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Protein Supplements: Which "Whey" to Go?
By Matthew T. Stratton, BS, Trisha VanDusseldorp, PhD, and Len Kravitz, PhD

As a fitness professional working with enthusiastic resistance training clients, the topic of protein supplementation in inevitable. Protein supplements are some of the most common and popular nutritional supplements on the market today (Pasiakos et al., 2014). However, it is easy to get lost in the colorfully stocked shelves and become confused on what type, how much, and when to use these supplements. This article will attempt to provide person trainers with practical answers and applications by examining the current scientific evidence. Guiding clients toward evidence-based literature and referring them to licensed dietary pros you trust--rather than recommending or prescribing specific supplements--is the smart approach when eading into these waters. Before getting started, review your scope of practice in this area, and know your boundaries in order to protect yourself.

The Basics of Protein
Protein is made up of nitrogen containing substances called amino acids. Furthermore, the 20 naturally occurring amino acids are further broken down into two subclasses: essential or nonessential. The term “essential” refers to the fact that these 9 amino acids must be obtained from food, because the body cannot synthesize them. The remaining 11 amino acids are deemed “nonessential” because the body can synthesize them. Overall, amino acids are the building blocks for many components in the body, like muscle protein, via a process referred to as muscle protein synthesis (MPS). Humans need to take in enough protein to provide adequate amino acids to support metabolic processes, like MPS to build or maintain skeletal muscle mass (Laymen et al. 2015; Phillips, 2004).

Not All Protein is Created Equal!
Dietary protein can come in one of two forms, complete protein or incomplete proteins. Complete proteins contain all essential amino acids needed for MPS, which means they are fine to take by themselves. Complete proteins are typically derived from animal and dairy sources. Several vegetable-based proteins are classified as incomplete proteins, meaning the protein is missing one or more essential amino acids and therefore would need to be combined with a second protein source missing a different amino acid. This would then provide all essential amino acids needed for optimal MPS, and is a practice called mutual supplementation (Onoja and Obizoba, 2009). With a basic understanding of what protein is why it is needed for MPS, let's shift the focus to protein supplements.

Whey: From Concentrate to Isolate…What is the Difference?
Today, there are a slew of protein supplements on the market. They can range from dairy derived protein, like whey and casein, to vegetable based proteins such as soy and quinoa. A commonly purchased and consumed protein supplement (as of late) is whey protein. Whey protein is derived from milk protein (20% whey, 80% casein). Whey protein, much like the other dairy and animal proteins, is a complete protein. Furthermore, whey protein is commonly categorized as isolate or concentrate. Whey protein concentrate is the closer of the two to its original milk protein form. Because whey protein concentrate is known to have some lactose still present in the powder, it may cause gastric issues to those who are lactose intolerant. Therefore, it would be best for these individuals to stick to using a whey protein isolate (WPI). In a WPI the protein goes through a process where it is separated from fat, cholesterol and lactose, meaning it is a purer protein as the end product. This in turn would make WPI safe for individuals who are lactose intolerant (Hoffman and Falvo, 2004). A protein label may include the term, hydrolyzed, which means the protein has been broken into its component amino acids. Currently, there is no literature investigating the efficacy of using a hydrolyzed whey protein isolate over the non-hydrolyzed counterpart.

Casein: The Night Time Protein
Probably the next most commonly seen form of protein supplementation is that of casein protein, which has a similar MPS to whey protein (Tipton et al., 2004). Casein protein, once again, is derived from milk protein, comprising the remaining 80% of milk protein that is not whey protein (Hoffman and Falvo, 2004). Casein is commonly recommended to take before long periods of not eating, such as before bed. This recommendation is based off of research demonstrating that casein is a slower digesting protein. Casein raises blood levels of leucine concentrations, which are detected about 40 minutes after ingestion and last for approximately 7 hours (Dangin et al., 2001). This is in contrast to whey protein, with which the same conditions are seen around 20 minutes and 3-4 hours respectively (Dangin et al., 2001). Casein is the logical protein nutritional advice for a person not able to eat for a long period of time. However, Bohe and colleagues (2001) have challenged this 'theoretical' claim. Their findings demonstrate the idea that having a slow digesting protein is not more beneficial before prolonged periods on fasting. Casein contains some lactose as well, so lactose intolerant clients should be informed.

What About Vegetarian Protein Options?
Aside from the animal and dairy derived proteins on the market, some of the popular vegetarian or vegan options include: soy, quinoa, pea, rice, amaranth and hemp protein. The primary consideration that must be made with these types of proteins is that aside from soy, quinoa, and amaranth protein, all vegetable protein sources are incomplete proteins. This is why blended plant proteins are commonly the best option when exploring supplementing with plant protein powders. For example, a protein powder of bean protein in combination with rice protein would satisfy all essential amino acid requirements and make a complete protein through mutual supplementation. A secondary consideration that must be taken into account with vegetable proteins is their amino acid levels to determine the necessary dosages needed per meal.

Leucine: The King of Amino Acids
Leucine, an essential amino acid, is often referred to as the 'king of amino acids,' because it is the 'engine' that drives MPS, while the other 19 amino acids are the 'fuel.' It has been well established that there is a minimum amount of leucine that needs to be present in a meal to see a meaningful rise in MPS (Laymen et al., 2015). This is where protein choice really comes into focus. With a WPI, leucine is commonly around 10.8% while in soy protein, leucine is significantly lower, typically around 6.2% (Phillips et al., 2009). The importance of this difference is that in order to get the same MPS response from other various proteins, they would need to be taken at different amounts in a single sitting. For example, to get the same MPS response seen with 30g of WPI, approximately 55g of soy protein would need to be ingested. The minimum amount of leucine needed to stimulate MPS is known as the leucine threshold, and this threshold rises with age (Katsanos et al., 2006). Due to the increased calories per MPS response, plant-based proteins may not be the optimal choice for clients concerned with weight management. Also, protein intake needs to increase as one ages due to a need for higher doses of leucine (Katsanos et al., 2006).

Putting it All Together: Take Home Guidelines For the Personal Trainer
One of the first questions a client may ask a personal trainer is whether too much protein is bad for you. The research indicates that diets high in protein do not negatively affect health in healthy individuals (Layman et al., 2015). Next, the chief factor to consider is how many grams of protein are needed per day. This number will vary depending on age and activity level. However, a recent meta-analysis published in the British Journal of Sports Medicine by Morton and colleagues (2017) recommends a targeted protein NOT greater than 1.6 g/kg/day for healthy resistance training women and men, double that of the current recommended dietary allowance (RDA). Another interesting finding by Morton and colleagues is that there is no difference in protein recommendations between sexes, though the researchers acknowledged more research is needed with female resistance training enthusiasts. In regards to protein intake timing, Morton et al. conclude it plays a minor, if any, role in determining resistance-exercise induced gains in muscle. In the conclusion of their exhaustive review, Morton et al state a most telling message for all personal trainers to share with clients. The researchers summarize and highlight that resistance exercise training, alone, is the most important and potent stimulus for developing optimal gains in muscle mass and strength. Alas, the 'magic bullet' message to clients is the following: taking a protein supplement may not be necessary if they are eating enough protein through whole foods and putting in the appropriate time and effort with their training!

Matthew T. Stratton is an undergraduate exercise science student at the University of New Mexico who is pursuing admission into a graduate program of physical therapy. His research interests are in performance enhancing supplementation and skeletal muscle hypertrophy.

Trisha VanDusseldorp, PhD, CISSN, CSCS is an Assistant Professor of Exercise Science at Kennesaw State University and is currently the Vice President of the International Society of Sports Nutrition. Trisha is passionate about studying the cellular and molecular responses to supplementation and nutritional interventions.

Len Kravitz, PhD, CSCS is the program coordinator of exercise science and a researcher at the University of New Mexico, where he received the Outstanding Teacher of the Year award. In addition to being a 2016 inductee into the National Fitness Hall of Fame, Len was awarded the 2016 CanFitPro Specialty Presenter Award.

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