I'm taking 400 mg a day at the moment. Is that not enough? Also, what is the most Calcium you can take in the same day (I live in west Africa and I could only find Calc/Mag combination tablets. They have 133mg of mag in each tab - I could take 4 tabs but that would be 533mg of magnesium. Would that be safe? . Thanks for your time, I really do appreciate it.