Vitamins, like minerals, are chemicals. There is absolutely not (1) difference in the chemical structure of the (2) nature vitamin C and the chemical structure of the synthetic (3) vitamin C. Also, while most substances are harmless at very low level of intake, all substance-even the elements (4) that are essential to life-can be dangerous if you overdo them. Take water for example. Six or eight glasses a day will keep your body in good fluid balance. But you can also be drown in it. Some people argue that individuals vary greatly in their need for nutrients, it cannot necessarily be stated any (5) given amount is too much; that is all relative. But since there is little solid information on what is the optimal intake of any essential nutrient in healthy individuals, it would (6) be impossible to give guidelines that take these proportional needs into the account. Just as with other drugs, the (7) relation to different vitamin dosages varies, with some people better able than others to tolerate large amounts. While we do (8) know that very specifically what the toxic level is for (9) vitamins A and D, we are far less sure about vitamin E, even though it, too, is fat-soluble, and we still don’t understand the water-soluble vitamin, the C and the B groups, which the body (10) can’t store.