How much protein does a big mushroom have? A closer look at mushroom nutrition

While fresh button mushrooms contain around 3 grams of protein per 100g, answering how much protein does a big mushroom have? requires examining specific varieties and preparation methods. A larger mushroom like a portobello contains a similar amount of protein per weight, but its density can offer a more substantial meal.

Quick Summary

The protein content of a big mushroom, such as a portobello, is modest on a fresh weight basis, but significantly higher when dried. Mushrooms are a high-quality, complete protein source for plant-based diets when prepared correctly.

Key Points

• Modest Fresh Protein: Fresh mushrooms, including large varieties like portobellos, offer a moderate amount of high-quality protein per 100g.

• Drying Concentrates Protein: Dried mushrooms contain significantly higher protein content per gram than fresh versions, making them a denser protein source.

• Complete Protein Source: Mushroom protein is considered complete, providing all nine essential amino acids, which is valuable for plant-based diets.

• Rich in Other Nutrients: Mushrooms also supply essential B vitamins, minerals like potassium and selenium, and powerful antioxidants, supporting overall health.

• Satiating Meat Substitute: The meaty texture and rich flavor of mushrooms can serve as a satisfying and low-calorie meat replacement in many dishes.

• Versatile Culinary Uses: Mushrooms can be enjoyed fresh, cooked, or in powdered form to boost flavor and nutrition in a variety of meals.

Deciphering Mushroom Protein: It's About Density, Not Just Size

The size of a mushroom can be deceiving when evaluating its nutritional content, especially regarding protein. A large portobello might seem like it contains a lot more protein than a handful of button mushrooms, but on a fresh-weight-for-fresh-weight basis, the difference is often less dramatic than you might think. The real protein revelation for mushrooms comes from how they are prepared, particularly when comparing fresh versus dried varieties.

How much protein does a big mushroom have? A look at Portobellos

When most people think of a "big mushroom," the portobello is likely the first that comes to mind. It's often used as a meat substitute due to its large size and hearty texture. So, how much protein are you actually getting from this large fungus? A raw, large portobello mushroom cap (about 85g) contains around 1.8 grams of protein. Per 100 grams, raw portobello mushrooms provide approximately 2.1 to 3.3 grams of protein, a figure that is quite comparable to smaller, fresh button or oyster mushrooms.

This shows that while a single large portobello cap offers a satisfying amount of total protein due to its size, the concentration of protein per 100 grams is similar across many fresh edible mushroom varieties. Its low-calorie count (around 22 kcal per 100g) means you can consume a sizable portion to feel full and gain a significant nutritional boost without a high caloric cost.

The Protein Power of Mushrooms: Fresh vs. Dried

The most significant change in mushroom protein content occurs during the drying process. As mushrooms are dehydrated, their water content is removed, which concentrates all other nutrients, including protein. This results in dried mushrooms having a substantially higher protein content per 100 grams compared to their fresh counterparts. In some cases, the protein density of dried mushrooms can rival that of animal-based sources like chicken breast, on a per-gram basis, but you'll typically eat far less of it in a meal.

A Comparative Look at Protein Content

To illustrate the difference, let's compare the protein content of fresh and dried mushrooms, specifically focusing on some of the more popular varieties. Note that values can vary slightly based on strain and growth conditions.

Type of Mushroom	Protein (g) per 100g (Fresh)	Protein (g) per 100g (Dried)
Button/White	3	24–29.9
Oyster	2.9–3.31	20–35
Shiitake	2.2–2.5	17.5–24
Portobello	2.1–3.3	38
King Oyster	2.9–3.0	28.8

This table clearly shows that dried mushrooms are an excellent way to add concentrated protein to a meal. For example, using dried, powdered mushrooms in a sauce or soup can dramatically increase the protein content without adding much bulk. However, even in their fresh state, mushrooms contribute a good-quality, plant-based protein to a balanced diet.

More Than Just Protein: The Full Nutritional Profile of Fungi

Beyond their modest protein contribution, fresh mushrooms offer a variety of other nutritional benefits that make them a valuable addition to your diet. Here's a quick look at some key nutrients:

• Vitamins: Mushrooms are a good source of B vitamins, including riboflavin (B2), niacin (B3), and pantothenic acid (B5). These are crucial for energy metabolism and nervous system health. Certain types, when exposed to sunlight or UV light, also become a natural, non-animal source of vitamin D.
• Minerals: They provide essential minerals like potassium, which helps regulate blood pressure, and selenium, a powerful antioxidant. Copper, iron, and zinc are also present in varying amounts.
• Antioxidants: Mushrooms are rich in antioxidants like ergothioneine and glutathione, which help combat oxidative stress and may lower the risk of chronic diseases such as cancer and heart disease.
• Fiber: They contain both soluble and insoluble fiber, including unique components like chitin. This fiber supports digestive health and promotes feelings of fullness, which can aid in weight management.
• Bioactive Compounds: Many mushrooms contain bioactive proteins with potent properties, including antimicrobial, antitumor, and antiviral effects. This makes them a subject of ongoing research for their pharmaceutical potential.

The Culinary Versatility and Dietary Role of Mushrooms

Mushrooms' meaty texture and umami flavor make them an excellent and satisfying replacement for meat in a variety of dishes. Their culinary flexibility allows for diverse preparation methods, from sautéing and grilling to roasting and baking. Here are a few ways to incorporate more mushrooms into your diet:

• As a Meat Substitute: Large portobello caps can be grilled or roasted and served as a burger patty or steak. Sautéed mushrooms can be mixed with ground meat or meat substitutes to reduce fat and calories while maintaining flavor and texture.
• In Sauces and Soups: Adding mushrooms or mushroom powder to sauces, stews, and soups not only enhances their savory flavor but also increases their nutritional content, particularly protein and fiber.
• In Stir-fries and Salads: Chopped or sliced mushrooms are a perfect addition to stir-fries and can add a savory element to salads.
• Breakfast Dishes: Sautéed mushrooms are a great way to start the day, providing fiber and protein alongside eggs or tofu scrambles.

Conclusion: Maximizing Mushroom Nutrition

So, how much protein does a big mushroom have? A large fresh mushroom, such as a portobello, offers a moderate amount of high-quality, easily digestible protein per serving. However, the most significant protein contribution from mushrooms comes from their dried form, which concentrates nutrients considerably. While not a primary, high-volume source of protein like meat or legumes, mushrooms are a valuable component of a balanced diet. Their rich profile of vitamins, minerals, antioxidants, and fiber makes them a potent addition to any meal, whether you’re vegetarian, vegan, or simply looking to enhance your nutrition. The best approach is to enjoy them regularly, utilizing both fresh and dried varieties to gain a wide range of flavor and health benefits.

Here is a fantastic resource on the topic of mushroom protein.

Key Takeaways

Fresh vs. Dried: The protein concentration in mushrooms is significantly higher in dried form due to moisture removal.

Portobello Protein: A large fresh portobello has a similar protein-per-weight ratio to other mushrooms but offers a substantial portion of protein and nutrients due to its size.

Quality over Quantity: Mushroom protein is a complete protein, containing all nine essential amino acids, making it an excellent option for vegetarian and vegan diets.

Beyond Protein: Mushrooms are packed with other health-promoting nutrients, including B vitamins, vitamin D (when UV-exposed), fiber, and powerful antioxidants.

Culinary Versatility: With their satisfying, meaty texture and flavor, mushrooms serve as a delicious and nutritious substitute for meat in a variety of dishes.

Dietary Supplement: Using dried mushroom powder is an easy way to boost protein and other nutrients in soups, sauces, and other meals without adding excessive bulk.

FAQs

Question: Are mushrooms a significant source of protein? Answer: Fresh mushrooms provide a modest amount of protein, typically 1-3 grams per 100g. They are not a primary source of protein for most people, but they offer high-quality protein that contains all essential amino acids.

Question: How does the protein in a portobello compare to a button mushroom? Answer: Per 100 grams of fresh weight, the protein content of a portobello is very similar to a button mushroom, around 2-3 grams. However, since a portobello is larger, one cap provides more total protein than a single button mushroom.

Question: Does cooking mushrooms affect their protein content? Answer: Cooking can slightly alter the nutritional profile, and some studies suggest it can affect amino acid content. However, the overall protein contribution remains comparable, and cooked mushrooms are generally easier to digest, making the protein more bioavailable.

Question: Is dried mushroom protein better than fresh mushroom protein? Answer: Dried mushrooms have a much higher protein concentration per gram because the water has been removed. This makes them a more potent source of protein by weight, but fresh and dried mushrooms both offer high-quality, complete protein.

Question: What are the best mushrooms for protein intake? Answer: While most edible mushrooms are a good source of protein, dried varieties offer the highest concentration. Dried portobello, oyster, and shiitake mushrooms all boast high protein levels per 100g, while fresh king oyster and oyster mushrooms are also good choices.

Question: How can I incorporate mushrooms to get more protein? Answer: Use dried mushroom powder in sauces, smoothies, or mixed into vegetarian burgers. For whole mushrooms, use larger caps like portobellos as a meat replacement, or add sautéed mushrooms generously to pasta sauces, stir-fries, and soups.

Question: Are there any downsides to relying on mushrooms for protein? Answer: The main limitation is their water content, which means you would need to eat a very large quantity of fresh mushrooms to meet your full daily protein requirements. It is best to use mushrooms as a supplementary source of high-quality protein alongside other diverse sources.

Citations

• Ayimbila, F., & Keawsompong, S. (2023). Nutritional Quality and Biological Application of Mushroom Protein as a Novel Protein Alternative. Current Nutrition Reports, 12(2), 290–307. https://pmc.ncbi.nlm.nih.gov/articles/PMC10088739/
• Erbology. (2025). Top High-Protein Mushrooms: Boost Your Diet Naturally. https://erbology.co/which-mushrooms-have-the-most-protein/
• Healthline. (2020). White Mushrooms: Nutrition, Benefits, and Uses. https://www.healthline.com/nutrition/white-mushroom-nutrition
• Juniper. (2025). How much protein is really in mushrooms? https://www.myjuniper.com/blog/how-much-protein-in-mushrooms
• La Mycosphère. (2024). Mushrooms: An Unexpected and Valuable Source of Protein. https://lamycosphere.com/en/blogs/the-future-is-fungi/mushrooms-an-unsuspected-and-precious-source-of-protein
• Lyman Orchards. (2025). The Power of Portobello Mushrooms. https://lymanorchards.com/the-power-of-portobellos/
• Quora. (2020). What is the protein in mushroom per 100g? https://www.quora.com/What-is-the-protein-in-mushroom-per-100g
• Verywell Fit. (2024). Shiitake Mushroom Nutrition Facts and Health Benefits. https://www.verywellfit.com/the-health-benefits-of-shiitake-mushrooms-89077
• WebMD. (2023). Health Benefits of Mushrooms. https://www.webmd.com/diet/health-benefits-mushrooms
• Wikipedia. (2025). Shiitake. https://en.wikipedia.org/wiki/Shiitake

Frequently Asked Questions

Are mushrooms a good source of complete protein?

Yes, unlike many plant-based foods, edible mushroom proteins contain all nine essential amino acids, making them a complete protein source. This makes them a particularly valuable addition to vegetarian and vegan diets.

How does the protein in a portobello compare to a button mushroom?

Per 100 grams of fresh weight, the protein content of a large portobello is very similar to a smaller button mushroom, typically around 2-3 grams. The main difference is that a single, large portobello cap offers a larger total portion of protein due to its size.

How much protein does a big mushroom have after drying?

When dried, a mushroom's protein content becomes highly concentrated because the moisture is removed. For example, dried portobello mushrooms can contain up to 38 grams of protein per 100 grams, significantly more than their fresh equivalent.

Can I use mushrooms as a meat substitute for protein?

Yes, mushrooms, especially larger, heartier varieties like portobellos and king oysters, make an excellent meat substitute. While they offer less protein by weight than meat, their satisfying texture and flavor can help reduce meat consumption while contributing high-quality plant-based protein.

What other nutrients do mushrooms provide besides protein?

Mushrooms are a nutritional powerhouse, offering B vitamins (B2, B3, B5), essential minerals like potassium and selenium, and a good amount of dietary fiber. They also contain potent antioxidants and can produce vitamin D when exposed to UV light.

Does cooking mushrooms increase or decrease their protein content?

Cooking does not significantly change the total protein content of mushrooms. However, moisture loss during cooking can increase the protein density per gram. Studies suggest that cooking and canning can slightly affect the concentration of specific amino acids.

How can I maximize my protein intake from mushrooms?

To maximize protein intake, use dried mushroom powder as an additive to meals. For whole mushrooms, incorporate them into high-protein dishes like stir-fries with tofu or lentils, or use larger caps as a filling meal centerpiece.