Is there a downside to eating a magnesium-heavy diet (and also supplementing magnesium citrate) ?

I tried finding studies on the perils of magnesium supplementation but found none, all evidence points to magnesium being awesome. Am I missing something? edit: magnesium heavy diet being one that consists of beans, oats, dark leafy greens, dark chocolate etc. but also has some meat and a little bit of dairy. edit2: I supplement 400mg magnesium citrate daily. edit3: I do not have the runs, lol. not even once.