Myths About Pea Protein

Pea protein acquired rumors faster than it managed to appear on the shelves of sports stores: from “an incomplete protein on which nothing grows” to “the ideal hypoallergenic product for everyone.” The editorial team checked the most widespread claims against amino-acid analyses and randomized studies.

Where the myths come from

Over the past decade pea protein has turned from a niche product for vegans into a full-fledged category of sports nutrition. Along with its popularity came rumors too: some call it “incomplete,” others “the ideal hypoallergenic protein for everyone.” Both extremes have little in common with study data.

A large part of the myths comes from transferring the properties of the whole pea to the isolated protein. Dry peas do indeed contain oligosaccharides, phytates, trypsin inhibitors and a lot of fiber. But during production of the isolate most of these components are removed together with the starch and the hull, so transferring the “pea” experience from the plate to the shaker is not correct.

The second source of confusion is marketing. Manufacturers of whey protein emphasize the shortcomings of plant proteins, while manufacturers of plant proteins, conversely, promise “purity,” “detox” and “no harm.” The editorial team believes that a correct assessment is possible only on the basis of amino-acid composition, digestibility and controlled human studies.

Below we have examined the most widespread claims about pea protein and checked which of them are supported by scientific data, which are exaggerations and which are outright fiction. For convenience, at the end of the article there is a summary “myth–fact” table.

Amino acids and muscle growth

Myth: “Pea protein is incomplete, it does not have all the essential amino acids.”In reality pea isolate contains all nine essential amino acids. It is another matter that their ratio differs from animal proteins: the limiting amino acid for pea is methionine, whereas it is comparatively rich in lysine, arginine and glutamine.

An analysis of commercial plant isolates conducted by Gorissen and colleagues (2018) showed that the essential amino-acid content in pea protein is lower than in whey, but higher than in many other plant sources. The content of leucine — the “trigger” amino acid of muscle protein synthesis — is moderate in pea, roughly at the level of soy.

Myth: “Muscles do not grow on pea protein.”This claim is refuted by direct comparisons. In a double-blind study by Babault and colleagues (2015), men trained with resistance for 12 weeks and received 25 g of pea or whey protein twice a day. The increase in the thickness of the biceps brachii in the pea and whey groups did not differ statistically.

A pilot work by Banaszek and colleagues (2019) with high-intensity functional training also found no significant difference between pea and whey in strength and body composition after 8 weeks. Both studies are small, so it is too early to speak of full equivalence, but the claim “it does not work” certainly does not match the data.

A key nuance: plant proteins may need a slightly larger single serving to reach the same leucine content as whey. With sufficient total daily protein in the diet, this difference, as reviews by Pinckaers and colleagues (2021) show, has little practical significance.

Bloating and “phytoestrogens”

Myth: “Pea protein inevitably bloats the belly.”Bloating after legumes is caused primarily by oligosaccharides of the raffinose family, which are not digested in the small intestine and are fermented by bacteria. In a quality isolate there are far fewer of them than in the whole pea, so the reaction to the powder and to pea soup are different things.

Nevertheless, in some individuals discomfort does occur. The causes may be a large volume of shake drunk in one go, polyol sweeteners added to the product (sorbitol, xylitol), gum or inulin, and also individual gut sensitivity. It is worth reading the composition rather than blaming pea alone.

Myth: “Pea protein contains phytoestrogens, like soy.”The isoflavones (genistein, daidzein) over which the disputes around soy revolve are characteristic specifically of soybeans. Pea contains them in negligible amounts, so hormonal fears, even if transferred from soy, do not apply to pea protein.

By the way, with soy too, clinical meta-analyses (Hamilton-Reeves et al., 2010; Reed et al., 2021) found no effect of soy protein on testosterone levels in men. So the “estrogenic” argument against pea is doubly weak.

Allergy and contamination

Myth: “Pea protein is hypoallergenic, everyone can have it.”Pea is not on the list of the 14 main allergens that in the EU must be highlighted on the label (Regulation 1169/2011), so it is often positioned as a safe alternative to milk and soy. But that does not mean pea allergy does not exist.

Pea belongs to the legume family, and in people with an allergy to peanut, lentils or lupin cross-reactivity is possible. Such cases are described in the clinical literature. People with a confirmed food allergy to legumes should discuss introducing pea protein with an allergist.

Myth: “All plant proteins are contaminated with heavy metals.”Plants do accumulate elements from the soil, and independent tests of individual brands periodically find lead or cadmium in plant powders. However, this is a matter of quality control of the specific manufacturer, not a property of pea protein as such.

The practical conclusion is simple: choose products from manufacturers who publish batch laboratory results or have third-party quality certification. The generalization “plant means poisonous” is just as incorrect as “plant means pure.”

Myth or fact: a summary table

So as not to get lost in advertising promises and scare stories, we have gathered the main claims into one table. In the right-hand column is a brief editorial conclusion based on the sources cited in the article.

Separately it is worth mentioning the “positive” myths too. Pea protein does not burn fat, does not “detoxify” the body and has no special effect on hormones. It is simply a concentrated source of protein with a decent amino-acid profile, convenient to use when dairy products are undesirable.

What really is worth considering when choosing:

• the protein content per serving (for an isolate — usually over 75–80% of the mass);
• the presence of sweeteners and thickeners that may irritate the intestine;
• the sodium content — in some pea isolates it is noticeable;
• batch laboratory-control data for heavy metals and microbiology;
• combining with other protein sources (for example, rice) for amino-acid balance.

This approach makes it possible to evaluate a product by the facts rather than by loud headlines on the tub or on social media.

Editorial conclusions

Most of the negative stereotypes about pea protein are not confirmed by data: it contains all the essential amino acids, and in controlled studies it provides a gain in muscle comparable to whey protein.

At the same time, pea protein is not “magic”: it has less methionine, somewhat less leucine than whey, and it does not guarantee the absence of allergy or gut discomfort.

The main selection criteria are the product composition, the protein content per serving and confirmed quality control, not loud promises on the label.

If the topic interested you, we recommend reading our materials “Pea protein: what it is and how it works,” “The benefit of pea protein for athletes: the evidence base” and “What to combine pea protein with.”

References

1. Babault N, Païzis C, Deley G, et al. Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, placebo-controlled clinical trial vs. whey protein. J Int Soc Sports Nutr. 2015;12(1):3.
2. Banaszek A, Townsend JR, Bender D, et al. The effects of whey vs. pea protein on physical adaptations following 8-weeks of high-intensity functional training (HIFT): a pilot study. Sports (Basel). 2019;7(1):12.
3. Gorissen SHM, Crombag JJR, Senden JMG, et al. Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids. 2018;50(12):1685–1695.
4. Pinckaers PJM, Trommelen J, Snijders T, van Loon LJC. The anabolic response to plant-based protein ingestion. Sports Med. 2021;51(Suppl 1):59–74.
5. Hamilton-Reeves JM, Vazquez G, Duval SJ, et al. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril. 2010;94(3):997–1007.
6. Reed KE, Camargo J, Hamilton-Reeves J, Kurzer M, Messina M. Neither soy nor isoflavone intake affects male reproductive hormones: an expanded and updated meta-analysis of clinical studies. Reprod Toxicol. 2021;100:60–67.
7. Regulation (EU) No 1169/2011 of the European Parliament and of the Council on the provision of food information to consumers. Official Journal of the European Union. 2011;L304:18–63.