Guide to DHA (Omega-3)

WRITTEN BY

The Levels Team

Updated: 05/22/2025|12 min read

Summary

Docosahexaenoic acid (DHA) is one of the body's three primary omega-3 fatty acids. It is used for cell membranes that support the brain, eyes, and nervous system. DHA also helps control inflammation and supports immune function. 

Why It Matters

DHA makes up about 40 percent of the fat in your brain and is concentrated in your retinas, making it essential for both cognitive function and vision. It helps neurons communicate effectively and supports memory. During pregnancy and early childhood, DHA also helps with brain and eye development.

Beyond its structural role, DHA helps control inflammation throughout your body in part by balancing the pro-inflammatory effects of omega-6 fatty acids. It's also instrumental in heart health, helping maintain normal heart rhythm and blood vessel function.

Your body can produce very limited amounts of DHA from alpha-linoleic acid (ALA), the plant-based omega-3 found in flaxseeds, chia seeds, and walnuts. Because this is an inefficient conversion process, most DHA must be obtained through diet or supplements. Unlike some nutrients that show problems quickly when low, DHA deficiency can develop slowly over time, affecting brain health and inflammation levels before obvious symptoms appear. So it's useful to keep an eye on it. Your DHA level also helps determine if you're getting enough omega-3s to balance your omega-6 intake.

Associated Symptoms

DHA levels themselves are laboratory findings rather than medical conditions. However, abnormal levels may be associated with various health conditions, each with its own symptoms.

Common symptoms that may indicate conditions associated with low DHA:

• Cognitive changes: Difficulty concentrating, mild memory issues, or brain fog, may be related to DHA's role in maintaining brain cell membrane fluidity and supporting neurotransmitter function
• Mood disturbances: Depression, anxiety, or irritability, can be associated with altered neurotransmitter signaling and brain cell communication
• Vision problems: Dry eyes, blurred vision, or light sensitivity, may be linked to DHA's structural role in retinal cells and visual processing
• Inflammatory conditions: Joint discomfort or digestive inflammation, may reflect DHA's role in regulating inflammatory pathways
• Cardiovascular symptoms: Irregular heartbeat, poor circulation, or reduced exercise tolerance, may be related to DHA's support of heart rhythm and vascular function
• Dry skin and hair: Flaky skin, brittle hair, or scalp issues, potentially connected to DHA's role in maintaining cell membrane integrity in skin tissues

Common symptoms that may indicate conditions associated with high DHA (rare, usually from excessive supplementation):

• Easy bruising or bleeding: Increased bleeding time or unexpected bruising, may be related to DHA's mild blood-thinning properties
• Digestive issues: Loose stools or nausea may reflect direct effects of high DHA supplement intake
• Medication interactions: Enhanced effects when taking blood thinners, potentially indicating compound effects on blood coagulation

It's important to understand that the relationship between DHA and these symptoms is complex. Low DHA may contribute to these conditions, while some conditions may also affect DHA metabolism or absorption. Many symptoms associated with DHA imbalance can result from numerous other factors, so they should be evaluated in the context of your overall health profile and other test results. Laboratory testing provides objective data about your DHA status that should be interpreted alongside clinical symptoms.

Clinical Ranges

Lab Reference Range: 1.4-5.1 % by wt

Lifestyle Factors That Can Impact It

Activities that can increase DHA levels include:

• Regular fatty fish consumption provides direct sources of DHA.
• Regular exercise improves DHA incorporation into cells.

Activities that may decrease DHA levels include:

• A high omega-6 diet competes with DHA absorption and use.
• Excessive alcohol use impairs DHA absorption.

Other Factors That Can Impact It

Medical Conditions

• Liver disease: may lower levels by reducing your body's ability to process fats
• Diabetes: may decrease levels by altering fat metabolism
• Digestive disorders: lower levels by reducing fat absorption
• Hypothyroidism: may decrease levels by slowing fat metabolism
• Kidney disease: can lower levels through altered fat processing
• Autoimmue conditions: may affect levels

Medications

• Blood thinners: don't change levels but increase DHA's blood-thinning effects
• Statins: may reduce levels by affecting fat metabolism
• Oral contraceptives: can increase levels by affecting fat processing
• NSAIDs: may affect how your body processes DHA

Testing Accuracy and Stability

Since DHA is a fatty acid that can be affected by recent diet and supplement use, proper timing and preparation are important for an accurate assessment.

Factors That Can Affect Your Test Results

• Recent meals with fatty fish can increase levels

How it Relates to Other Markers

Understanding DHA's relationship with other fatty acids and health markers helps provide context for your results. DHA interacts with many other substances in ways that affect your overall health. Key related markers include:

• Eicosapentaenoic acid (EPA): This fellow fatty acid works together with DHA. Higher EPA can mean better DHA function.
• Arachidonic acid: DHA helps balance this inflammatory omega-6 fatty acid. Higher levels could suggest an imbalance in the omega 3-omega 6 ratio, or excess animal protein intake.
• Omega-3 index: This test shows your total omega-3 status, including DHA.
• Inflammatory markers: Inflammation may be lower when DHA levels are adequate.
• Triglycerides: DHA helps lower triglycerides.
• Blood pressure: DHA helps maintain healthy levels.

Follow-up Considerations

If your DHA is low, your provider may recommend supplements and retesting your levels. The testing frequency and need for additional evaluation depend on your current levels and risk factors. You should always speak to your doctor if you have medical questions or before making medical decisions.

When Re-Testing May be Appropriate

• Normal levels: Every 6--12 months
• Low levels: Every 3 months until normalized
• During supplementation: Every 3--4 months

Additional Testing Your Doctor May Consider

• Cardiovascular risk markers
• Brain health markers
• Oxidative stress markers
• Autoimmune markers

When Additional Care May be Warranted

• Persistently low levels despite supplementation
• Neurological symptoms
• Cardiovascular concerns
• Pregnancy planning
• Chronic inflammation
• Poor response to supplementation

Further Reading

Why omega 3s are crucial to strong metabolic health

Bibliography