Most people don’t get enough Omega-3s 🧠 here’s why it matters
Week 7 of '8 Weeks to a Thriving Gut' series
We’re almost there!
It’s Week 7 of the 8 Weeks to a Thriving Gut series – just one more to go.
This week, we’re diving into omega-3s.
Omega-3s are fats you probably know for heart and brain health (making up an important part of your brain’s fat content).
But here’s what you’ll find surprising - your gut microbes use them too.
The problem? Low omega-3 levels are linked to a lower life expectancy of five years - similar to smoking.
So far, we've covered:
The gut microbiome basics (Week 1).
Fibre, the superstar nutrient (Week 2).
Prebiotics, the best fuel for your microbes (Week 3).
Probiotics – what they are and if you need them (Week 4).
Fermented foods and how they help (Week 5).
Polyphenols and their role in gut and brain health (Week 6).
Here’s what we’ll cover today:
What are omega-3s? The different types and where to find them.
How do omega-3s support your gut? The science behind their impact on the tiny living organisms living in your gut - your gut microbes.
Your action for the week: Easy ways to eat more omega-3s.
👉 Paid subscribers grab your Sustainable Fish Shopping Guide PDF (scroll down).
What are omega-3s?
Omega-3s are essential fats that your body mostly can’t make on its own - you need to get them from food.
The three key types are:
ALA (Alpha-linolenic acid): A plant-based omega-3 found in flaxseeds, chia seeds, and walnuts.
EPA (Eicosapentaenoic acid): Found in oily fish and algae.
DHA (Docosahexaenoic acid): Also found in oily fish and algae.
Your body can convert ALA into the other omega-3s, but not very well - at best, less than 10% of ALA gets converted to EPA, and less than 5% to DHA.
It’s DHA that is especially crucial for brain health as the most abundant omega-3 in the brain.
We’re not getting enough omega-3s
The Omega-3 Index measures the percentage of EPA and DHA in red blood cells, giving a longer-term view of your omega-3 levels over the past 3–4 months - the lifespan of red blood cells.
It’s a more reliable measure than plasma levels (the liquid part of your blood), which change daily based on what you eat.
A low Omega-3 Index (below 4.2%) is linked to living nearly 5 years less, similar to the estimated lifespan reduction from smoking.
A 2023 UK Biobank study found the UK’s average Omega-3 Index is 5.6%, while an earlier 2016 global study estimated it even lower, under 4%.
In the US, levels are similarly low at around 5.8% - far from the ideal 8%.
Omega-3s support gut health
Like polyphenols, omega-3s are considered to be potential prebiotics, based on early evidence.
A quick recap on what is a prebiotic:
It’s a specific substance.
It works by feeding specific gut microbes.
It has a positive effect on your health.
Omega-3 may influence your gut microbiome in a different way than prebiotic fibre, making slightly different healthy molecules linked to metabolism and heart health.
What about heavy metals in fish?
Fish is a great source of healthy protein, full of nutrients like omega-3s, vitamin D, and selenium that support your heart, lower excess inflammation, and keep you feeling good.
However, some larger fish - like swordfish, shark, and tuna - can have high levels of mercury.
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