Issue #8 - Omega-3 and heart health — Fad? Fact?

Welcome to Weekly.health’s eighth 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:

• 🔬 Longevity Spotlight: Oral health and exercise for better ageing

• 📚 Books We’re Reading Right Now

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

• 🛍️ Things You Might Like

• 🍣 Omega-3 and heart health — Fad? Fact?

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

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

🔬 Longevity Spotlight: Oral health and exercise for better ageing

How healthy is your mouth? If you’re brushing your teeth just once a day, not flossing, and not using mouthwash, you may be increasing your risk of poorer ageing.

Exercise, too, shows evidence of supporting healthy ageing, so if you’re moving from desk to sofa with little in between, it might be time to pick up a healthy habit, such as jogging, running, or cycling.

Keep your mouth healthy to age better: Long-term studies show that maintaining good oral health, like keeping your teeth, avoiding gum disease, and wearing dentures comfortably, significantly supports healthy ageing. Better oral health was linked to slower cognitive decline, fewer disabilities, and even lower mortality. If you want to age well, brushing and flossing can be just as vital as your diet or exercise. (source)

Exercise really does slow ageing: 
This review confirms that regular physical activity, especially endurance and high-intensity interval training (HIIT), can slow key ageing processes. Exercise improves mitochondrial health, reduces inflammation, enhances immune function, and even preserves muscle and brain mass. The earlier and more consistently you move, the better your defences against ageing. HIIT appears most effective in creating new mitochondria, and moderate to vigorous intensity is most effective overall for mitochondrial and cardiovascular health.

The evidence suggests at least 150 minutes of moderate-intensity, or 75 minutes of vigorous-intensity exercise, each week, is necessary to experience these benefits. If the exercise doesn’t make you sweat or make it somewhat difficult to have a conversation, you may not be exercising hard enough. (source)

📚 Books We’re Reading Right Now

📈 Research Digest: What’s New in Nutrition Science

Here’s the best of recent nutrition research:

🦠 A-Z Vitamins Boost Gut Health
Just 10 days of taking a standard multivitamin and multimineral (MVMM) supplement (at recommended UK levels) increased beneficial gut metabolites like butyrate and propionate, both linked to better gut and metabolic health, by over 30% in healthy adults. It also reduced bacteria tied to cardiovascular and bowel disease. Even without drastic diet changes, a daily MVMM could quietly upgrade your gut health. The supplement used was ‘A-Z Multivitamin’ from BOOTS, and although one author disclosed some ties to Nestlé, there was no clear conflict of interest with the BOOTs brand. (source)

🧬 Your Gut Microbiome Remembers Weight Loss
In this study, adults with obesity followed a 12-month diet and lifestyle program, losing 11% of their body weight on average. Notably, gut microbiota shifted significantly, particularly Bacteroides and Prevotella species, and some of these changes persisted six months after the program ended. Those with greater early microbial shifts were more likely to maintain weight loss, suggesting your gut bugs may play a role in long-term weight management. To make use of this, stick to your diet plan and ensure adequate fibre and variety of fruits and vegetables early on to reset your gut microbes quickly. (source)

🍈 Ginger Reduces Inflammation and Boosts Antioxidants
In a randomised trial, daily supplementation with 200 mg of ginger extract for 8 weeks significantly reduced inflammation markers (like CRP) and increased antioxidant enzyme levels in overweight women. These changes suggest ginger could help lower chronic inflammation and oxidative stress linked to ageing and disease. The amount of ginger extract used is equivalent to 3-10 grams of fresh ginger daily, or around 1-2 teaspoons of grated ginger. Try adding ginger to meals, smoothies, or add it to hot water for a spicy infusion. (source)

🛍️ Things You Might Like

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.

🍣 Omega-3 and heart health — Fad? Fact?

Omega-3 fatty acids are often touted for their benefits for the heart, but what does the evidence say, and are vegan sources better than fish?

In this issue, we cover some of the best evidence for heart health, but due to the significant amount of research on this topic, we’ll cover other effects in a later issue.

The two key omega-3 fatty acids are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), primarily found in marine sources like fatty fish and algae.

A third omega-3, ALA (alpha-linolenic acid), found in flaxseed, chia, walnuts, and other plant foods, is converted by the body to EPA and DHA before it can be used. Less than 10% of ALA is converted to EPA and DHA, meaning that, generally, marine sources are far more effective at raising omega-3 levels in the body.

Evidence is mixed in all directions, with pro-fish studies showing significant benefits from fish-based omega-3s, and pro-vegan studies showing significant benefits from algal-sources omega-3 (and often citing no or fewer benefits from fish-based omega-3).

Even pro-fish studies often show differing results, though much of this, as we cover below, appears to be studies using dosages that are simply too low.

The industry is rife with conflicts of interest. The supplement industry, the fishing industries, and plant-based industries all have significant interest in promoting supplements that support their business.

Evidence

A 2018 Cochrane review updated in 2020, with over 112,000 participants, found no statistically significant benefit of EPA/DHA supplementation on all-cause mortality (risk of death from all causes). Some studies it reviewed did suggest omega-3 reduced coronary heart disease (CHD) events, but the highest quality trials did not find this outcome. It found that increasing ALA intake similarly had no effect on many outcomes, but did appear to slightly reduce risk of cardiovascular events and may reduce risk of CHD mortality. (source)

A meta-analysis which included more recent trials than the Cochrane review, with 127,000 participants, found small but statistically significant cardiovascular benefits. Marine omega-3 supplementation was associated with an 8% reduction in heart attack risk and CHD mortality, and a 5% reduction in overall cardiovascular disease (CVD) events. (source)

Dosage

The above meta-analysis found that dosage matters - low-dose fish oil may not influence outcomes much, but higher dosages - 1g/day of EPA+DHA, with stronger effects at 4g/day EPA - saw much more substantial benefits.

The VITAL trial in 2018 showed that 1g/day of omega-3 (460mg EPA and 380mg DHA), equivalent to 1-2 servings of fatty fish per week, benefitted those with a low baseline intake of omega-3. It showed that those already consuming a reasonable amount of omega-3 through diet didn’t experience benefits. People with a low fish intake (<1.5 servings/week) experienced a 19% lower risk of major cardiovascular events. (source)

A larger systematic review and meta analysis in 2021 looked at 149,000 participants, finding that many trials with null results used lower dosages below 2g/day total omega-3, suggesting that these dosages may be insufficient. The strongest results were found at 2-4g/day EPA, suggesting that DHA may actually nullify some of the benefits of combined EPA and DHA supplements. (source)

Specific cardiovascular effects

Beyond heart attacks, strokes, and other broad outcomes, omega-3s do have clear effects on certain cardiovascular risk factors;

• Blood lipids (Triglycerides and Cholesterol): EPA and DHA reliably lower triglyceride levels, being one of the most consistent findings in nutrition science. Trials show that high doses of 2-4/day can reduce triglycerides by 20-50%, and are used clinically to treat hypertriglyceridemia. While both EPA and DHA had this same effect, DHA appears to raise LDL cholesterol, so EPA-only supplements are advised to those with concerns about LDL levels.

• Blood pressure and heart rhythm: Omega-3 intake has a mild effect on lowering blood pressure. Trials show both EPA and DHA reduce systolic blood pressure, and more than 2g/day reduces diastolic. Findings suggest that, in this case, DHA may significantly outperform EPA. (source)

To summarise the evidence as we see it at this point in time

While we would enjoy reviewing all of the evidence in this newsletter, there is simply too much to include in one issue. Here are some key takeaways from the research we’ve seen;

• Omega-3 fatty acids do appear to be associated with some cardiovascular benefits, but the effects may not be as significant as supplement manufacturers want you to believe

• Omega-3 supplementation appears primarily of benefit to those with low consumption of fatty fish

  • This could mean that vegetarians, vegans, and those who don’t consume fish, may experience the most benefits

• Dosages matter, with 1g of combined EPA and DHA daily appearing to be the lower end of clinically-relevant dosages, with 2g/day preferred, and 4g/day of just EPA has the strongest effects

  • Taking one capsule of an omega-3 supplement each day is likely insufficient - we often find 2-5 capsules are needed for clinically-relevant doses, depending on the supplement

• EPA alone is often preferred, with DHA appearing to nullify some benefits

  • DHA (as covered below) appears most beneficial for blood pressure, but may raise LDL cholesterol levels

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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.

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📖 Glossary of Terms in This Issue (Alphabetical Order)

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