Brain tumor research is a relatively modern science that parallels the explosion of molecular biology and modern neuroimaging. While the science is new, Mayo Clinic has a long history of brain cancer treatment and research stretching back over 100 years.
Vitamins come in two forms: water-soluble and fat-soluble. The water-soluble vitamins are vitamin C and the B-complex vitamins. If you take in more than your body can use of these, they end up passing through you as expensive urine. Vitamins A, D, E and K, on the other hand, require fat to dissolve. Your body stores these vitamins, and if you take too much, the amount in your body can build to a harmful level. Tolerable Upper Intake Levels The highest amount of a vitamin you can safely take per day is known as the tolerable upper intake level, or UL.
This is called vitamin D toxicity. Vitamin D toxicity, where vitamin D can be harmful, usually happens if you take 40,000 IU per day for a couple of months or longer, or take a very large one-time dose. Vitamin D is fat-soluble, which means your body has a hard time getting rid of it if you take too much.