Few foods are naturally rich in vitamin D3, though many foods and supplements are fortified with vitamin D like dairy products and cereals. Naturally containing sources are:
– oily fish and fish liver oils
– egg yolk
– cheese
– red meat
– some commercially sold mushrooms contain higher amounts of D2 due to intentionally being exposed to high amounts of ultraviolet light.
In the UK cow’s milk is not fortified in vitamin D as it is in some other countries (e.g., Sweden and Canada).