5 interesting studies: Kombucha, meat, and more

Nutrition science moves fast. So, to help you keep up, we’ll summarize five recent studies that we think are interesting.

We’ll explain what the researchers did, what fresh details they uncovered, and what their conclusions mean for your health.

So, let’s get to it.

1. Kombucha may lower blood sugar

Fermented foods can help support your gut microbiome. Can they also help support your general metabolism?

According to a recent pilot study on kombucha — a fermented sweet tea — they might.

What did they do?

The researchers recruited 12 people with type 2 diabetes. The participants consumed either kombucha or a placebo drink every day for 4 weeks. For the following 8 weeks, they drank neither.

Then, the groups swapped. So, those who’d been drinking the kombucha switched to the placebo and vice versa for another 4 weeks.

The scientists measured the participants’ blood sugar levels at the start of the study and after the first and fourth weeks.

What did they find?

  • After 4 weeks of kombucha: The participants’ blood sugar levels were lower than they had been at the start of the study.

  • After 4 weeks of the placebo: There was no significant difference in blood sugar levels.

What should you do?

This was a very small study, so scientists need much more research to confirm the effect. 

We should also note that two of the authors work for a company that makes products designed to alter the gut microbiome.

However, kombucha can be a healthy addition to your diet. It may or may not reduce your blood sugar levels, but it will probably support your gut health.

2. Limit processed meat

Processed meat has gotten a lot of bad press in recent years, and a new paper adds to the pile-on.

What did they do?

The researchers looked for links between different types of meat and cardiovascular disease.

They followed almost 2,000 people for an average of 20 years. None of the participants had cardiovascular disease at the start of the study.

What did they find?

According to the analysis, around:

  • 38% of the participants rarely or never ate meat 

  • 31% ate mostly red meat

  • 19% ate mostly white meat

  • 12% ate mostly processed meat

During the follow-up period, compared with those who rarely or never ate meat:

  • Those who ate mostly processed meat had a higher risk of developing cardiovascular disease.

  • Those who ate mostly white meat had a reduced risk of developing cardiovascular disease.

What should you do?

Research into white meat and health has been inconclusive so far. But generally, experts agree that eating it in moderation is fine.

Surprisingly, the scientists behind the recent study found no links between red meat and increased cardiovascular risk.

However, many other studies suggest that red meat does increase the risk of some forms of cardiovascular disease.

Red meat may also be linked to cancer risk. So, if it’s your thing, you should enjoy it just once in a while. 

The present study’s authors explain that their participants had a relatively low intake of red meat. This may be why there was no link with heart disease.

3. Does more protein provide more gains?

If you're passionate about boosting your biceps and developing your deltoids, you probably pay attention to your protein intake.

Because protein bars, shakes, and powders are everywhere, it’s easy to think that we’re not getting enough protein. 

But, on average, people in the United States and the United Kingdom take in more protein than they need each day.

Still, there’s a lot of confusion, especially among people looking to increase muscle size.

It’s easy to imagine that the more protein you eat, the bigger your muscles will get. A recent study investigates whether this is true.

What did they do?

The scientists recruited 48 men with an average age of 26 who regularly did resistance training.

The study ran for 16 weeks. During this time, half of the participants consumed 1.6 grams of protein per kilogram of body weight per day, and the rest consumed double that amount.

For reference, the recommended dietary allowance (RDA) of protein for adults is 0.8 g per kg of body weight.

The researchers followed the participants for 16 weeks and measured their muscle growth, endurance, and strength.

What did they find?

There was no significant difference between the two groups, in terms of muscule size or strength. 

So, the extra protein didn’t seem to boost muscle growth.

What should you do?

If you’re eating a well-balanced, varied diet, you’re probably already getting enough protein. 

So, unless you’re training incredibly hard, you probably won’t see any benefits from upping your protein intake.

Still, people going through menopause, older adults, and vegans may need to take steps to make sure that they’re getting enough protein.

For a fascinating protein deep dive, try this episode of the ZOE Science & Nutrition podcast.

4. Are you a ‘weekend warrior’?

Current guidelines recommend getting at least 150 minutes of moderate-to-vigorous physical activity each week.

But fitting exercise into your daily routine can be tough when you’re juggling kids, pets, work, family events, and so on. As a result, many of us squeeze in our exercise at the weekend.

A recent paper asks: Is it better to spread exercise across the week? Or do “weekend warriors” still get the benefits?

What did they do?

The team analyzed data from almost 90,000 people. Each wore a device to measure their physical activity.

During the analysis, the scientists split the participants into three groups:

  1. Inactive people: They got less than 150 minutes of physical activity per week.

  2. Weekend warriors: They got at least 150 minutes of physical activity per week — and at least half of it happened over 1–2 days.

  3. People active throughout the week: They got at least 150 minutes of physical activity, and it was spread more evenly across the week.

The researchers then compared the participants’ risk of cardiovascular events, like heart failure and stroke. 

What did they find?

  • People in the active groups had a lower risk of cardiovascular events than those in the inactive group. 

  • There was no significant difference between the weekend warriors and those who were active throughout the week.

What should you do?

In short, get active when you can. As far as your heart health is concerned, it doesn’t seem to matter whether you squeeze in your exercise at the weekend or do it throughout the week.

If you’d like to know how much cardio you need, try this podcast episode.

5. Sage for hot flashes?

Though almost half of us experience menopause, research into this transition is seriously lacking.

One of the most common symptoms is hot flashes. These can significantly reduce the quality of life — for example, by interfering with sleep and mood.

Although hormone replacement therapy can be effective for some people, many turn to alternative therapies, including sage supplements. 

Recently, scientists asked whether sage really can improve hot flashes.

What did they do?

The team pooled data from existing research and performed a meta-analysis. In all, they identified four relevant studies, which included 310 participants in total.

What did they find?

Sage supplements:

  • didn’t reduce the severity of hot flashes 

  • did reduce the frequency of hot flashes 

However, the authors note that scientists need to carry out larger trials to confirm the results.

What should you do?

If hot flashes affect you, sage might be worth trying. However, high doses can cause side effects. So, it’s worth speaking with a doctor before you start.

But if you’re adding standard amounts of sage to food, there’s no evidence of harm. And it’s delicious, too.

That’s all for this edition. Join us next time for more fascinating nutrition insights from the latest scientific papers.


Accelerometer-derived “weekend warrior” physical activity and incident cardiovascular disease. JAMA Network. (2023). https://jamanetwork.com/journals/jama/article-abstract/2807286 

Associations between meat type consumption pattern and incident cardiovascular disease: The ATTICA epidemiological cohort study (2002−2022). Meat Science. (2023). https://www.sciencedirect.com/science/article/pii/S0309174023002000 

Chemistry, pharmacology, and medicinal property of sage (Salvia) to prevent and cure illnesses such as obesity, diabetes, depression, dementia, lupus, autism, heart disease, and cancer. Journal of Traditional and Complementary Medicine. (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4003706/ 

Consumption of red meat and processed meat and cancer incidence: A systematic review and meta-analysis of prospective studies. European Journal of Epidemiology. (2021). https://link.springer.com/article/10.1007/s10654-021-00741-9 

Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males. Journal of the International Society of Sports Nutrition. (2023). https://www.tandfonline.com/doi/full/10.1080/15502783.2023.2236053 

Intake of unprocessed and processed meat and the association with cardiovascular disease: An overview of systematic reviews. Nutrients. (2021). https://www.mdpi.com/2072-6643/13/10/3303 

Kombucha tea as an anti-hyperglycemic agent in humans with diabetes — a randomized controlled pilot investigation. Frontiers in Nutrition. (2023). https://www.frontiersin.org/articles/10.3389/fnut.2023.1190248/full 

Maximizing the intersection of human health and the health of the environment with regard to the amount and type of protein produced and consumed in the United States. Nutrition Reviews. (2019). https://academic.oup.com/nutritionreviews/article/77/4/197/5307079 

Pharmacological properties of Salvia officinalis and its components. Journal of Traditional and Complementary Medicine. (2017). https://www.sciencedirect.com/science/article/pii/S2225411017300056 

The effect of Salvia officinalis on hot flashes in postmenopausal women: A systematic review and meta-analysis. International Journal of Community Based Nursing & Midwifery. (2023). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10363264/  

White meat consumption and cardiometabolic risk factors: A review of recent prospective cohort studies. Nutrients. (2022). https://www.mdpi.com/2072-6643/14/24/5213