Is it safe to take vitamin D and omega fatty acids (EPA and DHA) together?

Taking Vitamin D and Omega-3 Fatty Acids Together is Safe and May Be Beneficial

Yes, it is safe to take vitamin D and omega-3 fatty acids (EPA and DHA) together at standard supplementation doses, and this combination was specifically studied in the large-scale VITAL trial without safety concerns. 1

Evidence from Direct Co-Administration Studies

The VITAL (Vitamin D and Omega-3 Trial) provides the strongest evidence for safety of concurrent use:

• 25,871 participants aged ≥50 years (men) and ≥55 years (women) received daily vitamin D3 (2000 IU) and/or fish oil (460 mg EPA + 380 mg DHA) for a median of 5.3 years 1
• No safety signals or adverse interactions were identified between the two supplements 1
• The combination was well-tolerated with no increased risk of bleeding, atrial fibrillation, or other serious adverse events when used together 2

The ASCEND trial further supports safety, where 15,480 diabetic patients received 460 mg EPA plus 380 mg DHA daily, with some groups also receiving aspirin, demonstrating no concerning interactions over 7.4 years of follow-up 1

Recommended Dosing When Taking Both

For general cardiovascular health:

• Vitamin D3: 2000 IU daily 1
• Omega-3 (EPA+DHA): 500-1000 mg daily 3, 4

For documented coronary heart disease:

• Vitamin D3: 2000 IU daily 1
• Omega-3 (EPA+DHA): 850-1000 mg daily 3, 4

For hypertriglyceridemia:

• Vitamin D3: 2000 IU daily 1
• Omega-3 (EPA+DHA): 2-4 grams daily (requires physician supervision above 3 grams) 3, 4

Important Safety Considerations

No increased bleeding risk occurs with omega-3 doses up to 4 grams daily, even when combined with vitamin D or anticoagulant therapy 3, 4

Atrial fibrillation risk increases only at high omega-3 doses (≥4 grams daily), representing a 25% increased risk, but this is not related to vitamin D co-administration 3, 2

Common side effects are mild and primarily gastrointestinal (fishy taste, belching, nausea) from omega-3 supplementation, not related to vitamin D combination 3, 4

Timing and Administration

• Both supplements can be taken at the same time, preferably with a meal containing fat to enhance absorption 3, 4
• No specific separation of doses is required 1
• Consistency in daily administration is more important than specific timing 3, 4

Populations Requiring Monitoring

Physician supervision is recommended when:

• Taking more than 3 grams daily of omega-3 fatty acids 3, 4
• Using anticoagulant medications (though no increased bleeding risk has been documented) 3, 4
• Patients on ibrutinib should completely avoid fish oil supplements due to epistaxis risk 4

Clinical Outcomes from Combined Use

While the VITAL trial showed the combination did not reduce the composite cardiovascular endpoint, omega-3 supplementation (with or without vitamin D) demonstrated:

• 28% reduction in total myocardial infarction (RR 0.72; 95% CI 0.59-0.90) 1
• 50% reduction in fatal MI (RR 0.50; 95% CI 0.26-0.97) 1
• 77% reduction in MI among African Americans (RR 0.23; 95% CI 0.11-0.47) 1

The vitamin D component showed no interference with these omega-3 benefits, confirming the safety and independence of their mechanisms 1, 2