spesmilitis said:
Again, you didn't answer my original question even though I reiterated it after each of your responses. Try to make sure you address it this time, k?
If a certain supplement dosage is giving solid health/performance benefits, would it still be likely that the particular dosage is at a toxic level?
"There are some athletes that dont eat crap really, and that's why they are on a multi or get deficient."
So you've seen the studies and the athletes diets for those studies, and determined that they eat like crap? I admit, I have not analyzed the studies in that detail. But, have you? Or are you just talking out of your ass?
Firs off like I explained before and said, there are NO PERFORMANCE benefits from vitamins. As far as being toxic, toxic is toxic, cut and dry for a HEALTHY person. COULD it have a particular effect on one aspect of health (disease) wise, yes, it could, but again, the studies on megadoses of vitamins are sparse. The only way it does NOT become toxic is if the body is utilizing it for some reason. Say for instance it is cancer, and is attacking cancer cells as an example. That means the study showed lets say the cancer cells were absorbing 90% of Vit C or something. The body is then utilizing it.
You need to make sure you state whether it is a performance based supplement you are talking about as well, or a Vti/Min which are totally different things. So its better to say... Supplement of Vit C. Instead of just a supplement as most people term supplements with anything else besides Vit/Min
Example: Effect of vitamin C on prostate cancer cells in vitro: Effect on cell number, viability, and DNA synthesis
Remember too, INTRAVENOUSLY, not oral supplementation. Same goes with B12 injections.
Consuming vitamins in large amounts has not been shown to be of benefit for athletic performance. The only positive effects of vitamin supplements that have been shown for athletes is for those who are DEFICIENT in a particular vitamin. There is widespread belief among athletes that special nutritional practices will enhance their achievements in competition. Supplementation with vitamins, especially vitamin C, is equally popular. But because genetic predisposition, hard physical training and psychological factors play a most important role in determining performance, and because any potential difference in achievement will be small, it is almost impossible to obtain scientific evidence of a beneficial effect of a particular nutrient. There have been many investigations during the past four decades of the potential effect of high-dose vitamin C supplementation on physical performance. The variables used have included maximum oxygen uptake, blood lactic acid levels, and heart rate after exercise, and in some cases performance was assessed in competitive events. Almost all studies could not demonstrate an effect. On the other hand, a suboptimal vitamin C status results in an impaired working capacity which can be normalized by restoring vitamin C body pools. Athletes, who follow irrational, unhealthy eating patterns often not including vitamin-C-containing fruit and vegetables, are in need of nutrition education. Those who eat a well balanced diet and at most take a multi-vitamin supplement will not benefit from additional vitamin supplements.
Yes, the study I have seen, and read. I am not talking out of my ass.

I'm not a high school kid who heard something at the gym or from my buddy. You should know this.
ACSM. 2000. Nutrition & Athletic Performance. Medicine and Science in Sports and Exercise 32:2130-45
Athletes at the greatest risk of poor micronutrient
status are those who restrict energy intake or use
severe weight-loss practices, eliminate one or more of the
food groups from their diet, or consume high-carbohydrate,
low-micronutrient– dense diets. Athletes participating in
these types of behaviors may need to use a multivitamin and
mineral supplement to improve overall micronutrient status.
Supplementation with single micronutrients is discouraged
unless clear medical, nutritional, or public health reasons are
present, such as the supplementation of iron to treat iron
deficiency anemia or folic acid to prevent birth defects.
Iron depletion (low iron stores) is one of the most prevalent nutrient deficiencies observed in athletes, especially female athletes.
Again, the info above mostly was geared towards C, but apply that with any vitamin.