[Bartweiss]

> There's absolutely zero evidence that taking more than 100% of your daily required amount of any vitamin is effective for anything. Your body simply cannot absorb or make use of it.

I take your point, but I think it's important to say that this isn't strictly true. Your daily requirement is what you need for normal functioning, not what you can absorb.

For vitamin C, this isn't a huge distinction - it's water soluble, and the excess will be flushed, as you say. But for fat soluble vitamins, you absolutely can absorb more than a 100% dose. This is usually bad, and comes about from things like home overdosing or extremely narrow diets. It's occasionally medicinal, though, with something like isotretinoin being very similar to a major overdose of vitamin A.

I wouldn't suggest overdosing on vitamins to anyone unless a doctor tells you do, but it's worth noting that it does cause an effect - usually a bad one.