1) Sunlight
Promotes vitamin D synthesis from cholesterol in the skin.

2) Cod liver oil
1 tsp: 440 IU (over 100% DV)

3) Sardines
3 ounces: 164 IU (41% DV)

4) Salmon
3 ounces: 400 IU (100% DV)

5) Mackerel
3 ounces: 400 IU (100% DV)

6) Tuna
3 ounces: 228 IU (57% DV) 

7) Raw Milk
1 cup: 98 IU (24% DV)

8) Caviar
1 oz: 33 IU (8% DV)

9) Eggs
1 large: 41 IU (10% DV)

10) Mushrooms
1 cup: 2 IU (1% DV)

Credit: Dr. Axe | Food is Medicine on draxe.com