Multivitamins? Why are they important for some of us?

When I spoke to Tony Delroy on ABC radio about multivitamins and how they could be a licence for bad behaviour, I mentioned in passing that as far as my brief research revealed the jury was out on their benefit. That drew a response from Dr John Graham from South Australia who explained that there are some people who really need vitamin B supplements because of their genetic makeup. 
For some people multivitamins just result in expensive urine, for some they’re essential.

He agreed to speak to me and you can hear our broadranging conversation on the player below.