Overview

Combining fish oil and magnesium supplements may offer compounded benefits for people with heart conditions and hypertension. The supplement combo can also support mental health. While both supplements are generally safe, they may interact with certain medications, so you should consider consulting a healthcare provider before combining them.

Fish oil and magnesium are two popular supplements that, in some circumstances, can be even more beneficial when taken together.

Fish oil helps provide energy and aids in heart, lung, and immune system functioning. Magnesium facilitates many important bodily processes, like muscle and nerve function as well as blood pressure stabilization.

Based on your individual health needs, your healthcare provider may recommend you take supplements for both fish oil and magnesium.

Benefits of Taking Fish Oil and Magnesium Together

People with health conditions related to the heart and the brain are most likely to benefit from taking fish oil and magnesium together.

Since fish oil helps lower triglyceride levels and plaque buildup, the supplement may improve overall blood flow and help decrease blood pressure. Magnesium also helps open the blood vessels, which may help to lower blood pressure further.

This means people with heart conditions and high blood pressure may see compounded benefits by taking fish oil and magnesium together. Studies supporting this claim included a few specific types of magnesium supplements, like magnesium aspartate, magnesium lactate, magnesium citrate, and magnesium pidolate.

Research shows fish oil and magnesium may help improve mental health, so taking both supplements can also be beneficial for people with anxiety or depression.

Benefits of Magnesium

On their own, magnesium supplements offer plenty of benefits:

Promote heart health: Magnesium supplements may decrease blood pressure, which in turn lowers your risk of heart disease and stroke. However, research shows magnesium decreases blood pressure by only a small amount, so people with hypertension may see a benefit if they take magnesium with other blood pressure-lowering medications.
Manage blood sugar: Magnesium helps the body break down sugar, which may help reduce the risk of insulin resistance and the chances of developing type 2 diabetes.
Promote bone health: Magnesium is important for bone health, reducing the risk of bone fractures and osteoporosis in certain populations.
Manage migraine: Magnesium supplements can reduce the frequency of migraine headaches.
Improve mental health: Magnesium supplements may help lower symptoms related to stress and anxiety.

There are multiple types of magnesium, and some may be better at treating certain symptoms or health conditions than others. The magnesium supplement forms most easily absorbed by the body are magnesium aspartate, magnesium citrate, magnesium lactate, and magnesium chloride.

Benefits of Fish Oil

Whether consumed naturally from oily fish like salmon or in supplement form, fish oil provides your body with omega-3 fatty acids. Specifically, it's high in omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that boost energy and help various body systems function.

Some of the major benefits of fish oil overlap with magnesium, like keeping your heart and brain healthy. Taking a fish oil supplement can:

Promote heart health: Fish oil helps keep your heart healthy, protecting against issues like high blood pressure, stroke, and high cholesterol.
Reduce triglycerides: Fish oil has also been shown to reduce triglyceride levels. Triglycerides are a type of fat found in the blood that can raise your risk of heart disease. Fish oil helps remove plaque caused by triglycerides, which allows blood to flow more freely and blood pressure to decrease.
Prevent cancer: Fish oil and omega-3 supplements may reduce the risk of breast cancer and colorectal cancer.
Manage inflammation: Fish oil can improve inflammation and may relieve pain caused by inflammation, especially in people with rheumatoid arthritis.
Protect cognitive function: Fish oil may lower the risk of developing Alzheimer’s disease, dementia, and other cognitive function problems.
Prevent eye degeneration: Fish oil supplements may decrease the risk of developing age-related macular degeneration (AMD).
Improve mental health: Fish oil may also help reduce anxiety and depression symptoms.

How To Combine

Fish oil and magnesium are not available as one combination product—you'll need to take two different supplements.

Fish oil supplements can be purchased in either a soft gel capsule or liquid form and are taken by mouth. Magnesium supplements come in various forms, including capsules, tablets, powders, and liquids.

You can take magnesium supplements and fish oil supplements at any time of the day, depending on when works best for you.

Dosage

There's no recommended dietary allowance (RDA) for fish oil. Research from the American Heart Association suggests consuming 3 grams of DHA and EPA per day is enough to support a modest blood pressure reduction.

Typically, a fish oil supplement provides about 1 gram of fish oil. That amount usually has 180 mg of EPA and 120 mg of DHA. You can up your intake of these omega-3 fatty acids through your diet if you eat fish, seeds, and nuts.

The amount of magnesium in a supplement varies depending on the product, as does the type of magnesium. The daily recommended value for magnesium—from combined food and supplement sources—depends on your age and sex:

Men: 400 mg if you are 19–30, 420 mg if you are 31 or older
Women: 310 mg if you are 19–30, 320 mg if you are 31 or older
Pregnant people: 40 mg

Be sure to follow all dosage directions from your healthcare provider and the drug manufacturer.

Can You Take Too Much?

There is not an official upper recommended limit for fish oil. Taking high doses of fish oil is unlikely to cause adverse health effects.

Magnesium supplements should not be consumed above the upper recommended limit, unless recommended by a healthcare provider. The daily upper limit for magnesium in dietary supplements and medications in all adults is 350 mg. This limit does not include magnesium naturally found in food.

Side effects associated with taking too much magnesium include diarrhea, nausea, abdominal pain, irregular heartbeat, and cardiac arrest. The risk for side effects is higher in people with kidney issues.

Potential Drug Interactions

Fish oil and magnesium may each interact with medications you are already taking. Examples of medications that fish oil supplements can interact with include:

Anticoagulants: Fish oil may increase the risk of bleeding if taken with blood thinners such as warfarin.
Antihypertensives: Since fish oil may lower your blood pressure, taking the supplement with medications used to treat high blood pressure might lower your blood pressure too much and cause hypotension.
Contraceptives: Birth control pills may decrease the triglyceride-lowering effects of fish oil.

Magnesium supplements may interact with:

Bisphosphonates: Used for osteoporosis; magnesium can interfere with absorption. Take bisphosphonates two hours before or after magnesium.
Antibiotics: Some antibiotics may be less effective if taken with magnesium. Take them two hours before or 4–6 hours after taking magnesium.
Diuretics: Certain diuretics may raise magnesium levels too high when taken with supplements.
Zinc: High doses of zinc may interfere with magnesium absorption.

Check with your healthcare provider or pharmacist about any interactions fish oil and magnesium may have with other medications or supplements you are already taking.

A Quick Review

Fish oil and magnesium play essential roles in health. If you’re unable to get enough fish oil and magnesium from your diet, your healthcare provider may recommend taking supplements for both.

Taking fish oil and magnesium together may be beneficial to people with certain health conditions, including heart issues. You can talk with your healthcare provider about whether fish oil and magnesium supplements would be beneficial to you.

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