V-D and food

If you live north of 40 degrees north latitude (about the latitude of New York City) or south of 40 degrees south latitude (about the latitude of Wellington, New Zealand), for at least half of the year, you can't.

In Boston, Massachusetts, for instance, there is insufficient ultraviolet radiation in the sunlight for skin to make adequate amounts of vitamin D from early November to early March. On the South Island of New Zealand, vitamin D deficiency is a real risk from early May to early September. In Calgary, Alberta, residents don't get enough vitamin D even if they get daily sun exposure from October until nearly April. And in northern Europe, Alaska, and Russia, the problem is even worse.

Food Vitamin D (IU)
Cod liver oil 2218
Herring (raw) 2061
Shiitake mushrooms (dried) 1122
Catfish (raw) 1122
Button mushrooms (raw) 691
Pink salmon, canned 530
Sardines (canned) 521
Herring (pickled) 519
Mackerel, canned 214
Caviar 184
... ...
--original article