5 interesting studies: Cocoa, avocados, and more

Nutrition science moves at breakneck speed. To ensure that we, at ZOE, stay ahead of the curve, we pay a lot of attention to the latest research.

To help you keep up to date, too, we’ll share some of these interesting studies here. In today’s nutrition news roundup, we’ll cover omega-3s, antibiotics, avocados, and more.

So, without further ado, here are five recent nutrition studies and what the results might mean for your health. 

1. Omega-3s, mother, and baby

Scientists refer to omega-3s as “essential” fatty acids. This is because your body needs them to function, but it can’t make them. So, you have to take them in through your diet.

Over the years, some studies have shown that omega-3 consumption during pregnancy can protect the mother’s health and support the unborn baby's growth.

However, according to the authors of a new paper, the results of this research have been “inconsistent and conflicting.” 

So, to develop a clearer picture, they conducted a meta-analysis. This involves taking data from previous studies to reach conclusions about a certain body of research.

In particular, the scientists dug out 59 studies comparing females taking omega-3 supplements throughout pregnancy with those taking either no supplements or a placebo. 

What did they find?

After crunching the numbers, the team found that omega-3 supplements reduced the risk of:

  • high blood pressure during pregnancy and after labor (preeclampsia) by 24%

  • preterm birth (earlier than 37 weeks) by 14%

  • early preterm birth (earlier than 34 weeks) by 23%

Omega-3 supplements were also associated with slightly longer pregnancy and increased birth weight.

What should you do?

As we mentioned, omega-3s are essential, so you need to consume them to stay healthy.

In general, ZOE recommends getting them through your diet when possible. This way, you get the other benefits associated with whole foods. And there are many delicious, natural sources of omega-3s.

However, experts recommend that some of us take omega-3 supplements, such as people who are pregnant or have a vegan diet. So, chat with a doctor to find out what’s best for you.

If you’d like to learn more about these essential fatty acids and omega-3 supplements, ZOE has a podcast on the topic.

2. Antibiotics and thinking skills

One hundred years ago, even minor infections could be fatal. Today, they’re often easy to treat with antibiotics. There’s no doubt that these drugs have saved millions of lives. 

However, they’re not without their downsides.

At ZOE, we know that a thriving, diverse gut microbiome is associated with better overall health. And because antibiotics excel at killing bacteria, they can also disrupt your gut bugs.

Scientists have found links between long-term antibiotic use and serious diseases, including cardiovascular disease. But what about brain health?

Although some studies have found links between gut bacteria and intelligence, there’s been very little research into the effect of antibiotics on cognitive skills. 

A recent study has started to fill that gap.

What did they find?

The scientists used data from more than 14,500 female participants, who had an average age of 54.7 years. They followed the participants for 7 years.

The team found that those who took antibiotics for at least 2 months in midlife had lower cognitive scores 7 years later

After the researchers adjusted their analysis for factors that might influence the results, like education level and other health conditions, the end results were similar. 

The difference was significant but fairly small — roughly equivalent to 3–4 years of aging. But why?

The authors suggest that the gut-brain axis might be key. This axis is a two-way dialogue between your gut and brain, and experts believe that gut bacteria are important players in the conversation.

So, if gut bacteria are disrupted, it could impact brain health. But exactly how this might happen is an open question.

The authors acknowledge that scientists need to do more research — it’s possible that other factors, such as ongoing infections and other medications, might have affected the participants' thinking ability. 

What should you do?

If your doctor has prescribed you antibiotics, keep taking them as advised. They can be lifesavers.

Once you've finished the treatment, you can take steps to replenish your gut microbiome. For instance, there’s some evidence that probiotic foods or supplements might help.

Overall, having a gut-healthy diet that feeds you and your microbes is a good idea whether you’ve taken antibiotics or not. 

If you’d like to learn more, ZOE has a handy guide to supporting your gut microbiome.

3. Cocoa and heart disease

Both the public and the scientific community have long been interested in chocolate and its potential health benefits. In fact, we covered a chocolate study in last week’s nutrition news roundup.

But unlike most of the past research, today's study focuses on cocoa flavonol supplements rather than chocolate itself. 

Flavonols are a type of polyphenol, a group of plant compounds linked to health benefits.

In particular, the researchers wanted to know whether cocoa flavonol supplements could protect against cardiovascular events, like stroke or heart attack, in older adults.

What did they find?

The scientists conducted a carefully controlled study involving more than 21,400 participants. 

On average, the participants were 72 years old and had no cardiovascular diseases or recent cancer diagnoses. 

Each took either cocoa flavonol supplements or a placebo, and the scientists followed them for an average of 3.6 years.

Taking the flavonol supplements didn’t reduce the number of cardiovascular events significantly. 

But the supplements were linked to a 27% lower risk of dying from a cardiovascular event during the follow-up period.

What should you do?

Although some research suggests that chocolate has health benefits, we must be cautious. 

First, a lot of chocolate on the market is ultra-processed. This means it contains a lot of additives and not very much cocoa.

Less processed dark chocolate contains at least 70% cocoa, which doesn't leave room for loads of additives. So, this type, in moderation, can be a healthy addition to your diet

But even less processed chocolate likely contains much lower levels of flavonols than a pure supplement. The one in the study contained 500 milligrams of cocoa flavonols. 

In comparison, 20 grams of 60% cocoa chocolate contains around 34 mg, 20 g of milk chocolate contains 14 mg, and 20 g of white chocolate contains none.

It's important to note that this study was funded by the chocolate manufacturer Mars. This doesn’t mean we should dismiss the results — lots of nutrition research is funded by industry — but it’s worth keeping in mind.

4. Avocado and heart health

Avocados are a delicious, healthy addition to your diet. They’re rich in good fats, fiber, vitamins, and minerals.

But can avocado consumption protect long-term cardiovascular health? A recent study took a look.

According to the study's authors, some earlier research had investigated a relationship between eating avocados and markers of cardiovascular risk — for instance, levels of “bad” cholesterol in your blood.

However, few have explored the effects over a longer time. So, that’s what this study set out to do.

What did they find?

The researchers accessed data from almost 69,000 women and nearly 42,000 men spanning around 30 years of follow-up. At the start of the study, no participant had cardiovascular disease or cancer. 

After accounting for lifestyle and dietary factors, the scientists found that those who ate more avocados had a lower risk of cardiovascular disease.

Compared with those who didn’t eat avocados, the participants who ate two or more a week had a 16% lower risk of developing cardiovascular disease. 

They also had a 21% lower risk of developing coronary heart disease, which is when the arteries that supply blood to your heart get narrower due to a fatty buildup on their walls.

The scientists also did some calculations to assess the health effects of substituting avocados for other foods.

They found that “Replacing half a serving/day of margarine, butter, egg, yogurt, cheese, or processed meats with the equivalent amount of avocado was associated with a 16–22% lower risk of [cardiovascular disease]."

What should you do?

If you like avocados, crack on. If you don’t, not to worry. At ZOE, we know that your overall dietary pattern is what makes a difference to your long-term health.

Avocados are a welcome addition to your diet, but having a varied plant-based diet will likely reduce your cardiovascular disease risk with or without avocados. 

Prof. Tim Spector, ZOE’s scientific co-founder, recommends eating 30 different plants a week. One of these could be avocado, if you fancy it.

5. Polyphenols and blood sugar

We mentioned polyphenols when we covered the cocoa study above. They’re plant compounds that are associated with a range of health benefits.

A recent study examined whether they might help control blood sugar in older adults with type 2 diabetes or prediabetes.

Although earlier research had suggested that polyphenols might help improve blood sugar control, there was little direct evidence.

What did they find?

The researchers analyzed data from almost 6,000 people with an average age of 65 years. At the start of the study, all had overweight or obesity and metabolic syndrome. 

At the beginning and end of the 1-year study, the participants filled out food questionnaires. From this, the researchers calculated their polyphenol intake.

The scientists concluded that the participants who had upped their polyphenol intake had lower levels of sugar in their blood than at the study's start.

This seems like good news, but the study has some sizable limitations.

As the researchers explain, it’s very difficult to determine the amount of polyphenols in someone’s diet. For instance, their database didn’t account for all of the foods containing polyphenols. 

Also, the polyphenol content in fruits and veggies can vary based on a range of factors, including how the food is stored and processed and how ripe it is. 

What should you do?

Experts believe that polyphenols benefit your health. If you want to increase your polyphenol intake, here’s a handy list of high-polyphenol foods.

But scientists haven’t worked out all the details yet. The precise role of these plant compounds in human health and disease remains a little mysterious.

With that said, studies have shown that having a healthy plant-based diet is associated with a reduced risk of developing type 2 diabetes, and it can even help treat the condition.

And if you eat a range of plants, you’re likely to consume more polyphenols.

The takeaways

If you want some actionable strategies from today’s nutrition science roundup, here you go:

  1. If you’re pregnant or thinking about getting pregnant, speak with your doctor about omega-3 supplements. If this isn’t you, it’s still a good idea to make sure you get enough. They’re essential, after all.

  2. If you’ve recently taken antibiotics, consider adding more gut-healthy foods to your diet. If this isn’t you, it’s still a good idea to look after your gut bugs so they can look after your health.

  3. Add cocoa to your diet by eating minimally processed dark chocolate in moderation. It might protect your heart health.

  4. If you like avocados, keep eating them. They’re nutrient-rich, and they might reduce your long-term cardiovascular risk.

  5. Eat more plants. They’re rich in polyphenols and a whole host of other beneficial compounds. Plus, having a diverse plant-based diet could reduce your type 2 diabetes risk.


Adopting a high-polyphenolic diet is associated with an improved glucose profile: Prospective analysis within the PREDIMED-Plus trial. Antioxidants. (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8868059/ 

Association of midlife antibiotic use with subsequent cognitive function in women. PLOS One. (2022). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0264649 

Avocado consumption and risk of cardiovascular disease in US adults. Journal of the American Heart Association. (2022). https://www.ahajournals.org/doi/full/10.1161/JAHA.121.024014 

Dark chocolate. (n.d.). https://www.heartuk.org.uk/low-cholesterol-foods/dark-chocolate 

Dietary polyphenols, Mediterranean diet, prediabetes, and type 2 diabetes: A narrative review of the evidence. Oxidative Medicine and Cellular Longevity. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5572601/ 

Duration and life-stage of antibiotic use and risk of cardiovascular events in women. European Heart Journal. (2019). https://pubmed.ncbi.nlm.nih.gov/31216010/ 

Effect of cocoa flavanol supplementation for the prevention of cardiovascular disease events: The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial. The American Journal of Clinical Nutrition. (2022). https://academic.oup.com/ajcn/article/115/6/1490/6548186 

Impact of n-3 polyunsaturated fatty acid intake in pregnancy on maternal health and birth outcomes: Systematic review and meta-analysis from randomized controlled trials. Archive of Gynecology and Obstetrics. (2023). https://pubmed.ncbi.nlm.nih.gov/35348829/  

Perspective: Plant-based eating pattern for type 2 diabetes prevention and treatment: Efficacy, mechanisms, and practical considerations. Advances in Nutrition. (2021). https://academic.oup.com/advances/article/12/6/2045/6296092