stages[1]
* These values are averages and can vary based on individual health conditions, activity levels, and specific nutritional needs. It is essential to have a balanced diet to meet these amino acid requirements effectively.
The composition of varying proteins is unique with their influence on physiological function in the human body quite different. The quantity and quality of protein are vital in considering the nutritional benefits that it can provide. Determining the quality of protein is established by assessing its essential amino acid profile, digestibility, and bioavailability of the contained amino acids (refer back to Biological Value).
Milk Proteins
Generally speaking, we do not need to worry too much about individual amino acids as long as we consume sufficient amounts of high quality proteins as part of a healthy, well balanced meal
Milk proteins are high quality proteins due to their excellent amino acid profile, digestibility, and bioavailability[1] and so they are rightly considered to be an essential part of a balanced diet. Milk proteins are broadly classified into two categories of milk protein fractions: casein and whey proteins, which together, provide a complete amino acid profile and contribute to milk’s biological functionality.
The two primary types of proteins in milk are casein (approximately 80%) and whey (approximately 20%). Both types offer unique benefits.
When milk protein enters the stomach, it undergoes a process called coagulation due to the acidic environment and digestive enzymes present. This process forms a semi solid mass known as curd.
- Acidic Environment: The stomach secretes hydrochloric acid (HCl), which lowers the pH and creates an acidic environment.
- Enzymes: Pepsin, a digestive enzyme produced in the stomach, starts breaking down the milk proteins.
- Coagulation: Casein proteins in milk, which are insoluble in acidic conditions, coagulate to form a gel like substance or curd.
Importance of Curd Formation
The formation of curd in the stomach slows down the digestion of milk proteins, ensuring a gradual release of amino acids into the bloodstream. This slower digestion helps in the efficient absorption of nutrients from the milk. Curd formation is a natural and essential part of the digestive process for dairy proteins, ensuring that the body can properly utilize the nutrients found in milk.
To better understand the nutritional benefits of milk, here is a comparison of the amino acid composition percentages in cow’s milk casein and whey proteins. The values are expressed as the percentage of each amino acid in the total protein content.
Table 4
| Amino Acid | Casein (%) | Whey (%) |
| Essential Amino Acids | ||
| Histidine | 2.7 | 1.7 |
| Isoleucine | 5.3 | 6.5 |
| Leucine | 9.2 | 10.9 |
| Lysine | 7.4 | 9.8 |
| Methionine | 2.8 | 2.2 |
| Phenylalanine | 5.1 | 2.8 |
| Threonine | 4.2 | 6.7 |
| Tryptophan | 1.4 | 1.4 |
| Valine | 6.6 | 5.9 |
| Non Essential Amino Acids | ||
| Alanine | 3.0 | 5.0 |
| Arginine | 3.7 | 2.1 |
| Aspartic Acid | 6.1 | 10.0 |
| Cystine | 0.3 | 2.0 |
| Glutamic Acid | 20.5 | 15.4 |
| Glycine | 1.9 | 1.8 |
| Proline | 10.1 | 5.9 |
| Serine | 5.5 | 4.6 |
| Tyrosine | 5.6 | 2.9 |
Key Points
- Casein: Has a higher proportion of proline and glutamic acid. It is less soluble and forms a gel or curd in the stomach, leading to slower digestion.
- Whey: Contains higher levels of branched chain amino acids (leucine, isoleucine, valine), aspartic acid, and cystine. It is more soluble and digests quickly, providing a rapid source of amino acids.
These differences make casein and whey proteins suitable for different nutritional needs and uses. For instance, whey is often preferred for post exercise recovery due to its fast absorption, while casein is favoured for sustained protein release, such as before sleep.
Table 5. The primary types of casein proteins in milk[2]
| Casein Protein Factions and Their Actions | Actions and Benefits |
| Alpha casein (α casein)
The most abundant casein, comprising about 40 50% of total casein. It plays a crucial role in micelle formation and stability. |
Slow Digestion: Casein forms a gel like substance in the stomach, leading to a slow and steady release of amino acids into the bloodstream. This property makes it ideal for sustaining muscle protein synthesis over extended periods, such as overnight.
Muscle Maintenance: The prolonged release of amino acids helps in maintaining muscle mass, making casein beneficial for athletes and individuals seeking to preserve lean body mass. Satiety: Casein’s slow digestion can enhance feelings of fullness, aiding in weight management.
|
| Beta casein (β casein)
Constitutes about 25 35% of total casein and is important for micelle structure and function. |
|
| Kappa casein (κ casein)
Makes up 10 15% of total casein and stabilizes casein micelles by preventing their aggregation. |
|
| Gamma casein (γ casein)
Derived from the breakdown of beta casein, it is present in smaller amounts.
|
Whey: Known for its rapid digestion and absorption, whey protein is rich in branched chain amino acids (BCAAs) like leucine, which are critical for muscle protein synthesis[3]. Whey is often favoured by athletes and bodybuilders for post exercise recovery.
Table 6. The primary types of whey proteins in milk[4]
| Whey Protein Factions and their Actions | Actions and Benefits |
| Beta lactoglobulin (β lactoglobulin):
The most abundant whey protein, accounting for about 50 60% of whey protein. It is rich in branched chain amino acids (BCAAs), particularly leucine. |
Rapid Digestion: Whey proteins are quickly digested and absorbed, leading to a rapid increase in amino acid levels in the bloodstream. This makes whey ideal for post exercise recovery when quick protein synthesis is needed.
Muscle Protein Synthesis: The high leucine content in whey proteins effectively stimulates the mTOR pathway, promoting muscle protein synthesis and muscle growth. Immune Support: Immunoglobulins and lactoferrin in whey protein contribute to enhanced immune function and overall health. Antioxidant Properties: Whey proteins can boost the body’s antioxidant defences by increasing glutathione levels, a critical antioxidant in the body. |
| Alpha lactalbumin (α lactalbumin):
Comprises about 20 25% of whey protein and is high in essential amino acids, especially tryptophan. |
|
| Immunoglobulins:
These proteins, including IgG, IgA, and IgM, make up about 10 15% of whey protein and play a role in immune defence. |
|
| Lactoferrin:
A multifunctional protein that binds iron and has antimicrobial and anti inflammatory properties. |
|
| Bovine Serum Albumin (BSA):
Represents about 5 10% of whey protein and is a good source of essential amino acids. |
Milks unique combination of casein and whey proteins leverages the unique benefits of each, which cannot be recreated or reformulated in plant based milk alternatives.
The rapid absorption of whey provides immediate amino acids for muscle repair, while the slow digestion of casein ensures a prolonged supply, optimising muscle maintenance and growth[5]. This combination is particularly beneficial for athletes seeking comprehensive protein support.
Choose SuperNutrio’s milk for a significant nutritional upgrade. A complete amino acid profile from whey and casein proteins.
100% more protein, 80% more calcium, and 60% more phosphorus than standard cow’s milk.
Note that the additional calories are from protein, with the fat content remaining the same.
SuperNutrio’s milk range is a natural, whole food option for achieving a healthier, more nourished lifestyle.
[1] Goulding, D. A., Fox, P. F., & O’Mahony, J. A. (2020). Milk proteins: An overview. Milk proteins, 21 98.
[2] Goulding, D. A., Fox, P. F., & O’Mahony, J. A. (2020). Milk proteins: An overview. Milk proteins, 21 98.
[3] ncbi.nlm.nih.gov/pmc/articles/PMC7760188/
[4] Goulding, D. A., Fox, P. F., & O’Mahony, J. A. (2020). Milk proteins: An overview. Milk proteins, 21 98.
[5] Amawi, A., AlKasasbeh, W., Jaradat, M., Almasri, A., Alobaidi, S., Hammad, A. A., … & Ghazzawi, H. (2024). Athletes’ nutritional demands: a narrative review of nutritional requirements. Frontiers in Nutrition, 10, 1331854.
[1][1] Biochemistry, Essential Amino Acids StatPearls NCBI Bookshelf (nih.gov)
[1] Yu, Y. M., & Fukagawa, N. K. (2020). Protein and amino acids. In Present knowledge in nutrition (pp. 15 35). Academic Press.
