This is partly because people spend more time indoors, wear sunblock outside, and eat a Western diet low in good sources of this vitamin.
Wild salmon contains about 988 IU of vitamin D per serving, while farmed salmon contains 250 IU, on average. That’s 124% and 32% of the DV, respectively.
Herring contains 216 IU of vitamin D per 3.5-ounce (100-gram) serving. Pickled herring, sardines, and other fatty fish, such as halibut and mackerel, are also good sources.
Cod liver oil contains 448 IU of vitamin D per teaspoon (4.9 ml), or 56% of the DV. It is also high in other nutrients, such as vitamin A and omega-3 fatty acids.
Canned tuna contains 268 IU of vitamin D per serving. Choose light tuna and eat 6 ounces (170 grams) or less per week to prevent methylmercury buildup.
Eggs from commercially raised hens contain only about 37 IU of vitamin D per yolk. However, eggs from hens raised outside or fed vitamin-D
Mushrooms can synthesize vitamin D2 when exposed to UV light. Only wild mushrooms or mushrooms treated with UV light are good sources of vitamin D.
Foods such as cow’s milk, soy milk, orange juice, cereals, and oatmeal are sometimes fortified with vitamin D. These contain 54-136 IU per serving.