During the SynKETO project, we will examine whether taking a daily synbiotic supplement can help people maintain normal, healthy gut bacteria and microorganisms — and whether this prevents the typical increase in LDL (low-density lipoprotein) cholesterol when following a ketogenic diet.

A ketogenic diet involves limiting your carbohydrate intake in food and drinks to less than 50 g per day. It is described as ‘ketogenic’ because it causes the body to increase the production of ketones (made by the liver). Ketones provide energy and act as important signalling molecules.

Ketogenic diets are used by millions of people around the world for a variety of reasons. Some use them to support blood sugar control or weight management, while others are interested in their potential cognitive or neurological effects.

Although ketogenic diets have some benefits, a potential drawback is an increase in circulating LDL cholesterol (often referred to as ‘bad cholesterol’). Over years and decades, higher LDL cholesterol levels may increase the risk of cardiovascular disease.

Our data suggests that the increase in LDL cholesterol during a ketogenic diet could be caused by changes in the composition and function of intestinal microorganisms (e.g. gut bacteria). During the SynKETO project, we will examine whether taking a daily synbiotic supplement (a combination of a probiotic and prebiotic fibre) is effective, and whether it can help people gain the benefits of a ketogenic diet without the potential downsides.

Project funders

This project is funded by the UK Research Institute (UKRI) Biotechnology and Biological Sciences Research Council (BBSRC) Industrial Partnership Award (IPA) and IFF (Danisco USA Inc.).

Project team members

This project involves a team of researchers from the University of Bath and the University of Leeds, and food ingredients manufacturer, IFF. One researcher will be doing the research as part of a PhD (Doctor of Philosophy).

• Professor Dylan Thompson, University of Bath
• Dr Lucy Rogers, University of Bath
• Professor Javier Gonzalez University of Bath
• Dr Francoise Koumanov, University of Bath
• Dr Jean-Philippe Walhin, University of Bath
• Dan Rees, University of Bath
• Professor Kieran Tuohy, University of Leeds

The SynKETO project research study

To gather the data, we will run a research study involving 64 volunteers.

Across the total involvement period of approximately 14 weeks, participants will complete a 12‑week period during which they must adopt a ketogenic diet while taking a daily supplement.

This will begin with an initial screening visit to check eligibility and to set participants up with equipment to assess their usual diet and physical activity for two weeks. During this time, they will also use continuous monitors to measure their normal glucose and ketone levels.

After this, participants will attend the main trial day. This will include a range of measurements, such as blood and fat samples and a DEXA scan. Participants will also provide a stool sample.

They will then be randomly assigned to one of two groups. Both groups will follow a ketogenic diet, but one will take the synbiotic supplement while the other will receive a placebo.

After around 42 days (six weeks), participants will attend an interim visit for repeated measurements, including a DEXA scan and assessments of diet, glucose/ketone levels, and physical activity.

Participants will then continue the ketogenic diet and daily supplement, and these measures will be repeated again during the final 14 days of the study. They will attend a final main trial visit on day 84 (12 weeks).

Find out more about this research study and how to take part