Last updated: October 27, 2020

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Soy protein is an excellent source of amino acids for vegans, vegetarians, and anyone allergic to cow’s milk protein – especially if they are athletes or very active. This type of protein contains just the right amount of amino acids in proportions that can significantly promote muscle development.

Nowadays, there is a wide range of pure soy protein supplements on the American market. You will have to dissolve these powder products in water, milk, or vegetable drinks before consumption. But how does soy protein differ from Whey protein? Should you opt for soy protein isolate or concentrate? We will solve any doubts you have in our new guide.

Key Facts

  • Soy protein is a complete plant protein. This means that it provides all the essential and non-essential amino acids that the human body needs to build and repair muscle tissue, among other functions.
  • These supplements come in the form of powder and can be either soy protein concentrate or isolate. The latter is the most recommended for its higher protein content and better solubility.
  • You will have to evaluate various essential criteria before you can purchase the right soy protein product for your needs. These include the type of supplement (isolate or concentrate), the presence of potential allergens, the flavor, or the solubility, among others.

Our Selection: The Best Soy Protein Products on the U.S. Market

The supplement industry is in constant growth, with more products available every year. It’s certainly no different for soy protein. This great variety means that everyone can find the best supplement for them, but it can also be challenging to make a decision. To help you get it right, we have selected the most popular soy protein products currently available out there:

Best Soy Protein Supplement Overall

This natural oy protein isolate contains no artificial sweeteners or GMOs. Compatible with vegan diets, its recommended daily dose is 24 grams (for 20 grams of protein). As the powder has the original taste of soy, you are advised to mix it with fruits or plant-based milk. Get ready to finally have all the amino acids your body needs! $0.62 per ounce.

Best Flavored Soy Protein Powder

If you prefer to have a tasty powder to which you only have to add water for a daily protein intake, this is an excellent option. This vanilla-flavored supplement packs 24 vitamins and minerals to help you reach your weight loss goals. Note that this lactose-free product does not replace a healthy diet. $1.26 per ounce.

Best Soy Protein Isolate for Athletes

If you’re an athlete looking to increase your vegan protein intake as part of a diet to increase your muscle mass, BulkSupplements’ isolate powder is right for you. With one kilogram (2.2 pounds) in each pack, you’ll be getting all the amino acids your body needs, in addition to a large portion of your recommended daily allowance (RDA) in calcium. $0.57 per ounce.

Best Gluten-Free Soy Protein Product

This soy protein powder by Bob’s Red Mill is manufactured in a dedicated gluten-free facility, making it ideal for celiac individuals. Besides, each box contains four packs of 14 ounces of supplement you can take with you if you travel frequently. It’s also the most affordable soy protein of our selection, at $0.50 per ounce.

Shopping Guide: Everything You Should Know About Soy Protein

Soy protein is widely consumed by vegan athletes and people allergic to cow’s milk protein. Just like with any other dietary supplement, purchasing a high-quality product doesn’t necessarily guarantee optimal results. You have to know how it works and how to use it correctly. In the following section, we have answered the most common questions regarding soy protein.

portrait of smiling young woman with glass of milk in kitchen

Soy protein is widely consumed by vegan athletes and people allergic to cow’s milk protein.
(Source: Citalliance: 17800114/ 123rf.com)

What are soy protein supplements exactly?

Defatted soy flour is used to make these protein supplements. The raw material is treated in an acid or alkaline medium to separate the protein from the rest of the nutrients in the flour (carbohydrates and fiber) (1). The protein remaining is then dried and ground into a fine powder, in which colorants and flavorings are sometimes added.

Does soy protein have a high biological value?

In short, yes. Unlike soybeans, whose biological value is medium, soy powder supplements’ protein value is much higher. Three fundamental criteria are brought forward to support this claim:

  • Amount of protein: Soy concentrate provides approximately 70% of protein, while it represents around 85 to 90% of its composition in the isolate of this nutrient (2).
  • Type of amino acids: Two types of these units make up proteins – essential (that the body cannot produce on its own) and non-essential. Soy protein provides every amino acid, although methionine is found in minimal amounts (3).
  • Protein digestibility: This factor is decisive in determining the quality of a protein. Soy protein powder supplements are much more digestible than soybeans because the antinutrients (trypsin and phytate inhibitors) that affect the exploitation of soy protein have been removed during processing (3).

What types of soy protein products are there?

Soybeans allow us to produce oils, flours, soy meat, and vegetable drinks, among others. In our guide, we will focus on the two supplements that concentrate soy protein (2, 3):

  • Soy protein isolate: This is the most refined form of soy protein supplement. The raw material, defatted flour, is processed to remove both soluble and insoluble carbohydrates that make up the flour. It results in a fine powder that contains 90% protein and dissolves very well in liquids.
  • Soy protein concentrate: It is also produced from defatted soy flour. However, the treatment of the raw material only eliminates soluble carbohydrates. Soy protein concentrate provides at least 70% protein and small amounts of carbohydrates.
Characteristics Soy protein concentrate Soy protein isolate
Protein content At least 70 % Between 85 and 90%
Quantity of branched amino acids (mg/gram of protein) Leucine: 62 mg/g.

Isoleucine: 46 mg/g.

Valine: 48 mg/g.

Leucine: 66 mg/g.

Isoleucine: 53 mg/g.

Valine: 51 mg/g.

Solubility It tends to form lumps in both hot and cold water. It dissolves well in cold water. In hot water, it generally forms lumps as well. Its solubility is better overall.
Price More affordable More expensive
Carbohydrate content Around 20% Between 1 and 2%
Primary use In processed foods (meat, dairy, baked goods) Nutritional supplements for athletes, vegans, and individuals allergic to cow’s milk protein

Who can benefit from soy protein consumption?

These supplements are ideal for vegan athletes because they offer a complete amino acid profile and high digestibility that promotes the development of muscle mass. However, soy protein also provides various benefits for other population groups:

  • Athletes in general. Soy protein is rich in essential branched-chain amino acids (BCAAs), which are vital for muscle development and recovery after physical activity (4).
  • Individuals allergic to cow’s milk protein – athletes or otherwise – and who are looking to increase their protein intake.
  • Older adults who cannot meet their protein requirements in their regular diet. The versatility and affordability of soy protein powder, as well as our body’s generally good tolerance to it, make it an efficient product.
  • Individuals with poor digestive tolerance to soybean, meat, or flour. These foods can lead to bloating and flatulence due to the presence of raffinose and stachyose. In soy protein isolate, however, these indigestible compounds have been eliminated.
  • Young women. Isoflavones present in soy protein may exert a protective effect on cardiovascular health and bone loss in postmenopausal women. These benefits have been observed in women who consume soy from a young age (5).
Soy milk and soy bean on wooden background

Soy protein is rich in essential branched-chain amino acids (BCAAs), which are vital for muscle development and recovery after physical activity.
(Source: Petcharakul: 31138259/ 123rf.com)

Does soy protein offer additional health benefits?

Soy is a natural source of isoflavones, organic compounds that are further concentrated in supplements. These flavonoids possess antioxidant, anti-inflammatory, and hypocholesterolemic (cholesterol-lowering) properties. This is why you can reap the following rewards from consuming soy protein (6):

  • Reduction of oxidative damage due to antioxidant activity. High levels of oxidative damage are associated with an increased risk of developing heart conditions, atherosclerosis, and certain types of cancer.
  • Relief from menopause-related hot flashes and reduction of cardiovascular risk associated with decreased estrogen production during this biological stage (7).
  • Decreased levels of LDL (bad) cholesterol. This, in turn, reduces the risk of atherosclerosis, non-alcoholic fatty liver, and cardiovascular diseases (8).
  • Prevention of the risk of osteoporosis in postmenopausal women. Isoflavones mitigate the loss of bone density resulting from estrogen deficiency (9).

What are the advantages of soy protein for athletes?

The branched-chain amino acids leucine, valine, and isoleucine are essential and must be obtained through food or supplements. BCAAs are critical to the development of new muscle mass while helping to mitigate the destruction of muscle fibers after strength training (4).

Soy protein is an excellent plant source of leucine, isoleucine, and valine (6). While animal proteins are naturally richer in BCAAs, soy protein isolate and concentrate are highly recommended for vegan athletes, people allergic to cow’s milk protein, or anyone experiencing digestive discomfort from the consumption of Whey protein.

Branched-chain amino acids (BCAAs) Standard protein Soy protein isolate Whey protein isolate Pea protein
Amino acid content in mg/g of protein Amino acid content in mg/g of protein Amino acid content in mg/g of protein Amino acid content in mg/g of protein
Leucine 55 66 80 82
Isoleucine 25 53 59 44
Valine 32 51 54 49
determined man and woman running on road against trees. runners sprinting in full length of sporty male and female are in sports clothing. athletic runner fitness sport couple are exercising outside.

Soy protein is rich in essential branched-chain amino acids (BCAAs), which are vital for muscle development and recovery after physical activity.
(Source: Maridav: 47751079/ 123rf.com)

What is the difference between soy protein and Whey protein?

While both supplements provide all the amino acids your body needs, there are differences between these two types of proteins. You can compare them in the table below:

Characteristics Whey protein Soy protein
Origin Cow’s milk whey Defatted soy flour
Is it suitable for vegans? No Yes
Is it suitable for people allergic to cow’s milk protein? No Yes
Does it contain lactose? Yes, although you can find lactose-free Whey protein. No
Does it provide isoflavones? No Yes
Solubility High. It dissolves well in liquids and acquires a pleasant, soft, foamy texture. Its solubility is lower than that of Whey protein, but soy protein isolate tends to dissolve well in cold liquids.
Flavor Available in a wide range of flavors (neutral, strawberry, vanilla, banana, chocolate) Available in various flavors (neutral, natural, strawberry, vanilla, chocolate)
Price Average: $0.90 per ounce Average: $0.80 per ounce
Soy milk or soya milk and soy beans in spoon on wooden table.

These supplements are made from defatted soy flour.
(Source: Marctran: 80537409/ 123rf.com)

Is it harmful to consume too much soy protein?

In reality, this wouldn’t make any sense at all; the excess protein would be used to produce energy. Eating more protein does not mean that you would develop more muscle. You should always remember that the consumption of protein supplements must be accompanied by regular physical activity to build muscle.

Regarding potential side effects, soy protein won’t affect your kidneys as much as Whey protein, nor does it increase urinary calcium excretion too much (10). However, soy protein concentrate contains phytates (antinutrients), and these compounds can reduce the absorption of calcium and iron.

Do soy protein supplements have contraindications?

Anyone who has a chronic disease (liver, kidney, heart, endocrine) or is taking medication should consult their doctor before supplementing with soy protein. Here is a list of the population groups for whom this product may be contraindicated:

  • Individuals allergic to soybeans.
  • Women who have/had breast cancer.
  • Children, pregnant and breastfeeding women. We lack evidence to guarantee that soy protein supplements are safe at these stages of life.
  • People with hypothyroidism or a history of this thyroid disease. Isoflavones can affect the production of thyroid hormones (11).
  • Individuals with kidney diseases.
Did you know that the World Health Organization (WHO) determined that soy protein contains all essential amino acids in sufficient quantities to meet the protein requirements according to age and biological status?

Buyer’s Guide

Even if soy protein offers an excellent amino acid profile and its consumption is complemented by physical activity, the results you will notice depend largely on the type of supplement taken. Besides, you should take your personal preferences into account before making your purchase. In the section below, we have detailed the main shopping criteria to help you find the soy protein product that best suits you:

Type of Supplement

You should now be familiar with the differences between soy protein isolate and concentrate. We recommend opting for the former for its higher protein content. In addition, the amounts of carbohydrates, fiber, and fat have been reduced to a minimum during processing. Although it is slightly more expensive, it offers greater digestibility and solubility (3).

happy senior woman standing outside her house. content woman smiling and looking at camera. portrait of cheerful old grandmother relaxing outside the house.

Isoflavones present in soy protein may exert a protective effect on cardiovascular health and bone loss in postmenopausal women.
(Source: Rido: 56765974/ 123rf.com)

Allergens

Soy protein may contain traces of various allergens. This is due to the fact that these supplements are often processed and packaged in facilities where other allergens are also handled. This can potentially lead to contamination. The allergens that are generally found in soy protein include milk, peanuts, and eggs.

Flavor

You can find soy protein in various flavors: neutral, natural, strawberry, vanilla, chocolate, or caramel. Neutral-flavored protein can be added to smoothies and milkshakes, but you can also mix it with flours to make pancakes, waffles, and cakes. If you opt for artificially flavored soy protein, all you have to do is dissolve it in water or milk.

Presence of GMOs

The vast majority of soy protein supplements will feature a seal or logo on their packaging that specifies that the product is free of GMOs (genetically modified organisms). What this means is that the soybeans used to make the supplement are not genetically modified.

While many of us may not be interested in whether or not the soy protein is GMO-free, others see this as a decisive criterion as they do not include genetically modified foods in their diet. The primary reason for this is the ecological destruction (deforestation and contamination) associated with GMO cultivation.

Leena Hilakivi-Clarke, Ph.D.Professor of Oncology at Georgetown University
“Soy appears to be protective and is associated with a lower risk of breast cancer reoccurrence for women who have consumed soy throughout most of their life.”

Solubility

Solubility is the ability of soy protein powder to dissolve in water or any other liquid without forming lumps. As we mentioned earlier, isolate has a higher solubility than soy protein concentrate. Protein powder generally dissolves better in cold water than hot. The size of the particles, which will vary depending on the brand, also influences solubility.

Artificial Additives

Artificial additives, such as colorants and preservatives, increase the risk of digestive discomfort or skin rashes after consuming soy protein. This is why you are advised to purchase natural products. For example, you can find supplements that include beet pulp or beta-carotene to give them a pink or yellow color, respectively.

Summary

Soy protein is an amazing plant source of essential and non-essential amino acids. Soy protein isolates and concentrates are much more digestible than soybeans and flour as the antinutrients are removed during processing. Besides, the isolate can provide up to 90% protein.

In addition to promoting the development of muscle mass in athletes, this product reduces the risk of cardiovascular conditions, decreases bad cholesterol levels in the blood, and prevents osteoporosis. These wonderful benefits are due to isoflavones, a type of flavonoid that is naturally found in soy.

We hope that you enjoyed our shopping guide. If that’s the case, help us reach more people by sharing it on your social media. We’d love to hear your opinion too, so feel free to leave us a comment in the section below!

(Featured Image Source: Thi Hong Hanh Mac: 35317609/ 123rf.com)

References (11)

1. Messina M, Redmond G. Effects of Soy Protein and Soybean Isoflavones on Thyroid Function in Healthy Adults and Hypothyroid Patients: A Review of the Relevant Literature | Thyroid [Internet]. Mary Ann Liebert, Inc., publishers. 2006 [cited 22 September 2019].
Source

2. Jay R. Hoffman M. Protein – Which is Best? [Internet]. PubMed Central (PMC). 2005 [cited 22 September 2019].
Source

3. Cancelo Hidalgo M. Isoflavonas y salud ósea [Internet]. 2018 [cited 22 September 2019].
Source

4. Wong W, Smith E, Stuff J. Cholesterol-lowering effect of soy protein in normocholesterolemic and hypercholesterolemic men [Internet]. 1998 [cited 22 September 2019].
Source

5. Juliá M, Ferrer J, Allué J. Posicionamiento de la Asociación Española para el Estudio de la Menopausia sobre el uso clínico de las isoflavonas en el climaterio [Internet]. 2008 [cited 22 September 2019].
Source

6. Ridner E. Soja, propiedades nutricionales y su impacto en la salud [Internet]. 2006 [cited 22 September 2019].
Source

7. González Cañete N, Durán Agüero S. Isoflavonas de soya y evidencias sobre la protección cardiovascular [Internet]. 2014 [cited 22 September 2019].
Source

8. Shenoy S, Dhawan M, Singh Sandhu J. Four Weeks of Supplementation With Isolated Soy Protein Attenuates Exercise-Induced Muscle Damage and Enhances Muscle Recovery in Well Trained Athletes: A Randomized Trial [Internet]. 2016 [cited 22 September 2019].
Source

9. de Luna Jimenéz A. Valor Nutritivo de la Proteína de Soya. Investigación y Ciencia [Internet]. 2006 [cited 20 September 2019];:31, 32.
Source

10. de Luna Jimenéz A. Composición y Procesamiento de la Soya para Consumo Humano [Internet]. 2007 [cited 20 September 2019].
Source

11. Andújar G, Guerra M, Santos R. La Utilización de Extensores Cárnicos. Experiencias de la Industria Cárnica Cubana. [Internet]. 2000 [cited 20 September 2019].
Source

Why you can trust me?

Artículo científico
Messina M, Redmond G. Effects of Soy Protein and Soybean Isoflavones on Thyroid Function in Healthy Adults and Hypothyroid Patients: A Review of the Relevant Literature | Thyroid [Internet]. Mary Ann Liebert, Inc., publishers. 2006 [cited 22 September 2019].
Go to source
Artículo científico de PubMed
Jay R. Hoffman M. Protein – Which is Best? [Internet]. PubMed Central (PMC). 2005 [cited 22 September 2019].
Go to source
Artículo científico
Cancelo Hidalgo M. Isoflavonas y salud ósea [Internet]. 2018 [cited 22 September 2019].
Go to source
Artículo científico
Wong W, Smith E, Stuff J. Cholesterol-lowering effect of soy protein in normocholesterolemic and hypercholesterolemic men [Internet]. 1998 [cited 22 September 2019].
Go to source
Artículo científico
Juliá M, Ferrer J, Allué J. Posicionamiento de la Asociación Española para el Estudio de la Menopausia sobre el uso clínico de las isoflavonas en el climaterio [Internet]. 2008 [cited 22 September 2019].
Go to source
Libro científico
Ridner E. Soja, propiedades nutricionales y su impacto en la salud [Internet]. 2006 [cited 22 September 2019].
Go to source
Artículo científico
González Cañete N, Durán Agüero S. Isoflavonas de soya y evidencias sobre la protección cardiovascular [Internet]. 2014 [cited 22 September 2019].
Go to source
Artículo científico de PubMed
Shenoy S, Dhawan M, Singh Sandhu J. Four Weeks of Supplementation With Isolated Soy Protein Attenuates Exercise-Induced Muscle Damage and Enhances Muscle Recovery in Well Trained Athletes: A Randomized Trial [Internet]. 2016 [cited 22 September 2019].
Go to source
Artículo científico
de Luna Jimenéz A. Valor Nutritivo de la Proteína de Soya. Investigación y Ciencia [Internet]. 2006 [cited 20 September 2019];:31, 32.
Go to source
Artículo científico
de Luna Jimenéz A. Composición y Procesamiento de la Soya para Consumo Humano [Internet]. 2007 [cited 20 September 2019].
Go to source
Libro científico
Andújar G, Guerra M, Santos R. La Utilización de Extensores Cárnicos. Experiencias de la Industria Cárnica Cubana. [Internet]. 2000 [cited 20 September 2019].
Go to source