High EPA is natural in fish, but not in algae or the human body.

In humans, red blood cells naturally contain three to eight times more DHA than EPA. This DHA-dominant ratio is consistent across healthy, untreated individuals and reflects how the human body is designed to use omega-3 fats.

Fish, by comparison, naturally carry a different ratio. Fish tissue typically contains about twice as much DHA as EPA. This higher EPA level is normal for fish, but it exists because fish process the microalgae they consume, altering the original fatty acid profile through their own metabolism.

In other words, fish oil reflects fish biology—not human biology.

How the Body Processes Omega-3s

According to scientist Scott Doughman, PhD, studies show what he describes as “directional omega-3 metabolism.” This means the body processes omega-3s differently depending on whether they come from fish oil or algae oil.

Dr Doughman explains:

• With fish oil, EPA must undergo multiple metabolic steps to be converted into DHA.
• With algae oil, DHA undergoes a single-step retro-conversion into EPA.

Importantly, the body regulates how much EPA and DHA it ultimately needs. However, the retro-conversion of DHA to EPA appears to be more efficient, particularly at higher omega-3 intakes.

Why Algae Oil Does Not Need High EPA

Dr Doughman’s conclusion is clear:

“There is no nutritional reason for algae oil to contain high levels of EPA, other than to resemble fish oil.”

Human digestion naturally adjusts the DHA and EPA levels from any omega-3 source to match the body’s inherent DHA-dominant ratio. Because of this, the starting ratio in the oil is largely irrelevant from a nutritional standpoint.

Studies consistently show that high-DHA algae oil performs as well as—or better than—fish oil in terms of:

• Tissue incorporation
• Omega-3 metabolism
• Functional health benefits

This is due, in part, to the body’s ability to easily convert a small amount of DHA (around 5%) into EPA in precisely the amount required, based on individual needs.

What High EPA in Algae Oil Really Indicates

Algae oil that contains unnaturally high EPA levels—approaching half the DHA content—does not reflect natural algae biology.

This type of fatty acid profile strongly indicates that the algae has been genetically engineered to mimic fish oil rather than align with human physiology.

DHA Is the Dominant Omega-3 in the Human Body

Multiple studies confirm that DHA is the most abundant omega-3 fatty acid in human blood and tissues.

• Early composition studies of untreated individuals showed DHA to be significantly more prevalent than EPA in red blood cells (Sanders et al., 1978).
• Later studies found that even when individuals consumed high amounts of EPA from fish oil, DHA levels still remained higher in red blood cells (Herold & Kinsella, 1986).

This supports DHA’s role as the dominant—or “master”—omega-3 in human biology.

DHA Raises EPA — But Not the Other Way Around

Further research has clarified an important distinction:

• EPA levels increase when DHA is consumed
• DHA levels do not increase when EPA is consumed

This finding has been consistently observed in both fish oil and algae oil studies (Brenna et al., 2009).

A detailed human trial using algae-derived DHA showed blood omega-3 profiles equivalent to those seen in individuals taking high-dose fish oil (Conquer & Holub, 1996).

DHA: The Brain’s Primary Omega-3

DHA is especially concentrated in the brain, where it plays a structural and functional role. Importantly, DHA can be retro-converted into EPA, acting as a natural and regulated source of EPA as needed by the body (Nutrients, 2020).

This confirms that DHA-first nutrition aligns with how the human body is designed—whereas high-EPA algae oil does not. High levels of EPA are natural in fish, but they are not natural in either algae or humans.