However, as recommendations for vitamin D intake have recently been increased considerably, it is difficult to cover the requirements solely by foodstuffs. If milk and dairy products are not fortified, they are normally low in vitamin D, with the exception of butter because of its high fat content. Vitamin D concentrations in egg yolks range between the values for meat and offal.
The content in muscle meat is generally much lower.
The published data show that the highest values of vitamin D are found in fish and especially in fish liver, but offal also provides considerable amounts of vitamin D. The focus lies on the natural vitamin D-3 content because there are many countries in which foods are not regularly fortified with vitamin D. This paper therefore aims to provide an up-to-date overview of vitamin D-3 content in various animal foods. Animal foodstuffs (e.g., fish, meat, offal, egg, dairy) are the main sources for naturally occurring cholecalciferol (vitamin D-3). For this reason, dietary intake is also of great importance. However, in view of the current Western lifestyle with most daily activities taking place indoors, sun exposure is often not sufficient for adequate vitamin D production. Humans derive most vitamin D from the action of sunlight in their skin.
