Who should not take pea protein

Pea protein is often perceived as the «safest» protein: no lactose, no soy, no gluten. However, plant origin does not mean that the product suits everyone. Our editorial team examined for whom pea protein is contraindicated, who needs caution and how not to confuse real restrictions with myths.

Pea allergy and cross-reactions

The only absolute contraindication to pea protein for a generally healthy person is a pea allergy. It occurs less often than an allergy to peanuts or soy, but its significance is growing: pea protein is increasingly used in meat substitutes, plant milk and sports products, so contact with the allergen is becoming more frequent.

Pea belongs to the legume family, like peanuts, soy, lentils, chickpeas and lupin. The storage proteins of these plants — in particular vicilins and legumins — have a similar structure, so in people with an allergy to one legume crop cross-reactions to others are possible. Not every cross-sensitization detected in tests manifests clinically, but the risk should be assessed together with an allergist.

People with a known allergy to peanuts, lentils or chickpeas should not «test» pea protein on their own. The EAACI guidelines (Muraro et al., 2014) emphasize that the diagnosis of food allergy, including provocation tests, must be carried out under medical supervision, and the foundation of management is avoidance of the allergen.

It is also worth remembering hidden sources. Pea is not among the 14 mandatory allergens of the EU, so on labels it is not highlighted in a separate font like peanuts or soy. It can hide under the names «plant protein», «pea protein», «textured vegetable protein».

Kidney diseases and hereditary metabolic disorders

For patients with chronic kidney disease (CKD), protein intake is a subject of medical control. The KDOQI guideline on nutrition in CKD (2020 update) recommends for metabolically stable adults with CKD stage 3–5 not on dialysis and without diabetes a low-protein diet at a level of 0.55–0.60 g/kg of body weight per day under the supervision of specialists. Any protein supplement, including a plant one, in this case is possible only by the decision of a nephrologist.

There is a widespread opinion that plant protein is «gentler» on the kidneys than animal protein. Indeed, researchers are studying the benefits of plant-oriented nutrition in CKD, but this concerns an overall diet of whole foods, not concentrated protein powders. Pea protein isolate is still a concentrated source of protein, and often of sodium as well. In addition, in CKD potassium and phosphorus are controlled, and their content in the specific product should be clarified.

Phenylketonuria and other hereditary disorders of amino acid metabolism are another absolute restriction. Pea protein contains phenylalanine, like any complete protein. The European guidelines on phenylketonuria (van Wegberg et al., 2017) provide for strict control of natural protein intake, so any protein supplements for such patients are possible only within a diet calculated by a metabolic center.

The same applies to urea cycle disorders and other rare metabolic diseases in which a protein load can cause a dangerous rise in blood ammonia levels.

Gout, hypertension and sodium restriction

Legumes contain purines, from which uric acid is formed. People with gout are traditionally advised to watch their purine load, although the current guideline of the American College of Rheumatology (FitzGerald et al., 2020) places the main emphasis on drug-based reduction of uric acid and considers dietary measures as a supplement.

As for pea protein isolates, there is little data: during production part of the compounds is washed out, but how exactly regular use of the isolate affects uric acid levels has been insufficiently studied. Therefore patients with gout or hyperuricemia should discuss pea protein with a rheumatologist and, if needed, monitor uric acid in tests.

The second issue is sodium. During the production of the isolate the protein is neutralized, and in some products significantly more sodium is found than buyers expect. The ACC/AHA guideline on arterial hypertension (Whelton et al., 2017) considers reducing sodium intake as one of the main non-drug methods of controlling blood pressure.

So, for people with arterial hypertension, heart failure, kidney disease or other conditions in which a doctor has restricted salt, pea protein is not prohibited but requires careful reading of the label and accounting for sodium in the daily balance.

Sensitive gut and special groups

People with irritable bowel syndrome (IBS) often poorly tolerate legumes because of fermentable oligosaccharides that belong to the FODMAP group. The approach described by Gibson and Shepherd (2010) involves restricting such carbohydrates to reduce symptoms. Pea protein isolates contain significantly less of them than peas or concentrate, but individual tolerance varies.

For people with IBS, pea protein is not prohibited, but it is worth starting with small portions, choosing an isolate without inulin and sugar alcohols, and observing the reaction. If symptoms worsen, it is better to choose another protein source.

Children and adolescents usually get enough protein from food, and supplements for them are advisable only on the recommendation of a pediatrician or dietitian, for example in the case of a vegan diet with a risk of deficiency. In pregnant and breastfeeding women the protein requirement increases, but the use of supplements should be coordinated with a doctor, paying attention to the quality of the product and control for heavy metals.

People who take medications continuously should remember that protein is food. No direct significant interactions of pea protein with medications have been described, but in patients with several chronic diseases (for example, kidneys plus heart) the overall diet should be coordinated with a doctor.

What is not a contraindication

There are also false restrictions around plant proteins. Let us dispel the most common of them.

• Lactose intolerance.On the contrary, pea protein contains no lactose and is often a convenient alternative to whey.
• Celiac disease.Pea contains no gluten; however, it is worth choosing products with a «gluten-free» label because of the risk of cross-contamination in production.
• Healthy kidneys.In people without kidney disease, moderately high protein intake has not been proven harmful.
• Being male and «phytoestrogens».This is associated primarily with soy; pea is not a significant source of isoflavones.

Separately, let us mention favism — a hemolytic reaction in people with a deficiency of the G6PD enzyme. It is caused by broad beans (Vicia faba), not the field pea. However, people with G6PD deficiency should discuss any new legume products with a doctor.

Vegetarianism or veganism is also not a contraindication — it is precisely for these groups that pea protein is most relevant. But it is worth taking care of a variety of protein sources, combining pea with rice, grains, nuts and seeds.

Editorial conclusions

The absolute contraindications to pea protein are pea allergy, phenylketonuria and other hereditary disorders of amino acid metabolism. People with an allergy to other legumes, chronic kidney disease, gout and pregnant women need a doctor's consultation.

Relative restrictions apply to people with IBS and those who strictly limit sodium: they should choose the product carefully and monitor the reaction.

For most healthy people, including those with lactose or gluten intolerance, pea protein is a safe and convenient protein source.

We also recommend reading our articles «Side effects of pea protein», «Pea protein: product forms and which to choose» and «Who should not take egg protein».

References

1. Muraro A, Werfel T, Hoffmann-Sommergruber K, et al. EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy. Allergy. 2014;69(8):1008–1025.
2. Ikizler TA, Burrowes JD, Byham-Gray LD, et al. KDOQI clinical practice guideline for nutrition in CKD: 2020 update. Am J Kidney Dis. 2020;76(3 Suppl 1):S1–S107.
3. van Wegberg AMJ, MacDonald A, Ahring K, et al. The complete European guidelines on phenylketonuria: diagnosis and treatment. Orphanet J Rare Dis. 2017;12:162.
4. FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology guideline for the management of gout. Arthritis Care Res (Hoboken). 2020;72(6):744–760.
5. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults. Hypertension. 2018;71(6):e13–e115.
6. Gibson PR, Shepherd SJ. Evidence-based dietary management of functional gastrointestinal symptoms: the FODMAP approach. J Gastroenterol Hepatol. 2010;25(2):252–258.
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.