@frane You ask "...Is that something we should all be taking?" The answer is not necessarily. Most people are able to get adequate magnesium from a balanced diet.

Some people, whether due to poor diet, poor absorption, certain chronic health conditions, or medications, may need a supplement.

There are a number of ways to test for magnesium deficiency, some are more accurate than others.

Too much (over 420mg daily for women) is not necessarily better. Be sure to check all multi-ingredient supplements and multi-vitamins for added magnesium before adding a separate magnesium supplement.
Some people are sensitive to magnesium supplements, the most common reaction is diarrhea, gas & bloating.

Consult your provider before adding a magnesium supplement, especially if you have kidney disease or are taking other medications.

@frane my cardiologist said magnesium was good for the heart. He said he takes it himself.

@frane It depends, but the betting money would be on 'Yes.' But it does depend!!

In modern times, people who eat a typical N. American diet are not getting enough magnesium the way most humans got it hundreds of years ago...through vegetables, leafy greens, plenty of nuts, shellfish. Soils have become depleted in it as humans have used up the soils for large scale growth over the past 140 years or so. So, like Vitamin D, most of us are deficient. But it's one of those things you shouldn't decide willy nilly just because you saw it on a YouTube video or here on Mayo. It would be worth a visit and consultation with at least a registered dietician, but more likely you'll get the proper tests through a family doctor who is sympathetic and would like to know the answer for him/herself and for your sake.

Even so, there would be little harm or danger in taking between 200-400 mg daily because, if your kidneys are sound and functioning properly, they'll eliminate all the excess if even that small daily amount turns out to be excessive. But there you go again....ARE your kidneys in good condition? How would you learn so?

@frane I was just talking to someone about magnesium supplements, and they said the list of medications that can interact with it are much longer than you would imagine. So I went looking, and here are the 5 most commonly mentioned: antibiotics, blood pressure medications, thyroid medication, osteoporosis medications, and calcium.
So, if you use any of these, certainly don't start magnesium until you have a doctor or pharmacist check for interactions.