Key Takeaways
- Magnesium and fish oil may help lower blood pressure, but their effects together are not well researched.
- On their own, magnesium and fish oil can modestly reduce blood pressure in people with hypertension.
Magnesium and fish oil are two supplements many people use to support blood pressure and heart health. Both can have benefits on their own, but it’s not totally clear if taking them together gives any extra perks for blood pressure.
How Magnesium and Fish Oil Could Affect Blood Pressure
Currently, there is limited research examining whether combining magnesium and fish oil provides additional blood-pressure-lowering benefits compared to taking either one alone.
Most studies look at these supplements independently. That said, there are possible reasons why the combination might offer extra benefits, especially for certain people.
Magnesium and fish oil support the body in different ways that may work well together. Magnesium primarily affects blood vessel relaxation and electrolyte balance, while fish oil can influence inflammation, the function of your blood vessels, and their flexibility.
In theory, targeting multiple contributors to high blood pressure simultaneously could lower it.
It’s also possible that combining them doesn’t lead to greater blood pressure reductions than either supplement alone, particularly in people with normal blood pressure or adequate nutrient status.
Blood pressure regulation is a complex process, and supplements tend to make subtle changes, rather than dramatic shifts.
What Research Says About Magnesium and Blood Pressure
Research suggests that magnesium supplementation on its own may modestly lower blood pressure, particularly in people with hypertension or low magnesium intake.
Most large studies generally show average reductions of approximately 2-3 mmHg in systolic blood pressure and 1-2 mmHg in diastolic blood pressure.
The changes are modest, but even small reductions in blood pressure can add up to meaningful heart health benefits.
How Magnesium May Lower Blood Pressure
One of the key functions of magnesium is its ability to act as a natural calcium antagonist. Calcium promotes muscle contraction, including in the smooth muscle that lines blood vessels.
Magnesium helps counterbalance this by limiting calcium’s entry into these cells, allowing blood vessels to relax and widen, which may help reduce blood pressure.
Magnesium may also support the health of the endothelium, the thin layer of cells lining blood vessels. A healthy endothelium helps produce nitric oxide, which allows blood vessels to relax and widen.
Additionally, magnesium has mild anti-inflammatory and antioxidant properties, which may help reduce vascular stiffness over time.
It’s worth noting that when magnesium intake is already adequate and blood pressure is normal, supplementation tends to have little effect on a person’s blood pressure.
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What Research Says About Fish Oil and Blood Pressure
Fish oil supplements, which contain the omega-3 fatty acids EPA and DHA, have also been studied for their effects on blood pressure. Research suggests that omega-3s may produce small but consistent reductions in blood pressure, particularly in people with untreated or unmanaged hypertension.
On average, studies show reductions of roughly 3-5 mm Hg systolic and 2-3 mm Hg diastolic in people with high blood pressure, especially at higher doses (generally above 2-3 grams of EPA and DHA per day). Effects are typically smaller in people with normal blood pressure.
How Fish Oil May Lower Blood Pressure
Omega-3s appear to work through several potential pathways. They help improve endothelial function, helping blood vessels respond more effectively to changes in blood flow.
Omega-3s also reduce inflammation and oxidative stress, both of which contribute to arterial stiffness and impaired blood vessel function.
As with magnesium, fish oil is not a replacement for blood pressure medications when those are needed, but it may provide supportive benefits.
Potential Drawbacks of Taking Magnesium and Fish Oil
There aren’t any known drawbacks of taking the two supplements together. For most healthy adults, taking magnesium and fish oil is generally considered safe, but there are a few considerations.
- Fish oil may increase bleeding risk: Higher doses of fish oil have mild blood-thinning effects, which can be a concern for people on blood thinners or with bleeding disorders.
- Digestive discomfort is common: Taking too much magnesium can cause diarrhea or stomach upset, while fish oil may trigger nausea, reflux, or a fishy aftertaste.
- Not ideal for everyone: People with kidney disease should be cautious with magnesium, as excess amounts can build up in the body.
- More isn’t better: Taking higher doses doesn’t guarantee better results and can increase side effects, making proper dosing and supplement quality important.