Mushrooms

Food · Vegetable · Food, Typed Supps

One of the only foods that can still make vitamin D after being picked.

Stage by stage

Intake (Fibrous structure): Chewing releases nutrients from their fibrous structure.
Stomach (Releases B vitamins & selenium): Digestion begins releasing B vitamins, selenium, and (if UV-exposed) vitamin D.
Small intestine (Fat-dependent D absorption): Vitamin D2, if present, absorbs alongside any dietary fat, similar to other fat-soluble vitamins.
Bone & immune tissue (Vitamin D & selenium support): Absorbed vitamin D and selenium support bone and immune-related processes.

Timing

With a little fat if UV-exposed, to help absorb the vitamin D.

Time to effect

Weeks: Regular intake contributes to selenium and B vitamin status.

Allergens

None of the fourteen major allergens. Derived from what this food is, not from a product label.

Eating patterns

Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Keto, Gluten-free. Depends on the product: Low-FODMAP.

In season

September to November in the northern hemisphere, March to May in the southern.

Satiety

The satiety index is measured on 240 kcal servings. At 27 kcal per 100 g that is 889 g of this, which is not a serving anyone eats — so the index has nothing to say about it.

Environmental footprint

0.5 kg CO2e and 108 litres of freshwater per kg, matched to "Other vegetables" in Poore & Nemecek (2018), Science 360.

Cost band

Cheap — roughly £2.5 per kg, as a band midpoint rather than a price.

Key nutrients

Selenium
B vitamins
Vitamin D2 (if UV-exposed)

Nutrition per 100g

Calories: 27
Protein: 2.2g
Carbohydrate: 2g
of which sugars: 0.8g
Fat: 0.8g
of which saturated: 0.2g
Fibre: 1.4g
Sodium: 7mg

Food vs. supplement

Standard mushrooms have very little vitamin D, but UV exposure after harvest (something some brands now do deliberately) can raise vitamin D content close to a meaningful supplemental dose — check the label, since this varies enormously by brand.

Kitchen tip

Leaving them in direct sunlight for 15 to 20 minutes before cooking can meaningfully raise their vitamin D content.

Common myth

“All mushrooms are a good vitamin D source.” In reality: Only mushrooms deliberately exposed to UV light after harvest have meaningful vitamin D — standard supermarket mushrooms grown in the dark have very little.