Can You Take Magnesium and Omega 3 Together?

December 19, 2025 •

3 min read

According to the National Institutes of Health, a significant portion of the adult population in the U.S. does not meet the daily recommended intake for magnesium, while omega-3 deficiencies are also common. Taking these two popular supplements together is generally considered safe and can offer a range of synergistic health benefits for the heart, brain, and muscles.

Quick Summary

Taking magnesium and omega-3 supplements together is considered safe and beneficial. Their combined effect offers comprehensive support for cardiovascular health, improved brain function, enhanced mood, and better sleep by addressing inflammation and nervous system regulation from different angles. Proper timing, with omega-3s taken with food and calming forms of magnesium in the evening, optimizes absorption and effectiveness.

Key Points

Generally Safe: Taking magnesium and omega-3 together is considered safe and beneficial, with no adverse interactions reported.
Synergistic Benefits: The combination offers enhanced support for cardiovascular health, brain function, mood, sleep, and muscle recovery.
Optimal Timing: Take omega-3s with a meal containing fat to improve absorption and reduce side effects like fishy burps. Consider taking calming forms of magnesium, like glycinate, in the evening to aid sleep.
Potential Side Effects: High doses of magnesium can cause digestive issues such as diarrhea, while omega-3s have a mild blood-thinning effect. Start with lower doses and consult a doctor, especially if on medication.
Choose the Right Form: Select highly-absorbable magnesium forms like glycinate or L-threonate for targeted benefits. Ensure fish oil is high-quality and third-party tested.

Understanding Magnesium and Omega-3

Magnesium is a vital mineral involved in over 300 biochemical reactions in the body, impacting functions like muscle and nerve activity and energy creation. Omega-3 fatty acids, especially EPA and DHA found in fish oil, are essential as the body cannot produce them. They are crucial for cell structure and have strong anti-inflammatory properties.

The Synergistic Duo: How They Work Better Together

Combining magnesium and omega-3s can provide enhanced support for various bodily systems. Their complementary actions can boost health benefits for inflammation, heart health, and mental well-being more effectively than either nutrient alone.

Heart Health: Both nutrients benefit the cardiovascular system. Magnesium helps manage blood pressure and heart rhythm by relaxing blood vessels. Omega-3s reduce triglycerides, inflammation, and plaque buildup. Together, they offer comprehensive support for heart health.

Brain Function and Mood: The combination supports cognitive function and mental health. Omega-3s aid in building healthy brain cells and reducing inflammation, supporting cognition and mood. Magnesium calms the nervous system by regulating neurotransmitters and stress hormones. This partnership can lessen anxiety and improve focus.

Muscle Recovery and Sleep: Athletes and those with muscle issues can benefit. Omega-3s decrease exercise-related inflammation and soreness, while magnesium relaxes muscles and prevents cramps. Magnesium also aids sleep, and omega-3s are linked to better sleep quality, making this combination good for recovery and rest.

Optimizing Your Supplement Routine

Timing and consistency are important for best results and fewer side effects. While taking them together is fine, some prefer splitting doses.

Take with meals: Omega-3s are fat-soluble, so taking them with food improves absorption and can reduce fishy burps.
Consider timing: Magnesium is often taken in the evening for its calming effect, about an hour before sleep. Omega-3s can be taken anytime with food, so routines vary.

Choosing the Right Supplements

Different forms of magnesium and omega-3 exist, and selecting the right one is important.

Omega-3 Sources

Fish Oil: A main source of EPA and DHA. Choose quality brands tested for purity.
Krill Oil: Contains omega-3s in phospholipid form and astaxanthin.
Algae Oil: A plant-based source providing DHA and sometimes EPA.

Magnesium Forms

Magnesium Glycinate: Highly absorbable, gentle, and known for calming effects.
Magnesium Citrate: Well-absorbed but can cause a laxative effect.
Magnesium L-Threonate: May cross the blood-brain barrier, good for cognitive support.
Magnesium Oxide: Common and inexpensive but poorly absorbed and may cause stomach issues.

Potential Side Effects and Precautions

Combining is generally safe, but be aware of potential issues. High doses of magnesium can cause digestive upset. Omega-3s have a mild blood-thinning effect; consult a doctor if on anticoagulants. Magnesium can affect the absorption of some medications, so space doses apart.

Supplement Comparison: Forms and Effects


Feature	Omega-3 (Fish Oil)	Magnesium Glycinate	Magnesium Citrate
Best Absorbed	With a meal containing healthy fats	Well-absorbed, gentle on stomach	Well-absorbed, but can cause laxative effect
Primary Benefit	Anti-inflammatory, heart & brain health	Calming, sleep, nerve function	Laxative, general magnesium repletion
Main Function	Essential fatty acid for cell structure	Cofactor in 300+ reactions	Cofactor, osmotic laxative
Common Side Effect	Fishy burps, mild GI upset	Generally none	Diarrhea, stomach upset
Best Time to Take	Any time with food	Evening, for calming effect	Anytime, with food if sensitive

Conclusion

Taking magnesium and omega-3 together is safe and effective for supporting heart health, brain function, mood, and sleep. By understanding the forms and timing, you can optimize benefits. Always consult a healthcare provider before starting any new supplement, especially with existing conditions or medications. Choosing quality supplements helps ensure you get the most from this combination.

Frequently Asked Questions

Combining magnesium and omega-3 offers enhanced benefits for heart health by helping regulate blood pressure and triglyceride levels, and for brain function by supporting nerve communication and reducing inflammation. It can also improve mood, aid in sleep, and support muscle recovery after exercise.

While consistency is most important, many people benefit from a split schedule. Take fat-soluble omega-3 with a meal containing some fat (like breakfast or lunch) to maximize absorption. Magnesium, particularly calming forms like glycinate, is often taken in the evening to promote relaxation and sleep.

There are no known adverse interactions from combining magnesium and omega-3. However, side effects can occur from high doses of either supplement individually. Excess magnesium may cause diarrhea, and high doses of omega-3 can have a mild blood-thinning effect.

Yes. Magnesium can interfere with the absorption of certain medications, such as antibiotics and thyroid medication, if taken simultaneously. Omega-3's mild blood-thinning effect requires caution if you are on anticoagulant medication. Always consult your healthcare provider about potential interactions.

While you can and should include magnesium-rich foods (like spinach, nuts) and omega-3-rich foods (like fatty fish) in your diet, many people still fall short of optimal levels. Supplements can help fill these nutritional gaps, especially for specific therapeutic goals.

For broad benefits and good tolerability, combining a high-quality fish oil (look for EPA/DHA content and third-party testing) with a bioavailable magnesium like magnesium glycinate is a popular choice. Avoid poorly-absorbed forms like magnesium oxide.

Both magnesium and omega-3 are important during pregnancy, but proper dosing is essential. Expectant or breastfeeding individuals should always consult their healthcare provider before beginning any new supplement regimen to ensure safety for both mother and baby.