RecruitingNAINTERVENTIONAL

Effects of Cranberry on Gut and Metabolic Health

This study explores how cranberry drinks might improve the health of people who are overweight. Berries are full of good things called polyphenols, which could help protect against diseases linked to being overweight. Cranberries, in particular, contain special compounds that might improve gut health and how your body uses sugar and fats. We want to find out if drinking cranberry can help with blood sugar levels, how sensitive your body is to insulin, the fats in your blood, and the types of bacteria living in your gut. Participants will try both a cranberry drink and a dummy drink over two 12-week periods to compare the effects.

At a glance

Status

Recruiting

Phase

Sponsor

Laval University

Enrolment target

Start

07 Jul 2025

Estimated completion

01 Dec 2026

Overweight/Obesity Metabolic Syndrome Insulin Resistance Microbiota

What is this study about?

You might have heard that eating plant-based foods, especially berries, is good for you. This is because they contain natural helpful substances called 'bioactive compounds'. Cranberries are particularly rich in a type of these compounds called proanthocyanidins (PACs). These PACs are thought to offer protection against long-term health problems often linked to being overweight.

This study is designed to explore whether regularly drinking a cranberry beverage can positively impact several aspects of health in people who are overweight or have obesity. Specifically, we'll be looking at how cranberries affect your body's ability to manage sugar (glucose metabolism), how well your body responds to insulin (insulin sensitivity), the levels of fats in your blood (lipid levels), and the community of bacteria living in your gut (gut microbiota). Sometimes, changes in these areas can lead to conditions like metabolic syndrome or insulin resistance.

While cranberries are known to be healthy, scientists don't yet fully understand their specific effects on gut health and wider metabolic health. This research aims to fill that gap, providing clearer insights into how cranberries might benefit your health. Hopefully, the findings could contribute to better advice on diet and health for a wide range of people.

Key takeaways

This study investigates if cranberry drinks improve health in overweight or obese individuals.
It focuses on blood sugar, insulin, blood fats, and gut bacteria.
Participants will try both cranberry and a dummy drink over time.
The study involves regular health checks and body measurements.
It's 'double-blind,' meaning no one knows which drink is being given.
Participation helps scientists understand diet and health better.

Who may be eligible?

To join this study, you would typically need to be between 25 and 70 years old. You should also be considered overweight, which means having a Body Mass Index (BMI) between 25 and 40. In addition, you would need to show at least one sign that your body might be having a bit of trouble with sugar or fat, such as slightly higher-than-average blood sugar, insulin, or triglyceride levels.

There are some reasons why you might not be able to take part. For example, if you really dislike cranberry products, regularly drink a lot of alcohol (more than two glasses a day), or have had a big change in your weight (up or down by 5%) in the last three months. Also, if you're taking certain medications that could mess with the study results, like those for diabetes, high cholesterol, or certain steroids, you wouldn't be able to join. The same applies if you regularly take probiotic or prebiotic supplements, including other berry-based ones.

Other reasons for not being able to join include having eating disorders, having had major surgery recently, experiencing problems absorbing food, or having serious liver or kidney conditions. Also, if you are pregnant, planning to become pregnant, or breastfeeding, this study would not be suitable for you.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 25 and 70 years old?
Do you have a Body Mass Index (BMI) between 25 and 40 (considered overweight to obese)?
Do you have slightly higher-than-average blood sugar, insulin, or fat levels?
Are you able to avoid certain medications or supplements during the study?
Are you comfortable drinking cranberry products?
Are you not pregnant, planning pregnancy, or breastfeeding?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you'll first have a two-week period where you keep your lifestyle stable. After that, the main study involves two separate 12-week periods. During one 12-week period, you'll drink a cranberry beverage, and during the other, you'll drink a 'dummy' (placebo) beverage that looks and tastes similar but has no active ingredients. There will be a four-week break between these two periods.

Throughout the study, you'll have regular check-ups. These will involve various assessments to understand your health. We'll look at your blood sugar control, how well your body responds to insulin, and the types of fats in your blood. We'll also measure your body composition (like how much fat and muscle you have) and take samples to understand the bacteria in your gut. Some female participants will also have an MRI scan to look at liver fat. Additionally, we’ll check for signs of inflammation, how your appetite is regulated, your overall gut health, and lifestyle factors. You'll switch between the cranberry and dummy drink, so everyone gets to try both. The total duration of the study, including the stable lifestyle phase, intervening break, and the two treatment periods, will be around 30 weeks.

Potential risks and benefits

Taking part in a study like this might have some potential benefits, such as gaining a better understanding of your own health from the assessments. You'll also be contributing valuable information that could help others in the future by improving our understanding of diet and health. As for risks, these are generally low. You might experience minor discomfort from blood tests or MRI scans, and there's always a small chance of side effects from the drinks, although the dummy drink should not have any. Remember, your participation is completely voluntary, and you have the right to withdraw from the study at any time without giving a reason, and it won't affect any of your current or future medical care.

Locations (1)

INAF, Université Laval
Verified postcode
Québec, Canada· Recruiting

Common questions

What exactly will I be drinking?

You'll be drinking either a cranberry beverage or a similar-looking and tasting 'dummy' drink that doesn't contain the active cranberry ingredients. You'll try both at different times.

Will I know if I'm getting the cranberry or the dummy drink?

No, this is a 'double-blind' study, meaning neither you nor the research team will know which drink you're taking at any given time. This helps ensure fair results.

How often will I need to visit the study site?

The study involves regular visits for assessments over the course of about 30 weeks, including the two 12-week intervention periods and other phases.

What kind of tests will I have?

You'll have various checks, including blood tests for sugar and fats, body measurements, stool samples for gut bacteria, and possibly an MRI scan for some participants.

Can I eat other berries or supplements during the study?

No, you would need to avoid taking regular probiotics, prebiotics, and other fruit or berry polyphenol supplements during the study period.

How to find out more

Julie Marois, M.Sc.

julie.marois@fsaa.ulaval.ca 1-418-656-5258 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.