by Matt Hansen EdD

In February of 2013, the First Endurance blog covered an important topic: ‘The Facts About Protein.’ You can find the full post HERE. At that point in time, whey protein easily rises to the top as

Matt Hansen wins Ironman Texas – 2015

the superior protein source to use for supplementation purposes. Since the original posting of this article, a number of things have changed. First, technological advancements in the food industry have opened the door for the extraction of proteins from different food sources. Second, sustainability issues and a more informed consumer base has lead to the investigation of numerous different protein sources. Finally, a growing need has been identified for protein supplement sources that fit into a vegan and allergy free diet. The purpose of this discussion will be to revisit the merits of whey protein as well as introduce a few additional protein sources which have shown to have equivalent (and possibly even greater!) merits to whey.

A number of different protein sources have been offered up recently as alternatives to whey. These include pea, rice, hemp, avocado, barley, buckwheat, cranberry-seed, goat milk, Brazil-nut, and even bug protein (you can thank reality TV shows like Fear Factor and Man vs. Wild for this one…). For reasons which will hopefully become apparent by the end of this article, this discussion will focus on pea and rice protein and compare the two proteins to the reference standard whey. We’ll start with a review from our discussion on whey, discuss the different methods of analysis that proteins are evaluated on, including Protein Digestibility Corrected Amino Acid Score (PDCAAS), Protein Efficiency Ratio (PER) and Biological Value (BV), introduce pea and rice protein, then conclude with a comparison between the three proteins.

Whey Protein (Excerpts taken from 2013 blog post)

Whey protein is a high quality complete protein containing all of the essential amino acids required by the body each and every day. There are several different methods that are used today to evaluate protein quality.  No matter which method is used, whey proteins have been proven to be an excellent, pure source of protein. To help prevent the breakdown of muscle tissues, whey protein contains beta-lactoglobulin, a rich source of branched-chain amino acids (BCAAs). Whey protein is also a rich source of the amino acid cystein and has been shown to increase glutathione levels in the body. Glutathione is an antioxidant that helps provide an added boost to the immune system.

Whey proteins have a Protein Digestibility Corrected Amino Acid Score (PDCAAS) of 1.14. The reported score is 1.0, which is the maximum value allowed by the USDA for reporting purposes. The PDCAAS is the USDA’s officially approved method of scoring protein quality.

Whey proteins have a Protein Efficiency Ratio (PER) of 3.2, making it one of the highest single source proteins. The PER rating is based upon the evaluation of the growth of animals consuming a fixed amount of dietary protein from a single source. As the PER increases, so does the quality of the protein.

Biological Value (BV) is an evaluation of the protein quality that measures the amount of protein that is retained from the absorbed protein for maintenance and growth. It measures the fraction of nitrogen in the diet that remains after the nitrogen losses in waste products have been subtracted. The Biological Value (BV) of whey proteins is 100, which is higher than the value for casein (milk protein), soy protein, beef, or wheat gluten.


Pea Protein

Is a pea a vegetable? A fruit? The debate continues. Regardless, this legume contains a good deal of protein. Protein powder extraction typically begins with yellow peas (aka split peas). They are ground into a powder and concentrated/purified by removing a majority of the carbohydrates, leaving a powder that is approximately 90% protein. In general, it is a great source of protein for people who are Vegan and seek an allergy free option. It is obviously not a good option for anyone with an allergy to peas.

Pea protein is particularly rich in the essential BCAA’s leucine, isoleucine, and valine. Increases in leucine concentrations in the blood have shown to enhance muscle protein synthesis. Pea protein has also been shown to stimulate the satiety-related signaling. Studies have demonstrated that dietary replacement of animal protein with pea protein does not weaken gastrointestinal satiety signaling and has the potential to promote protein synthesis at similar levels as animal sources post exercise. It is important to recognize however, that legume proteins are low in methionine.

Rice Protein

Rice is not typically the first thing that comes to mind when one thinks about adding protein to a meal. Typically, rice is great carbohydrate compliment to a protein due to the fact that it is a low-glycemic carb source. But the fact of the matter is, brown rice does have protein in it. One cup of brown rice contains roughly 5 grams of protein, so to get the post exercise required 20-25g of protein from rice, you would need to consume 4-5 cups. Ok, so maybe going to rice as a whole food protein source is not the greatest option. However, when the brown rice is processed and the carbohydrates are separated, you can come up with a protein powder that is roughly 70% protein. Similar to pea protein, brown rice protein is a good alternative for those looking for a vegan allergy free protein powder or for those with milk-protein allergies. It can have a fairly bitter taste if taken as a mix with water alone, however.

Brown rice protein contains more arginine than any other protein powder. Arginine is converted to nitric oxide in the body which suggests that brown rice protein can enhance blood flow allowing for superior nutrient delivery during and after exercise. Brown rice protein also contains a great deal of glutamine which promotes muscle growth and immune function and has also been shown to reduce fatigue during workouts in some studies. Rice protein has shown to have higher levels of the amino acid methionine than most other plant sources. Brown rice is also rich in leucine with sufficient levels to promote hypertrophy (muscle growth) if consumed in combination with resistance training.



Most researchers consider whey protein the standard protein supplement. Because of this, it is common for well-designed studies to have three groups when researching alternative protein sources: the test protein, whey protein, and a placebo carbohydrate group. This helps us to compare both pea and rice protein directly to whey protein.

Pea protein has similar or higher levels of numerous essential amino acids including leucine, isoleucine and valine as noted above. Specifically, they have nearly three times more arginine as whey protein. Multiple studies have shown a similar rate of hypertrophy and strength gain as whey protein supplements, with no significant difference between whey and pea. The similar gains have been attested to the characteristics of both proteins. Protein synthesis is 20% higher after ingesting a protein source high in leucine, when compared to one without leucine. Pea protein has also shown to have similar digestion characteristics as whey. Whey signaled a higher insulin response but both proteins induced a large CCK (cholecystokinin) response suggesting both proteins have a high bioavailability. Numerous researchers have suggested pea protein as an equal alternative in protein supplements marketed for athletes.

Rice protein has also shown to compare well to whey protein. It is also high in leucine and has shown to yield similar results in hypertrophy and strength increases as whey protein. Rice protein has four times more arginine than whey protein. Although there are slightly lower levels of leucine in rice protein than whey, it has been demonstrated that there is sufficient levels of the amino acid to optimize muscle growth.



It is important to keep in mind that it is the composition of the nutrient and not just the net protein content that will affect protein balance. Studies have shown that only the essential amino acids can stimulate muscle protein synthesis. Also, the type of protein can significantly affect digestion characteristics which will also affect the rate of muscle protein synthesis as well as the hormonal response post ingestion. This is where most plant based protein supplements fall short. They often lack specific amino acids necessary to stimulate protein synthesis. Furthermore, their PDCAAS score typically is not high enough to make it a good alternative to whey protein. However, combining plant protein sources together in the right ratios offers an amino acid profile that closely approximates whey protein. For example, combining pea protein with rice protein gives the following amino acid profile:



Rice Protein 90%                                          0.65

Pea Protein 80%                                           0.78

Rice/Pea Blend (55%/45%)                        1.00

Whey Protein 90%                                       1.00

Furthermore, thanks to technological advancements, when you use a 55/45% blend of rice and pea protein, it is possible to get a PDCAAS score of 1.0 (the highest allowable score by the USDA). This blend compares very favorably with whey protein and can potentially change the game in protein supplementation. Watch for products with this blend to be coming to market soon!



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