Can magnesium glycinate, omega-3 (fatty acids) and vitamin C be taken at the same time?

Can Magnesium Glycinate, Omega-3, and Vitamin C Be Taken Together?

Yes, magnesium glycinate, omega-3 fatty acids, and vitamin C can safely be taken together without clinically significant interactions or safety concerns.

Safety Profile of Individual Supplements

Magnesium Glycinate Safety

• Magnesium supplements are safe well above the current tolerable upper intake level (UL) of 350 mg/day from supplemental sources. 1
• Recent comprehensive evidence from 10 studies (including 5 meta-analyses) examining magnesium intakes of 128-1200 mg/day found no significant differences in diarrhea occurrence between intervention and control groups. 1
• Only 40 attributable cases of gastrointestinal adverse events were found in FDA adverse event reporting, with only one-third noting diarrhea. 1
• Magnesium glycinate specifically is well-tolerated and has been studied in combination with other supplements without safety concerns. 2, 3

Omega-3 Fatty Acids Safety

• Omega-3 supplements are safe up to 5 grams daily without increased bleeding risk, even with concurrent antiplatelet or anticoagulant therapy. 4
• The Society for Perioperative Assessment and Quality Improvement explicitly recommends continuing fish oil/omega-3 supplements until surgery, as they do not increase perioperative bleeding risk. 5
• For general cardiovascular health, 400-500 mg/day EPA+DHA is recommended, with doses up to 4 grams daily used therapeutically under physician supervision. 4

Vitamin C Safety

• Vitamin C supplements up to 2000 mg/day are safe for most adults. 6
• Clinical trials have shown no consistent pattern of adverse effects at any intake level, with only occasional gastrointestinal upset or mild diarrhea from osmotic effects of unabsorbed quantities. 6
• The tolerable upper intake level established by the Institute of Medicine is 2000 mg for adults. 6

Documented Combination Safety

Magnesium + Vitamin C + Omega-3

• A large observational study of 810 children demonstrated excellent safety when omega-3 fatty acids were combined with magnesium and zinc over 12 weeks. 2
• Only 1.7% of participants reported adverse events possibly related to the supplement combination, and only 5.2% discontinued due to acceptance problems. 2
• No serious adverse events occurred with this multi-nutrient combination. 2

Magnesium + Vitamin D (Related Evidence)

• Combined magnesium glycinate (360 mg) with vitamin D supplementation in 95 overweight/obese participants over 12 weeks showed no safety concerns. 3
• This demonstrates magnesium glycinate's compatibility with fat-soluble vitamins similar to omega-3. 3

Pharmacokinetic Considerations

Vitamin C + Other Supplements

• One small study (n=6) found vitamin C increased paracetamol absorption when taken concomitantly, but this does not apply to magnesium or omega-3 interactions. 7
• No documented pharmacokinetic interactions exist between vitamin C and either magnesium or omega-3 fatty acids. 7

Absorption Optimization

• All three supplements can be taken together without compromising absorption of any component.
• Omega-3 fatty acids are fat-soluble and best absorbed with meals containing fat.
• Magnesium glycinate and vitamin C are water-soluble and can be taken with or without food.

Clinical Pitfalls to Avoid

• Do not confuse general population omega-3 recommendations with critically ill patient guidelines. The Surviving Sepsis Campaign recommends against omega-3 as an immune supplement in sepsis/septic shock, but this does not apply to healthy individuals taking supplements. 8
• Avoid exceeding 2000 mg/day of vitamin C to prevent osmotic diarrhea, though this is not dangerous. 6
• Monitor for loose stools if taking high-dose magnesium (>350 mg supplemental), though evidence suggests tolerance is much higher than previously thought. 1
• Doses of omega-3 above 4 grams daily may increase atrial fibrillation risk by 25%, so stay within recommended ranges unless under physician supervision. 4

Practical Dosing Guidance

• Take all three supplements together with a meal to optimize omega-3 absorption and minimize any potential gastrointestinal effects from vitamin C or magnesium.
• Standard safe doses: magnesium glycinate 200-400 mg, omega-3 500-2000 mg EPA+DHA, vitamin C 500-1000 mg daily.
• No need to separate timing of these supplements—concurrent administration is safe and convenient.