Updated 27th June 2023

5 interesting studies: Dementia, inflammation, and more

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Welcome to the latest ZOE Nutrition Science Roundup. In this series, we outline recent scientific studies that we think you’ll find interesting.

We'll explain what the researchers did, what they found, and what it means for your diet and health.

This week’s edition covers dementia, inflammation, sweet treats, and much more.

Dementia and the Mediterranean diet

Worldwide, dementia affects around 55 million people. The most common form is Alzheimer’s disease, accounting for about 60–70% of dementia cases.

As it stands, there’s no cure. So, as some scientists investigate new treatments, others are looking for ways to lower risk. And some of these researchers are looking at our diets.

A recent study asks whether following the Mediterranean diet might reduce your risk of developing dementia

What did they do?

As the study's authors point out, scientists have investigated this question before, but results have conflicted. This, they suggest, might be partly because previous studies were relatively small.

So this time, the scientists used a much larger pool of data — from 60,298 people in the UK Biobank. And they used data gathered for an average of 9.1 years.

The team collected information about the participants' diets. Then, they used two scoring systems to assess how closely the people had followed the Mediterranean diet.

What did they find?

The scientists found that participants who followed the Mediterranean diet most closely had a lower risk of developing dementia during the study period, compared with those who followed it least closely.

Importantly, this effect was independent of genetic risk. 

In other words, following the Mediterranean diet was associated with a lower risk of developing dementia during the study, even in people with an increased genetic risk of dementia.

What should you do?

The Mediterranean diet is rich in vegetables, seeds, pulses, and healthy fats. Overall, it’s a healthy (and delicious) dietary pattern. 

So, if you decide to follow it more closely, it’s likely to have health benefits, compared with a standard Western diet. This is true even if the Mediterranean diet doesn’t reduce your dementia risk. 

There’s evidence that it might support your health in other ways. For instance, some research led by ZOE’s Scientific Co-Founder Prof. Tim Spector concluded that the Mediterranean diet improves outcomes for people undergoing cancer treatment

It might also reduce your risk of developing diabetes

However, we should note that the Mediterranean diet might not be the best option for everyone. We’re all different, and we all respond differently to foods.

If you’d like to learn about your responses and receive personalized recommendations, you can start by taking our free quiz

Does exercise lower biological age?

Scientists have known for a long time that exercise is good for your health. It reduces the risk of cardiovascular disease and certain cancers. And it can even reduce your mortality risk.

But little is known about how exercise might influence your biological age.

Your chronological age is how many years you’ve been alive, but determining your biological age is much more complex.

Your biological age takes into account a range of factors, including your chronological age, lifestyle, nutrition, and genetic factors. 

For example, if your chronological age is 25, but you smoke a pack a day, regularly drink alcohol to excess, and never exercise, your biological age might be 35. 

On the other hand, if your chronological age is 55, but you have a healthy diet and exercise regularly, your biological age might be 45.

A recent study set out to understand whether intense exercise could make a measurable difference to your biological age.

What did they do?

The participants' chronological ages were 40–65, and they were all relatively inactive. The researchers used a genetic method to measure their biological ages. 

Then, they assigned some participants to a placebo group that did no exercise, and the rest did three high-intensity interval training sessions a week for 4 weeks. This type of exercise is sometimes called HIIT.

At the moment, there’s no single best way to measure biological age. In this study, the scientists used a model that calculates the so-called transcriptomic age. 

This, they explain, provides “comprehensive molecular surveys of biological processes that collectively contribute to healthspan and lifespan.”

What did they find?

At the end of the 4 weeks, the scientists found that the participants who’d been exercising had lower transcriptomic ages than at the start of the study. 

In fact, their biological ages had dropped by an average of 3.59 years. Meanwhile, those in the no-exercise group had increased their biological ages by 3.28 years.

What should you do?

Researchers are still working out the nuances of biological age. So, it’s difficult to know what reducing your biological clock by a little over 3 years might mean in the long run. 

We also don’t know, for example, whether you'd put those years back on if you stopped exercising.

It was surprising that the control group had gained more than 3 years of biological age in 4 weeks, considering that the scientists had asked them not to change anything during the experiment.

The bottom line: Exercise is good for you. So, find something physical that you enjoy doing, and get out there to do it.

It doesn’t have to be a marathon or a sprint, just make sure you move your body regularly.

A sweet and fatty study

In the Western world, many of us have access to a near-infinite array of sugary, fatty foods. 

They're very easy to overeat, and scientists are keen to understand what’s going on in our brains when we consume these products regularly.

According to the authors of a recent study, experts already know that there’s a link between obesity and altered dopamine in the brain.

Dopamine is a neurotransmitter that’s important in your brain’s reward pathways.

But many questions remain. For instance, do people have altered dopamine pathways before they develop obesity, or do pathways change as a result of obesity?

Alternately, perhaps exposure to a Western diet directly changes our dopamine pathways.

A group of researchers recently conducted an experiment to help get us closer to an answer.

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What did they do?

The scientists recruited 49 people with a “healthy weight” to participate in an 8-week study.

They gave the participants either a high-fat, high-sugar or a low-fat, low-sugar snack twice a day for 8 weeks, to have alongside their regular diets. 

What did they find?

The team found that people who’d eaten the high-fat, high-sugar snacks had a reduced preference for lower-fat foods than at the start of the study.

This group also showed increased brain responses to a high-fat, high-sugar milkshake.

Meanwhile, the participants with the low-fat, low-sugar snacks didn’t show this increased response.

According to the authors, the results imply that regularly consuming high-fat, high-sugar foods might make these foods more attractive — and healthier options less attractive.

What should you do?

Although the results are intriguing, this was a short study with few participants. Scientists need to do more work to replicate the findings.

With ZOE, no food is off the table. Food in all its wonderful forms can be part of a healthy diet. 

However, it's best to enjoy some foods just once in a while, including high-fat, high-sugar options. 

Building muscle: Vegan vs. omnivore 

For years, there’s been a great deal of debate about whether nonanimal protein can build as much muscle as animal protein after resistance training.

A recent study takes a fresh look at this divisive topic.

What did they do?

In the study's first phase, the researchers recruited 16 healthy young adults and had them follow a tailored 3-day, high-protein diet. 

Half of the participants only consumed vegan protein sources, and the other half ate omnivorous protein sources. Each day, they did resistance leg exercises.

For the second phase, the scientists recruited 22 healthy young adults. Ten followed the vegan diet and 12 the omnivorous diet.

For 10 weeks, they all participated in a resistance exercise program 5 days a week.

What did they find?

The scientists found that both diets had a similar effect on muscles. Both increased protein synthesis and muscle volume by a comparable amount.

What should you do?

Unless you’re specifically looking to build muscle, these results might not be particularly meaningful to you. However, it’s great news if you’re vegan and trying to build muscle.

We should also note that because this study was conducted in young, healthy adults, the findings might not apply to older people, for example.

If you’re interested in learning more, we have a fascinating podcast on protein and how much you need.

ZOE also has an in-depth article on foods to eat after intense exercise and a different podcast on protein and exercise.

Fruits, veggies, and inflammation

Experts agree that eating a wide variety of fruits and vegetables benefits health and reduces the risk of developing many conditions. 

But scientists are still digging into precisely how fruits and veggies boost health.

A recent study looks at how plants in your diet influence a range of factors, including inflammation and oxidative damage.

What’s oxidative damage? As your cells go about their day, they produce reactive molecules called free radicals. Your body has mechanisms to make sure that these dangerous compounds don’t build up and cause damage.

But sometimes, these mechanisms can’t keep up, and free radicals build up. This causes oxidative damage.

What did they do?

In the recent study, scientists in the United Arab Emirates recruited 965 participants. In all, 30% were overweight, and 62% had obesity.

The scientists asked about their fruit and veggie intake and measured levels of inflammation, oxidative damage, metabolic risk, and other factors.

After an average of 427 days, the scientists once again took note of the participants' fruit and veggie consumption, and they repeated the tests.

What did they find?

The team found that people who ate the most fruits and veggies had lower levels of markers that indicate inflammation and oxidative damage than people who ate the least.

Those who ate the most fruits and veggies also had higher levels of antioxidant enzymes, which are part of the body’s natural defense against free radicals. 

What should you do?

Eat more plants! At ZOE, we know that a diverse, plant-rich diet is best for your health. Prof. Spector recommends eating 30 different plants a week.

Still, the study above does have limitations. For instance, it relies on people reporting what they’ve eaten, which can sometimes be inaccurate.

But overall, many health benefits are associated with eating more plants. So, whether it reduces inflammation and oxidative damage or not, upping your intake is a solid idea.

The takeaway

As nutrition science races headlong into the future, we slowly build a clearer picture of what we should eat to keep in tip-top shape.

So, what have we learned from this round of studies? Here are today’s five takeaways:

  1. Following the Mediterranean diet might reduce your dementia risk. And if it doesn’t, it’s still a healthy eating plan for most people.

  2. Exercising might reduce your biological age. And if it doesn’t, it’s still linked to a wide range of health benefits. So, get active when you can.

  3. Regularly eating high-sugar, high-fat foods might make you enjoy healthy food less. And if it doesn’t, it’s still best to eat high-sugar, high-fat foods just once in a while.

  4. Vegan sources of protein seem to help you build muscle just as well as animal sources.

  5. Eating more fruits and veggies might reduce inflammation and oxidative damage. And if it doesn’t, upping your plant intake is still a healthy thing to do.

Sources

Cardiorespiratory fitness and mortality from all causes, cardiovascular disease and cancer: Dose–response meta-analysis of cohort studies. Sports Medicine. (2022). https://bjsm.bmj.com/content/56/13/733 

Dementia. (n.d.). https://www.who.int/news-room/fact-sheets/detail/dementia 

Habitual daily intake of a sweet and fatty snack modulates reward processing in humans. Cell Metabolism. (2023). https://www.sciencedirect.com/science/article/pii/S1550413123000517 

Increased fruit and vegetable consumption mitigates oxidative damage and associated inflammatory response in obese subjects independent of body weight change. Nutrients. (2023). https://www.mdpi.com/2072-6643/15/7/1638 

Mediterranean diet adherence is associated with lower dementia risk, independent of genetic predisposition: Findings from the UK Biobank prospective cohort study. BMC Medicine. (2023). https://link.springer.com/article/10.1186/s12916-023-02772-3 

UK Biobank. (n.d.). https://www.ukbiobank.ac.uk/ 

Vegan and omnivorous high protein diets support comparable daily myofibrillar protein synthesis rates and skeletal muscle hypertrophy in young adults. The Journal of Nutrition. (2023). https://www.sciencedirect.com/science/article/pii/S0022316623126800

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