Dietary proteins are the source of new amino acids for the body. The nutritional actions of dietary protein are in fact the actions of the absorbed amino acids.
The quality of a dietary protein, as scored by the system of the World Health Organization, is determined by the profile of amino acids in the protein and the extent to which those amino acids are absorbed.
When an amino acid supplement is consumed, digestion is not required. Rather, there is complete absorption of the ingested amino acids. The question is, which is better—dietary protein or amino acid supplements? There are a number of factors to consider when answering this question.
Dietary Proteins—the “Natural” Way to Obtain Amino Acids
There is a school of thought in the nutrition community that natural food sources are always better than supplements. However, the scientific basis for this perception is unclear. For example, individuals who have had large portions of their intestines removed surgically can live for many years on entirely artificial nutrition given intravenously.
The water is particularly muddied in the case of dietary protein vs. amino acid supplements. Amino acids are not only natural components of the diet (albeit in the form of protein), but essential amino acids (the nine amino acids that cannot be produced in the body), are the only macronutrients required for survival.
The nutritional purpose of dietary protein is to deliver amino acids to the body. Is there really a difference in how natural it is to ingest amino acids directly or in the context of dietary protein, even if it is as a “supplement”?
A further complication in distinguishing between the advantages of dietary protein or amino acid supplements arises when considering specific dietary supplements of protein, such as whey protein. Is whey protein a natural protein food source? While whey protein occurs in the same form as it does in nature, it is still a byproduct of milk, the original protein food source.
Clearly, when it comes to distinguishing between “natural” protein food sources and amino acid supplements, there is a lot of room for interpretation. Rather than worry if a nutritional supplement is natural, it is more relevant to consider whether there is a difference between the nutritional benefits of protein that occurs as part of a normal diet and the nutritional benefits of amino acids supplements.
Why Consume a Protein or Amino Acid Supplement?
Protein is a fundamental part of our diets, and optimal amino acid and protein nutrition starts with the protein component of our meals. However, in many circumstances the amount of protein in the regular diet is insufficient to obtain maximal benefit of amino acid intake. In some cases, this is due to limitations in the ability to consume adequate high-quality proteins in the diet.
It may be that living circumstances limit the availability of high-quality protein. College students living in dorms would be a good example of this. Maybe the taste of protein food sources isn’t pleasing, or you have difficulty chewing meat, two common problems in aging. Adherence to a vegetarian or vegan diet commonly results in insufficient intake of high-quality protein as well.
There are also circumstances that increase the optimal amount of dietary protein intake. Participation in a competitive sport is one example, and the natural aging process is another. Recovery from a serious injury/illness and wound repair are also circumstances that may increase the amount of dietary protein you should consume.
A mismatch between the optimal amount of dietary intake and the amount actually eaten can be addressed by taking a protein or amino acid supplement. A protein supplement may come as relatively pure preparations of protein. Whey protein isolate is a good example. Alternatively, protein may be a component of a more complete food product that also contains carbohydrates and fat. Protein bars or meal replacement beverages are examples of these sources of dietary protein that are meant to be supplements to the normal diet. Amino acid supplements may also come as part of a complete nutritional supplement containing fat and carbohydrate, but more commonly amino acid supplements are in pure form consumed either as a beverage or in capsules.
Nutritional Benefits of Protein and Amino Acid Supplements
Amino acids absorbed from a protein supplement perform a wide range of functions, including production of key chemicals that regulate a variety of physiological functions including immune function, regulation of blood flow, and production of brain neurotransmitters. However, the predominant role of amino acids is to stimulate the production of new proteins in the body, particularly in muscle. The value of protein supplements has therefore traditionally been evaluated in terms of the ability to stimulate the production of new muscle protein.
The extent to which a protein supplement can stimulate the production of new muscle protein is highly dependent on the specific protein and how much is consumed. Intact proteins are composed of essential amino acids (EAAs) and nonessential amino acids (NEAAs). High-quality proteins such as whey protein have close to 50% EAAs, while collagen protein has about 10% EAAs. The EAAs are the active components of dietary proteins. The NEAAs in protein have no impact on the production of new muscle protein. Consequently, the amount of EAAs in protein determines how well the protein stimulates muscle protein synthesis. Further, all the EAAs are required for a sustained stimulation of muscle protein production. Incomplete proteins, meaning proteins that have only some of the EAAs, are not effective.
What Protein Supplement Is Most Effective?
Whey protein has been shown to be the most effective protein supplement in terms of stimulating the production of new muscle protein. In general, plant-based proteins like pea protein are ineffective. Soy protein is the exception—it is the only plant-based protein classified as a high-quality protein. Nonetheless, whey protein is more effective than soy protein.
The response to whey protein is dose dependent to an extent, but progressively larger doses get less and less effective. Doses greater than 30 grams have little added benefit compared to lower doses.
Whey protein isolate in pure form has greater effectiveness than when it is contained in a meal replacement. In fact, meal replacement protein supplements often have little to no beneficial effect. The problem may be the added non-protein calories in the form of carbohydrates and fats, but it is more likely that low-quality proteins have been added to the whey protein in the formulation. Labels are required to list total protein content in a serving of the product but are not required to list how much of each protein of a mixture is contained in that serving. It is particularly common to add collagen, a very low-quality protein that is appealing because of its low cost and ease of mixing into an overall formulation. If you are going to use a protein supplement, be sure to check that it is composed of only whey protein if muscle protein synthesis is your goal. If it is a combination of proteins, be sure that they are all high-quality proteins.
Amino Acid Supplements
Amino acid supplements have many benefits. The profile of amino acids in the supplements is completely controlled, so only the active amino acids are included. Amino acid supplements are also fully and rapidly absorbed. The peak concentrations of EAAs reach a high level more quickly than when a similar amount of protein is consumed. As a result, a blend of EAAs may stimulate muscle protein synthesis three times as much or more than a similar amount of whey protein. A very small amount of EAAs (less than 4 grams) can effectively stimulate muscle protein synthesis.
While amino acid supplements, particularly those made with all the EAAs, have many advantages over protein supplements, there are a few disadvantages to amino acid supplements that do not also include a dietary protein component such as whey. Peak concentrations of amino acids are reached much quicker than when whey protein is consumed. The concentrations also drop away much quicker. Thus, the response to an amino acid supplement is not as sustained as the response that might occur with whey protein. Also, amino acids may be somewhat difficult to make into a palatable production, while proteins such as whey protein tend to be tastier.
Your Best Bet: Amino Acid/Protein Supplements
It is clear from the above discussion that both EAAs and protein supplements, particularly whey protein isolate, have benefits. But one is not necessarily better than the other, especially when they can be combined for maximum benefit.
The rapid, intense response to EAAs can be merged with whey protein to achieve a more sustained response in a flavorful product. There are some circumstances, such as before exercise, that the rapid absorption of the amino acids make aminos a preferable choice. But in other cases, such as after exercise, a combination of EAAs and whey protein capitalizes on the benefits of each.
In summary, both amino acids as well as high-quality proteins like whey protein can be helpful dietary supplements. A mixture of EAAs has many important advantages, but the rather short period of stimulation is a limitation in some circumstances that can be prolonged by the ingestion of whey protein isolate at the same time.