Protein Supplementation

What are proteins?

Our bodies require different nutrients and substances for sustenance. Generally, there are three groups of nutrients that are categorized as macromolecules (macros): carbohydrates, fats, and proteins. Each macro serves a different purpose in helping with bodily function. Typically when someone hears "protein," their mind might go straight to muscles, but proteins do a lot more than make people look bigger. Yes, muscles are composed of a majority of the body's protein, but of all our different cell types consist of proteins. They carry out different functions like enzymatic activity and relaying signals for specific processes.

Whey vs. Casein

Two common protein supplements that you'll find are whey and casein. The main difference between the two is their rate of digestion. Whey protein is digested quickly, while casein protein takes longer for the body to break down. As a result, the levels of circulating protein in our blood varies between the two. With whey, the protein level will have a more immediate increase followed by a steady decrease. Casein will give a lower maximum level of protein but is also accompanied with a prolonged effect over a longer period of time [1]. What's interesting is that studies comparing the two types of protein have found:

1) The increase of protein synthesis is greater after ingesting whey protein than ingesting casein protein. 

2) Casein protein inhibits the breakdown of pre-existing protein. 


Muscle Growth

Studies have shown a positive effect of protein supplementation on muscle growth (hypertrophy). Recommended protein intake lies anywhere between 1-2 grams per kg of body weight [2]. Also, an important component of protein supplements is a compound known as leucine. Proteins are synthesized in our cells by the activity of ribosomes (an object that is made of smaller parts). Leucine facilitates signaling in cells to promote the formation of ribosomes and, thus, protein synthesis [3]. Studies looked at protein supplementation consisting of leucine vs. protein supplementation lacking leucine, following weightlifting resistance exercise. Individuals that ingested greater amounts of leucine had significant increases in protein synthesis than those that did not have additional leucine supplementation [3, 4]. 

Timing

A common concern is when to have your protein shake, and many individuals advise post-workout. A study observed the ingestion of protein between two regimens, and how it impacted the one-rep max of male individuals for bench presses and squats [5]: 

1) Two protein supplements, one in the morning and one in the evening.
2) Two protein supplements, one before and after a workout. 

Results indicated a significant increase in strength in both protein groups when compared to the group that did not receive any protein supplementation. However, the time of protein supplementation did not have an effect on strength gain [5]. The information from this study aligns with the fact that muscle repair and growth occurs outside the gym throughout the day. As long as there is a steady deliverance of protein to the body, increases in strength and overall performance can be expected. 

One final point which I found pretty interesting was about comparing whey vs. casein protein supplementation. A study observed a similar increase in muscle protein levels and protein synthesis after administering the types of protein after resistance exercise [6]. This was seen despite whey and casein having different protein behavior in the blood. There is still room for further research though. It would be good to understand the effects of whey and casein after a long period of time after exercise since the main difference between the two is their rates of digestion. We already know that casein promotes protein synthesis to a lesser extent, but for a longer period of time than whey. But would this be enhanced after a workout? If so, would one enhance protein synthesis after a workout more than the other? It'd be good to have an understanding on whey vs. casein well after weightlifting.

Personally, I have a scoop of whey and a scoop of casein with milk every day (Helps me meet my daily protein goal!). I've been taking protein supplements for a few years now with no issues. Protein supplements are quite safe, but in excess can cause nausea, bloating, cramps, etc. Like all supplements, if you're starting protein supplements for the first time, exercise some caution. Maybe start low and slowly build up to a normal amount of protein powder per day. As always, if any complications arise, consult your doctor. Whether it's good form or good supplementation, safety first! 











References

1. Boirie Y., et al., "Slow and fast dietary proteins differently modulate postprandial protein accretion," PNAS. December 23, 1997. 94 (26) 14930-14935.
2. Gropper S, Smith J, Groff J. Advanced Nutrition and Human Metabolism. 5th. California: Wadsworth Cengage Learning; 2009. Protein; pp. 179–250
3. Dreyer HC., et al., "Leurine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle." Am J Physiol Endocrinol Metab. 2008 Feb;294(2):E392-400.
4. Koopman R., et al., "Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects." Am J Physiol Endocrinol Metab. 2005 Apr;288(4):E645-53.
5. Hoffman JR., et al., "Effect of protein-supplement timing on strength, power, and body-composition changes in resistance-trained men." Int J Sport Nutr Exerc Metab. 2009 Apr;19(2):172-85.
6. Tipton KD., et al., "Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise." Med Sci Sports Exerc. 2004 Dec;36(12):2073-81.

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