The Type Of Magnesium That Could Help You Poop And Lower Blood Pressure

Magnesium supplements can be a little overwhelming. There are so many kinds, and each one seems to promise something different. Some magnesium supplements promise better sleep, while others focus on brain health. Common antacids like Maalox and Mylanta actually contain magnesium, too. And if you've ever reached for Milk of Magnesia to get things moving in the bathroom, you've taken a magnesium-based laxative.

One type you've probably seen in your multivitamin is magnesium oxide. It's closely related to magnesium hydroxide, which is the type of magnesium found in those antacids and laxatives. Magnesium oxide works in a similar way by drawing water into your intestines to ease constipation.

Interestingly, magnesium can also play a role in managing blood pressure. Magnesium encourages your blood vessels to relax and reduces the release of stress-related nerve signals. While other forms of magnesium may be more effective for lowering blood pressure, magnesium oxide might still offer some benefit in helping to keep your numbers in check.

You'll get about 100 milligrams of magnesium oxide in a multivitamin, but that's not enough to reduce your blood pressure. A 2018 study in Nutrients had 48 people with hypertension take 300 milligrams of a magnesium oxide supplement every day for a month. At the end of the month, their systolic blood pressure dropped by an average of 9 points, and their diastolic blood pressure was reduced by about 6 points. The study also found that the magnesium oxide reduced the workload of the heart. However, this study was relatively small, and there wasn't a control group given a placebo. It also didn't note any of magnesium oxide's laxative side effects. (Read why magnesium is essential for healthy aging.)

An older study published in Hypertension also found some evidence for magnesium oxide's effect on blood pressure. In this study, 60 people with hypertension took almost 500 milligrams of magnesium oxide a day or a placebo for eight weeks. When they took magnesium, their blood pressure was reduced, particularly among people whose blood pressure was higher. Supplementing with magnesium also increased the amount of magnesium in their blood and urine.

The effect of magnesium supplements on blood pressure may depend on whether you've been diagnosed with hypertension and whether you're taking medication for it, according to a 2021 review in Nutrients. Magnesium doesn't appear to lower blood pressure in people without hypertension, or in those whose blood pressure is already controlled with medication. It's important to note that taking too much magnesium can have hidden, serious side effects. The National Institutes of Health advises against taking more than 350 milligrams of magnesium a day from supplements.

Earlier studies from the 1990s found that magnesium oxide and magnesium hydroxide could lower blood pressure in people with hypertension who weren't on medication. However, participants took 600 milligrams of these forms daily — an amount that may cause side effects like diarrhea. Other forms of magnesium, and lower doses of magnesium oxide, weren't effective.

Some people take medications such as beta blockers or diuretics yet still struggle to control their blood pressure. In these cases, magnesium may help. Forms like magnesium oxide, chelate, chloride, pidolate, and aspartate have been shown to reduce blood pressure when used alongside antihypertensive medications. Notably, magnesium chloride and magnesium aspartate were effective at doses below 300 milligrams per day.