Synbiotic supplementation during a ketogenic diet
Research type
Research Study
Full title
The effect of Synbiotic Supplementation on Hypercholesterolaemia during a Ketogenic Diet: A Randomised Controlled Trial
IRAS ID
363636
Contact name
Dylan Thompson
Contact email
Sponsor organisation
University of Bath
Duration of Study in the UK
4 years, 11 months, 31 days
Research summary
Ketogenic diets are being used by millions of people around the world. A ketogenic diet involves limiting your carbohydrate intake in food and drinks to less than 50g a day. This is called “ketogenic” because is causes your body to increase the production of ketones (by your liver). Ketones provide energy and also act as important signalling molecules and messengers.
Although ketogenic diets are helpful for some outcomes, one potentially negative consequence from consuming a ketogenic diet is an increase in circulating LDL cholesterol concentrations (“bad cholesterol”). Over years and decades, an increase in LDL cholesterol may increase the risk of cardiovascular disease.
Our preliminary data indicate that the increase in LDL cholesterol might be due to changes in the composition and function of intestinal microorganisms (e.g., gut bacteria). To investigate this hypothesis, we will examine if taking a daily synbiotic supplement prevents the typical increase in LDL cholesterol when people start to follow a ketogenic diet. A synbiotic supplement is a combination of a prebiotic and a probiotic. Prebiotics support the growth of beneficial microorganisms (e.g., fibre), whereas probiotics are live microorganisms (e.g., similar to microorganisms found in yoghurts). We will use a randomised controlled trial (RCT) over 12-weeks in men and women (Synbiotic versus Placebo, N=64) and examine LDL-C concentrations and lipoprotein profile. We will also examine gut microbial composition and measures of cholesterol and bile acid metabolism and absorption. We will examine distal effects of synbiotic supplementation in adipose tissue biopsies taken in basal conditions and 6h after meal ingestion, and we will use in vitro approaches to interrogate key pathways, including experiments using media conditioned with ex vivo serum from our human RCT (e.g., fasted/fed).
REC name
Wales REC 7
REC reference
25/WA/0351
Date of REC Opinion
16 Dec 2025
REC opinion
Further Information Favourable Opinion