Soy Vs. Pea Protein – Definitive Guide To Which One Is Best


Are your trying to choose between soy and pea protein? Nowaday, there are a lot of vegan protein powders you can choose from, so it’s no wonder that people find it difficult to decide which one to buy. From soy and pea protein to rice, hemp, sunflower, and pumpkin seed protein, avoiding animal-based protein supplements has never been easier.

While soy and pea protein are the two main plant-based proteins that are jockeying for dominance in the protein powder industry, if you’re looking to make the switch but aren’t sure which one to go with stick around to find out everything there is to know about these types of protein supplements so you can decide which one would work best for you.

What is Soy Protein?

soy vs. pea protein

Soy protein is isolated from soybeans and is most commonly referred to as soy protein isolate. What makes this type of protein so popular among other plant-based options is that it is cheaper and more easily available. 

Additionally, soy protein is a complete protein, which is not common for plant proteins and it provides complete nutritional value that other plant proteins don’t have. It contains all the essential amino acids that are needed to support muscle growth.

Due to its full amino acid profile, soy protein has a major advantage over other plant-based proteins.

Soy protein can be used to help you gain weight, build muscle and boost your energy levels. Soy has a rich nutritional profile. It is high in protein, vitamins, minerals, fiber, and antioxidants. Soy protein is low in saturated fat and cholesterol and is effective at lowering serum cholesterol and LDL cholesterol (“bad cholesterol”) levels.

However, soy is considered a somewhat controversial food. Some see it as a nutrient-dense powerhouse, while it is shunned by others. We’ll delve deeper into the subject below when we discuss the pros and cons of using soy protein.

Pros and Cons of Soy Protein

Both soy and pea proteins can be very effective in increasing markers of muscle growth quite effectively, at times even as effectively as dairy – whey protein.

However, when considering their amino acid profile, out of these two types of protein, soy is often considered the best option.

Here are its main benefits in comparison to other protein options.

Pros of Soy Protein

  • Complete protein with high digestibility rate

Soy has the highest digestibility rate of all the plant-based proteins available. Protein digestibility refers to how well the body can digest and use a certain protein source.

There are a few factors that determine the protein’s digestibility, one of which is its amino acid composition. Soy has a complete amino acid profile, making it a complete source of protein. Soybeans are also one of the most nutritiously-packed legumes.

  • May help reduce risk of prostate and breast cancer

Other common benefits of using soy protein instead of protein from animal sources include lowering the risk of prostate cancer and breast cancer, due to high doses of isoflavones found in soy, which can block the more potent, natural estrogen in the blood. Since increased estrogen has been linked to certain types of breast cancer, blocking it can have the effect of reducing the risk of these types of cancer.

  • Can help lower cholesterol levels

Additionally, soybeans have also been linked to lower cholesterol levels and lower rates of heart disease.

Cons of Soy Protein

While its properties give it an edge over other vegan-friendly options, soy protein is subject to a certain level of controversy. Let’s check out the main risks associated with taking soy protein isolate.

  • Isoflavones 

While in certain studies, high doses of isoflavones have been proven to block the natural estrogen in the body and reduce its levels, some studies have suggested that isoflavones may be beneficial to some, but harmful to others. That’s why more research needs to be done into the effects of isoflavones on estrogen levels in the body.

  • Thyroid function

Animal studies have found that some compounds in soy can reduce thyroid function and lead to hypothyroidism. However, human studies have found little to no negative effects of soy on humans with healthy thyroid function.

  • GMOs

A common concern with soybeans and soy protein is the fact that most soybeans are genetically modified, thus may contain more herbicides and fewer nutrients in comparison to organic soy. However, if you want to avoid consuming genetically modified soy, you can look for organic brands such as True Nutrition, AdvantaSoy, or others.

  • Allergies

A big concern for people when using soy protein powder are the rising rates of soy allergies that can cause inflammation, itching, and hives. People who have soy allergies can look for alternative options, such as pea protein, which is hypoallergenic (free from common allergens).

What is Pea Protein? 

soy vs. pea protein

Pea protein is a protein supplement made from yellow split peas. It is mostly found in energy bars, veggie burgers, meal-replacement shakes, and even cereals.

It is used to boost protein intake and has been gaining popularity in vegetarians and vegans who are looking for a healthy, dairy-free option when it comes to protein supplements.

Unlike soy protein, pea protein has a nearly complete amino acid profile. While it has all 9 essential amino acids in its profile, it is low in one of them and that’s methionine. 

What this means is that you should take it as one of your protein sources, but not as your major choice. However, there’s a way around this and we’ll discuss it in detail below.

Aside from being a good source of high-quality protein, peas are a great source of iron. Pea protein is also high in fiber, helping keep you full for a longer time, while also benefiting gastrointestinal health.

Studies have shown that pea protein is more satiating than whey protein, making it a better choice for those who are looking to control their appetite.

Note: Since iron found in plant-based foods is not as easily absorbable as the one found in animal products, combine your pea protein powder with vitamin C for greater absorption.

Pea protein is vegan, gluten-free, and dairy-free and it’s safe for people with allergies to eggs, cow’s milk, peanuts, tree nuts, wheat, fish, shellfish, and soy, which are some of the most common ones. This makes pea protein a suitable choice for a variety of diets, no matter how restrictive they may be. Only those intolerant or allergic to peas should avoid it.

Pros and Cons of Pea Protein

While it may not be considered as a complete protein by some, compared to other plant-based options, pea protein may beat out its competition in terms of its amino acid profile.

In comparison to soy protein, let’s check out some of the benefits it can offer, as well as some of its downsides.

Pros of Pea Protein

  • Easy to digest (for most)

While peas and legumes, in general, are harder to digest due to their high levels of fiber and starch, pea protein powder loses most of its starch and fiber when processed, making it easier to digest. Pea protein powder is made of proteins that are 95-98% digestible and easy to absorb, meaning that the body can get them quickly and use them wherever they’re needed most.

Its high digestibility and absorption rates make it suitable to take just before or after exercising so you can get all the amino acids needed to build and repair muscle right away.

  • Hypoallergenic

Unlike soy or whey protein powder, pea protein doesn’t contain any of the common allergens and allergic reactions to it are very rare. Pea protein is gluten-free and lactose-free, making it a suitable choice for those with such dietary restrictions.

  • Helps curb appetite

Pea protein powder is low in calories and has a high protein content, making you feel full for longer and promoting appetite control.

Cons of Pea Protein

  • Not a complete protein

While it contains all 9 essential amino acids, some still don’t consider pea protein a complete protein, due to its low methionine amount.

Protein powders made from plant sources, in general, have lower levels of some of the essential amino acids needed to stimulate muscle protein synthesis (MPS) and build muscle, particularly Lysine, Methionine, and Leucine.

This is why pea and rice protein are often combined together in certain vegan protein blends. Peas are lower in methionine but higher in lysine, while rice is lower in lysine and higher in methionine, giving these blends a better amino acid profile.

You can also compensate by adding brown rice to your diet, which has a high methionine content.

  • Some experience digestive upset

Pea protein contains purines, which break down into uric acid. While purines aren’t bad in normal amounts, excess amounts can cause uric acid build-up and make it difficult for your kidneys to get rid of all the uric acid.

Due to increased amounts of uric acid in the blood, crystals can form in the joints and cause inflammation and pain. Those who suffer from gout or have reduced kidney function should speak to their doctor before taking pea protein. 

Soy vs. Pea Protein

If you’re still on the fence when it comes to choosing between pea and soy protein, this next part should help clear things up. Aside from their main health benefits and downsides, let’s take a closer look at their main features and see how they compare.

Soy vs. Pea Protein: Taste

  • Soy protein powder has a smooth to medium grainy texture. It has a slightly nutty flavor and goes well with both sweet and savory dishes and drinks. Since it has little to no taste, you can even mix it with water and it will taste fine. If you’re looking to improve the taste, you can add some vanilla flavor, cinnamon, cocoa powder, or whatever works best for you.

    Certain brands of soy protein powder may include stabilizers and additives in their composition, so they can achieve a richer and creamier texture. That’s why we recommend trying several brands before you settle on the one that tastes and works best for you.
  • Pea protein powder has a naturally fluffy texture, is less chalky than most protein powders and has a sweet, nutty flavor.

    Its flavor is mild, so it won’t stand out in taste when mixed with other ingredients. Since it’s pretty much unflavored, pea protein is a suitable option for adding it to smoothies and a variety of meals. You can even mix it in with a glass of water and it will still have a nice taste.

    Pea protein is commonly mixed with rice protein to improve its texture, flavor and create a more balanced amino acid profile, so if you’re looking to get even more benefits out of your pea protein supplement, look for a mixture of pea and rice protein powder.

Soy vs. Pea Protein: Nutrition

  • Soy protein isolate belongs to the ‘legumes and legume products’ food category. It contains 95 calories per serving (28.35 g), although this depends mostly on the brand of product you choose. If there are additional ingredients in its composition, such as added sugar and so on, the calorie count will be higher. Those calories are made up of 82.84% protein, 8.39% fat and 8.86% carbohydrates.

    Soy is a great source of vitamins and minerals, including iron, phosphorus, copper, manganese and antioxidants.
  • Pea protein isolate is also a part of the ‘legumes and legume products’ food category. It contains 80 calories per serving (20 g), although this depends mostly on the brand of product you choose. Some brands of pea protein have additional ingredients in their composition so the calorie count in those will be higher. Out of those 80 calories per serving, there are typically 15 grams of protein, 1.5 gram of fat and 1 g of carbohydrates.

    Similar to soy protein, pea protein isolate is also a great source of vitamins and minerals, including iron, copper, phosphorus, manganese, folate, vitamins B6, B2, niacin, molybdenum, and vitamins C, A, and K.

Soy vs. Pea Protein: Cost

When it comes to the price tag of these two types of proteins, soy protein is definitely the cheaper option. Although its prices could eventually increase due to the disruption in the logistics and production chain caused by the coronavirus pandemic, soybean prices remain low.

The rising interest in pea protein could potentially put a strain on the pea protein industry and may even lead to a shortage of this type of protein, eventually leading to producers struggling to keep up with demand, which may cause its prices to rise as well.

Soy vs. Pea Protein: Best for muscle gain

soy vs. pea protein

Both soy and pea protein are great choices when it comes to plant-based proteins, as they are rich in essential amino acids, which are typically known as the building blocks of protein, necessary for muscle growth and recovery.

However, soy protein isolate is a complete protein, containing all 9 essential amino acids, while pea protein is low in one important essential amino acid – methionine.

For this reason, combining pea protein with other protein sources which are rich in methionine is important and even necessary in making a complete protein. One of the easiest ways to achieve that is to consume methionine-rich foods, like brown rice, quinoa, oats, sunflower seeds, hemp, and so on. Combining these protein sources at the same time is not necessary, as long as you have a nice balance of essential amino acids over the course of the day.

While pea protein may be lacking in methionine, it has a high leucine and arginine content and is thus great at promoting muscle growth.

Soy vs. Pea Protein: Best for weight loss

soy vs. pea protein

Pea protein has been proven to increase feelings of fullness as it is absorbed slower than other types of protein, especially whey protein, making you feel full for longer by boosting your levels of satiety.

Another study found that pea protein showed a strong effect on food intake and appetite when taken as a preload. Taking just 20 grams of pea protein 30 minutes before a meal, decreased the food intake throughout the day by increasing satiety in the participants.

While pea protein has been proven to be optimal for weight loss and maintaining muscle, soy protein doesn’t stand far behind. Soy protein helps reduce cravings as well and aids in reducing body fat production.

Ultimately, whichever protein powder you decide to take, when it comes to weight loss, the most important part of the equation is increasing your protein intake.

Having 25–35% of your total daily caloric intake come from protein seems to be most beneficial for weight loss. In addition to taking protein powder in supplement form, increase your protein intake through whole foods, so you can meet your protein needs via food.

Best Soy Protein

With tons of different soy protein brands available on the market, you might be left wondering which to choose. While there are a lot of great options out there, we’ve selected the top three ones that consumers like best. In the end, it’s up to your personal preferences, your budget, and your needs to decide which product you’ll select.

soy vs. pea protein
  1. BulkSupplements Soy Protein Isolate

If you’re looking for an affordable, yet pure and effective soy protein powder, BulkSupplements Soy Protein Isolate is the one for you. It is one of the most affordable options on the market since it comes in bulk. It is 90% protein, meaning no calories are wasted on other ingredients. It has 27 grams of protein per serving and can aid you in muscle building and recovery.

Six Star Pro Nutrition Soy Protein contains 100% soy protein with added vitamins, including B6 and B12, calcium, and iron. It comes in a french vanilla flavor, mixes well and is very affordable.

Universal Nutrition Advanced Soy Protein Isolate is a 100% water-washed isolate for optimal health benefits. There are no additives or harmful substances in its composition, so you can get the maximum benefits from it, in a natural way.

Best Pea Protein

Let’s take a look at some of the best options on the market when it comes to pea protein supplements.

  1. Naked Pea from Naked Nutrition

This pea protein isolate is extracted from yellow split peas grown in the US and Canada. It is 100% pea protein with no additives or artificial sweeteners in its composition. It is very affordable, processed without the use of chemicals, and is one of the cleanest, highest quality proteins available on the market.

NOW Plant Protein from Now sports is a blend of pea, brown rice, hemp, and quinoa protein, providing all essential amino acids in one plant protein complex. 

If you’re looking for a more affordable option that’s clean and pure and has no additives or fillers in its composition, the Pea Protein Isolate from BulkSupplements is the one for you. 

Soy vs. Pea Protein: Takeaway

When you take all of these facts into consideration, it’s up to you to decide which of these two popular choices of plant-based proteins works best for you. This depends on a lot of factors, including your budget, your dietary preferences, the goals you want to achieve, and much more.

Both pea and soy protein are great choices offering lots of benefits for people whose diets are lacking in protein, or who wish to gain more muscle. They are great sources of essential amino acids and have comparable amounts of protein and fiber, so in the end, it comes down to personal preference and tolerance when deciding which protein powder to go with.


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