Do you need EPA if you take DHA? A Comprehensive Nutrition Diet Guide

November 2, 2025 •

3 min read

The omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), perform different but vital functions in the human body, from supporting heart health to brain function. This raises a common question for many people considering supplements: Do you need EPA if you take DHA?

Quick Summary

The body requires both EPA and DHA for optimal function. While a small amount of DHA can be retro-converted to EPA, this process is inefficient and unreliable, making supplements containing both ideal for meeting specific needs.

Key Points

Distinct Functions: EPA primarily supports cardiovascular health and reduces inflammation, while DHA is crucial for brain structure, eye health, and cognitive function.
Inefficient Conversion: While a small amount of DHA can be converted to EPA, the process is not efficient enough for DHA to fully replace the need for EPA in your diet or supplement.
Complementary Benefits: Taking both EPA and DHA is recommended because their benefits are complementary, offering more comprehensive support for heart, brain, and inflammatory health.
Ratio Matters: The optimal ratio of EPA to DHA can vary depending on health goals, with higher EPA favored for mood and inflammation and higher DHA for cognitive support.
Reliable Sources: The most reliable sources for both EPA and DHA are fatty fish, fish oil supplements, and algal oil for those following a plant-based diet.

The Distinct Roles of EPA and DHA

While often grouped, EPA and DHA are not interchangeable. Each has a unique profile and contributes differently to overall health. Knowing the distinction is key to understanding whether a DHA-only supplement is enough.

The Functions of EPA

EPA is best known for its potent anti-inflammatory effects throughout the body, acting as a precursor to signaling molecules that help regulate the inflammatory response. Its benefits include supporting heart health by lowering blood triglycerides and blood pressure, improving mood, and managing inflammatory conditions.

The Functions of DHA

As a primary structural component of the brain and retina, DHA plays a central role in neurological and visual health. DHA is crucial for fetal brain and eye development, supports cognitive function throughout life, and is a major component of the retina, linked to a lower risk of age-related macular degeneration.

The Myth and Reality of DHA-to-EPA Conversion

It was once thought that the body efficiently converts DHA back into EPA. However, recent research suggests that any increase in EPA after DHA supplementation may be due to DHA sparing existing EPA rather than a direct conversion. The conversion of DHA to EPA is considered low and variable among individuals. This means taking DHA alone is unlikely to meet your body's specific EPA needs.

Why You Need Both EPA and DHA

Because EPA and DHA have distinct, yet complementary functions, a supplement with both is often recommended for comprehensive benefits. While DHA supports brain structure, EPA's anti-inflammatory action protects brain cells. Together, they offer broader support for cardiovascular health and overall well-being.

Choosing the Right Omega-3 Sources

Reliable sources of preformed EPA and DHA are important. Fatty fish like salmon, mackerel, and sardines are excellent dietary sources. For those who don't eat fish regularly, fish oil or algal oil supplements are good alternatives, with algal oil being suitable for vegetarians and vegans. Plant-based omega-3s (ALA) are poorly converted to EPA and DHA. Supplements offer various EPA:DHA ratios; a balanced ratio is often recommended, but specific ratios may be better for targeting certain health goals.

EPA vs. DHA at a Glance


Feature	EPA (Eicosapentaenoic Acid)	DHA (Docosahexaenoic Acid)
Primary Role	Anti-inflammatory action, precursor to anti-inflammatory eicosanoids	Structural component of cell membranes, particularly in the brain and retina
Key Benefits	Heart health (lower triglycerides), mood regulation, joint inflammation	Brain development, cognitive function, vision health, muscle recovery
Concentration	Highest in fatty fish, marine oil supplements	Highest in the brain and eyes, also found in fatty fish and algae
Conversion to the other	Can be converted to DHA (relatively efficient).	Can be retro-converted to EPA, but process is inefficient.
Ideal Ratio for Supplements	Higher EPA ratios (e.g., 2:1 or 3:1) often used for mood and inflammation	Higher DHA ratios (e.g., 2:1 or higher) prioritized for brain and eye health

Conclusion

Yes, you likely need EPA even if you take DHA. Both EPA and DHA are vital for health, and the body's conversion process is not sufficient to meet the need for both. They have distinct roles: DHA for brain and eye structure, and EPA for inflammation and mood. The best approach for most people is to ensure a balanced intake of both through diet or a high-quality supplement. Consult a healthcare professional to determine the best approach for your individual needs. For more information, visit the NIH Office of Dietary Supplements at https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/.

Frequently Asked Questions

A DHA-only supplement is effective for supporting brain and eye health, but it will not provide the same level of anti-inflammatory and mood-related benefits that EPA offers. For comprehensive health, a supplement containing both is generally recommended.

Yes, a process called retroconversion can convert DHA to EPA, but it is generally very inefficient. Some studies suggest that DHA may primarily function by sparing existing EPA rather than actively converting into it.

For general health, many supplements offer a balanced ratio, such as 1:1 or slightly higher EPA. This ensures you receive the benefits of both fatty acids for overall wellness.

DHA is the most important omega-3 for brain structure and cognitive function, making it particularly beneficial for brain health. However, EPA is also important for reducing neuro-inflammation, so a combination is often optimal.

Eating fatty fish like salmon, sardines, and mackerel at least twice a week is the best way to get both EPA and DHA from your diet. For vegetarians or vegans, algal oil supplements provide a direct source.

Plant-based sources like flaxseed contain ALA, which the body can convert into EPA and DHA. However, this conversion is very limited and not a reliable way to meet your needs for these specific fatty acids.

Yes, purity is important. High-quality supplements undergo rigorous testing to ensure they are free from contaminants like mercury and other toxins. Look for third-party testing certifications, such as those from GOED.