Would taking magnesium help my mood/anxiety? is it toxic if taken in large doses?

Is toxic for sure: It is said that magnesium supplementation in those who are truly deficient and have mood disorders can improve their picture. However, it is not just as simple as raising levels or simply taking supplements. You should be thoroughly examined by a psychiatrist or similarly capable person before spending time and money on supplements which may not help. And yes, magnesium in high doses can be toxic.