Protein intake that exceeds the recommended daily allowance is widely accepted for both endurance and power athletes. However, considering the variety of proteins that are available much less is known concerning the benefits of consuming one protein versus another. Animal proteins is an important source of protein containing all essential amino acids, however potential health concerns do exist from a diet of protein consumed from primarily animal sources. With a proper combination of sources, vegetable proteins may provide similar benefits as protein from animal sources. Combining animal and plant proteins might provide an optimal approach to healthy protein intake and better results than a single source. In this post, we try to analyse two major sources of protein (i.e. milk and soy) based on their health benefits and scientific evidence.
Milk protein consists of two major components; Whey and Casein
Whey is a general term that typically denotes the translucent liquid part of milk that remains following the process (coagulation and curd removal) of cheese manufacturing. Whey is a complete protein whose biologically active components provide additional benefits to enhance human function. Whey protein contains an ample supply of the amino acid cysteine. Cysteine appears to enhance glutathione levels, which has been shown to have strong antioxidant properties that can assist the body in combating various diseases (Counous, 2000). In addition, whey protein contains a number of other proteins that positively effect immune function such as antimicrobial activity (Ha and Zemel, 2003). Whey protein also contains a high concentration of branched chain amino acids (BCAA) that are important for their role in the maintenance of tissue and prevention of catabolic actions during exercise. (MacLean et al., 1994).
Casein exists in milk in the form of a micelle, which is a large colloidal particle. Casein is the major component of protein found in bovine milk accounting for nearly 70-80% of its total protein and is responsible for the white colour of milk. Similar to whey, casein is a complete protein and also contains the minerals calcium and phosphorous. An attractive property of the casein is its ability to form a gel or clot in the stomach. The ability to form this clot makes it very efficient in nutrient supply. The clot is able to provide a sustained slow release of amino acids into the blood stream, sometimes lasting for several hours (Boirie et al. 1997). This provides better nitrogen retention and utilisation by the body.
Soy is the most widely used vegetable protein source. Based on accurate PDCAAS scale, soy protein is reported to be equivalent to animal protein with a score of 1.0, the highest possible rating (Hasler, 2002). Soy’s quality makes it a very attractive alternative for those seeking non-animal sources of protein in their diet and those who are lactose intolerant. Soy is a complete protein with a high concentration of BCAA’s. There have been many reported benefits related to soy proteins relating to health and performance (including reducing plasma lipid profiles, increasing LDL-cholesterol oxidation and reducing blood pressure). . Epidemiologists were most likely the first to recognise soy’s benefits to overall health when considering populations with a high intake of soy. These populations shared lower incidences in certain cancers, decreased cardiac conditions, and improvements in menopausal symptoms and osteoporosis in women (Hasler, 2002). Based upon a multitude of studies examining the health benefits of soy protein the American Heart Association issued a statement that recommended soy protein foods in a diet low in saturated fat and cholesterol to promote heart health (Erdman, 2000). The health benefits associated with soy protein are related to the physiologically active components that are part of soy, such as protease inhibitors, phytosterols, saponins, and isoflavones (Potter, 2000). These components have been noted to demonstrate lipid-lowering effects, increase LDL-cholesterol oxidation, and have beneficial effects on lowering blood pressure.
References