What is pea protein? Features and benefits of its pea-derived source
What is Pea Protein? Protein Derived from Peas
Do you find yourself choosing products labeled "pea protein" without knowing exactly what they are made of or how they differ from other plant-based proteins? This article explains the raw materials of pea protein, its nutritional characteristics, and what you should look for on labels when selecting a product.
The Raw Material Is the Pea
Pea protein is made by extracting protein from peas and processing it into powder or food products. According to the Standard Tables of Food Composition in Japan, mature peas used for food are classified as legumes, while immature snow peas are classified as vegetables (MEXT, Standard Tables of Food Composition in Japan). Even though they are both "peas," their classification changes depending on the stage of maturity. Dried green peas, the raw material, contain 21.7g of protein per 100g of edible portion. Once boiled, the water content increases, causing the protein content to drop to 9.2g per 100g. Since pea protein is a concentrated form of protein extracted from these dried beans, it allows you to consume more protein in one serving than eating the whole beans. When choosing foods containing pea protein, it is recommended that you check the label for carbohydrates and energy (calories) in addition to the protein content, and use them to supplement any deficiencies in your regular diet. Points to keep in mind regarding the raw materials are also covered in What are the drawbacks of plant-based protein? An explanation of how to read protein, carbohydrate, flavor, and ingredient labels, so please refer to that as well.
What is protein made of in the first place?
Protein is a compound formed by peptide bonds of 20 types of L-amino acids (Ministry of Health, Labour and Welfare, "Dietary Reference Intakes for Japanese (2025 Edition)"). Among these, those that cannot be synthesized in the body and must be obtained through diet are called essential amino acids; for adults, there are nine types (Ministry of Health, Labour and Welfare, e-Health Net, "Amino Acids"). Whether it is pea protein or dairy-derived whey protein, even if the raw materials differ, the quality of the protein is evaluated based on how much of these nine essential amino acids it contains and in what balance. We will look at the specific characteristics of pea protein's amino acid balance in the next chapter along with specific numerical values.
Nutritional Characteristics of Pea Protein
Pea protein has several characteristics regarding its quality as a protein and features not found in other foods. Let's look at what you should know before choosing, including the balance of amino acids, allergy considerations, and findings from research.
Amino Acid Score and Low Methionine Content
A study published in 2024 reported the Digestible Indispensable Amino Acid Score (DIAAS) of pea protein to be 0.70, with cysteine and methionine cited as limiting amino acids (LWT 2024 published paper). The score is below 1.0 because of the low content of cysteine and methionine, known as sulfur-containing amino acids. On the other hand, the same paper reported a score of 0.83 for tryptophan and 0.96 for total sulfur-containing amino acids. Amino acids vary in abundance, and it is clear that pea protein is not "perfect" in every respect; it is a protein with distinct strengths and weaknesses.
Low Allergenicity and Low GI Value
Peas are not as widely known as an allergen as soy or milk. In the Consumer Affairs Agency's allergy labeling materials, while soy is recommended for labeling as a "substance equivalent to specified raw materials," peas are not listed as such (Consumer Affairs Agency, "Regarding Allergy Labeling"). It is noteworthy that this expands the ingredient options for people with soy or milk allergies. However, since it does not mean that an allergy to peas themselves cannot occur, those concerned about their constitution should check the ingredient label and try a small amount first.
Research Findings on Cholesterol
In a randomized, double-blind study of 175 adults with moderate hypercholesterolemia, a group that consumed bars containing a combination of pea protein and oat fiber saw a 135mg/L (4.7%) decrease in total cholesterol, while a group that consumed bars containing a combination of pea protein and apple pectin saw a 168mg/L (6.4%) decrease (PubMed, 2012). However, this result was for bars combined with dietary fiber and does not indicate the effect of pea protein alone. If you are concerned about cholesterol, it is better to view it as part of an overall review of your diet rather than relying solely on pea protein.
How Does Pea Protein Differ from Soy Protein?
Both are plant-based proteins, but if the beans used as raw materials differ, the amino acid content and allergy considerations will also change. Let's look at the specific differences, including taste preferences, usage, and research findings on post-exercise recovery.
Differences in Raw Materials and Amino Acid Balance
As mentioned above, pea protein is made from peas. Soy protein, on the other hand, is made from protein extracted from soybeans. Even though they are both plant-based proteins, the amino acid composition varies depending on the bean used. As noted, pea protein is reported to be low in methionine and cysteine. Since soy protein is made from a different bean, its amino acid balance is also different. It is important to choose them as foods with different raw materials rather than debating which is superior.
Differences in Allergies, Taste, and Usage
Soybeans are a food for which labeling is recommended as a substance equivalent to specified raw materials by the Consumer Affairs Agency (as mentioned above). Protein bars and powders using soy protein may be difficult for people with soy allergies to choose. Because pea protein does not use soy, it may be easier for people with soy allergies to choose after checking the ingredient label. In terms of taste, while some people find soy protein has a distinct soy flavor, pea protein also has a bean-like aroma and richness, and which one suits your taste varies from person to person. As for usage, both are widely used in items such as protein bars, smoothies, and baking ingredients.
Is There a Difference in Post-Exercise Recovery?
A systematic review of 24 studies (22 randomized controlled trials and 2 observational studies) targeting healthy young adults reported that single-source plant proteins, including peas, generally had a limited effect compared to animal-based proteins in terms of recovery after resistance exercise (Nutrients, 2025). This study targeted healthy young adults and cannot necessarily be applied to everyone. It should be kept in mind as a reference as a general trend common to plant-based proteins, including soy. For those interested in daily health, not just post-exercise nutrition, please also refer to What are the effects of Lion's Mane (Yamabushitake)? Current research, how to eat it, and precautions, as it is a plant-derived material currently gaining attention.
Does Pea Protein Strain the Kidneys? Who Should Be Careful?
Among those who incorporate pea protein into their daily diet, some are concerned about the impact on their kidneys. Here, we specifically explain the recommended daily protein intake, what those with underlying conditions should check first, and how to adjust your intake to continue without strain.
How Much Protein Is Needed Per Day?
According to Ministry of Health, Labour and Welfare materials, the daily protein maintenance requirement for adults is 0.66g per kg of body weight (Ministry of Health, Labour and Welfare, "Points for Establishing the Dietary Reference Intakes for Japanese (2025 Edition)"). Furthermore, the intake goal is 13-20% of energy for ages 18-49, 14-20% for ages 50-64, and 15-20% for ages 65 and older (Ministry of Health, Labour and Welfare, "Dietary Reference Intakes for Japanese (2025 Edition)" Report). This figure is not limited to pea protein but is a standard for total daily protein, including meat, fish, and eggs. When adding pea protein products, it is best to consider the amount based on how much you are getting from your total diet.
Consult Before Amount If You Have an Underlying Condition
People with decreased kidney function or those undergoing hemodialysis may have restrictions on their protein intake. We recommend that you consult your primary doctor or a registered dietitian before incorporating high-protein foods, including pea protein, into your daily routine. It is important for those under treatment to follow the treatment plan rather than increasing or decreasing the amount on their own. If you are concerned about your health checkup results, please visit a medical institution and consult about the appropriate amount for your current situation before choosing products.
Tips for Continuing Without Overdoing It
You do not need to consume pea protein products on days when you are already getting enough protein from your regular meals. For example, on days when you have had a meal with plenty of meat or fish, it is fine to cut back on foods containing pea protein. Conversely, on days when you have been eating out and have had few fish or soy products, incorporating them as a supplement is a balanced approach. It is recommended to adjust the amount according to the day's diet rather than continuing the same amount every day.
How to Choose Without Regret
There are an increasing number of pea protein products, and many people may be wondering what criteria to use when choosing. We will look specifically at which parts of the nutritional information and ingredient labels to check, and what points often divide opinions in reviews.
Items to Check First in Nutritional Labeling
The Consumer Affairs Agency states that it is mandatory to display energy, protein, fat, carbohydrates, and sodium (as salt equivalent) for processed foods for general consumers in containers and packaging (Consumer Affairs Agency, "Regarding Nutritional Labeling"). When you pick up a package, first check the amount of protein. The actual amount you can consume changes depending on whether the figure is per serving or per 100g. Also, since sodium is displayed as salt equivalent, you can see the figure as a direct guideline for salt. On days you use these as snacks, take a look at the salt equivalent as well.
What You Can Learn from Ingredient Labeling
The Consumer Affairs Agency states that ingredients used in food should be listed in descending order of weight, and additives should be displayed separately from ingredients (Consumer Affairs Agency, "Food Labeling You Should Know"). For pea protein products, where the pea-derived protein is written in the ingredient column tells you whether it is used as a main ingredient. Since there are products with many sweeteners and flavorings, checking if there are any additives you are concerned about will make it easier to choose. It is also helpful to check whether there are any descriptions of soy or milk ingredients in the allergy labeling.
Difficulty in Dissolving and Taste Vary in Reviews
For example, user reviews on Rakuten Ichiba note that the powder can feel gritty or like clay when dissolved in water (Rakuten "Everyone's Reviews"). Also, some voices in Rakuten reviews express that the taste or the smell that lingers in the nose did not suit their preferences, leaving them unsure how to use the remainder (Rakuten Product Reviews). Because perceptions vary from person to person for the same product, it is recommended to search for reviews close to your own preferences before purchasing.BRAIN PRO Ingredients and Use of Pea Protein
Based on the characteristics of pea protein we have examined so far, let's look at how it is used in actual products. We will specifically introduce the ingredient label, protein content, and carbohydrate/calorie figures of BRAIN PRO.
BRAIN PRO Ingredients and the Position of Pea Protein
The ingredients of BRAIN PRO, in order, are: almond paste, pea protein, almonds, soy puffs, cocoa powder, coconut oil, cocoa butter, inulin syrup, agave syrup, Lion's Mane (Yamabushitake) powder, rock salt, flavoring, and sweetener (stevia). As mentioned above, since ingredients are listed in descending order of weight, it can be seen that pea protein is used second only to almond paste. It contains no white sugar, preservatives, wheat, casein, trans fatty acids, animal-derived ingredients, or coloring. However, because it contains soy and almonds as ingredients, those with allergies to these should be careful. It is an easy option for those looking for a protein bar that does not use animal-derived ingredients.
Comparing Protein Content in Protein Bars
When choosing a protein bar, first check the protein content per bar. There is a wide range, from about 5g per bar to over 15g, and the contents can be quite different even for the same "protein bar." BRAIN PRO contains 11.1g of protein per 35g bar. For those who want to easily increase their protein intake as a snack or for those looking for a supplement for days when there is a long gap until the next meal, this is a clear numerical guideline. It is also helpful to check whether the package label is per bar or per 100g to make comparing the amount you will actually eat easier.
| Product | Content | Carbohydrates | Artificial Sweeteners | White Sugar | Protein (Source) |
|---|---|---|---|---|---|
| 1-Pon Manzoku Bar Cereal Black 80% Off Sugar | 37g | 19g | Used (Sucralose) | Used | 2.4g / Cannot determine from label |
| Cream Genmai Bran Cacao | 36g | 17g | Not used | Used | 5g / Soy |
| in Bar Protein Yogurt | 37g | 9.6g | Used (Sucralose) | Used | 11g / Soy, Milk |
| Zavas Protein Bar Chocolate Flavor | 44g | Not listed (Sugar 7.6g) | Used (Sucralose) | Used | 17.2g / Milk, Soy |
| BRAIN PRO | 35g | 4.9g | Not used | Not used | 11.1g / Plant-based (Pea) |
Figures for each product are based on nutritional labeling posted on each manufacturer's official website as of September 25, 2026. Figures may change due to product revisions.
Check Carbohydrates and Calories Per Bar Together
By looking at carbohydrates and calories along with protein content, it becomes easier to judge whether it is easy to incorporate as a snack. BRAIN PRO is 190kcal per bar with 4.9g of carbohydrates. These carbohydrates are not from white sugar, but are sweetened with inulin syrup, agave syrup, and stevia. BRAIN PRO is recommended for those who want to choose snacks without giving up sweet things or those who want to avoid white sugar. Fat is 13.5g, dietary fiber is 2.2g, and salt equivalent is 0.4g, so check these other items if you are concerned.
Frequently Asked Questions
What is the difference between pea protein and soy protein?
Both are plant-based proteins, but they differ in that pea protein is made from peas and soy protein from soybeans. Because the raw materials are different, the composition of amino acids they contain also differs. In addition, while soy is listed as an allergen for which labeling is recommended by the Consumer Affairs Agency, peas are not included in this category. Those with soy allergies can easily choose pea protein after checking the ingredient label.
Is pea protein bad for the kidneys?
There is no evidence in the materials cited so far that pea protein itself is bad for the kidneys. However, people with decreased kidney function or those on hemodialysis may have restrictions on their protein intake. Those with underlying conditions should not increase or decrease their intake on their own and are advised to consult their primary doctor or a registered dietitian before incorporating high-protein foods, including pea protein.
Summary
Pea protein is a plant-based protein made from peas, with unique characteristics in amino acid balance and low allergenicity. When choosing, it is important to check the nutritional information and ingredient labels, and adjust the amount according to your own constitution and diet. Those with kidney conditions or concerns about their health results should consult a medical institution before deciding on intake and consider it based on their individual situation. For any concerns, please consult your primary physician.