If you eat fish a couple of times a week because you’ve been told it’s good for your heart, this one might challenge that a little.
Omega-3 is one of the most important nutrients for cardio-metabolic health. It plays a role in your cholesterol, blood pressure, blood sugar, and the low-grade inflammation that quietly drives so much cardiovascular risk. But a growing body of research is raising an uncomfortable question: are we actually getting enough of it, even when we follow the guidelines? This review of the evidence covers the mechanisms in detail)
As a registered nutritionist focused on preventing cardio-metabolic disease (and recovery), I pay close attention to this kind of research because it shapes the advice I give. So let’s look at what omega-3 really does, why the active forms matter most, and whether food alone is enough.
What omega-3 actually is, and why EPA and DHA matter most
Omega-3 isn’t a single nutrient. It’s a family of essential fats – meaning we have to eat them, as the body can’t make them – and three feature prominently in health and nutrition:
- ALA (alpha-linolenic acid) – found in plant foods like flaxseed, chia, walnuts and rapeseed oil.
- EPA and DHA – the “active” forms, found mainly in oily fish and algae. EPA is closely involved in regulating inflammation, and DHA supports brain and eye health.
However, your body can only really use ALA once it’s converted into EPA and DHA, and that conversion is remarkably inefficient. Estimates vary, but only about 4-8% of ALA converts to EPA and DHA.
In practical terms, that means relying on plant sources alone rarely delivers enough of the active omega-3s your heart and metabolism actually need. When we talk about omega-3 for cardio-metabolic health, we’re really talking about EPA and DHA – not ALA.
Why omega-3 matters for your heart, blood sugar and blood pressure
EPA and DHA influence several of the systems that sit right at the centre of cardio-metabolic health:
- Triglycerides and cholesterol. Omega-3 has a well-established triglyceride-lowering effect, particularly at higher doses, and triglycerides are an often-overlooked driver of cardiovascular risk.
- Blood pressure. Regular EPA and DHA intake has a modest but genuine blood-pressure-lowering effect.
- Inflammation. This is arguably where omega-3 does its most important work. EPA and DHA are the raw materials your body uses to switch off inflammation, and low-grade, chronic inflammation is one of the shared drivers behind high blood pressure, insulin resistance, and arterial stiffening.
- Blood sugar. The evidence here is still developing, but as part of that wider anti-inflammatory picture, omega-3 appears to support insulin sensitivity and healthier metabolic function.
- Clotting and stroke risk. Omega-3 also influences how easily the blood clots, which brings us to the research that prompted this blog. (keep reading…)
If you want to see how these pieces fit together, our blog on cardiovascular risk beyond cholesterol walks through the full cardio-metabolic picture, and what a “normal” HbA1c can still miss covers the blood sugar side in more depth.
Not sure where omega-3 fits into your own health picture? You can book a free call, and we’ll help you work out what’s actually worth prioritising for you.
Where to find omega-3 in food
The richest sources of the active forms, EPA and DHA, are oily fish such as salmon, mackerel, sardines, herring, anchovies and trout.
Plant foods provide ALA rather than the active forms; think flaxseed and flaxseed oil, chia seeds, walnuts and rapeseed oil.
And if you don’t eat fish, algae oil is the only plant source that provides EPA and DHA directly, making it a genuinely useful option for vegetarians and vegans. However, doses are lower than in fish oils, and although these are adequate for children, it’s arguably not enough for adults.
The problem with “just eat more oily fish”
Here’s where it gets interesting: standard advice is to eat two portions of fish a week, one of them oily, but two recent studies suggest that may not be enough.
First, the research. A 2025 clinical trial compared fish oil supplements against eating oily and white fish at UK-recommended levels, over 12 weeks, in 42 healthy adults. It measured two blood markers – the number of extracellular vesicles and thrombin generation (this is the clotting marker mentioned above), both linked to stroke and cardiovascular risk.
The result: 1g a day of EPA from a supplement meaningfully reduced both markers. Eating fish at the recommended level didn’t move either, simply because the recommended portions didn’t deliver enough EPA. The authors concluded that achieving this kind of cardiovascular benefit may require going beyond current fish guidelines.
Second, the reality. According to the latest National Diet and Nutrition Survey, over 86% of adults and 94% of children in the UK aren’t even meeting the current fish recommendations in the first place. So we have guidelines that most people don’t meet, and emerging evidence that meeting them may still not be enough.
In clinic, when I ask our clients how often they actually eat oily fish, “not really” is a far more common answer than “twice a week or more.” That’s not a criticism as it’s understandable that many people just don’t enjoy the strong taste. It reflects what the national data shows, and it’s a big part of why I don’t think advice pitched purely at fish intake is working for most people.
There’s a further hurdle to overcome. Current NHS advice caps oily fish at two portions a week for girls and women who may have children (and four for boys and men), because of pollutants that can build up in fish. Add in growing concerns about microplastics in marine life, water quality and fish farming practices, and a genuine question emerges that I’m currently scratching my head about: how realistically can most people get enough EPA and DHA from fish alone?
So should you be supplementing?
This is where my own thinking has shifted. I’m not suggesting anyone stop eating oily fish – it’s a genuinely nourishing food (microplastics aside…). But given how hard it is to get enough EPA and DHA from fish alone, I think a good-quality omega-3 supplement deserves far more consideration than it usually gets, especially for anyone who doesn’t eat fish regularly.
The key phrase, though, is good-quality, because not all supplements are equal. A few things worth checking before you buy:
- Look at the EPA and DHA numbers, not the “fish oil” number. A capsule can say “1000mg fish oil” and contain very little actual EPA and DHA. The active compounds your body needs are what matter.
- Check which brands test for purity (heavy metals and other contaminants) and for freshness, as omega-3 oils can oxidise.
- Look for brands that work with Friend of the Sea or similar to consider fishing sustainability.
- Consider the form. Triglyceride-form omega-3 is generally better absorbed than the cheaper ethyl ester form.
- If you’re plant-based, choose an algae oil that provides EPA and DHA directly.
We’ve pulled together the omega-3 supplements we currently rate, and what to look for, in our omega-3 recommendations guide.
A quick but important note if you take blood thinners
Because omega-3 has a mild effect on how easily your blood clots, it’s worth a word of caution. If you take blood-thinning or antiplatelet medication, such as warfarin, apixaban, edoxaban, or regular aspirin, speak to your GP or pharmacist before adding an omega-3 supplement.
For most anticoagulants (excluding warfarin, which interacts with most things), doses of up to around 1.5g a day of omega-3 are generally considered safe, but this is exactly the kind of decision you should make with your prescriber rather than on your own. Consideration for the reason you’re on anticoagulants, what other medication is at play, your health history and blood tests and potential staging of omega-3 to assess tolerance is what we specialise in and support clients with in our Personalised 1-1 Nutrition support.
How we use this with clients at Integral Wellness
At Integral Wellness, omega-3 is one piece of a much bigger cardio-metabolic picture. We look at the markers that standard testing often misses – the real drivers behind your cholesterol, blood pressure, blood sugar and inflammation – and build a personalised plan around what your body actually needs, rather than generic advice.
If you’re not sure whether you’re getting enough omega-3, or what is happening with your cholesterol, blood sugars, or inflammation, a wellness check gives you a baseline, whereas our more bespoke 3- and 6-month programmes offer longer-term, 360 support. Working with us is about giving you answers and clarity so you know what you’re really working with.
If you’d like to understand your own cardio-metabolic health more clearly, you can book a free 20-minute call to talk it through, or download our free guide, Cholesterol Explained: the markers that really matter, for a deeper look at the numbers that shape your long-term risk.
Being truly healthy – for prevention or remission – is about giving your body what it actually needs, not about following generic public health guidelines which, as we’ve just discussed, don’t really suffice.
