A type of fibre that stimulates GLP-1 release approved for use in food
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- Inulin-propionate ester (IPE) received European Food Safety Authority approval as safe to eat, ending a 12-year regulatory process led by Gary Frost at Imperial College London and Douglas Morrison at the University of Glasgow.
- A randomized-controlled trial of 60 overweight people aged 40-65 found that a 10-gram daily dose of IPE raised blood GLP-1 and PYY levels, reduced food intake, and left none of the IPE group with significant weight gain after six months versus 17% of controls; the only side effect noted was increased flatulence.
- A separate RCT of 270 overweight people aged 20-40 found no body-weight difference after a year, but IPE users gained more than a kilogram of fat-free mass on average — though the method could not determine whether that tissue was muscle.
- IPE was engineered by attaching propionate to inulin; gut bacteria in the large intestine split the compound, releasing propionate to drive short-chain fatty acid levels high enough to trigger GLP-1 and PYY release at ~10g rather than the roughly 80g of ordinary fibre animal studies suggest would otherwise be required.
- Frost and Morrison are in talks with food companies to launch IPE-containing smoothies, cereals and breads on EU shelves within 12 months and expect the UK regulator to quickly follow EFSA's lead; the team is also planning studies on whether IPE can preserve lean mass during GLP-1 drug use and limit weight regain when those drugs are stopped.
- Brendan Gabriel at the University of Aberdeen called the evidence for IPE's benefits 'not very strong,' arguing the weight-gain trial involved too few participants and that the younger-adult fat-free-mass finding did not distinguish muscle from other non-fat tissue.
Why it matters: At just 10 grams per day versus roughly 80g of regular fibre animal studies suggest is needed, IPE activates the same GLP-1/PYY appetite-suppressing pathway as injectable drugs like Ozempic at food-grade doses. Frost and Morrison expect EU breads and smoothies containing IPE on shelves within 12 months, though Aberdeen researcher Brendan Gabriel calls the trial evidence 'not very strong' and questions whether the younger-adult lean-mass gain is actually muscle.
