Natural works for me.
Having tired of synthetic supplements which seemed to produce no effect, I turned to Lifestream, firstly because of their reputation, and secondly because I felt that 'natural' should offer an easily assimilated food-based alternative. It did, and the results showed early in the course. The energy I lacked came back again and my daily achievement list grew considerably with no onset of tiredness. While I was obviously B-deficient, the synthetics did not work, whereas the natural sources did. No prizes for guessing whatI'll be looking for in the future!