- Fatty fish like mackerel, tuna and salmon contain high levels of vitamin D.
- Fish liver oil is considered the best and the most reliable source of Vitamin D.
- There are traces of vitamin D in beef liver, egg yolks and cheese.
- Most of the milk supply in the U.S. consists of 100 I.U. of vitamin D per cup.
- Vitamin D2 is derived from plant sources. Vitamin D3 is derived from animal sources.
Diagnosis of Vitamin D deficiency is simple. A lab test called 25(OH)D can be performed.