Is thiamin good or bad for you?

Question

i looked at the back of a 1 gallon orange juice bottle and it said 10% thiamin...

Answer 1

Thiamin is a necessary vitamin, but all vitamins can be toxic unless they are taken in balanced combination with all of the other necessary vitamins and nutrients.

Answer 2

Did you look up this ingredient at all, or just post your Q here willing to take your chances on incorrect info?  

Thiamin is vitamin B1.

You need vitamin B1. It's an essential nutrient. Oranges and other foods contain vitamin B1.

The orange juice bottle probably gives 10% as the amount you get in a serving. So, 10 measured glasses = 100% of your MINIMUM daily requirement. Like all water soluable vitamins, vitamin B1 taken in excess will be excreted in your urine without long-term damage. It's merely wasteful to overdose on water soluable vitamins.