Mushrooms: Nutrition Facts, Health Benefits, and the Only Food That Makes Vitamin D Like You Do

Mushrooms occupy a genuinely unique position in the food world. They aren’t plants — they can’t photosynthesize and have no chlorophyll — and they aren’t animals. They belong to the fungal kingdom, a completely separate branch of life that is, biologically, more closely related to animals than to plants. That isn’t just trivia: it helps explain several of mushrooms’ distinctive nutritional properties, including their rich B vitamin and copper content, their own type of fiber, and — most fascinatingly — their ability to make Vitamin D when exposed to UV light, through chemistry that closely parallels how human skin makes it.

At just 28 calories per 100g cooked, white mushrooms provide 56% of daily copper, 43% of pantothenic acid, 28% of niacin, 23% of riboflavin, and 22% of selenium — a remarkable nutrient density for a food with so few calories.

Mushrooms Nutrition Facts (per 100g, cooked)

USDA’s figures for white mushrooms, boiled and drained, without salt.

Mushrooms Nutrition Facts (per 156g serving — approximately one cup cooked)

A single cup of cooked mushrooms provides 87% of daily copper, two-thirds of daily pantothenic acid, and over a third of daily niacin, riboflavin, and selenium for just 44 calories — one of the most striking nutrient-to-calorie ratios of any food in this collection.

Vitamins in Mushrooms (per 100g, cooked)

Standout: Mushrooms’ B vitamins are impressive for 28 calories per 100g. Pantothenic acid at 43% DV is exceptional — it’s needed to make Coenzyme A, central to energy metabolism. Niacin at 28% DV is the precursor of NAD, a coenzyme involved in hundreds of enzyme reactions, and riboflavin at 23% DV forms the FAD and FMN coenzymes used in the mitochondria’s energy-producing chain. Together, these make mushrooms one of the best non-animal sources of several B vitamins.

Minerals in Mushrooms (per 100g, cooked)

Standout: Mushrooms’ copper — 56% DV per 100g cooked — is genuinely remarkable for a food at this calorie level. Copper is essential for iron metabolism, for cross-linking collagen in connective tissue, and as part of the enzyme that completes energy production in mitochondria. Selenium (22% DV) supports the glutathione peroxidase antioxidant enzymes and thyroid hormone activation, and mushrooms also provide iron (10% DV) and potassium (356mg per 100g).

Why Mushrooms Are Not Plants: The Biology Behind the Nutrition

This is the key context for understanding what makes mushrooms nutritionally distinctive.

Mushrooms are the fruiting bodies of fungi — organisms that form their own kingdom, separate from plants, animals, and bacteria. Several differences from plants matter nutritionally:

No photosynthesis — unlike plants, fungi can’t make their own food from sunlight. They release enzymes into organic matter and absorb the broken-down nutrients, and they take up minerals from the material they grow on.

Chitin and glucan cell walls, not cellulose — plant cell walls are built mainly from cellulose, while fungal cell walls contain chitin (the same material as insect exoskeletons) along with beta-glucans. Mushroom beta-glucans are a different type from the beta-glucans in oats and barley, with their own properties, discussed below.

Ergosterol instead of cholesterol — fungi use a sterol called ergosterol in their cell membranes, where animals use cholesterol. Ergosterol is the precursor of Vitamin D2 — which is why mushrooms can make Vitamin D when exposed to UV light, something plant foods can’t do.

The Vitamin D Sunlight Story: The Most Remarkable Thing About Mushrooms

This is one of the most fascinating — and most underappreciated — facts in mushroom nutrition.

How Mushrooms Make Vitamin D

When mushrooms are exposed to ultraviolet light — from sunlight or UV lamps — the ergosterol in their cell membranes is converted to ergocalciferol, Vitamin D2, one of the two main forms of Vitamin D.

It’s strikingly similar to what happens in human skin, where UVB light converts 7-dehydrocholesterol — a close relative of cholesterol — into Vitamin D3.

The Vitamin D figure in the table above (0.2µg per 100g, just 1% DV) reflects ordinary commercially grown mushrooms, which are raised in the dark. On their own, they provide almost no Vitamin D.

The Sunlight Trick

Here’s the genuinely practical piece of information most people have never heard:

Placing mushrooms gills-up or sliced in direct midday sun for around 15–60 minutes can raise their Vitamin D content dramatically — in studies, from almost nothing to several hundred IU (10µg or more) per 100g, enough for a meaningful share of daily needs from one serving. How much you get depends on the season, latitude, time of day, and weather.

Exposing the gills or cut surfaces works best, and it needs to be outdoors: window glass blocks most of the UVB light needed. Some supermarkets also sell mushrooms that have been treated with UV light — check the label for their Vitamin D content.

The Vitamin D formed is reasonably stable — UV-treated mushrooms keep much of it through refrigerated storage and cooking.

Why This Matters

Low Vitamin D is common worldwide, especially at higher latitudes and in winter, and few foods naturally contain much of it — mainly oily fish, egg yolks, and fortified foods. UV-exposed mushrooms are one of the only non-animal whole foods that can provide meaningful Vitamin D, which makes them especially useful for vegetarians and vegans. One caveat: the Vitamin D2 that mushrooms make appears to be somewhat less effective at raising blood Vitamin D levels than the D3 made in skin or found in animal foods — but it still counts.

Beta-Glucans: Mushrooms’ Distinctive Fiber

Much of the fiber in mushrooms comes from their cell walls — chitin and beta-glucans. Mushroom beta-glucans have a branched structure that differs from the beta-glucans in oats and barley, and they’ve been widely studied in immunology research:

Immune activity — mushroom beta-glucans interact with receptors on immune cells such as macrophages and natural killer cells, and in laboratory and some clinical studies they have shown effects on immune activity. One purified shiitake beta-glucan, lentinan, has been used as an add-on to cancer treatment in Japan.

Prebiotic activity — mushroom fiber feeds gut bacteria, adding a different type of fiber to the mix available to your gut microbiome from plant foods.

The research note: much of the strongest beta-glucan research has focused on extracts from specific mushrooms — particularly shiitake, maitake, reishi, and turkey tail — rather than on eating ordinary white mushrooms. Common supermarket mushrooms do contain beta-glucans, but the immune effects of normal food amounts are much less clear.

Health Benefits of Mushrooms

Outstanding Copper and Useful Selenium for Very Few Calories

At 56% DV copper and 22% DV selenium per 100g for just 28 calories, mushrooms provide these trace minerals at a very low calorie cost. Copper supports iron metabolism, collagen formation, and energy production in mitochondria; selenium supports antioxidant defenses and thyroid hormone activation. Getting more than half your daily copper from 28 calories is one of the most calorie-efficient nutrient sources in the nutrition facts collection.

B Vitamins for Energy Metabolism

Mushrooms’ pantothenic acid (43% DV), niacin (28% DV), and riboflavin (23% DV) per 100g support three central parts of cellular energy production: Coenzyme A, the NAD coenzymes, and the FAD and FMN coenzymes. This is particularly useful for vegetarians and vegans, since animal foods are often the main sources of these vitamins.

Vitamin D Through UV Exposure

As detailed above, ordinary mushrooms provide almost no Vitamin D — but a short spell in the sun before cooking, or buying UV-treated mushrooms, turns them into a meaningful non-animal source.

Potassium for Heart Health

At 356mg per 100g (555mg per cup), mushrooms provide useful potassium — the mineral that helps counter sodium’s effect on blood pressure — for very few calories, and they’re essentially sodium-free (2mg per 100g) when cooked without salt.

Weight Management

At 28 calories per 100g, with some protein (2.2g), fiber (2.2g), and a rich savory flavor, mushrooms are one of the most useful foods for adding volume and nutrition to meals without adding many calories. They’re often used to replace part of the meat in dishes like bolognese or burgers, cutting calories while keeping flavor.

Mushrooms for Athletes and Active People

B Vitamins for Energy Production

Mushrooms’ pantothenic acid, niacin, and riboflavin contribute to the coenzymes that convert food into ATP to power training — for almost no calories.

Selenium for Antioxidant Defense

Intense training increases oxidative stress, and mushrooms’ selenium supports the glutathione peroxidase enzymes that are part of the body’s own antioxidant defenses.

Copper for Connective Tissue and Iron Use

At 56% DV per 100g, mushrooms’ copper supports the enzyme that cross-links collagen in tendons and ligaments — relevant for athletes whose connective tissue is under constant training stress — and helps the body use iron to carry oxygen.

Volume Eating for Cutting Phases

At 28 calories per 100g, mushrooms are one of the most valuable volume foods for fat-loss phases, when managing hunger is the main challenge. A 200g serving of cooked mushrooms adds just 56 calories to a meal, while providing more than a full day’s copper, most of a day’s pantothenic acid, and nearly half the daily riboflavin and selenium.

White vs Shiitake Mushrooms

Different mushrooms have quite different nutritional profiles. Here’s how common white mushrooms compare with shiitake, both cooked:

Shiitake provide a full day’s copper per 100g and about twice the selenium and much more pantothenic acid than white mushrooms, while white mushrooms are richer in niacin, riboflavin, potassium, and iron — at half the calories. Eating a variety of mushrooms gives you the best of both.

Common Mushroom Varieties

The main data on this page is for white button mushrooms (Agaricus bisporus) — the most widely eaten mushroom in the world. Other varieties differ in flavor and somewhat in nutrition:

White button mushrooms — the standard supermarket variety; mild flavor and very versatile.

Cremini (chestnut or brown) mushrooms — the same species as white button, a brown-skinned strain with a richer flavor and very similar nutrition.

Portobello mushrooms — fully mature cremini mushrooms, larger and meatier, with a richer flavor.

Shiitake mushrooms — richer in copper and selenium, as shown above. They contain eritadenine, a compound studied for lowering cholesterol, and lentinan, a well-researched beta-glucan.

Oyster and king oyster mushrooms — mild in flavor with a firm texture, and among the richest sources of ergothioneine, a unique antioxidant amino acid discussed below.

Medicinal mushrooms (reishi, lion’s mane, chaga, turkey tail) — usually taken as supplements, extracts, or teas rather than eaten, because of their tough texture; they’ve been studied for immune, neurological, and other effects, though much of the research is still preliminary.

Ergothioneine: A Unique Antioxidant Found Almost Nowhere Else

This deserves a brief mention, because it’s one of the most scientifically interesting compounds in mushrooms.

Ergothioneine is an unusual antioxidant amino acid made almost entirely by fungi and certain bacteria. Plants and animals pick up only small amounts, and mushrooms are by far the richest dietary source. Humans can’t make it, but we have a dedicated transporter protein that absorbs it and concentrates it in tissues — which has led some researchers to suggest it may be an important dietary antioxidant.

Research is still developing, but some observational studies have linked higher mushroom intake with lower markers of oxidative stress and inflammation, and with lower rates of cognitive decline in older adults. These are associations rather than proof, but ergothioneine is a compound worth watching.

Practical Ways to Include Mushrooms in Your Diet

Sautéed with garlic and olive oil — the simplest and most popular preparation. Mushrooms cooked over medium-high heat until golden develop a rich, savory flavor from Maillard browning.

In omelettes or scrambled eggs — mushrooms and eggs make a great pairing, combining mushrooms’ copper, B vitamins, and selenium with eggs’ complete protein, choline, and Vitamin D.

In soups and stews — mushrooms add depth, umami, and nutrition to any soup or stew.

As a meat substitute or extender — portobellos make a satisfying burger substitute, and chopped mushrooms can replace part of the minced meat in bolognese, chili, or burgers.

Sunning before use — as detailed above, placing mushrooms gills-up or sliced in direct midday sun for 15–60 minutes before cooking can substantially increase their Vitamin D content.

Dried mushrooms — dried shiitake and porcini have concentrated flavor and a long shelf life. Keep the soaking water and use it in cooking — it carries flavor and some of the water-soluble B vitamins.

Potential Considerations

Commercially grown vs wild-foraged — commercially grown mushrooms are safe and consistent. Wild mushrooms carry a real risk of misidentification and poisoning — several deadly species closely resemble edible ones. Only forage with genuine expert identification skills, or with an experienced guide.

Cooking is generally recommended — cooking makes mushrooms easier to digest and reduces agaritine, a naturally occurring compound in raw white mushrooms. Eating raw mushrooms in salads occasionally isn’t a concern for most people.

Shiitake dermatitis — rarely, eating raw or undercooked shiitake causes a distinctive, itchy, streaky skin rash, triggered by lentinan. Cooking shiitake thoroughly prevents it.

Medicinal mushroom supplements — some medicinal mushroom products, particularly reishi, may affect blood clotting and blood pressure. People taking anticoagulants or blood pressure medication should talk to their doctor before using them. Ordinary culinary mushrooms in normal amounts aren’t a concern.

Sodium in canned or processed mushrooms — canned mushrooms are usually much higher in sodium than fresh; rinsing them helps.

Nutrient data: USDA FoodData Central, SR Legacy — mushrooms, white, cooked, boiled, drained, without salt (FDC ID 169252). Comparison: mushrooms, shiitake, cooked, without salt (FDC ID 168437). % Daily Values use the FDA’s current Daily Values.