It depends what you mean my natural. In my book natural means what our body obtains/digests/manufactures from food, while man-made means all supplements, both natural and syntetics. Even Vit.A, E, and D supplements come in both syntetic and natural version, I still consider all of them man-made and therefore, easy to overdose. Any Vit. supplements especially fat soluble, are easy to overdose. But while water soluble like C and B we can simply get rid of by drinking more water, fat soluble can accumulate in fatty tissues and start to build up. As I understand, natural vit.D comes from fatty fish, egg youlks and is made by exposing our body to UVA/B for at least 15 minutes a day and is manufactured from cholesterol.