Protein hydrolysates/hydrolysed proteins have a clear advantage over the intact proteins particularly in terms of higher rate of absorption and better muscle protein synthesis. It has a broad range of application and could be used effectively by individuals recovering from sickness/ injury and elderly where malabsorption is common, to individuals engaged in physical activity for faster recovery post work out. This article thus elaborates the various benefits of protein hydrolysates compared to intact proteins.
Nutritional supplements are designed to provide complete or partial nutritional support to individuals who are unable to ingest adequate amounts of food in a conventional form. In people who are recovering from an illness/surgery, nutritional supplements play an important role. Specialized nutritional support is also needed for people with particular physiological and nutritional needs (such as women with gestational diabetes, elderly people). The nutrition supplements could help to bridge the nutrition gap from the diet and thereby assist to maintain the nutritional status of individuals.
Among the various nutrients, dietary proteins have been extensively studied for their use in clinical diets and specific formulations (Clemente, 2000). The Proceedings of the first Protein Summit joined by more than 60 nutrition scientists, health experts, and nutrition educators summarized the role of protein in various health conditions. Some of them were greater weight loss, fat mass loss, better preservation of lean body mass, a more significant reduction of blood pressure, serum triglycerides, and waist circumference following higher protein vs. low protein restricted diets, both in the short and long term.
In many clinical conditions, especially those affecting the digestive and absorptive capacity of the body, it may not be feasible to administer adequate amounts of intact protein. In allergic patients, there is a possibility of intact proteins triggering immune mediated hypersensitive reactions. In these cases, we need alternatives to intact proteins, which could be - 1.Protein hydrolysates and 2. Mixture of synthetic amino acids. Among the two, protein hydrolysates show several advantages over a mixture of free amino acids and considered to be a more efficient method of protein delivery (Clemente, 2000).
What are hydrolysed proteins?
Protein hydrolysates are produced from purified protein sources by heating with acid or preferably, addition of proteolytic enzymes, followed by purification procedures. It mimics the digestion process and result in intact proteins breaking down into smaller peptide strands containing few polypeptides along with tri and di peptides and free amino acids (Manninen, 2009).
How is the digestion and absorption of hydrolysed proteins faster than intact protein?
Intact proteins: Intact proteins are complex protein molecules containing higher peptide groups which require several steps of digestion and absorption, elicited by hydrolytic enzymes in the stomach, pancreas and small intestine, as described below (Erickson and Kim, 1990).
- Intact proteins are first split into smaller fragments - pepsin (stomach) or trypsin/ chymotrypsin (pancreas) –Proteoses, peptones and poly peptides are obtained.
- These enter into the small intestine and are acted upon by trypsin, chymotrypsin and carboxypeptidase -further broken down into smaller peptides.
- Smaller peptides are acted upon by di peptidases and amino peptidase in the brush border and release di and tri peptides, and a few free amino acids.
- Tri and di peptides enter the enterocytes where they are acted upon by intracellular peptidase - to convert them to single free amino acids. These enter the blood stream and are transported to liver by the hepatic portal system.
Hydrolysed protein/Protein hydrolysate: Contain mostly di and tri peptides which are easily absorbed through the brush border, escaping out the earlier steps of digestion (Manninen, 2009). Hence, it can be said that protein hydrolysates are a form of “pre-digested” proteins that are easily digested and absorbed by the human body as compared to intact proteins.
What are the advantages of hydrolysed protein over intact protein?
Hydrolysed protein are said to be more effective in stimulating skeletal muscle protein synthesis than intact protein (Manninen, 2006). The following beneficial effects have been attributed to hydrolysed protein:
- Increased & faster availability of amino acids
Protein hydrolysates are known to increase plasma amino acid concentrations compared to intact protein, accelerates protein digestion and absorption from the gut, augments postprandial amino acid availability, and tends to increase the incorporation rate of dietary amino acids into skeletal muscle protein (Koopman et al, 2009).
- Protein hydrolysate induced a 25-50% higher plasma amino acid peak compared to intact protein (Koopman et al, 2009) thereby leading to greater muscle protein synthesis.
- The hydrolysates elicited about 50% more gastric secretion than the whole protein solutions, leading to better amino acid absorption (Calbet and Holst, 2004).
- Protein hydrolysates are absorbed at a faster rate from the small intestine than are intact milk proteins, as reflected by the rapid increase in the plasma concentration of branched-chain amino acids in peripheral blood. A 37% higher increase in plasma amino acids was seen with protein hydrolysate compared to intact protein (Manninen, 2006).
- Greater insulinotropic effect
Protein hydrolysates have a significantly higher insulinotropic effect i.e. enhancing the production/activity of insulin, compared to intact protein. It has been suggested that the greater insulin response contributes to muscle protein anabolism (Manninen, 2006).
- Ingestion of protein hydrolysate caused 28% higher insulin concentration compared to intact protein (Power et al, 2009)
- Plasma insulin responses were found to be 108% higher in an athlete group consuming Carbohydrate + protein hydrolysate meal compared to those consuming only carbohydrate meal (Kaastra et al, 2006).
- Faster recovery post workout and intra workout performance
There is evidence that protein hydrolysates can speed tissue repair following damage and may therefore be useful for accelerating recovery from exercise induced muscle damage. In a study by Buckley et al (2010), participants consuming protein hydrolysate recovered after eccentric exercise within 6h whereas those consuming intact protein or flavored water did not fully recover till 24h (Buckley et al, 2010).
- Effective in Elderly population
There is reduction in rate and efficiency of protein digestion and subsequent absorption of amino acids in elderly. It is suggested that the ingestion of protein hydrolysates, as opposed to its intact protein, might accelerate protein digestion and absorption, increase plasma amino acid availability and as such, augment the postprandial muscle protein synthetic response (Koopman et al, 2009).
Protein hydrolysates offer several advantages over intact proteins and therefore could be effectively utilized for various conditions wherein the absorption capacity of nutrients is compromised and the need for protein is high. Hydrolysed proteins could also be advantageous when included in the diets of healthy individuals engaged in physical activity, mainly due to its effect on recovery post exercise and better muscle protein synthesis compared to intact proteins.