Benfotiamine is similar to thiamine (vitamin B1), but is absorbed by the body better than thiamine. The body changes benfotiamine to thiamine.

Since the body absorbs benfotiamine better than thiamine, benfotiamine can increase how much thiamine is in the body. This may help prevent or treat certain symptoms or diseases caused by low thiamine levels. Benfotiamine can be made by certain plants, such as garlic and onion. It can also be made in a lab. 

https://www.webmd.com/vitamins/ai/ingredientmono-1574/benfotiamine