Pre-digested B Vitamins?

Hello, I was hoping someone here could help with something! My boss is a highly active man in his 60s and has come to me for help, so I have come to you guys. He had regularly taken a b vitamin for many years and he told me that regular b vitamins give him debilitating cramps for three days after taking one. 15 years ago he explained that to a guy at a vitamin place and the man told him to try this one brand that had "pre digested b vitamins" and he took them happily for fifteen years no problem. Well, that company no longer makes them. So he is back on the hunt for finding a b vitamin that won't give him such pain. Does anyone know of suh a vitamin that could work for him without those side effects? I had never heard of pre digested vitamins before and can only picture birds feeding their babies. Help!