By Katherine A. Beals, PhD, RD, FACSM, CSSD and Breanne Nalder, MS
In the last two protein articles we discussed the role of protein in athletes’ diets, recommendations for protein intake for training and competition and getting adequate protein on a vegetarian diet. In this third and final article we will discuss protein supplements. What are they? Are they necessary or beneficial? Who (if anyone) can benefit from supplementing with them? And, are there any potential hazards associated with consuming them?
What are Protein Supplements?
The Dietary Supplement Health and Education Act (DSHEA) defines supplements as any product that is intended to supplement the diet, contains one or more dietary ingredients (including vitamins; minerals; herbs or other botanicals; amino acids) or other constituents, is intended to be taken by mouth as a pill, capsule, tablet, or liquid, and is labeled as being a dietary supplement.
A key aspect of this definition is the notion that a protein supplement is meant to supplement the diet, not replace food sources of protein in the diet. Unfortunately, many athletes overlook this distinction to the detriment of their wallets and possibly their health and performance (as will be discussed later).
There are a plethora of protein supplements on the market today, including powders, drinks, shakes, bars and even pills. In addition, supplements can be comprised of whole or intact proteins or single amino acids and derived from a variety of animal or plant sources. The most common animal sources of intact proteins are albumin (egg protein), casein (one of the milk proteins) and whey (the other milk protein). Soy is the most common plant source of intact protein found in supplements. Each of these is described in more detail below.
- Albumin: The primary protein found in eggs. Despite popular belief, all of the protein is not found in the egg white. In fact the average egg contains about 6.29 grams of protein, of which just over half (3.6 grams) is found in the white. The rest is found in the yolk (along with most of the other important vitamins and minerals!)
- Whey: is a soluble protein and comprises about 20% of the total protein in milk. It’s often referred to as “fast” protein because it remains soluble in the digestive tract; thus, it is digested and absorbed more quickly. Whey protein supplements generally come in one of three forms:
- Whey concentrates: are 80% protein, which means on a dry basis, 80% of the total weight is protein.
- Whey isolates: are typically about 92% protein (dry basis), meaning you get more protein and less total carbohydrate, lactose, fat and cholesterol per equivalent dose.
- Whey Hydrosylates: Most whey concentrates and isolates are available as intact proteins, but either can be also hydrolyzed. Hydrolysates have been partially broken down by exposing the protein to heat, acid or enzymes that break apart the bonds linking amino acids. This makes it taste more bitter and theoretically promotes more rapid digestion and absorption. However, whey concentrates and isolates are already rapidly digested so a hydrolysate is likely not worth the bad taste or the extra cost.
• Casein: Comprises about 80% of the total protein in milk. Casein is an insoluble protein and is often referred to as a “slow” protein because it remains insoluble in the digestive tract; thus, it is digested and absorbed more slowly.
- Soy Protein: is the protein isolated from the soybean. It is made from soybean meal that has been dehulled and defatted. The soybean meal can then be further processed into soy protein concentrate and soy protein isolate.
- Soy Protein Concentrates: produced by removing the oil and most of the soluble sugars from defatted soybean meal, come in the form of a white powder containing 65-90% protein (average 70%), plus most of the soybeans vitamins, minerals, and finely pulverized dietary fiber.
- Soy Protein Isolates: essentially soy protein concentrates minus almost all their dietary fiber. It contains at least 90% protein.
As discussed in the first article of this series, there are 20 amino acids and, thus, single amino acid supplements can be comprised of any number or combinations of amino acids. The most common amino acid supplements include L-arginine (often marketed as nitric oxide or NO), L-glutamine, the branch chain amino acids (BCAAs) leucine, isoleucine and valine and HMB, (which is not an amino acid but, rather, a metabolite of the amino acid leucine). The merits (or lack thereof) of each will be discussed below.
Will protein supplements enhance athletic performance?
The answer is “maybe”. Certain types of protein supplements, for certain athletes under certain conditions may be beneficial. But before getting into those specific provisos, lets rule out those supplements that are not helpful for anyone under any conditions, starting with amino acid supplements.
Research examining effects of single amino acid supplements on promoting muscle protein synthesis, preventing muscle injury or soreness, and/or enhancing recovery post-exercise has consistently shown no beneficial effects in young healthy, trained individuals (i.e., athletes). A few studies have demonstrated some limited benefits of leucine and HMB supplementation in terms of enhanced protein synthesis and/or prevention of protein catabolism for older and/or untrained individuals. Similarly, there is some limited evidence to suggest that supplementing with BCAAs during high-intensity, ultra endurance events may improve performance; but the dietary comparisons were generally inadequate/inappropriate; thus, the results of these studies need to be interpreted with caution.
The disappointing results from amino acid supplementation research are really not surprising when you think about it. Remember, muscle protein is comprised of peptide chains consisting of hundreds of amino acid. Delivering a single amino acid (or even couple of amino acids) via a supplement is not going to be sufficient to support muscle protein synthesis. Similarly, the amount of the amino acid supplied by a serving of the supplement (typically milligrams) is inadequate in terms of the amount needed to stimulate muscle protein synthesis (i.e., grams). And, the provision of non-essential amino acids, such as L-glutamine is a complete waste because muscle tissue synthesis will never be limited by a lack of this amino acid since it is non-essential (i.e., the body manufactures as much as it wants when and where it wants it).
The research on possible benefits of whole or intact proteins is a little more inconsistent and, thus, more difficult to interpret. The most frequently studied protein supplements include whey, casein, milk and soy. Some studies indicate that muscle protein synthesis is greater after whey protein consumption than either casein or soy both at rest and after resistance exercise. While, others show that protein supplementation before or after resistance training, regardless of the source, increases lean tissue mass and strength over isocaloric placebo. It is worth noting that those studies, which have shown benefits of whey over other protein sources, have examined short-term effects on indirect measures of muscle protein synthesis (i.e., not actual gains in lean tissue and/or strength). The few long-term studies examining the effects of different protein sources on lean body mass accrual and/or strength gains have either found no difference between sources or have found milk protein to be superior to either whey or casein.
It should also be emphasized that of the studies demonstrating beneficial effects of protein supplementation on muscle protein synthesis, the majority have been done on individuals undergoing resistance-training protocols. There is little scientifically valid evidence indicating that protein supplementation will improve either performance or recovery in cyclists (especially if carbohydrate intake is adequate). In fact, of the few studies that have examined this issue (three at last count) only one has shown a benefit, and again it was on acute, indirect indices of muscle protein synthesis. Studies that have actually employed direct measures of recovery (i.e., markers of muscle tissue damage, indices of muscle soreness and fatigue and/or subsequent performance) have found no advantage of protein supplementation post exercise.
Finally, it is important to point out that the amounts of protein typically used in supplement studies are small (in the range of 10-20 grams of protein supplying just 6-10 grams of essential amino acids). Such small amount are easily and much more inexpensively obtained from protein rich foods. And, research has shown that there are diminishing returns with protein intakes greater than 20 grams (i.e., protein taken in amounts greater than that is simply oxidized—in other words, used for energy, not muscle protein synthesis).
Ok so they don’t really help; but can they hurt?
Besides being expensive, protein supplements may displace carbohydrate-rich foods from the athlete’s diet. And, for the endurance athlete this can be extremely detrimental to performance (since carbohydrates are the primary fuel for high intensity exercise). Once your muscles become carbohydrate depleted, fatigue sets in and you can kiss your performance goodbye. A cyclists diet should provide extra carbohydrates, not extra protein. Finally, excess intake of protein supplements (to the exclusion of “real food”) may result in nutrient deficiencies since no manufactured supplement can provide the extensive variety of vitamins, minerals and phytochemicals found in whole, natural foods.
So is there anyone who can benefit from a protein supplement?
As was indicated in the first article of the series, both research and anecdotal evidence suggests that the majority of endurance athletes either meet or exceed the current protein recommendations; thus, a supplement is completely unnecessary (and largely a waste of money). However, for those athletes who are unable or unwilling to consume adequate amounts of protein from food sources, a supplement might help them meet their protein requirements. If an athlete falls into the above categories he/she should choose a whole/intact supplement containing albumin, soy and/or milk proteins at a dose of approximately 20-40 grams.
Read Part 2 and Part 3 of this Series.
Katherine Beals, PhD, RD, FACSM, CSSD is an associate professor (clinical) in the Division of Nutrition at the University of Utah. She is a registered dietitian, a certified specialist in sports dietetics and a fellow of the American College of Sports Medicine.
Breanne Nalder, MS recently completed here master’s degree in nutrition with an emphasis in sports dietetics at the University of Utah and is a competitive Cat 1 cyclist. For personal nutrition coaching, you can reach Breanne at 801-550-0434 or [email protected].
