Sunlight
10,000 IU from 15-20 minutes of midday summer sun
Oysters
270 International Units (IU) of vitamin D per half-dozen
Dried shiitake mushrooms
172 IU per 100g

Mackerel
643 IU per 100g. Halibut gives you 230 IU per 100g, pickled herring 113 IU per 100
Tinned sardines
23 IU per 12g fish. Tinned salmon gives you 550 IU per 100g, tinned tuna 270 IU per 100g

Hard-boiled eggs
26 IU per egg; 25 IU per egg yolk
Fortified cows’ milk
250 IU per pint
Fortified orange juice
270 IU per pint

Fortified tofu
120 IU per 80g
Vitamin D capsules
100-5,000 IU; most multivitamin pills contain 400 IU of vitamin D
Cod liver oil
450 IU per teaspoon; capsule amounts vary