Quick answer

Over weeks of training they performed about the same. In the largest head-to-head trial, 161 men taking 25 g of pea protein or whey twice a day gained similar muscle thickness and strength. Whey carries more leucine per gram, so about 38 g of pea protein matches 25 g of whey.^1,2

Key facts

An isolate is over 90 percent protein; a concentrate is 29 to 80 percent.³
Soy and animal proteins gave similar gains in strength and lean mass across 9 trials.⁴
Milk is one of the nine major food allergens; pea is not on the list, though pea allergy does occur.^5,6
Most proteins that are not dairy or meat are absorbed at a medium to slow pace, soy being an exception.³

What head-to-head trials found

In the largest head-to-head trial, 161 young men taking 25 g of pea protein or whey twice a day through 12 weeks of training gained similar muscle thickness and strength. Three of the authors worked for a pea protein maker.¹

In an 8-week pilot trial of 15 adults, 8 men and 7 women, 24 g of pea or whey protein around workouts gave similar strength and body composition results.⁷

Across 9 trials of 6 weeks or more, soy protein gave gains in strength and lean mass similar to whey and other animal proteins.⁴

Plant proteins can support training gains close to those of animal proteins when total protein intake is adequate; this fava and yeast blend is untested*^8,9,10

Early evidence

A meta-analysis of 16 trials found no difference between plant and animal protein for gains in absolute lean mass or strength, though animal protein did slightly better for percent lean mass and in adults under 50; the plant proteins were soy, pea and rice, not fava or yeast. In the one fava trial, about 23 g did not raise muscle protein synthesis above a control drink of non-essential amino acids in 16 adults, and a 6-month trial of yeast protein in 92 older adults found no change in muscle mass or grip strength.

Amount studied: Soy, pea or rice protein in diets with total protein generally above the RDA

The large pea trial enrolled only young men and was partly run by a pea protein maker, and the pilot had 15 people. Pooled trials found animal protein slightly ahead for lean mass in adults under 50, so the result is less certain for some groups.^1,7,8

Leucine and essential amino acids

Pea protein isolates are about 80 percent protein, rich in lysine and low in methionine. They hold less leucine than whey, so about 38 g of pea protein supplies the leucine in 25 g of whey.²

Whey is one of the complete proteins in milk and is the protein in most powders and drinks. It is digested quickly.^3,11

Protein needed to match the leucine in 25 g of whey²
Protein	Amount	Essential amino acid below need
Whey	25 g	None
Casein	34 g	None
Brown rice	37 g	Lysine
Pea	38 g	Methionine
Soy	40 g	Methionine

Isolate, concentrate and hydrolysate

A protein concentrate is 29 to 80 percent protein by dry weight, and sports products usually use 70 to 80 percent. Extra filtering removes more lactose and fat, and a product above 90 percent protein is called an isolate.³

Hydrolyzed whey is broken into smaller pieces before you drink it. In one comparison its amino acids reached the blood faster than those from milk protein.³

Fast and slow

Casein is the main protein in milk. It is digested more slowly than whey, so its amino acids reach the blood more gradually.¹¹

Given the same 10 g of essential amino acids, whey raised muscle protein building more than slowly digested casein at rest and after exercise, and more than soy after exercise, in young men.¹²

Faster is not the whole story: over 12 weeks of training, pea protein kept pace with whey, and in pooled trials protein timing mattered less than the daily total.^1,13

Choosing between them

Choose on diet and tolerance more than on muscle. Whey suits people who eat dairy; pea, soy or a blend suits people who avoid milk, and a pea shake about half as large again as a whey shake covers the leucine gap.^2,5

Combining plant proteins, or plant with animal proteins, can give an amino acid profile closer to animal protein than a single plant protein.²

What's in ours

What’s in ours

Collagen Peptides: Protein, 18 g per serving, from the label
Collagen Peptides: Protein, 18 g per serving, from the label
Plant Protein: Protein, 20 g per serving, from the label
Plant Protein: Protein, 21 g per serving, from the label

Our Plant Protein uses fava bean protein isolate with fermented yeast protein rather than pea, and neither has been compared with whey in a training trial. Collagen Peptides, also listed here, are not a complete protein.^9,10,14

Allergies

Milk is a major food allergen, so whey and casein are out for people with a milk allergy. Pea is not among the nine major allergens, but severe reactions to pea have been described, sometimes linked to peanut allergy.^5,6

Questions people ask

Is pea protein absorbed as well as whey?

Plant proteins other than soy tend to reach the blood more slowly than whey, and pea carries less leucine per gram. In short lab studies whey raised muscle protein building more than soy, yet over 12 weeks of training pea and whey gave similar results.^1,3,12

Is whey isolate better than concentrate?

For muscle, an 8-week trial of hydrolyzed whey against two whey concentrates found the same gains in strength and lean mass. Isolate has more protein per gram and less lactose and fat.³

See what we make

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See the Full Measure line Collagen Peptides Collagen Peptides Plant Protein

Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.