The Omega-3 Index is more than just a blood test. It is both:
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A biomarker of heart disease risk, much like cholesterol.
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A test you can take yourself to measure your omega-3 status.
Unlike cholesterol, which most doctors routinely test, the Omega-3 Index is rarely checked during annual visits—even though research shows that the majority of people do not consume enough omega-3s through diet alone.
What Is a Risk Factor?
According to the National Institutes of Health (NIH), risk factors are habits or conditions that increase the likelihood of developing disease or worsening existing health problems. The good news is that risk factors can often be modified or improved through lifestyle and nutrition.
The National Heart, Lung & Blood Institute lists well-known risk factors for heart disease, including:
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High blood pressure
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High cholesterol
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Diabetes and prediabetes
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Smoking
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Being overweight or obese
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Physical inactivity
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Family history of early heart disease
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History of preeclampsia in pregnancy
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Poor diet
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Age (55+ for women)
Noticeably absent from this list is the Omega-3 Index—a strong and emerging risk factor for heart disease.
Why the Omega-3 Index Matters
The Omega-3 Index was first proposed as a heart disease risk factor in the American Journal of Clinical Nutrition by Dr. Bill Harris, co-inventor of the test.
He argued that the Omega-3 Index meets all the scientific requirements of a true risk factor:
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Consistent evidence across populations
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Plausible biological mechanisms
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Reliable and reproducible measurements
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Independence from traditional risk factors
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Modifiability through diet and supplementation
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Demonstrated risk reduction when levels increase
In fact, raising your Omega-3 Index could be just as important—if not more—than lowering cholesterol when it comes to protecting your heart.
Understanding Omega-3 Index Risk Zones
Your Omega-3 Index result is expressed as a percentage of EPA and DHA in your red blood cell membranes:
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High Risk: Below 4%
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Intermediate Risk: 4–8%
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Low Risk (Optimal): Above 8%
For example, if your red blood cell membrane contains 64 fatty acids and only 3 of them are EPA or DHA, your Omega-3 Index would be 4.6%—placing you in the high-risk category.
Unfortunately, most Americans fall in this danger zone:
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Many people test at 4% or below, which is linked to a 90% higher risk of sudden cardiac death.
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Even those who supplement often hover around 6%, still below the optimal range of 8–12%.
EPA and DHA: The Only Omega-3s That Count
Not all omega-3s will raise your Omega-3 Index. Only EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—found in fish, seafood, and high-quality fish oil supplements—make a measurable difference.
ALA (alpha-linolenic acid) from plant sources like flax, chia, and walnuts does not significantly increase EPA and DHA in the blood and therefore does not raise your Omega-3 Index.
Low Omega-3 Levels and Health Risks
A low Omega-3 Index has been associated with multiple health concerns beyond heart disease, including:
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Alzheimer’s and cognitive decline
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Age-related eye disease
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Joint discomfort
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Increased systemic inflammation
By regularly monitoring your Omega-3 Index and taking steps to raise it, you can significantly reduce your risk of these conditions and improve long-term wellness.
Final Thoughts
The Omega-3 Index is both a test and a powerful risk factor. While cholesterol and blood pressure are routinely measured, omega-3 levels are often overlooked. Yet the evidence is clear: keeping your Omega-3 Index in the 8–12% range is one of the most effective steps you can take for protecting your heart and overall health.
To achieve and maintain optimal levels, prioritize foods rich in EPA and DHA—like salmon, sardines, and mackerel—or add a high-quality omega-3 supplement to your daily routine.