You've probably heard that fish is good for the heart. Maybe you've even tried to swap in salmon once in a while, or picked up a bottle of fish oil.
For most Americans, that effort doesn't go as far as it looks.
For the first time, the CDC measured omega-3 fatty acids in the blood of a nationally representative sample of Americans.
The result, published in the agency's 2026 nutrition biomarker report in June, is striking.
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More than half the US population aged 6 and up has an undesirable omega-3 level, and almost 98 percent fall below the level researchers consider protective for the heart.
The underlying analysis was published in May in Current Developments in Nutrition.
It looked at red blood cell samples from more than 7,200 people aged 6 and older, collected between August 2021 and August 2023.
What the omega-3 index actually measures
The omega-3 index is the share of EPA and DHA, the two long-chain omega-3 fats found mainly in oily fish, in red cell membranes. The US average came in at 4.12 percent.
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A level below 4 percent is considered undesirable. An index of 8 percent or above is the target linked to lower cardiovascular risk.
Only about 2 percent of Americans sit in that protective range.
Why low omega-3 can hurt the heart
EPA and DHA have been studied for decades. At higher intakes, they lower triglycerides, a type of fat in the blood tied to heart disease.
They may also ease the chronic, low-grade inflammation that drives hardening of the arteries.
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According to the Harvard T.H. Chan School of Public Health, omega-3 fats help the heart hold a steady rhythm, lower blood pressure and heart rate, and improve how blood vessels work.
The CDC study authors note that both diet and the amount of omega-3 in red blood cells are inversely linked to the risk of cardiac arrest.
In plain terms, people with higher levels tend to be less likely to die suddenly from a heart rhythm problem.
Where to actually get more EPA and DHA
The most direct route is oily fish. Salmon, mackerel, sardines, herring, and albacore tuna all deliver EPA and DHA.
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Eating fish about twice a week is the long-standing public health benchmark.
Plant foods such as walnuts, flaxseed, and chia are often marketed as omega-3 sources.
They carry a different form, alpha-linolenic acid or ALA, which the body converts into EPA and DHA only in small amounts.
That gap in how the body uses plant omega-3s is one reason a morning scoop of chia may look impressive on the label and still leave the actual blood level low.
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In the CDC data, people who regularly took omega-3 supplements had higher blood levels than those who didn't.
Smokers and people with obesity tended to have lower levels, regardless of what they ate.
This article is made and published by Mie Hermansen, who may have used AI in the preparation.