What diseases are caused by DHA deficiency and how to prevent them?

October 27, 2025 •

4 min read

Worldwide, a significant portion of the population consumes insufficient amounts of docosahexaenoic acid (DHA), a key omega-3 fatty acid, potentially impacting health. A deficiency can impair the structure and function of cell membranes, particularly in the brain and retina. Understanding what diseases are caused by DHA deficiency is the first step towards prevention and improved well-being.

Quick Summary

DHA deficiency is linked to a range of serious health conditions, including neurological and psychiatric disorders, cognitive impairment, visual deficits, and increased cardiovascular disease risk due to chronic inflammation.

Key Points

DHA is critical for brain function: Deficiency impairs memory, focus, and learning, and is linked to psychiatric disorders like depression and anxiety.
Vision and eye health depend on DHA: Low DHA levels are associated with visual impairment, dry eyes, and increased risk of age-related macular degeneration (AMD).
DHA deficiency raises cardiovascular risks: Insufficient DHA can lead to elevated triglycerides, high blood pressure, and atherosclerosis, increasing the risk of heart disease.
Chronic inflammation is exacerbated by low DHA: Since DHA possesses anti-inflammatory properties, a deficiency can worsen conditions like arthritis and autoimmune diseases.
Fetal and infant development are compromised without DHA: Adequate maternal DHA is essential for optimal fetal brain and eye development, with deficiencies linked to poor visual and neural outcomes in children.
Supplementation and diet can prevent deficiency: The most effective strategies involve consuming fatty fish or taking supplements like fish oil, krill oil, or algal oil.

The critical function of DHA

Docosahexaenoic acid (DHA) is a long-chain omega-3 polyunsaturated fatty acid that is a primary structural component of the brain and retina. It is particularly concentrated in the grey matter of the brain and the photoreceptor cells of the eye. A key function of DHA is to maintain the fluidity and permeability of cell membranes, which facilitates efficient communication between nerve cells. While the body can convert some alpha-linolenic acid (ALA), a plant-based omega-3, into DHA, this process is highly inefficient, making dietary intake of DHA from marine sources essential. Low levels of DHA compromise these vital functions, contributing to various health disorders across the lifespan.

Neurological and cognitive disorders

Impaired brain function is one of the most well-documented consequences of DHA deficiency. The high concentration of DHA in the brain means even small deficits can significantly impact cognitive and mental health.

Developmental issues in children

For infants and children, DHA is crucial for proper brain growth and nerve signal transmission. Maternal DHA intake during pregnancy directly affects the fetus's levels, and a deficiency can lead to developmental problems. Low DHA levels in children are associated with ADHD, learning disabilities, and behavioral problems.

Mood and psychiatric disorders

Low DHA levels have been observed in individuals with various psychiatric conditions, partly due to its role in neurotransmission and membrane function. Deficiency can alter neurotransmitter function and increase susceptibility to stress, anxiety, and depression. Some studies indicate low omega-3 levels in individuals with bipolar disorder and schizophrenia.

Age-related cognitive decline

As DHA levels naturally decrease with age, maintaining sufficient intake is vital for protecting brain health. Higher blood DHA levels are associated with a reduced risk of dementia and Alzheimer's, as DHA helps protect against oxidative stress and reduce amyloid plaque formation. Studies have shown that DHA supplementation can improve memory and learning.

Ocular and vision problems

The retina is highly concentrated with DHA, which plays a critical role in visual function. DHA deficiency can cause visual impairment, particularly in infants and children. Low DHA intake is associated with reduced tear production, leading to dry eye syndrome. There is also an increased risk of age-related macular degeneration (AMD) linked to long-term DHA deficiency.

Cardiovascular and metabolic conditions

DHA is known for its protective effects on heart health, primarily through its anti-inflammatory and lipid-regulating properties. DHA can significantly reduce blood triglycerides and may lower blood pressure. It also helps prevent plaque buildup in arteries. A deficiency can negatively affect insulin sensitivity and glucose metabolism.

Inflammatory and immune disorders

Chronic inflammation is a root cause of many diseases, and DHA is a potent anti-inflammatory agent. A lack of omega-3s can worsen inflammatory joint conditions like rheumatoid arthritis. DHA deficiency is linked to conditions like lupus and psoriasis, and can lead to a weakened immune system.

Physical symptoms and presentation

In addition to more severe chronic illnesses, DHA deficiency can manifest through noticeable physical signs like dry, flaky skin, brittle hair and nails, fatigue, and memory issues.

DHA-rich diet versus a DHA-deficient diet


Feature	DHA-Rich Diet	DHA-Deficient Diet
Brain Function	Improved memory, focus, and cognitive performance.	Reduced concentration, memory impairment, and higher risk of mental disorders.
Heart Health	Lower triglycerides, regulated blood pressure, and healthier arteries.	Higher risk of heart disease, hypertension, and atherosclerosis.
Eye Health	Good visual acuity and protection against age-related macular degeneration.	Vision problems, dry eye syndrome, and increased AMD risk.
Inflammation	Reduced chronic inflammation and fewer symptoms of inflammatory conditions.	Exacerbated inflammatory responses and increased pain in joints.
Development	Supports optimal neural and visual development in infants and children.	Impaired visual and neural development in infants and potential behavioral issues.
Dietary Sources	Fatty fish (salmon, mackerel, herring), fish oil, algae.	Imbalanced intake, often high in pro-inflammatory omega-6 fats.

Prevention and supplementation strategies

Preventing DHA deficiency primarily involves dietary choices and, when necessary, supplementation. Direct intake of EPA and DHA is the most effective approach.

Dietary Interventions

Include fatty fish: Regular consumption of cold-water, fatty fish like salmon, sardines, and mackerel is highly effective.
Consider algae: For vegetarians and vegans, certain microalgae species are a direct source of DHA and EPA.
Balance omega-6 intake: Reducing high omega-6 sources while increasing omega-3 intake helps optimize their balance.

Supplementation

Fish oil, krill oil, or algal oil: These supplements provide concentrated sources of DHA.
Guidance from healthcare professionals: It is advisable to consult a healthcare provider to determine the appropriate dosage, especially for individuals with existing conditions or those taking blood-thinning medication.

Conclusion

DHA deficiency can have significant consequences across neurological, cardiovascular, and immune systems, impacting infant development, cognitive function, and increasing the risk of chronic diseases. Prioritizing DHA intake through diet and supplementation is a proactive strategy for maintaining long-term health and well-being.

For more detailed information on omega-3 fatty acids, consult the National Institutes of Health Fact Sheet.

Frequently Asked Questions

The most effective sources of DHA are cold-water, fatty fish like salmon, mackerel, herring, and sardines. Vegetarians and vegans can get DHA directly from certain types of microalgae.

While plant-based foods like flaxseeds and walnuts contain ALA, the body's conversion to DHA is very inefficient. The most reliable way for vegetarians and vegans to obtain sufficient DHA is through algal oil supplements.

There is no single diagnostic test, but a healthcare provider can assess an individual's omega-3 status by measuring the fatty acid composition of red blood cells. The 'omega-3 index' is a common indicator used to evaluate long-term intake over several months.

Recommended daily intake varies by age, health status, and country. For example, some guidelines recommend 200-300 mg of DHA daily for pregnant and breastfeeding women, while general adult recommendations often involve a combination of EPA and DHA.

Yes, supplementation is an effective way to boost DHA levels, especially for those with low dietary intake. Studies show that supplements can significantly increase DHA levels in the body, improving memory and other cognitive functions in healthy adults.

To improve this ratio, reduce your intake of foods high in omega-6 (e.g., certain processed foods and vegetable oils) while increasing your consumption of omega-3 rich foods like fatty fish. Aiming for a balanced ratio is more effective than just increasing omega-3.

Signs in children can include learning disabilities, difficulty with concentration, behavioral problems (such as hyperactivity and aggression), and impaired vision. These symptoms arise because of the critical role DHA plays in a child's developing brain.