What is Protein?

• Protein is the second most important nutrient for our body after water.
• Proteins are a major active component of all of our cells in the body and are dynamically turning over all the time – meaning they are constantly being broken down into their constituent amino acid units and resynthesized into the macromolecules that they are.
• Maintaining an adequate level of protein mass in the body is crucial for normal health and development.

What is milk protein?

• Milk Protein is a type of protein that is derived from filtered milk and is formed from whey and casein proteins.
• The Milk Protein yielded is an excellent source of calcium, high in branch chain amino acids and low in fat.

Whey Protein and It’s Importance in performance nutrition?

• Whey protein is part of milk protein, about 20% of the total proteins of bovine milk are Whey proteins.
• Whey protein acts as a fast protein.
• Whey Protein is high in Branched Amino acids (BCAA) which helps in muscle development and fastest recovery

Salient features of Milk Protein

Whey and casein - Protein Combination and quality

• Whey and casein are digested at different rates. Protein digestion increases plasma amino acid concentration and the rate at which this increase occurs determines whether a protein source is considered slow or fast.
• Whey protein acts as a fast protein (i.e. quickly or easily to digested) Casein (milk protein) is a slow protein (i.e. It gets slowly digested and releases amino acids into circulation slowly in a constant rate). Although whey does peak plasma amino acid levels it does not begin to digest any faster than other sources of protein.
• Protein digestibility corrected amino acid score (PDCAAS) is a method of evaluating the protein quality based on both the amino acid requirements of humans and their ability to digest it. The PDCAAS score for casein and whey are identical thus; both are high in quality [USDE Council 1999and FAO/WHO/UNU 2007].
• Protein:Energy ratio (P:E - energy contributed from protein) ~14% which is an appropriate recommended level for adults according to recent FAO/WHO/UNU 2007 report. Usually high P:E ratio is recommended in people who train with heavy physical activity (e.g. resistance exercise by athletes or sportspersons). In the case of N-NO, the P:E ratio is higher at 17% [www.cimsasia.com July 2012] .

Amino acid profile

• Branch chain amino acids (BCAA) (leucine, valine, phyenylalnine and tyrosine) content are lower in casein than whey protein but valine and phenylalanine are higher
• Leucine is essential for muscle protein synthesis by enhance the activation of mTOR-signalling proteins.
• Valine, phenylalanine and tyrosine are limited in whey protein and since amino acids in whey are absorbed very fast, there is a sudden rise in the amino acid pool which can’t be adequately assimilated into muscle proteins and instead may be oxidized and lost. But the slow protein: fast protein ratio to lead to a sudden rise in the amino acid pool which leads to better muscle protein synthesis.

Physical activity and post-prandial protein utilization

• Rapid release of amino acids from the higher level of fast protein (whey) is beneficial for people with strenuous physical activity like body builders and athletes. But in sedentary people and hospitalized patients, the slower release of amino acids for protein synthesis from the higher proportion of slow protein (casein) leads to better bio-availability in the terms of prolonged supply of amino acid into the circulation than the fast protein and less protein degradation.

Summary of different proteins and functions (adapted from Paul 2009)

Functions	Whey protein	Casein	Combination
Complete protein	✔	✔	✔
Digestion	Fast	Slow	Prolonged
Adds Lean Body Mass	✔	✔	✔
High in Leucine	✔		✔
High in Glutamine		✔	✔