Plant Protein Powders: Soy, Pea, Rice and Blends

Overview

Plant protein powders are made from soy, peas, rice and other plants, alone or in blends. They are dietary supplements, which in the US are not reviewed for safety before sale. [1] For most people a balanced diet already provides enough protein, plant-based or not. [2] The direct comparison with whey sits on Whey vs Plant Protein. This page covers what we know about each plant source.

Evidence labels: evidence in adequately nourished people (trials in healthy people), mixed (studies disagree), insufficient evidence (too few good studies).

Quality differences

A 2020 overview found whey and soy averaged a DIAAS of 75 or more, while pea, rice, hemp and some other plant proteins fell below 75; potato, soy and pea proteins raised scores when mixed with other plant proteins. [3] The authors work for a potato-protein company. [3] A review of plant versus animal proteins adds that most plant proteins have relatively low leucine content, and that combining sources can give a more balanced profile. [4] It also notes few studies have measured muscle protein synthesis after plant proteins. [4] See Protein Quality.

What trials show

Across trials, a meta-analysis of 16 randomized trials found protein source did not change absolute lean mass or strength overall, though animal protein tended to favor percent lean mass, especially in younger adults. [10] In a trial of habitual vegans and omnivores both given about 1.6 g per kg a day with supplemental soy or whey, gains in muscle and strength did not differ. [11]

Reading a plant powder label

Check the protein per serving, the protein sources listed, and any added sugar, since the British Heart Foundation notes many "high protein" products carry added sugars and fats. [2] A blend of several plant proteins may give a more balanced amino acid profile than one source alone. [4] Doses in the trials above ranged from 24 g to 50 g of protein a day, and the trials were short, so do not assume the same results from a longer, different product. [7][6]

Allergens and sensitivities

The NHS lists soybeans and peas among common allergic foods. [12] In the US, soybeans are among the major food allergens. [13] Blends can contain several allergens, so read the allergen statement. Any powder can carry contaminants; see Protein Powder Safety.

Who might consider them

People avoiding dairy or animal products, or with a milk allergy, may find plant powders useful. See Protein for Older Adults and Vegetarian or Vegan Diets. Food sources such as beans and pulses are also good protein sources. [14]

Safety

People with kidney disease may need to limit protein. [15] Supplements can interact with medicines; see How Interactions Work.