Thiamin and Vitamin World's "Mega Vitamins for the Hair"

So I was at the Mega Mall in West Nyack today. (It's really called the Palisades Center, but the place is just MAMMOTH.) Anyway, they have every shop under the sun there, EXCEPT a GNC! So I couldn't buy more Ultra Nourishair. Unfortunately I did find other things to spend money on. I found a Grover t-shirt at Hot Topic!!

Ahem... ANYWAY. They had a store called Vitamin World. Which I see is based in NY, so maybe they only have stores in this part of the country.

Vitamin World sells something called "Mega Vitamins for the Hair." Which I looked at but quickly put down, because the label said it contains 5,600% of your RDV of Thiamin!
Now, on this board, we've talked about lots of things that help hair grow, but Thiamin is almost never mentioned. I searched, it's in like 2 posts from last fall, that's it.
So what is the deal?? I would never take 5,600% of my RDV of ANYTHING without consulting a doctor or nutritionist first! I feel reluctant about taking 500% of something!

Incidently, this Mega Vitamins for the Hair stuff is also loaded with Vitamins C, B-2, B-6, B-12, and a goodly amount of Biotin. I know you're supposed to not get too much of the B vitamins, so that also makes me question this product.

Any thoughts?

Thiamin is another name for Vitamin B1. I agree that one should not be taking 5600% of the recommended daily value of it!

The Vitamin B-complex (B1, B2, B6, B12), like Vitamin C, are water-soluble vitamins, meaning that extra doses will be removed from the body through urine.