Milk protein is considered as one of the best sources of protein. Proteins are broken down into amino acids when metabolised, which play a crucial role in keeping our body’s processes functioning normally. Out of 20, there are a total 9 essential amino acids which our body is unable to synthesize on its own, therefore, has to be supplied externally either through diet or supplement.
Milk is one such food that provides two excellent sources of protein - whey and casein. Both contain all essential amino acids along with other nutrients like calcium, sodium, magnesium, zinc and phosphorus. Due to their excellent nutritional profile and digestibility, whey and casein are consumed separately in the form of supplements, especially by athletes and fitness enthusiasts.
Both whey and casein are extracted from milk. They have excellent protein quality but may differ in their carbohydrate and fat content. Other two factors on which whey and casein differ is their amino acid releasing property and content of amino acids.
Whey protein is a fast-digesting protein which means that when consumed, it gets digested rapidly and quickly supplies amino acids to our body. Due to this reason whey protein is preferably consumed post an intense exercise or workout session as it's fast releasing amino acid property aids in swift recovery of muscles. It transitions our body from catabolic to an anabolic state. Also, the most abundant amino acid present in whey is leucine. It is one of the branched-chain amino acids, which is referred to as the anabolic amino acid as it significantly maximises muscle protein synthesis. Hence, whey protein is ideal when there is a prompt need of amino in the body.
Casein protein, on the other hand, is regarded as the slow-digesting protein. This makes casein beneficial for muscle maintenance and sustained recovery of muscles for a longer duration. Casein protein is recommended at bedtime for overnight recovery and to prevent any dip in the amino acid level of the body. For instance, if an athlete has an early morning competition like a marathon and has less time to consume any pre-sport meal. In such cases, casein protein consumed at bedtime, one night before competition assists in providing strength to muscles to bear the stress during running. It reduces injury risk and minimises muscle damage. Similarly, a strength athlete going to the gym in the evening can also consume casein protein in the morning to reap its benefits during an exercise session without causing a load on the stomach. Casein protein has also been shown as a boon for our mental health. This is because it contains glutamic acid amino acid in abundance, which is utilised by our body to synthesize GABA. Gamma-aminobutyric acid (GABA) is a neurotransmitter that alleviates stress, anxiety and reduces the likelihood of depression.
To sum up, both whey and casein protein are excellent for our health. They both have a PDCAAS value of 1 indicating a good quality protein source. Whey one on hand stimulates muscle growth and casein, on the other hand, helps maintain a positive nitrogen balance in the body during fasted state at night and preserve our muscles. Hence, to enjoy their benefits, one needs to carefully assess the timing of whey and casein intake as both are equally fab for our health. These days, one can find supplements containing a blend of whey and casein protein, which is also the best approach.