Don: Vitamins, Yael. I'm really into my health these days. I take a pill for nearly every vitamin my body needs. I'm insuring myself against vitamin deficiency.

Y: I hope you know what you're doing. Just as vitamin deficiency can make you sick so can vitamin toxicity. Vitamins can be very dangerous if you take them in high quantities.

D: Oh, you mean vitamins A and D. I've heard about that. I don't understand, though,  why it's okay to take lots of one vitamin, but not another.

Y: First off, vitamins A and D are the most likely to make you sick if you take too much of them, but they aren't the only vitamins that can be dangerous. All vitamins have the  potential to be toxic if you ingest too much of them.

Part of the reason why A and D put you at higher risk than Vitamin C and others has to do with the way vitamins are dissolved. Vitamin C dissolves in water. Thus, if you  take in excess Vitamin C, your body flushes it out through urine. Vitamins A and D dissolve in oils and melted fat. When you take too much of one of these vitamins, rather than flushing the excess out, the body stores the surplus in fat or in fatty tissues such as the liver and the brain. Accumulation of water in the brain, severe headaches, and birth defects are just three of the problems toxic levels of Vitamin A can cause.

If you keep a relatively well-balanced diet, you'll most likely get the vitamins your  body needs without the use of supplements.