Does Magnesium Prevent or Improve Afib?

March 11, 2024

Foods high in magnesium on counter, spinach, avocado, oats, nuts,banana

Magnesium is one of those nutrients that can significantly affect our health, yet it remains underappreciated and less known among patients. Because of its beneficial effects on muscle, of which the heart is one, magnesium has been posited as a potential preventative measure or treatment for atrial fibrillation / Afib. However, does science support this claim, and should patients consider supplementing to improve heart health?

Let’s get right to it and say that unless you have a deficiency, it’s unlikely that a magnesium supplement will make a significant difference, at least in atrial fibrillation. That’s not to say that none of our patients will benefit from magnesium supplementation; we all have different nutritional requirements. We’re simply stating that for most, magnesium supplementation taken orally should not be counted on alone to make a significant difference.

With that said, patients already experiencing Afib, even paroxysmal or occasional episodes, are best served by taking the condition by the horns and visiting an electrophysiologist like Dr. Banker to get started with a proper diagnosis and comprehensive treatment plan. While there are many stages, treating Afib at its earliest presentation is most effective. Further, the technology we have, including cardiac catheter ablation, is exceptionally effective in well-selected patients.

But Isn’t IV Magnesium Used to Improve Rate & Rhythm Control?

If you are asking this question, you probably read about a meta-analysis published in the journal Cardiology in 2021 that discussed the possible benefits of intravenous magnesium in addition to the standard of care. The study showed a significant benefit of intravenous magnesium when administered alongside traditional care options. Improvements were seen both in rate and rhythm control. Interestingly, the lower dose of IV magnesium – less than 5g seems more effective than a higher dose of more than 5g.

Knowing this, how can we say that we are unsure about the effects of magnesium on Afib? It’s quite simple. First, this study does not seem to consider whether the patients had an existing magnesium deficiency, which is very important to understand. Also, most patients will not take magnesium intravenously, which introduces the nutrient into the blood immediately. Instead, the average patient will consume the supplement orally. While this also offers good bioavailability, depending on the type of magnesium consumed, which we will discuss below, one would not take anywhere near 5g. Anything more than a few hundred milligrams, considered the upper limit, can cause gastrointestinal upset.

Should You Take a Magnesium Supplement?

As mentioned above, most patients will not benefit from a magnesium supplement if their only concern is to prevent or reduce the effects of Afib. However, if patients have a nutrient deficiency, it’s very important to speak to a primary care physician, dietitian, or nutritionist to understand how to supplement. Of course, we always suggest that supplementation be pursued primarily through what you eat rather than supplements bought in pill or capsule form. This is mainly for three reasons. First, the foods that contain lots of magnesium are typically heart-healthy. Second, the FDA does not regulate supplements, and the purity of what you buy may be questionable. Lastly, excess magnesium ingested through natural foods is better processed than supplements – the latter can cause uncomfortable side effects.

Is There a “Best” Magnesium Supplement?

If, while under the care of your primary care physician or nutrition specialist, you are suggested to take a magnesium supplement, there are differences between the ones you will find on the shelves. Magnesium oxide is the least bioavailable and may not be the best option for someone looking to raise magnesium levels in the blood. Instead, you may consider magnesium citrate, magnesium glycinate, eight, and magnesium L-threonate.


  1. Ramesh T, Lee PYK, Mitta M, Allencherril J. Intravenous magnesium in the management of rapid atrial fibrillation: A systematic review and meta-analysis. J Cardiol. 2021 Nov;78(5):375-381. doi: 10.1016/j.jjcc.2021.06.001. Epub 2021 Jun 20. PMID: 34162502.