• Jen Bennett RD CDE

Should I take a Magnesium Supplement?

You know how people always say “take a magnesium supplement” when you have a twitchy eye or when your leg muscles are sore? We’re going to break down magnesium for you so the next time someone gives you that suggestion, you can make a more informed decision about whether to take a supplement or not. We’ll also talk about some other cool things magnesium is important for. Here we go!

Magnesium is an essential mineral (meaning, we need it to LIVE!) and it is the second most prevalent electrolyte in the body. It’s responsible for hundreds of different biochemical processes and physiological systems that help us function. Magnesium plays an important role in regulating blood pressure, blood sugar, muscle/nerve function and is a key player in bone health. It has also shown some evidence of having a protective effect against depression and ADHD. Who knew this little mineral was such an all star? Well, now you do!

Can we be low in magnesium?

Yep. We sure can. So, the people who are most at risk of magnesium deficiency (or “hypomagnesemia”) are those suffering from alcoholism, anorexia, malabsorption issues, kidney disease, type 2 diabetes, or long-term low magnesium diet. Deficiency levels do not always produce symptoms unless the deficiency is chronic.

However, signs of deficiency might include:

  • Poor appetite

  • Fatigue or weakness

  • Muscle cramps, menstrual cramps

  • Abnormal Heart Rate

  • Higher blood pressure

  • Nausea, vomiting

  • Anxiety, trouble sleeping

So to address our first comment about magnesium supplementation and muscle cramps...the evidence does not actually support this treatment for leg cramps. A Cochrane review of seven randomized control trials did not find a significant difference in intensity or duration of cramps in people using a supplement vs. placebo.

What about the twitchy eye situation? It also appears that a twitching eye could be more related to low calcium rather than low magnesium. But as we mentioned above, adequate magnesium is important for so many other processes in the body so could be helpful for managing things like blood pressure, menstrual cramps, sleep, fatigue, etc.


So how much do you need? How do you know if you need a supplement and if you do, how much should you take?

We’ve got answers!

Magnesium can be found naturally in foods like legumes, dark leafy greens, nuts, seeds, whole grains and fortified cereals (oh, and chocolate! Especially dark chocolate. YUM!). It is also in fish, poultry and beef. Magnesium is found in our soil but overtime, has become more depleted so the more variety of these foods you can eat, the better!

The recommended daily allowance (RDA) of magnesium for adults ages 19-51 year is

420 mg/day for men

320 mg/day for women

350-360 mg/day in pregnancy and

310-320 mg/day in lactation

There are several different types of magnesium supplements and the one you choose will depend on your gut health or what you are looking to achieve. Your dietitian can help you with this decision too! Magnesium citrate is a popular choice because it is affordable and very bioavailable (meaning we absorb and use it well). Just don’t take too much as it can have a laxative effect at high doses. Magnesium glycinate and magnesium chloride are also well absorbed. Magnesium oxide is used as a laxative so if you’re suffering from constipation, that’s your guy!


The {tolerable} upper limit (UL) for magnesium (from supplements) is 350 mg/day, which does not include magnesium from food. So what does all of that mean? If you are going to take a supplement, don’t take more than 350 mg.

Again, taking too much magnesium can have a laxative effect so more is not better...unless you are prepared to have the runs! No thank you!

Anyways, we hope that shed some light on magnesium for ya! Let us know if you have any questions. Our dietitians at The Nutrition Room can assess whether you are getting enough magnesium and other vitamins/minerals in your diet. We are here to help!






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