Omega-3 Index: The Blood Test That Reveals Your Heart and Brain Health

Quick answer

The omega-3 index measures EPA and DHA as a share of the fat in your red blood cells. It reflects your intake over the past 2 to 4 months. The healthy target is above 8%. Most adults score below 4 to 5%. A higher score links to fewer heart problems, slower brain aging, and lower inflammation.

What the omega-3 index measures

EPA and DHA are two essential fats. Your body needs them, but cannot make them on its own. They become part of your cell walls throughout your body, including your red blood cells.

The omega-3 index measures EPA plus DHA as a share of all the fat in your red blood cells. Red blood cells live about 120 days. This means the index reflects your average intake over the past 2 to 4 months, not just what you ate yesterday.

What the numbers mean

Large studies set these cutoffs by tracking heart deaths across many people over time. Here is why above 8% is the optimal omega-3 index, and what it takes to get there.

Why it matters

A higher omega-3 index links to:

• Fewer heart events, such as heart attacks.
• Lower overall risk of death, in some long term studies.
• Slower brain aging in older adults.
• Less severe depression, in some groups studied.
• Lower inflammation, your body's stress response.
• Healthier triglycerides, a type of blood fat.
• Fewer repeat heart attacks, after a first one.

EPA and DHA calm inflammation. They also support how your blood clots, how your blood vessels work, and how flexible your cell walls stay.

Why most people fall short

The omega-3 index depends heavily on diet. Most adults here score below the healthy target for a few reasons.

1. Not enough fatty fish

EPA and DHA come mainly from cold-water fatty fish, such as salmon, sardines, mackerel, and anchovies. Most people eat far less than 2 servings a week.

2. Plant sources do not convert well

Flaxseed, chia, and walnuts contain a plant form called ALA. Your body converts only a small share of ALA into EPA and DHA. Plant sources alone rarely raise the index by much.

3. Too much omega-6 fat

Modern diets are heavy in omega-6 fats, found in soybean oil, corn oil, and many processed foods. High omega-6 intake crowds out omega-3 in your cells.

4. Weak supplements

Many fish oil products contain less EPA and DHA than the label suggests. The total "fish oil" amount is not the same as the actual EPA plus DHA amount.

How to raise your omega-3 index

1. Eat more fatty fish

Aim for 2 to 3 servings a week:

• Salmon.
• Sardines, canned in oil or water.
• Mackerel.
• Herring.
• Anchovies.

Sardines are cheap and widely available, and a smart everyday choice.

2. Take an EPA and DHA supplement

Most adults do well with 1,000 to 2,000 mg of combined EPA and DHA a day.

When reading labels, check the actual EPA plus DHA content, not just the total fish oil weight. A higher concentration product needs fewer capsules for the same dose. The triglyceride form absorbs better than the ethyl-ester form.

3. Try an algae-based supplement

For anyone who avoids fish, algae-based EPA and DHA works just as well. A dose of 500 to 1,000 mg a day is effective.

4. Cut back on omega-6 fats

Use less soybean, corn, and sunflower oil. Cook with olive oil or avocado oil instead.

5. Check quality

Pick a product that has been tested by an outside lab, for purity. Keep it in the fridge once opened. Skip any product with a strong fishy smell, a sign it has gone off.

How long it takes to see a change

The omega-3 index responds slowly, over 2 to 4 months.

• A small rise shows up by 6 weeks.
• A bigger rise shows up by 12 weeks.
• Your new level settles in by 16 to 20 weeks.

Retest at 16 weeks or later to check your progress.

Beyond the basic score

Specialty labs also offer:

• Omega-3 to omega-6 ratio. A more balanced ratio tends to support better health.
• AA to EPA ratio. A lower number links to less inflammation.
• Trans fat share. This should stay near zero.

For most people, the omega-3 index alone gives the most useful single number.

Who should get tested

• Anyone with heart disease, or a strong family history of it.
• Anyone starting a fish oil supplement, to track results.
• Anyone with high triglycerides.
• Vegetarians and vegans.
• Older adults concerned about brain health.
• Anyone planning a pregnancy, since DHA matters for the baby's brain growth.

If any of these sound like you, a full panel can include the omega-3 index alongside your other heart markers.

How &you Labs handles omega-3 testing

The omega-3 index is available as an add-on to your &you Labs panel. Your report shows your score, your risk band, and clear guidance for your supplement dose. See the full list of markers on our biomarker page.

Frequently asked questions

Is fish oil safe to take?

Yes, at normal doses of 1,000 to 2,000 mg of EPA and DHA a day. Very high doses can raise bleeding risk slightly. Talk to your doctor if you take blood thinners. Choose a quality product to avoid contaminants.

Will flaxseed raise my omega-3 index?

Only a little. Your body converts plant omega-3 poorly into EPA and DHA. Fatty fish or an algae-based supplement works far better.

How much fish do I need to eat?

2 to 3 servings a week of fatty fish gets most adults close to, or above, the healthy target. A supplement can fill any gap.

Is this test covered by insurance?

Usually not. It is a specialty test, and most people pay for it out of pocket.

Will a higher score help my mood?

The evidence is mixed. Some studies show a modest benefit for low mood, especially with more EPA. Think of it as a support, not a cure.

Key takeaways

• The omega-3 index measures EPA and DHA in your red blood cells, reflecting 2 to 4 months of average intake.
• The healthy target is above 8%. Most adults score below 4 to 5%.
• A higher score links to fewer heart events, slower brain aging, and lower inflammation.
• Raise your score with 2 to 3 servings of fatty fish a week, or a quality EPA and DHA supplement.
• Retest at 16 weeks or later, to confirm your score has moved.