Issue 21: Should You Take Omega-3?

In partnership with

Welcome to Weekly.health’s 21st issue. Every week, we explore cutting-edge research, actionable advice, and science-backed nutrition insights to help you live longer and healthier.

Our aim is to help you live another 10 healthy years and cut your risk of age-related disease.

🗒️ In This Issue:

• 🔧 Coming Next Week: Something New for Weekly.health Readers

• 📚 Books We’re Reading Right Now

• 📈 Research Digest: What’s new in nutrition science

• 💊 Supplement Deep Dive: Omega-3

• 🛍️ What We Suggest

• ❤️ Support Weekly.health: Help us keep the research flowing

• 📘 Glossary of Terms: Definitions for technical terms in this issue

🔧 Coming Next Week: Something New for Weekly.health Readers

Over the past month I’ve been building something new behind the scenes - a separate platform where you’ll be able to use practical nutrition tools and short, evidence-based courses designed to help you improve your health.

The tools will help you:
– Estimate your daily calorie needs
– Set personalised macro and protein targets
– Generate meal ideas with an AI meal planner

I’m opening the very first version next week exclusively to Weekly.health readers.

It’ll be completely free to use the tools.

Our Foundations of Nutrition course will launch shortly after.

📨 Want early access next week?

I’m opening the very first version of the platform to a small group of Weekly.health readers before the full public launch.

If you’d like early access to the tools (and the chance to help shape how they work), join the early-access list using the poll below.

📘 Foundations of Nutrition - quick update

I’m also finishing the first version of our Foundations of Nutrition course.

It’ll be short, practical, grounded in real science, and designed for busy people like you.

In just 10 minutes a day, you’ll learn both what to do to improve your nutrition and why it works - based on real evidence, not influencer trends.

This course will live on the new platform, and you’ll hear more about it once early access opens next week.

Weekly.health readers will also receive a launch-only discount for the Foundations of Nutrition course.

📚 Books We’re Reading Right Now

📈 Research Digest: What’s New in Nutrition Science

Here’s the best of recent nutrition research:

🧠 High-fat diets impair brain health
A recent review in the International Journal of Molecular Medicine links chronic high-fat, saturated-fat–rich diets to memory loss, inflammation, and oxidative stress. Such diets disrupt gut bacteria and insulin signalling, accelerating cognitive decline. Shifting towards Mediterranean or DASH-style diets, regular exercise, and gut health support may help protect against dementia and Alzheimer’s. To reduce risk, replacce saturated fats from red meat, dairy, and processed foods, with unsaturated fats such as olive oil, nuts, and oily fish. (source)

🍄 Mushroom fibres that balance your immune system
A 2025 Food Chemistry review shows that β-glucans - natural fibres from mushrooms like shiitake, reishi, and turkey tail - help the immune system stay balanced. These compounds interact with immune cells to improve how the body responds to threats while preventing over-inflammation. Regularly eating β-glucan-rich mushrooms or supplements may support immune resilience and overall health in a gentle, natural way. (source)

🍫 Cocoa compounds may protect ageing hearts
A recent trial found that healthy adults aged 55+ who took 1,000 mg of cocoa flavanols daily (containing 160 mg of epicatechin) for 30 days showed a 13 % reduction in left-atrial volume - a sign of better heart relaxation - and a 6 mmHg drop in blood pressure. These natural compounds, also found in dark chocolate and cocoa, may help slow age-related heart stiffness and support cardiovascular health.

To match the 1,000 mg/day used in the study, it’s very difficult to get there from typical food sources alone. Even 100 g of standard cocoa or many ‘raw cacao’ powders may provide well under 1,000 mg of flavanols, and eating that much daily would be impractical and unpalatable. In practice, high-flavanol cocoa extracts or supplements are the most realistic way to reach this dose. (source)

🟢 Sponsor: The Daily Upside

Smart Investors Don’t Guess. They Read The Daily Upside.

Markets are moving faster than ever — but so is the noise. Between clickbait headlines, empty hot takes, and AI-fueled hype cycles, it’s harder than ever to separate what matters from what doesn’t.

That’s where The Daily Upside comes in. Written by former bankers and veteran journalists, it brings sharp, actionable insights on markets, business, and the economy — the stories that actually move money and shape decisions.

That’s why over 1 million readers, including CFOs, portfolio managers, and executives from Wall Street to Main Street, rely on The Daily Upside to cut through the noise.

No fluff. No filler. Just clarity that helps you stay ahead.

Subscribe free today.

💊 Supplement Deep Dive: Omega-3 (EPA & DHA)

Should you be taking taking Omega-3 fatty acid supplements?

1-minute verdict

Try (targeted): Worth it for people with low fish intake or raised triglycerides, using evidence-based doses. Benefits are small for general prevention, clearer for triglyceride lowering, and strongest with high-dose EPA in specific high-risk groups.

• Outcomes that matter;

  • Triglycerides ↓ ~20–30% at 4 g/day prescription-strength omega-3 (often EPA-only).

  • Small reductions in major cardiovascular (CV) events overall; signals larger with higher total dose and EPA-only regimens.

  • Modest blood pressure reductions at ~2–3 g/day.

  • Greatest CV benefit in people with low baseline fish intake.

• Time to benefit: 4–12 weeks for blood lipids and blood pressure; CV event reduction evidence comes from multi-year trials.

• Who might skip or adjust: History of atrial fibrillation (discuss high doses with your clinician); those on anticoagulants/antiplatelets; pre-op patients; fish/seafood allergies. Pregnancy: prefer food sources or algal DHA; avoid fish liver oils.

• Upper limit: EFSA: supplemental EPA+DHA up to 5 g/day appears safe for adults. FDA labelling advises not exceeding about 3 g/day EPA+DHA in total, with no more than 2 g/day coming from supplements.

Does it actually do anything?

Evidence for broad cardiovascular prevention is mixed. The latest Cochrane review (2020) concludes increasing EPA/DHA has little or no effect on all-cause mortality or overall CV events, with at most very small reductions in CHD events. (source)

However, larger meta-analyses that include newer trials show small but significant relative risk reductions in MI and CHD mortality, with dose and formulation mattering (EPA-only often outperforming EPA+DHA). (source)

For people with low baseline fish intake, the VITAL trial found benefits from 1 g/day (460 mg EPA + 380 mg DHA), particularly fewer heart attacks; those already eating fish didn’t benefit. (source)

For secondary prevention in high-risk, statin-treated patients with elevated triglycerides, purified EPA at 4 g/day (icosapent ethyl) produced a ~25% reduction in major CV events (REDUCE-IT). Mixed EPA+DHA at 4 g/day (STRENGTH) did not reduce events. (source)

Beyond events, omega-3s reliably lower triglycerides in a dose-dependent manner (clinically used at 4 g/day), though DHA-containing products can raise LDL-C slightly. (source)

Blood pressure effects are modest, with optimal reductions seen around 2–3 g/day combined EPA+DHA. (source)

Plant ALA (flax, chia) converts poorly to EPA/DHA in humans (<15%), so marine or algal sources are far more effective at raising EPA/DHA status. (source)
Good news for vegans: algal oils raise EPA/DHA effectively and show comparable bioavailability to fish oils when dose-matched. (source)

Dose & form

• Effective dose range:

  • General maintenance: 250–1,000 mg/day EPA+DHA.

  • Triglyceride lowering: 4,000 mg/day prescription-strength (ideally EPA-only).

  • Blood pressure: 2,000–3,000 mg/day combined EPA+DHA.

• Form: Look for EPA/DHA content per serving (not just total fish oil). For CV event reduction, evidence is strongest for EPA-only 4 g/day (icosapent ethyl - prescription). For supplements, high-concentration triglyceride or re-esterified triglyceride forms improve pill burden. DHA-heavy products may nudge LDL-C up.

• With food? Take with meals containing fat; split large doses (e.g., 2 g twice daily).

• Testing: Consider an Omega-3 Index check and fasting lipids after 8–12 weeks; monitor LDL-C if using DHA-containing products.

Our picks - what to buy

Stack sensibly (optional)

• Mediterranean-style diet + oily fish 1–2×/week if you prefer food-first to replace supplements on fish days. On non-fish days, take the appropriate dosage of omega-3 liquid or capsules.

Mechanism minute (for the curious)

EPA/DHA are incorporated into cell membranes, shifting eicosanoid production towards less pro-inflammatory mediators and reducing hepatic VLDL synthesis, which lowers triglycerides. They also produce specialised pro-resolving mediators (resolvins/protectins) that modulate vascular inflammation.

Reader lab (tell us what you do)

Safety & cautions

• Generally well tolerated (fishy aftertaste, mild GI upset). Atrial fibrillation has been observed more often with some high-dose omega-3 regimens; UK regulators advise patients prescribed omega-3 ethyl esters to seek help for palpitations, dizziness or breathlessness.

• Bleeding risk: EFSA considers up to 5 g/day (0.18 oz/day) EPA+DHA not to raise bleeding concerns in healthy adults, but caution remains sensible with anticoagulants/antiplatelets or before surgery.

• Pregnancy & breastfeeding: Prioritise food sources; many authorities support +200 mg/day DHA in addition to usual intake. Choose algal DHA if avoiding fish and avoid fish liver oils (vitamin A).

• Allergy: Avoid fish-derived products if you have fish allergy; algal DHA/EPA are suitable alternatives.

🛍️ What we suggest

Discover the products, services, and retailers we’ve mentioned in past Weekly Health issues, all in one place so you can explore at your own pace.

📥 Finding this newsletter useful so far?

Your friends could benefit, too!

It would really help us if you could share Weekly.health with your friends either in person or through social media. You could even just forward this email to them.

Every subscriber helps us towards our goal of improving lives and helping people live longer.

📥 Feedback or suggestions?
We really appreciate any feedback you can give. Your feedback can help shape Weekly.health to change lives.

Reply directly to this email - we'd love to hear from you and we’ll be sure to reply!

🙏 Thanks for Reading!

That’s the end of this issue of Weekly.health.

This newsletter is written by a small, independent team, led by James — who’s been following nutrition science for nearly 20 years and is now working towards a formal, industry-recognised qualification.

We’re based in England, so if you’re over the pond, you might notice a few strange spellings.

Our goal is to make cutting-edge, evidence-based nutrition advice simple, useful, and genuinely applicable to everyday life.

We don’t want to bombard you with adverts, but a few of the links in this email may reward us when you click and make a purchase. This goes towards helping us to continue bringing you this newsletter.

We’ll keep improving with every issue. If you’ve got any feedback or suggestions, we’d love to hear them (just reply to this email).

See you next week!

📖 Glossary of Terms in This Issue (Alphabetical Order)

Want to start your own newsletter like this? Join Beehiiv.