How to increase your omega-3 index
- 2 days ago
- 6 min read
I eat well. Oily fish a few times a week, flax and chia in breakfast or smoothies, walnuts always somewhere in the cupboard. I love crushing walnuts over apple slices with almond butter and a pinch of sea salt. Try it if you haven't.
So when I tested my omega-3 index last August and it came back at 6.2%, against an optimal range of 8-11%, I was genuinely surprised. I wrote about that experience and why I decided to test in the first place in the Why I tested my omega-3 while in the UK (and what I learned from it) (we used to live in Spain at the time).
This post is about what happened next.
I made some targeted changes. Retested this March, so six months later. My result: 7.2%.
Better. Moving in the right direction. Still not where I want it to be. And the gap between what I eat and what's actually in my cells? That's what I keep coming back to. Because it challenges something most of us assume: that eating well is enough.
What is the omega-3 index and why does it matter?
The omega-3 index measures the percentage of two specific fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in your red blood cell membranes. It's not a snapshot of what you ate last week. It reflects your actual cellular status over the past three to four months.
The test I use is the HS-Omega-3 Index, a high-sensitivity version available as an at-home finger-prick test in the UK through Regenerus Labs.
The optimal range is 8-11%. Research links levels in that range to better cardiovascular health, improved mood and cognitive function, healthier skin, hormonal balance, better eye health, and improved recovery. Most people are nowhere near it, I am pretty certain.
Signs of low omega-3 levels: could this be you?
Low omega-3 status often doesn't announce itself with a dramatic single symptom. It tends to show up as a cluster of things that quietly wear you down.
Common signs of omega-3 deficiency include:
Persistent fatigue that doesn't resolve with rest
Low mood, irritability, or anxiety
Brain fog and difficulty concentrating
Dry skin, dull hair, or worsening skin conditions
Joint aches and low-grade inflammation
Poor sleep quality
PMS, hormonal symptoms, or perimenopause feeling harder than it should
Slow recovery after exercise
The trouble is, most of these symptoms get put down to stress, age, or just being busy. They rarely get traced back to something as measurable and addressable as omega-3 status.
Most people I know have never heard of the omega-3 index test. That's exactly why I keep talking about it.
Why your omega-3 levels might be lower than you'd expect
This is the part that surprises people most, and the part my own results have made real for me.
You can be eating all the right things and still come up short. Here's why.
Plant-based omega-3 sources don't convert efficiently
Flax, chia, and walnuts contain alpha-linolenic acid (ALA), a plant-based omega-3 that your body has to convert into EPA and DHA before it can be used. That conversion rate is often poor, sometimes as low as 5-10%. So even a diet rich in plant-based omega-3 foods doesn't guarantee adequate levels of the forms your cells actually use.
This was likely a significant factor in my own results. I was relying heavily on plant sources alongside fish, assuming the conversion would take care of itself. It doesn't, not reliably.
Your physical demands may be higher than average
More activity means a greater need for omega-3s. If you exercise regularly, your baseline requirement is simply higher than standard dietary recommendations assume. Those "eat two portions of oily fish per week" guidelines aren't calibrated for most active people.
Fat absorption might not be optimal
Omega-3s are fats, so they require bile and good digestive function to be properly absorbed. If digestion is sluggish, or bile flow isn't where it should be, you can eat well, supplement consistently, and still not be getting the full benefit. Supporting fat digestion is a piece of the puzzle that often gets missed entirely.
Without testing, you'd never know which of these applies to you. Often it's a combination.
What I changed between my two tests
Three things. Nothing dramatic.
More small oily fish, more often
I increased my intake of sardines, mackerel, salmon, and anchovies. The standard recommendation of twice a week won't shift things significantly for most people, particularly if your starting point is low or your needs are higher than average. Small oily fish like sardines and mackerel also tend to have higher EPA and DHA concentrations than farmed salmon.
A fish oil supplement to deliver EPA and DHA directly
I added a high-strength fish oil supplement. This bypasses the ALA conversion problem entirely, delivering EPA and DHA in a form the body can use directly.
Worth being honest here: I had stopped taking my supplement about two months before my March retest, which almost certainly held my result back. Red blood cell turnover takes around three to four months, so a two-month gap would have measurably lowered my numbers. My 7.2% is likely an underrepresentation of where I actually am. Moving forward I will continue using the supplement on days I don't eat oily fish.
Supporting fat digestion and bile flow
This is the piece most people overlook. If your body isn't efficiently digesting and absorbing fats, your dietary and supplemental omega-3s aren't landing where they need to.
Supporting bile flow and digestive function is something I work on with clients regularly, and it's part of my own protocol too.
What the research says about raising your omega-3 index
The evidence on this is consistent: the primary driver of omega-3 index levels is EPA and DHA intake, not ALA from plant sources. Studies show that supplementation with combined EPA and DHA meaningfully raises the omega-3 index in most people within three to six months, with the amount of increase depending on the starting level and the dose.
Research also shows that people who both eat oily fish regularly and supplement are the most likely to reach the optimal range of 8% or above. Diet alone, particularly if it leans on plant sources, is rarely sufficient.
The key message is that you cannot know your status without measuring it. No amount of dietary logic will tell you what's actually happening in your red blood cells.
Why retesting matters
I'll be retesting again in a few months, this time with consistent supplementation throughout on days I don't eat oily fish. That's the whole point of this kind of testing: you establish a baseline, you make targeted changes, you retest, and you learn something real.
The measure-modify-monitor approach is what separates personalised health from guesswork. And it's the approach I bring to working with clients, not just on omega-3 status but across every area of nutritional health.
7.2% is progress. The gap between 6.2% and 7.2% tells me that what I changed was working, even accounting for the supplement gap before retesting. Getting to 8% or above is achievable. It just requires consistency, the right combination of diet and direct EPA and DHA supplementation, and support for actual absorption.
How to increase your omega-3 levels: a practical summary
If you want to support your omega-3 status, here's where to focus:
Prioritise fatty fish: Sardines, mackerel, anchovies, herring, and salmon are the best dietary sources of EPA and DHA. Small oily fish tend to offer higher concentrations and lower mercury exposure than larger species.
Don't rely on plant sources alone: Flax, chia, hemp seeds, and walnuts contribute ALA, which is beneficial, but the conversion to EPA and DHA is too inefficient to rely on as your primary strategy.
Consider a high-quality EPA and DHA supplement: Whether fish oil or algae-based, look for a supplement that clearly lists the separate EPA and DHA content per serving, not just total omega-3 or total fish oil. The EPA and DHA content is what matters.
Support fat digestion: Omega-3s are best absorbed when eaten with meals containing fat, and good digestive function, including adequate bile production, makes a significant difference to how much you actually absorb.
Reduce omega-6 seed oils: Vegetable oils high in omega-6 (sunflower, soybean, corn) compete with omega-3 for absorption and incorporation into cell membranes. Reducing these supports a healthier fatty acid balance.
Test and retest: There's no substitute for knowing your actual number. Retesting every four to six months when you're actively trying to shift your levels gives you the data to know whether what you're doing is working.
Should you test your omega-3 index?
If any of those symptoms sound like your normal, or if you eat mostly plant-based omega-3 sources and assume that's sufficient, testing is worth considering. It's a single at-home finger-prick test, the results are meaningful and actionable, and the information it gives you is something no food diary or dietary recall can replicate.
Knowing your omega-3 index is exactly the kind of data-informed, personalised approach to health that I build my work around. Not following generic advice for the average person, but understanding what's actually happening in your body and addressing it specifically.
If you'd like help making sense of your results, or working out what changes would actually move the needle for you, I'd love to support you.
