How Does DHA Work in the Body?

November 12, 2025 •

4 min read

DHA (docosahexaenoic acid) makes up over 90% of the omega-3 fatty acids in the brain, showcasing its vital structural importance from an early age. This essential fatty acid performs a multitude of crucial functions throughout the body, playing a key role in maintaining cellular health and facilitating communication between cells.

Quick Summary

DHA functions by integrating into cell membranes, particularly in the brain and retina, to promote fluidity and enhance cell signaling. The body acquires DHA through diet or inefficient conversion from ALA. Its anti-inflammatory properties, mediated through resolvins and neuroprotectins, and its role in neurotransmitter activity make it critical for brain, eye, and heart health.

Key Points

Cellular Integration: DHA incorporates into cell membranes, especially in the brain and eyes, to enhance their fluidity and function.
Enhanced Signaling: Its presence in neural membranes improves cell-to-cell communication and the efficient transfer of electrical signals.
Inflammation Resolution: The body converts DHA into potent anti-inflammatory compounds called resolvins and protectins that actively resolve inflammation.
Brain Development: DHA is critical during pregnancy and infancy for proper brain growth, gray matter development, and neural network formation.
Visual Function: A key component of retinal photoreceptor membranes, DHA is essential for healthy vision and activating light-sensitive proteins.
Neuroprotection: It provides antioxidant protection for neurons, helping to reduce oxidative stress that contributes to age-related cognitive decline.
Metabolic Precursor: While the body can synthesize small amounts of DHA from ALA, efficient levels depend on dietary intake from marine sources or supplements.

DHA: A Structural Master in Cell Membranes

DHA’s primary mechanism of action is its role as a key structural component of cell membranes, particularly in the brain and retina. The unique, flexible structure of DHA, with six double bonds in its long carbon chain, imparts special fluidity and responsiveness to the membranes it's incorporated into. This enhances a cell's ability to transmit electrical signals efficiently, which is particularly vital for nerve cells. Without adequate DHA, membranes become more rigid, potentially compromising cellular communication and function.

The Role of DHA in Neuronal Signaling and Brain Function

In the brain, DHA is concentrated in the gray matter, the areas responsible for processing information, emotions, and memory. Here's how it supports brain health:

Enhancing Synaptic Communication: By maintaining the fluidity of synaptic membranes, DHA facilitates the release of neurotransmitters like dopamine and serotonin and improves the function of associated receptors. This supports better mood regulation, cognitive performance, and memory.
Supporting Neurogenesis: DHA supports the growth of new nerve cells (neurogenesis) and promotes neurite outgrowth, which is essential for establishing strong neural connections, especially during early development.
Providing Neuroprotection: The body converts DHA into anti-inflammatory molecules called resolvins and neuroprotectins, which can protect against oxidative stress and damage. This protective effect is crucial for mitigating age-related cognitive decline and reducing the risk of neurodegenerative diseases like Alzheimer's.

DHA and Eye Health: A Focus on the Retina

Similar to the brain, the retina has a high concentration of DHA, which is essential for visual function. DHA's role in the eye includes:

Photoreceptor Function: DHA is a major structural lipid in the photoreceptor cells of the retina. It is integral for activating rhodopsin, a membrane protein that converts light into electrical signals, enabling vision.
Anti-inflammatory Effects: The anti-inflammatory properties of DHA help protect the retina from oxidative damage and inflammation, which are factors in age-related macular degeneration (AMD) and dry eye disease.

The Anti-Inflammatory Effects of DHA

DHA is a powerful anti-inflammatory agent, which helps protect against chronic diseases associated with age-related inflammation, such as heart disease and rheumatoid arthritis. It works in several ways:

Resolving Inflammation: DHA serves as a precursor to specialized pro-resolving lipid mediators (SPMs) like resolvins and protectins. These molecules actively promote the resolution of inflammation, helping to return tissues to a healthy state after an immune response.
Balancing Omega-3 and Omega-6: Many Western diets have a high ratio of inflammatory omega-6 fatty acids to anti-inflammatory omega-3s. Increasing DHA intake helps correct this imbalance, promoting an overall anti-inflammatory state in the body.

Comparison of DHA and EPA Functions

While both DHA and EPA are vital omega-3 fatty acids found in marine sources, they have distinct specialties in the body.


Feature	DHA (Docosahexaenoic Acid)	EPA (Eicosapentaenoic Acid)
Primary Role	Structural component, especially in brain and retina; enhances cell membrane fluidity and nerve signaling.	Anti-inflammatory agent; precursor to signaling molecules (eicosanoids) that regulate inflammation.
Best Known For	Brain and nervous system development; vision support; cognitive health.	Cardiovascular health; reducing triglycerides; mood balance.
Concentration	Highest in the brain and retinal tissues.	High in fatty fish; lower concentration in the brain compared to DHA.
Metabolism	Synthesized from ALA, but conversion is limited.	Synthesized from ALA; serves as a precursor for DHA production.
Specific Action	Improves cell-to-cell communication by altering membrane properties.	Produces anti-inflammatory eicosanoids and helps reduce platelet aggregation.

DHA During Pregnancy and Early Life

DHA is particularly important during the final trimester of pregnancy and the first few years of life, as the infant's brain and eyes undergo rapid growth. During pregnancy, DHA is preferentially transferred from the mother to the fetus via the placenta, supporting crucial neurological development. Breast milk is also a significant source of DHA for infants. Adequate maternal DHA intake during this period has been linked to better problem-solving skills, enhanced visual acuity, and improved neurodevelopmental outcomes in children.

Conclusion

In summary, DHA is a crucial long-chain omega-3 fatty acid that supports physiological function primarily by maintaining the structural integrity and optimal fluidity of cell membranes, particularly in the brain and retina. Its versatile mechanisms include enhancing nerve cell communication, promoting neuroprotection and neurogenesis, and actively resolving inflammation through the creation of specialized molecules. These actions contribute to improved cognitive function, healthy vision, reduced risk of chronic disease, and robust fetal and infant development. Sourcing sufficient DHA through diet, especially fatty fish or algae-based supplements, is essential for lifelong health, as the body's ability to produce it is limited. For more detailed information on DHA's role and benefits, consult resources like the NIH Office of Dietary Supplements fact sheet.

Frequently Asked Questions

The primary role of DHA is to act as a crucial structural component of cell membranes, particularly in the brain and retina. It promotes membrane fluidity, which is essential for efficient communication between nerve cells.

DHA supports brain health by improving nerve cell communication, promoting the growth of new neurons (neurogenesis), and protecting against inflammation and oxidative stress. It is concentrated in the brain's gray matter, where it supports memory, learning, and mood regulation.

DHA is a major structural fat in the retina's photoreceptor cells, which are responsible for converting light into signals the brain can interpret. Adequate DHA levels are vital for visual acuity, activating light-sensitive proteins, and protecting against damage.

Yes, DHA is a powerful anti-inflammatory fatty acid. It is converted into specialized molecules called resolvins and protectins, which help resolve inflammation and promote tissue healing after an immune response.

The body primarily obtains DHA from the diet, particularly from marine sources like fatty fish and algae. While the body can convert a small amount of plant-based omega-3 (ALA) into DHA, this process is very inefficient, making direct dietary intake important.

DHA and EPA are both omega-3s, but DHA's primary role is structural support for brain and eye tissue, while EPA is more known for its anti-inflammatory and cardiovascular benefits.

Yes, DHA is especially critical during the final months of pregnancy and early life, as it supports the rapid development of the infant's brain and eyes. It is transferred from the mother to the fetus and is found in breast milk.