5 interesting studies: Inflammation, coffee, and more

Welcome to the fifth ZOE Nutrition Research Roundup. This series showcases nutrition science studies that we think are interesting and insightful.

Today, we cover fascinating research on coffee, tea, and irritable bowel syndrome (IBS). We also look at intriguing links between diet and osteoporosis, among other studies.

First, let’s investigate the relationships between diet and depression.

1. Depression and inflammation

Globally, depression affects a staggering 1 in 20 people. Despite this high prevalence, experts still don’t fully understand why people develop the condition.

However, scientists agree that inflammation plays an important part, at least for some people.

And because certain dietary patterns can increase inflammation, some scientists are asking if these factors might be connected.

Recently, a group of researchers dug into the links between diet, inflammation, and depression.

They also investigated whether insulin resistance might be involved in the relationship.

What did they do?

The scientists had access to data from 10,951 participants. This included information about their diet, sex, age, and other characteristics. 

The team assessed the participants' diets using two related measures:

  1. the dietary inflammatory index (DII): a measure of how pro-inflammatory a diet is

  2. energy-adjusted DII (E-DII): the same measure but also taking into account calorie intake

What did they find?

After the analysis, the scientists concluded that individuals who ate more foods associated with inflammation were more likely to experience depression.

In other words, “The higher the DII or E-DII score, the higher the risk of depression.”

However, the team found no evidence of a link between insulin resistance and depression risk.

What should you do?

At ZOE, we know that a wide range of plant foods is the cornerstone of a healthy diet. And plant-based foods are generally anti-inflammatory

So, ZOE recommends eating pro-inflammatory foods, like processed meats and refined grains, only once in a while.

Overall, upping your plant intake is likely to benefit your health, and it might reduce your risk of experiencing depression.

If you’d like to learn more, we have an interesting podcast on food and mood. We also have more information about diet and inflammation.

2. Omega-3s and PCOS

Polycystic ovary syndrome (PCOS) is a collection of symptoms caused by a hormone imbalance.

It arises in people with at least two of these conditions: no ovulation, high levels of androgens, and abnormal ovary growth.

Symptoms can include changes to your metabolism and menstrual cycle, increased hair growth, and infertility.

PCOS also increases the risk of developing type 2 diabetes, obesity, and cardiovascular disease.

Drugs can help treat PCOS, but because of the side effects, some scientists are investigating the potential benefits of supplements. 

A recent meta-analysis asked whether omega-3 supplements might help improve metabolic measures in people with PCOS.

What did they do?

The researchers reviewed and analyzed 11 previous studies, including data from 816 participants total. The studies took place in Australia, Iran, and Venezuela, and they lasted 8–24 weeks.

What did they find?

The authors concluded that omega-3 supplements improved some metabolic measures in people with PCOS, including blood fat levels and markers of better blood sugar control.

What should you do?

Omega-3s are called “essential” fatty acids because your body needs them to work.

Rather than supplements, ZOE recommends getting your omega-3 from food sources. That way, you get the nutritional benefits of the food, too.

However, some people, like vegans and pregnant people, might benefit from supplements.

If you'd like more information, we have articles on natural sources of omega-3s, omega-3 supplements, and why omega-3s are important.

We’ve also got a deep dive into what omega-3s do in your body.

3. ‘Good’ fat and liver fat

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver disease globally and the leading cause of liver-related mortality. It’s caused by a buildup of fat in your liver.

NAFLD is also linked to an increased risk of metabolic conditions like type 2 diabetes.

To treat it, doctors recommend losing weight, either by reducing your energy intake, getting more exercise, or both. 

But because these weight loss interventions often fail, experts are looking for other lifestyle changes that could help. 

A recent study investigated whether the NutriAct dietary pattern might help treat NAFLD. This diet focuses on increasing your intake of “good,” unsaturated fats, as well as plant protein and fiber.

What did they do?

The scientists recruited 502 people aged 50–80 with “risk factors for unhealthy aging.” 

These risk factors included high blood pressure, cardiovascular disease, cognitive impairment, and decreased physical function. About a third of the participants had NAFLD at the start of the study.

The researchers split the participants into two groups. One followed the NutriAct diet, and the other followed standard healthy eating guidelines. 

Individuals in both groups received nutrition support from professional dietitians. 

What did they find?

The main finding was that a diet high in unsaturated fatty acids, plant protein, and fiber was associated with significantly less fat in the participants’ livers, compared with a standard diet.

Those following the NutriAct diet also saw a larger drop in “bad” cholesterol and total cholesterol in their blood.

Both groups had improved insulin resistance and blood fat levels.

What should you do?

Over the years, fat has been demonized. But not all fat is equal. “Good” fats, like unsaturated fats, can benefit your health. It’s easy to forget that fat is an essential nutrient.

At ZOE, we know that some fat-containing foods, like nuts and avocados, are great for health.

If you’d like to learn more, we have a podcast that dispels some myths about fats and oils and an article explaining the importance of fat.

4. Coffee, tea, and IBS

IBS symptoms can vary from person to person, but they often include constipation, diarrhea, bloating, and stomach cramps.

Globally, IBS affects around 11% of people, but experts still don’t fully understand why it occurs in some of us and not others.

Recently, a group of scientists investigated associations between drinking coffee and tea and the risk of developing IBS.

What did they do?

The researchers followed 425,387 participants for an average of 12.4 years. Using an online questionnaire, they collated information about these individuals’ tea and coffee consumption.

At the start of the study, no participant had IBS, inflammatory bowel disease, celiac disease, or cancer.

What did they find?

Both coffee and tea consumption were linked to a lower risk of developing IBS during the study period.

More specifically, people who drank at least half a cup of coffee every day had a reduced risk of IBS.

Interestingly, the scientists noted a dose-response relationship: The more coffee people drank, the lower their risk, particularly for instant and ground coffee.

As for tea, drinking half a cup or a cup every day was linked to a reduced risk of developing IBS. But drinking more or less than this wasn’t related to IBS risk.

What should you do?

The study found associations between IBS and coffee and tea consumption.

But because of the study's design, it doesn’t show that coffee or tea causes the reduced risk. So, scientists need more research to confirm the findings.

At ZOE, we know that coffee can be good for your gut health. So, if you like coffee, feel free to carry on drinking it. 

However, the caffeine in coffee can affect some people negatively. If that’s you, don’t feel like you need to take it up.

ZOE has an intruiging podcast on coffee if you’d like to dig a little deeper.

5. Plants and bone health

Osteoporosis, a condition that weakens bones, affects about 1 in 5 women over 50 and 1 in 20 men.

Although treatments are available, prevention is always better than a cure.

So, a recent study investigated whether dietary changes might reduce the risk of developing osteoporosis.

What did they do?

The researchers recruited 9,613 older adults living in Liaoning Province, China. Using questionnaires, they calculated how much healthy plant food the participants ate — beans, nuts, pulses, and the like.

The team also assessed how much unhealthy plant food, like refined grains, the participants ate.

What did they find?

The results showed that those with more healthy plant foods and less animal and unhealthy plant foods had a lower risk of osteoporosis.

And this relationship was more pronounced in women.

The foods with the most beneficial effects were whole grains, fresh fruits, fresh vegetables, nuts, legumes, and tea. 

What should you do?

At ZOE, we’re big fans of a healthy plant-based diet. So, although this study only shows an association and not causation, adding more plants to your diet is likely to benefit your health.

ZOE’s scientific co-founder, Professor Tim Spector, recommends eating 30 different plants a week.

It might help keep your bones healthy as you age, and it will almost certainly protect your health in other ways.

The take-home 

So, that was a mixed bag of delicious and nutritious science. What should we remember from this week’s edition? 

Here are your top five takeaways:

  1. Create a diverse, plant-based diet: This will help reduce levels of inflammation for some people and might reduce your risk of depression, too.

  2. Make sure you get enough omega-3s: It’s best to do this through food, but take supplements if you need to. Omega-3s are important for good health, and if you have PCOS, they might reduce your blood fat levels and improve your blood sugar control.

  3. Focus on healthy, unsaturated fats: If you have risk factors for unhealthy aging, making this change might reduce fat levels in your liver and blood, and reduce insulin resistance.

  4. Drink coffee and tea if you like it: Coffee might reduce your risk of developing IBS, and a spot of tea might help, too. If they don’t, coffee is great for your gut microbiome anyway.

  5. Eat more plants: It’ll likely improve your health, and it might reduce your risk of osteoporosis, too.


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