There are so many vitamins, hormones, and who knows what else in the body that we do not know about yet OR are not being let in on.
By the way, it is my understanding that vitamin D is more like a hormone than a vitamin and this vitamin "f" talked about here sounds like a hormone as well just from this statement alone "consists of essential polyunsaturated fatty acids (linoleic, linolenic & arachidonic acid)".
The other thing I always harp on is that there are checks and balances throughout the body with who knows how many built in redundancies for EVERY vitamin, mineral and hormone... that is why supplementing or doing herbals when we are not certain of what we are doing can cause problems.