Know2eat

UV-exposed mushrooms

Agaricus bisporus

What uv-exposed mushrooms has been studied for

2 associations assessed — 1 with at least some human evidence behind it. Strongest first.

  • 1 Limited
  • 1 Insufficient
3 things to know first — allergies, interactions and intake limits

About uv-exposed mushrooms

Ordinary white mushrooms deliberately exposed to ultraviolet light after harvest, which converts their ergosterol into vitamin D2. They are otherwise the same mushroom as any other button mushroom.

Also known as Vitamin D mushrooms, UV-treated mushrooms, Sunshine mushrooms

Bone HealthImmune Health

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how impressive the food is. How we rate evidence.

Bone mineral density

Bone Health
Limited evidence

Randomised trials show that eating UV-exposed mushrooms raises blood 25-hydroxyvitamin D in people who are deficient, roughly comparably to a modest D2 supplement. No trial has followed that through to bone density or fracture, so the bone step is an assumption.

What may be going on: Ultraviolet light converts ergosterol in the mushroom to ergocalciferol, which the body hydroxylates to 25-hydroxyvitamin D2.

Limited evidence. Early human work, or mostly lab and animal research.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Immune function

Immune Health
Insufficient evidence

Vitamin D status is linked to immune function, and UV mushrooms raise vitamin D status, so the two are often chained together in marketing. No trial has tested UV mushrooms against infection rates or any immune outcome.

Insufficient evidence. Not enough human research to say anything useful yet.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Ask about UV-exposed mushrooms

Ask about UV-exposed mushrooms

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories22 kcal1%
Protein3.09 g6%
Total fat0.34 g0%
Carbohydrate3.26 g1%
Fibre1 g4%
Total sugars1.98 g—
Water92.5 g—
Fats
Saturated fat0.05 g0%
Monounsaturated fat0 g—
Polyunsaturated fat0.16 g—
Cholesterol0 mg0%
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)0.16 g—
Vitamins
Vitamin C2.1 mg2%
Vitamin D26.2 µg131%
Vitamin E0.01 mg0%
Vitamin K0 µg0%
Thiamin (B1)0.081 mg7%
Riboflavin (B2)0.402 mg31%
Niacin (B3)3.61 mg23%
Pantothenic acid (B5)1.5 mg30%
Vitamin B60.104 mg6%
Folate17 µg4%
Vitamin B120 µg0%
Choline17.3 mg3%
Minerals
Calcium3 mg0%
Iron0.5 mg3%
Magnesium9 mg2%
Phosphorus86 mg7%
Potassium318 mg7%
Sodium5 mg0%
Zinc0.52 mg5%
Copper0.318 mg35%
Manganese0.047 mg2%
Selenium9.3 µg17%
Other measured compounds
Caffeine0 mg—
Ash0.85 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Mushroom, white, exposed to ultraviolet light, raw (USDA FoodData Central, FDC ID 169376).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

  • driedIncreases vitamin D2

    Drying mushrooms gill-side up in direct sunlight generates substantial vitamin D2 from ergosterol, the same reaction as commercial UV treatment. Drying indoors or in the dark does not.

  • cookedPreserves vitamin D2

    Vitamin D2 in mushrooms is reasonably heat-stable, and normal frying or baking retains most of it.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Worth knowing

    Vitamin D2 is not identical to vitamin D3

    Mushrooms produce ergocalciferol, vitamin D2. It does raise blood 25-hydroxyvitamin D, but comparison trials generally find it less potent gram for gram than the D3 in oily fish or supplements, and the rise is less well maintained between doses.

  • Worth knowing

    Only mushrooms labelled as UV-exposed contain it

    Mushrooms grown in the dark, which is nearly all of them, contain almost no vitamin D. There is no way to tell from appearance. If the pack does not say UV-exposed or claim vitamin D content, assume it has none.

  • Worth knowing

    Agaritine

    Like all Agaricus mushrooms, these contain agaritine, a hydrazine derivative that causes tumours in rodents at high doses. Human risk at ordinary intakes is considered very low, and cooking and refrigeration both reduce it.