DHA (Docosahexaenoic Acid)

What Is DHA (Docosahexaenoic Acid)?

Docosahexaenoic acid (DHA) is a long-chain omega-3 polyunsaturated fatty acid with 22 carbon atoms and 6 double bonds. It is the most abundant omega-3 fatty acid in the human brain — comprising approximately 15–20% of total fatty acids in the cerebral cortex — and is a major structural component of the retina, accounting for up to 60% of polyunsaturated fatty acids there. Like EPA, DHA is an essential fatty acid that must be obtained through diet or supplementation.

Although the body can theoretically convert the plant-based omega-3 ALA into DHA, this conversion is highly inefficient, with estimates typically below 1–4%. Direct consumption of preformed DHA from marine or algal sources is therefore necessary to maintain adequate tissue levels.

Key Functions and Health Benefits

DHA's structural role in neural and retinal tissues underlies its critical importance across the lifespan:

• Brain development: DHA is essential during the third trimester of pregnancy and the first two years of life, when rapid brain growth occurs. Adequate maternal and infant DHA intake is linked to better cognitive outcomes, visual acuity, and reduced risk of preterm birth.
• Cognitive function: In adults, higher DHA levels are associated with reduced risk of cognitive decline and Alzheimer's disease. DHA supports neuronal membrane fluidity, synaptic transmission, and neuroprotectin synthesis.
• Visual health: DHA is required for photoreceptor function; deficiency impairs vision and may contribute to age-related macular degeneration.
• Cardiovascular support: DHA reduces triglycerides, lowers blood pressure, and has anti-arrhythmic properties.

The World Health Organization recommends a DHA intake of at least 200 mg/day for pregnant and lactating women, and 100–150 mg/day for children aged 2–4 years.

Food Sources

• Fatty fish: salmon, sardines, mackerel, and tuna are the richest dietary sources, providing 500–1,500 mg DHA per 85 g serving.
• Algae: the primary source of DHA for fish; algal oil supplements provide 200–500 mg DHA per capsule and are suitable for vegetarians.
• Fortified foods: some eggs (from hens fed DHA-enriched diets), dairy products, and infant formulas are fortified with DHA.