GutGard

Liquorice root, from the Glycyrrhiza glabra plant, has a long history of traditional use for digestive complaints. GutGard is a specific extract of the root that has had most of the glycyrrhizin removed, the compound in raw liquorice responsible for raising blood pressure and causing water retention with prolonged use, making it suitable for everyday use. It's standardised instead to its flavonoid content, mainly glabridin, which appears to be behind most of its activity.

In a randomised, double blind, placebo controlled trial in people with functional dyspepsia, GutGard brought about a 51% reduction in total symptom score over 30 days, compared with 29% for placebo, with 56% of the GutGard group showing marked improvement in symptoms against none in the placebo group.

A separate trial in people with H. pylori found that after 60 days, 56% of the GutGard group tested negative for H. pylori on a stool antigen test, compared with 4% on placebo.

The most recent trial, in people with heartburn and regurgitation, found GutGard brought about an 88% reduction in reflux related quality of life scores and an 87% reduction in heartburn frequency by day 28, with the benefit continuing for roughly a week after people stopped taking it.

Alongside the human trials, laboratory and animal research has looked at why it might work this way. One study found the extract helped protect the gut lining itself, restoring the tight junction proteins that keep the gut barrier intact, in both a human cell model and in animals with induced colitis. Other research has found it speeds up gastric emptying to a degree comparable with domperidone, a registered pharmaceutical prokinetic, and that it's compatible with probiotics and has little effect on digestive enzymes. Safety studies have found it well tolerated, with no significant adverse effects reported across the trials.