Which is Best – Whey, Soy, or Pea Protein Powder?

UK Fitness Pro
UK Fitness Pro
· 7 min read
Pea and soy protein powders

Can you get enough protein from plant-based proteins to support muscle growth? Yes, here's why...

Essential Amino Acids

Whey powders are often considered the "gold standard" due to their complete amino acid profile. However, as you can see from the graphs below, pea and soy protein powders are very similar to whey protein powders in terms of their amino acid content (Gorissen et al., 2018)

Grams of Essential Amino Acids per 100 Grams of Pea Protein Isolate and Whey Protein Isolate

A graph showing the essential amino acids in pea protein powder and whey protein powder

To discover more about these types of protein powder, check out my article comparing whey and pea protein. You might also be interested in my articles comparing collagen and whey protein and comparing essential amino acid supplements and whey protein

Grams of Essential Amino Acids per 100 Grams of Soy Protein Isolate and Whey Protein Isolate

Like pea protein powder, soy protein powder contains all the essential amino acids and so is a complete protein source. However, it should be noted that leucine, in particular, is known to promote muscle protein synthesis (Garlick, 2005), and there's more leucine in whey compared to pea or soy proteins. While this is one of the key differences between these powders, only 3.5 grams of leucine per day can lead to significant increases in power and endurance (Crowe et al., 2006), and it wouldn't be hard to get this from either of the plant sources. ​

You might also like my articles on soy and whey protein and soy protein concentrates and isolates

Amount of Protein

As you can see from the table below, powders made from plant proteins often have as many grams of protein per 100 grams as whey protein powder—if not more. For instance, the two soy protein isolates in the table have more protein than a typical whey protein concentrate, and at least as much as a typical whey protein isolate. Therefore, plant-based options can be an excellent choice if you want to increase your protein intake. 

Calories and Macronutrients per 100 Grams of Pea, Soy, and Whey Proteins from Myprotein (MP) and Bodybuilding Warehouse (BW) 

BW pea protein isolate3958036
MP pea protein isolate388802.65.5
BW soy protein isolate3689061
MP soy protein isolate360901.81.5
MP whey concentrate405778.37.1
MP whey isolate359814.61.1
BW whey concentrate375804.75.7
BW whey isolate3749011

Muscle Mass

Pea Protein Powder vs. Whey Protein Powder

One study found that after 12 weeks of resistance training, pea protein supplementation significantly enhanced the thickness of bicep muscle tissue compared to a placebo. Additionally, there was not a significant difference in muscle gain between the pea protein and whey protein groups (Barbault et al., 2015).

A sample of pea protein powder

sample of pea protein powder from Myprotein. If you're undecided about which protein powder to go for, picking up cheap samples like this is a good option. 

Soy Protein Powder vs. Whey Protein Powder

A randomised controlled trial demonstrated that during resistance training, both whey and soy protein supplements significantly contributed to building muscle mass compared to a placebo (Candow et al., 2006).

Muscle Strength

Pea Protein Powder vs. Whey Protein Powder

One study revealed that after an 8-week high-intensity functional training programme, supplementation with either whey or pea protein resulted in comparable gains in strength, with no significant differences observed between the two types of protein (Banaszek et al., 2019).

A sample of soy protein powder

sample of soy protein from Myprotein. With 90 grams of protein per 100 grams, soy protein isolate is a popular choice among those who want a powder that packs a lot of protein in each serving. 

Soy Protein Powder vs. Whey Protein Powder

The study above by Candow et al. (2006) discovered that soy and whey protein powders not only promoted muscle tissue growth to a similar extent but also resulted in comparable increases in strength after a 6-week training programme.

Weight Loss

Pea Protein Powder vs. Whey Protein Powder

The study by Banaszek et al. (2019) mentioned previously showed that during an 8-week high-intensity functional training programme, supplementation with whey and pea protein led to comparable improvements in body composition.

A bag of whey protein powder

Whey protein has probably been researched more than any other dietary supplement. Time and again, evidence indicates that it can help people capitalise on the effort they put into their physical activity. You can get samples of whey protein for £1–2. 

Soy Protein Powder vs. Whey Protein Powder

Although many studies have shown that plant-based and whey proteins have similar effects, whey protein might be slightly more advantageous for weight loss. A study that compared whey protein and soy protein use among overweight and obese individuals found that whey was more effective in reducing body weight and fat mass (Piri Damaghi et al., 2022).

You might also like my article on the best protein supplement for weight loss. If you'd like to avoid weight loss, check out my article on the best protein supplements for weight gain

Environmental Impact

The production of plant-based proteins typically has a smaller environmental footprint than animal-based proteins (Bryant, 2022). However, not all plant proteins have the same impact; for example, pea production is generally less harmful to the climate and consumes less water than soy production (Cellura et al., 2022). Therefore, pea protein powder may be the better option if environmental sustainability is important to you. 

Other Types of Plant-Based Protein Powders

Brown Rice Powder

Brown rice protein powder is another option for those on a vegan diet. You can find out how it compares to other type of protein powder in these articles:

Hemp Protein Powder

Hemp protein powder is made from hemp seeds. While it tends to be less dense in protein, it could still be a great option for those looking for a vegan protein powder to help them get extra protein in their diet. You can find out more in these articles:

Food Sources

Protein powders usually offer substantial amounts of protein but lack other essential nutrients. 

Therefore, maintaining a balanced diet that includes whole foods, which supply necessary micronutrients, is crucial. As discussed on the BBC Good Food website, various vegan foods are rich in protein, including quinoa (4 grams per 100 grams), lentils (9 grams per 100 grams), beans (7-10 grams per 100 grams, depending on the variety), oats (10 grams per 100 grams), and broccoli (4 grams per 100 grams).

If you're interested in animal sources of protein, eggs, chicken, and turkey are popular choices among bodybuilders

You might also like my article comparing egg protein with whey protein

Frequently Asked Questions About Protein Powders

Do Protein Powders Contain Heavy Metals?

A study featured in Toxicology Reports analyzing 133 whey and plant protein powders concluded that the levels of heavy metals in these powders were not likely to pose significant health risks (Bandura et al., 2020). Peas, like many plants, often contain trace amounts of heavy metals, which are naturally present in the soil and absorbed by plant roots (Adeferati et al., 2017).

Do Protein Powders Contain Artificial Sweeteners?

Yes, most protein powders contain artificial sweeteners, including those from plant-based protein sources. If you'd like to avoid these, you could opt for an unflavoured protein powder. I wouldn't recommend making protein shakes with unflavoured powder, but it can be good in smoothies as other ingredients can provide the flavour. 

What Are Protein Powders Made From?

Of course, the answer to this depends on the type of protein powder. Whey protein comes from cow's milk, pea protein from yellow peas (specifically, yellow split peas), and soy protein from soy beans.


If you have lactose intolerance, experience an allergic reaction to whey, or your personal preference is to avoid animal proteins, you can certainly get a lot of high-quality protein from powders made from peas and soy beans. If your fitness goals include building muscle, increasing strength, or losing weight, the high protein content of these protein powders makes them a good choice for those on a plant-based diet. 

You might also be interested in these articles:

About the Author

Dave Robinson, a co-founder of ukfitness.pro, has a background in psychology (BSc) and neuroscience (MSc, PhD). As well as strength training, he enjoys endurance challenges and has run ultramarathons, cycled across several countries, and completed the Three Peaks Challenge. When writing, he draws on scientific evidence to understand the pros and cons of different diets, supplements, and training regimes.