Magazine Critic: 5 benefits of casein protein. Exercise has a profound result on muscle growth and for muscle protein metabolism, amino acid availability is an important regulator (Tipton and Wolfe, 2001). Casein protein has been identified as being a ‘slower’release protein which results in an attenuated release of its amino acids (Kerksick et al., 2006). An article published by Men’s Health Magazine (2017) compiled a list of the five most important benefits of consuming casein, listed below: 1. Casein “lasts” longer in your systemMen’s Health Magazine (2017) highlights casein’s greatest strength as being timing. According to Men’s Health Magazine (2017), ‘Casein has the ability to provide your bloodstream with a slow and steady flow of amino acids that could last for hours’. Casein is considered a ‘slow’ protein as it is emptied from the stomach slower than ‘fast proteins’ such as whey proteins (Tipton et al., 2004). Tipton et al., 2004 suggest that amino acids from casein appear in the blood more slowly and peak at a lesser magnitude however where they differ to fast proteins is that the response lasts longer. A study conducted by Boirie et al., (1997) demonstrated that amino acid absorption was faster with whey protein than with casein. Boirie et al., (1997) identified that casein promotes protein deposition by inhibiting protein breakdown without increasing amino acid concentrationexcessively, where-as in contrast, a fast-dietary protein stimulates both protein synthesis and oxidation. Whey protein has been found to cause increases in blood amino acids in under an hour, with peak levels under 90 minutes (Kollias, 2017). In contrasts casein takes longer to increase blood amino acids but remains elevated for over 300 minutes (Boire et al., (1997). 2. Casein yields greater gainsMen’s Health Magazine (2017) refer to a Texas study consisting of 36 males who performed a heavy resistance training programme where results concluded that the group consuming a whey and casein combination had significantly improved performance levels when compared with participants who consumeda combination of whey, BCAAs, and glutamine supplement. The Texas study referred to was completed by Kerksick et al., (2006) which evaluated whether 2 different forms of protein supplementation (whey protein with casein or whey protein with BCAA and glutamine) would elicit greater changes following a 10-week training program in comparison to subjects who ingested an isoenergetic amount of carbohydrates. A double-blind manner was applied to methodology eliminating the element of bias. Significant improvements in 1RM bench and leg press were demonstrated after 10 weeks of training. It was identified that the greatest increase in fat-free mass was found within the whey and casein protein group which is suggested that these findings can be used to improve body composition during resistance training. It is important to note that these findings were based on casein being used in conjunction with whey protein alongside a resistance training programme therefore more research is needed to examine the effects of casein supplementation alone, alongside evaluating the timings of supplementation in conjunction with training programmes. A study conducted by Pennings et al., (2011) found that whey protein stimulated greater postprandial muscle accretion more effectively in elderly subjects than casein which was attributed to whey’s faster digestion, absorption kinetics and higher leucine content. Findings by Burd et al., (2012) match that of Pennings et al., (2011) in a small study of 14 older male participants who conclude that whey protein stimulates greater rates of myo-fibrillar protein synthesis at rest and after resistance exercise. Leucine is a key amino acid for activating protein synthesis and uniquely activates protein synthesis through mammalian target of rapamycin (mTOR) pathway and since whey protein has a greater content of leucine it is the primary choice for building muscle mass (Kollias, 2017). 3. Casein helps improve metabolic rateMen’s Health Magazine (2017) base this claim on a study conducted in the Netherlands ‘found that by multiplying casein intake by two and a half times, participants had improved overall fat balance and increased metabolic rate whilst sleeping. Also of note is that satiety levels were 33% higher.’ The study referred to was a randomised crossover design conducted by Hochstenbach-Waelen et al., (2009), where 30 subjects were required to stay in a respiration chamber for 36hours twice. Subjects received 1 of 2 diets (10En% or 25En% protein diet with casein as the only protein source) while in the chamber. This methodology of a randomised crossover design could yield a more efficient comparison of treatments however it could be argued that the carry over effects from the initial sampling could affect results. A study conducted by Kinsey et al., randomly assigned 12 obese males in a crossover design to either ingest casein protein (within 30 min of sleep) or a non-nutritive placebo before sleep. Results demonstrated that consumption before sleep had no effect on glucose and fat metabolism or reduce appetite in hyper-insulemic obese men.Similar findings were found in a small study of 11 participants by Madzima et al., (2014) who concluded that although night time consumption of whey, casein and carbohydrates elicited favourable effects on metabolism, there was no significant difference between whey and casein. It is suggested that further research is required assessing the effects of casein on metabolic rate on greater sample sizes to improve validity. 4. Casein yields greater strengthMen’s Health Magazine (2017) refer to a Massachusetts study by Demling and DeSanti (2000), where researchers found that casein doubled the effect that whey protein had on legs, chest, and shoulder strength results. Results were believed to be due to casein’s well-known anti-catabolic abilities. Demling and DeSanti (2000) evaluated body compositional changes in overweight police officers between a hypocaloric diet alone and hypocaloric diet plus resistance exercise plus a high-protein intake (1.5 g/kg/day) using a casein protein hydrolysate. Mean increase in strength for chest, shoulder and legs was greater for casein compared with whey. It can be disputed that it is difficult to relate these findings to the general population as it is a ‘niche’ study evaluating the effects on a small sample size of specifically overweight police officers. In contrast to these findings, during a 10-week resistance programme conducted by Cribb et al., (2006) participants who supplemented whey protein into their diet found a significant difference in lean mass, change in fat mass and improvements in strength compared to participants who supplemented casein. Although the study conducted was a double-blind protocol to allow for elimination of bias – again it was conducted with a relatively small participant group of only 13 male recreational body builders therefore it can be argued whether findings are representable to the whole population. 5. Casein beefs up your teethThe final claim is referred from a U.K study which reports casein has the potential to reduce or prevent the effects of enamel erosion. The article ends by stating ‘So if you drink a lot of fruit juices, or just can’t kick the soft drink habit, at least consider protecting your teeth by adding some casein protein to your diet.’Milk has been proven to reduce the acid solubility of enamel (Jenkins and Ferguson, 1966; Weiss and Bibby, 1966a). It is suggestive that milks demineralisation reducing properties originating from its calcium and phosphate content (Jenkins and Ferguson, 1966). However, Weiss and Bibby (1966b) demonstrated that this protective effective from milk was due to casein in the decalcifying buffer which was far superior than ion effect of calcium and phosphate content. Furthermore, it has been suggested in several studies that casein absorbs to the tooth surface, altering the surface chemistry and that the protective effect of milk is related to caseins ability to reduce bacterial adhesion (White, Gracia and Barbour, 2011). White, Gracia and Barbour (2011) concluded that solutions of casein, CPP or GMP reduce surface softening and erosion in vitro erosion models with the suggestion of a number of possible ways in which the protein layer could be protective against erosion. In a small study of 10 participants, conducted by Vashisht et al., (2010) a casein phosphor-peptide-amorphous calcium phosphate nano-complexes (CPP-ACP) paste was found to be effective in preventing demineralisation of tooth enamel. Vashisht et al., (2010) contribute findings to the CPP-ACP pastes ability to buffer free calcium and phosphate ions thereby promoting a state of supersaturation and as a result preventing demineralisation and enhancing remineralisation. There is sufficient evidence to demonstrate positive training effects for both whey and casein as since whey increases protein synthesis rapidly whilst casein inhibits protein breakdown, it is suggested that a combination of both would stimulate the greatest training effects, rather than casein alone. Protein requirements should be met through the food first approach, especially seeing as casein is so prevalent in dairy. However, for individuals who are insufficient due to training demands, there is evidence to suggest positive benefits of consuming casein supplementation.