evidence: Harvesting Vitamin D3 from Sheep Wool The most fascinating source of Vitamin D3 is lanolin - a natural fat found in sheep's wool. Lanolin contains 7-dehydrocholesterol, which is a precursor of Vitamin D3. In the industrial process, this ingredient is exposed to UVB radiation, transforming it into fully-fledged Vitamin D3. This process is a perfect example of how nature works with science to provide people with valuable nutrients. [...] Although lanolin from sheep wool is a popular source of Vitamin D3 in supplements, there are also other methods of obtaining it. Vitamin D3 can also be synthetically produced or obtained from other natural sources, such as fish oil. It is important to pay attention to their origin when choosing supplements, especially if you prefer vegan or vegetarian products.