It’s advised that you don’t exceed more than 400 mg of magnesium per day, as you may experience symptoms such as diarrhea, nausea and abdominal cramps. Supplementing with 200 mg should generally be sufficient and safe on top of a balanced diet.
If you are taking magnesium to treat a diagnosed deficiency, doses of 250-600 mg are often recommended. However, if you’re not treating a deficiency, limit your intake to no more than 350 mg from supplements (the tolerable upper intake level).
Medlin adds: "Always check with your pharmacist or doctor if you are prescribed antibiotics and routinely take magnesium supplements as they can interact negatively. High doses of magnesium can cause nausea, vomiting, abdominal pain and diarrhoea."
It is always best to consult your doctor before introducing a new supplement to your routine, particularly if you have been diagnosed with a deficiency.
Form
You can buy the best magnesium supplements in tablet, capsule, liquid and powder form. Liquid and powder are ideal for those who have trouble swallowing non-chewable tablets. It’s also easier to modify or control your dose in liquid form.
Other ingredients
You can often find magnesium in other supplements, such as the best multivitamin for women. But bear in mind that this will often be in lower amounts. Magnesium is often sold in combination with calcium too, but it is better to take these nutrients individually at higher doses because they can compete for absorption.
One study in the Journal of the American College of Nutrition also found that very high doses of zinc from supplements (142 mg/day) can interfere with magnesium absorption and disrupt the magnesium balance in the body. So consider when you are taking your supplements, if you are taking multiple at once.