Magnesium supplements can be a bit overwhelming due to the variety available, each promising different benefits. Some focus on better sleep, while others target brain health. Common antacids like Maalox and Mylanta contain magnesium as well. If you’ve ever used Milk of Magnesia, you’ve taken a magnesium-based laxative.
Magnesium oxide, often found in multivitamins, is similar to magnesium hydroxide, the type found in antacids and laxatives. It helps with constipation by drawing water into the intestines.
Interestingly, magnesium plays a role in managing blood pressure by encouraging blood vessels to relax and reducing stress-related nerve signals. While other forms may be more effective, magnesium oxide could still help maintain healthy blood pressure levels.
Magnesium oxide may help people with blood pressure
In a multivitamin, you’ll find about 100 milligrams of magnesium oxide, which isn’t enough to lower blood pressure. A 2018 study in Nutrients had 48 people with hypertension take 300 milligrams of magnesium oxide daily for a month. Their systolic blood pressure dropped by an average of 9 points, and diastolic by about 6 points. The study noted a reduced workload on the heart, though it was small and lacked a placebo control group. It also didn’t mention magnesium oxide’s laxative effects. (Read why magnesium is essential for healthy aging.)
An older study in Hypertension also found evidence supporting magnesium oxide’s effect on blood pressure. In this study, 60 people with hypertension took nearly 500 milligrams daily or a placebo for eight weeks. Magnesium supplementation reduced blood pressure, especially in those with higher initial levels, and increased magnesium levels in blood and urine.
When magnesium may not lower blood pressure
According to a 2021 review in Nutrients, the effect of magnesium on blood pressure may vary based on a hypertension diagnosis and medication use. It doesn’t seem to lower blood pressure in those without hypertension or those whose levels are controlled by medication. Excess magnesium intake can have serious side effects. The National Institutes of Health advises against taking more than 350 milligrams daily from supplements.
Studies from the 1990s showed that magnesium oxide and magnesium hydroxide lowered blood pressure in people with untreated hypertension, but at 600 milligrams daily, which can cause diarrhea. Other forms, or lower doses of magnesium oxide, weren’t effective.
For those on medications like beta blockers or diuretics struggling with blood pressure, magnesium may help. Forms such as magnesium oxide, chelate, chloride, pidolate, and aspartate have shown efficacy in reducing blood pressure when combined with antihypertensive medications. Notably, magnesium chloride and magnesium aspartate were effective at doses below 300 milligrams per day.
“`
