Dual Proteins: For Steady Protein Release And Muscle Formation In Children And Adults

Dual protein combinations containing a blend of soy and dairy proteins (whey and casein) have sufficient essential amino acid content, various digestion rates and longer aminoacidemia compared to single protein isolates to offer unique advantage to health. This article will focus on different source of proteins and their effect on health and disease.

Proteins are the major building blocks or structural components of muscles and various other tissues of the body. They are used in production of hormones, hemoglobin and enzymes, and can also be utilized as a source of energy. The composition of various proteins differs from each other, which influences their physiological role in the body [1]. While considering the nutritional value, the quality of a protein depends on the essential amino acid composition and its bioavailability or digestibility [2].

Types of proteins

There are various animal and plant sources of proteins available. Animal proteins are complete containing all the essential amino acids. Plant sources of proteins are usually incomplete of atleast one or more essential amino acids, with soy as an exception. The following table provides an overview on each type of protein along with its constituents and varieties [1, 3]. (Fig 1)

Fig. 1 Different types of proteins from animal and plant sources

Benefits Of Different Type Of Proteins

  1. Whey:
  • Antimicrobial, immune modulating and anticancer activities [4].
  • Cardiovascular benefits
  • Cysteine enhances glutathione levels and exerts strong antioxidant properties [1].
  • High glutamine content of whey prevents stomatitis and peripheral neuropathy during chemotherapy [5].
  • Therapeutic effect on type 2 diabetic patients by reducing postprandial blood glucose levels and stimulating insulin release [6,7].
  • Improves weight loss, decrease body fat, lower blood pressure and improve hypertension by inhibiting angiotensin converting enzyme that causes arterial vasoconstriction [4].
  1. Casein:
  • Exists in the form of micelles that have an attractive property of forming clot or gel in the stomach.
  • Facilitate efficient nutrient supply by providing sustained slow release of amino acids (several hours after ingestion) into the blood stream.
  • Bioactive peptides of casein such as casoplatelins and αs1-casein-f play antithrombotic and antihypertensive role in cardiovascular system respectively
  • caseinophosphopeptides (CPP) and glycomacropeptide (GMP) play agonistic as well as antagonistic role in nutrition system. [8].
  1. Soy:
  • Physiologically active components of soy- isoflavones, saponins, phytosterols and protease inhibitors [1].
  • Soy protein supplementation has a positive effect in maintaining bone mineral content
  • Lowering menopausal symptoms severity and reducing breast cancer and prostate cancer risk [1, 9].

Protein digestibility corrected amino acid score (PDCAAS)

In 1989, FAO and WHO jointly stated that the quality of a protein can be determined by calculating the percentage of content of the 1st limiting essential amino acid present in the test protein to the same amino acid content in a reference protein [1, 2, 10]. The reference values were based upon the requirement of essential amino acids by children of preschool age. The percentage is subsequently corrected for true fecal digestibility of test protein, which is measured by rat assay. This value is called protein digested corrected amino acid score (PDCAAS).

The formula for calculating PDCAAS percentage is –

(mg of limiting amino acid in 1g test protein / mg of same amino acid in 1g reference protein) x true fecal digestibility % x 100

The highest PDCAAS score is 1.0, which means that after digestion, the protein provides 100% or more of the required essential amino acids.

Dual protein for steady protein release and muscle synthesis

Protein intake exceeding the recommended daily allowance is widely accepted to support over all growth, development, and weight management. In addition, an area of expanding research is the evaluation of comparative effects of individual and dual protein sources [1, 11]. Dual proteins are formed by blending soy protein with milk proteins (whey and casein) and offer several advantages over individual proteins; as follows:

Table 1. depicting the advantages of dual protein combination

Benefits of Sustained Amino Acid Release

Several protein and amino acid supplementation have a rapid release (RR) formulation. However, RR presents several complications and can also lead to unknown metabolic fate or higher content excretion via urine. For example, RR of β-alanine supplementation results in  greater risk of paresthesia symptoms, which include flushing, irritation, and pricking of skin. In contrast, dual proteins are formulated with sustained amino acid release formulation that can reduce complications and potentially allow a greater daily dose for consumption along with greater amino acid availability to the muscles [12].

Due to demands of growth and development, adequate protein consumption is particularly significant during childhood and adolescence. As children generally are fussy eaters, malnourished, low in immunity, or fall sick often, dual protein serves as an important source for growth, improves immunity, supports brain development, and by fulfilling the nutritional gap. Younger adults who are gym enthusiasts or want to reduce weight, undergo strength and resistance training for muscle building that leads to increased protein demands [1]. Muscle protein synthesis is stimulated at a higher pace with exercise as a stimulus. In such cases, dual proteins act as an essential reserve of proteins that contribute to muscle hypertrophy, by providing essential amino acids over sustained duration and reducing their metabolic excretion [13]. In addition, dual proteins also contain branch chained amino acids (BCAAs), which along with exercise directly increase protein synthesis in the skeletal muscle. Moreover BCAAs have anabolic effects on protein metabolism by increasing and decreasing the rate of protein synthesis and protein degradation, respectively that induce an increase skeletal muscle mass [14].

However, in adults, nutritional requirements continue to differ as per age-related biological and physiological changes. Several studies have demonstrated that body weight and body mass index start declining after the age of 50 years. The etiology of weight loss is a decline in the skeletal muscle mass, mainly characterized as wasting, cachexia, or sarcopenia and is caused due to poor dietary intake, chronic diseases, and age related changes. The recommended dietary allowance (RDA) for adults irrespective of age is 0.8 g protein/kg body weight per day, which is the minimum amount of protein to avoid progressive loss of lean body mass [15]. Dual protein supplementation in such cases can significantly improve muscle mass, strength, and function in adults. In addition, high protein sources have been shown to increase energy and protein intake in critically ill patients. Supplements have also been shown to improve clinical and functional outcomes and reduce mortality rate [13].

Evidence for Dual Protein benefits

Reidy et al performed a randomized, double-blind, clinical trial demonstrating the effect of soy-dairy protein blend on muscle protein synthesis following resistance exercise compared to whey isolate [16]. They studied 19 young adults, before and after ingesting the soy-dairy protein blend or whey protein 1 hour after high-intensity leg resistance exercise. They found that protein blend was non-inferior in stimulating muscle growth compared to whey protein. Additionally, the protein blend also stimulated fractional synthetic rate (FSR) into late post-exercise period, compared to whey which only stimulated FSR in the early recovery period.

In another randomized, double-blind clinical trial, Reidy et al demonstrated that ingesting soy-dairy protein blend prolongs the net amino acid balance in human skeletal muscle compared to whey protein [17]. Skeletal muscle proteostasis is determined as the balance between muscle protein synthesis and mucle protein breakdown. The essential amino acids ingested from dietary protein sources stimulates synthesis of skeletal muscle proteins including sarcoplasmic, myofibrilar and mitochondrial proteins [18, 19]. Essential amino acids stimulate the key signaling  m-TOR pathway that regulates the muscle protein synthesis by enhancing phosphorylation of mTOR, 4EBP-1 and p70S6K1 [18].

In conclusion, the dual protein blend can be more beneficial because of the unique properties of each protein. This facilitates optimal delivery of essential amino acids according to the varying requirements of human body.

CTA-  What do you think are the benefits of using a dual protein combination for improving health?


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