Can you take too much magnesium?
Yes, too much magnesium can be dangerous, although serious toxicity through ordinary supplements is rare in people with healthy kidneys. With kidney problems or the use of intravenous magnesium, medical supervision is genuinely necessary.
Yes, you can take too much magnesium, but how great that risk is depends strongly on how you get it into your body. Standard tablets or capsules that you swallow do measurably raise your blood magnesium. In almost half of the patients who repeatedly received magnesium citrate as a laxative, blood magnesium rose above normal values. Dangerously high levels were not reached in those cases, but that was in a medical setting with close monitoring.
Intravenous magnesium, administered through a drip, is an entirely different matter. A documented case shows serious neurological deterioration caused by an overdose delivered via a drip. In pre-eclampsia, overdosing is such a real risk that doctors check the knee-jerk reflex every hour: it disappears as an early warning sign before things become truly dangerous. This risk does not apply to supplements bought at a pharmacy or health shop.
Too little magnesium is also dangerous. A deficiency can cause or worsen heart-rhythm disorders, particularly in people who use certain heart medications or diuretics. Without sufficient magnesium, cells also lose potassium, and that cannot be corrected by supplementing potassium alone.
With ordinary supplements at normal doses, serious toxicity is unlikely for healthy people with healthy kidneys. With kidney problems, where the kidneys excrete magnesium less efficiently, blood levels can indeed rise. On the label, look for the amount of elemental magnesium in milligrams per tablet, because that is what your body actually absorbs. The salt form, citrate, oxide or bisglycinate, is also listed and matters for absorption: magnesium oxide is absorbed less well than organic forms such as citrate. The total amount of magnesium salt in the capsule, without stating the elemental content, tells you little. If you have heart problems, kidney problems or take certain medications, discuss this with your doctor before you start.
Based on five claims: one observational study in laxative users, one case report on intravenous overdose, one clinical guideline on eclampsia treatment, one limited association study on cardiac arrhythmias, and one clinical-experimental claim on magnesium deficiency. No RCTs specifically examining oral supplement overdose in healthy individuals.
Which form of magnesium is best to take?
Magnesium citrate has the strongest evidence for absorption into the body. Magnesium oxide, the cheapest option, demonstrably performs the worst and is best avoided.
How much magnesium glycinate can you safely take per day?
In Europe the limit is 250 mg of elemental magnesium per day from supplements (350 mg in the United States), although more recent research suggests that higher doses do not cause diarrhoea in most people. How much magnesium glycinate specifically can be taken safely has not been well studied, so stick to the European limit and check your label.
Why does magnesium work for some people but not others?
Whether magnesium works for you depends strongly on which form you take and how high your dose is. Preferably choose an organic form such as citrate rather than oxide, and give it at least two months.
What exactly does magnesium glycinate do in your body?
Magnesium glycinate is well absorbed, but for most healthy people it is not demonstrably better than citrate. For those with poor intestinal function or a sensitive stomach, it is a worthwhile choice.
How much magnesium do you need per day?
Research suggests that your body reaches balance at around 165 mg per day, but official recommendations are higher and there is considerable individual variation. In any case, make sure you get enough magnesium-rich foods, as a large part of the population falls short.
Is it better to take magnesium in the evening?
Evening intake sounds logical given magnesium's role in melatonin and sleep, but no research directly compares evening versus morning use. Take magnesium at the time that is easiest for you to stick to consistently, preferably with a meal to limit stomach complaints.