Guest post by Paul Fairbairn, BSc (hons) in Sport and Exercise Science & Nutrition MSc student.
When we think of protein the first thing that springs to mind is usually muscle mass, the two very much go hand in hand and for good reason. In order to gain muscle the three basic things we require are:
1.) To be in a caloric surplus
2.) To have a training stimulus (to work the desired muscle) and
3.) To have a positive protein turnover/balance (this is where the rate at which proteins are being created outweighs the rate at which proteins are being broken down).
The importance of protein is not limited to athletes and gym junkies, it also plays a role in the creation of enzymes, hormones, immune cells and transport mechanisms (Geissler & Powers, 2005).
The dietary reference value for protein is 0.8g per kg of body weight, so for an average 70kg person that would be 56g. This is quite a modest amount when we consider that, 56 grams is the amount of protein in a large chicken breast.
Several experts believe this recommendation needs updating as it appears to be adequate to prevent deficiency, but not enough to allow peak function/performance for sportsmen and women (Manore & Thompson, 2000). In fact it has been proposed that most adults benefit from protein intakes above the current recommended intake (Layman, 2009). However, it should be noted though that as a population we already consume more than the Recommended Nutrient Intake (RNI) of 0.8g/kg.
The American College of Sports Medicine recommends an intake of 1.2-1.7g per kilogram of body weight. This recommendation is for individuals regularly taking part in physical activity or keen sportsmen and women (training 3-5 times per week). Strength athletes or individuals with extremely heavy training schedules may require more, but generally this recommendation would be sufficient for most people who are physically active (ACSM, 2015).
Protein Quality
When considering our protein intake it’s important to think not only about grams but also the quality.
Protein is made up of amino acids all bound together by peptide bonds. When protein is digested it’s broken down into these individual amino acids, which are then utilised by the body in a number of different ways. There are 22 different amino acids in total, of which nine are essential. Some amino acids can be created by the body but essential amino acids cannot, their requirement can only be met through the diet.
The nine essential amino acids are: phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. Arginine, cysteine, glycine, glutamine, proline and tyrosine are sometimes referred to as conditionally essential meaning that under certain conditions they may be essential (Geissler & Powers, 2005).
One amino acid that appears to have a unique role in muscle building is leucine, this is both an essential and branch chained amino acid. Leucine has been referred to as the “switch” that stimulates protein synthesis, it has a much greater power in this process compared to all other amino acids (Norton et al., 2014; Koopman et al., 2006; Anthony et al., 2002). For this reason it has been theorised that leucine intake is just as important, if not more important, than total protein intake. However if you are consuming adequate servings of high quality protein, it’s likely you will be meeting your demands for both. The following is a table showing both the protein and leucine contents of some commonly consumed foods.
Food | Protein/100g | Leucine/100g |
Beef | 25g | 3165mg |
Chicken breast | 31g | 2652mg |
Tuna | 39.3g | 2293mg |
Butter Beans | 14.7g | 776mg |
Peanuts | 40.5g | 1812mg |
Soy Beans | 22.5g | 3223mg |
Whey Powder (this often varies depending on brand and product) | 70.5g | 10,000mg |
Do we need Protein Supplements?
The short answer to this is no we don’t. We can get more than adequate amounts of protein in terms of grams and individual amino acids, including leucine, from whole foods. Just because we don’t NEED them doesn’t mean they can’t be useful for athletes or individuals who are very active. Protein powders are convenient, rapidly absorbed and often manufacturers will add other ingredients to tailor a specific blend to a particular goal.
Added in ingredients can be beneficial, but they can also be something to be wary of, too. For example someone looking to add muscle might opt for a weight gainer product, these are often very high in sugar. It should also be noted that whey protein does elicit an insulin response, however Diabetes UK has deemed it “safe for consumption” and has published an article promoting it as a way to control blood sugar levels (Diabetes UK, 2015). On the other hand an individual aiming to increase their protein intake to preserve lean mass whilst losing fat might opt for a “lean” variety of protein powder. These often contain caffeine, guarana, green tea extract or other stimulants so wouldn’t be suited for someone with high blood pressure or a sensitivity to stimulants.
Ultimately, if you are going to use a protein supplement, do your research into what else is in the product first.
A final point here with any supplement whether that be protein, fish oil, or a multivitamin, we have to remember these are SUPPLEMENTS. They cannot replace a healthy balanced diet based or whole foods. They shouldn’t be used to make up for a poor diet, only to enhance a good one.
The foods we eat are the foundations, walls, windows and doors, and supplements (including protein supplements) are the pretty paintings on the wall.
References
Acsm.org, (2015). [online] Available at: https://www.acsm.org/docs/default-source/brochures/protein-intake-for-optimal-muscle-maintenance.pdf?sfvrsn=4 [Accessed 28 May 2015].
Anthony, J., Reiter, A., Anthony, T., Crozier, S., Lang, C., MacLean, D., Kimball, S. and Jefferson, L. (2002). Orally Administered Leucine Enhances Protein Synthesis in Skeletal Muscle of Diabetic Rats in the Absence of Increases in 4E-BP1 or S6K1 Phosphorylation. Diabetes, 51(4), pp.928-936.
Beasley, J., Shikany, J. and Thomson, C. (2013). The Role of Dietary Protein Intake in the Prevention of Sarcopenia of Aging. Nutrition in Clinical Practice, 28(6), pp.684-690.
Diabetes.co.uk, (2015). Whey protein controls after breakfast blood sugar levels. [online] Available at: http://www.diabetes.co.uk/News/2014/Aug/Whey-protein-controls-after-breakfast-blood-sugar-levels-92959228.html [Accessed 28 May 2015].
Geissler, C. and Powers, H. (2005). Human nutrition. Edinburgh: Elsevier/Churchill Livingstone.
Helms, E., Zinn, C., Rowlands, D. and Brown, S. (2014). A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. IJSNEM, 24(2), pp.127-138.
Kalman, D. (2014). Amino Acid Composition of an Organic Brown Rice Protein Concentrate and Isolate Compared to Soy and Whey Concentrates and Isolates. Foods, 3(3), pp.394-402.
Koopman, R., Verdijk, L., Manders, R., Gijsen, A., Wagenmakers, A., van Loon, L. and Kuipers, H. (2006). Co-ingestion of Protein and Leucine Stimulates Muscle Protein Synthesis in Young and Elderly Men.Medicine & Science in Sports & Exercise, 38(Supplement), p.S113.
Layman, D. (2009). Dietary Guidelines should reflect new understandings about adult protein needs.Nutrition & Metabolism, 6(1), p.12.
Manore, M. and Thompson, J. (2000). Sport nutrition for health and performance. Champaign, IL: Human Kinetics.
Norton, L., Wilson, G., Layman, D., Moulton, C. and Garlick, P. (2012). Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats. Nutr Metab (Lond), 9(1), p.67.