Supplements are good for helping improve the effectiveness of your lucid dreaming techniques, but they in and of themselves do not cause lucidity. And if they don't cause lucidity, DO NOT try to take a higher dose to make them cause lucidity.

And that is the moral of the story of the time I took 600mg of vitamin B6 before bed. Sure, I remembered like 9 dreams that night, but also had almost no restful sleep for 3 days.