Modified dietary fat intake for treatment of gallstone disease in people of any age

Background

The prevalenceof gallstones varies between less than 1% and 64% in different populations andis thought to be increasing in response to changes in nutritional intake andincreasing obesity. Some people with gallstones have no symptoms butapproximately 2% to 4% develop them each year, predominantly including severeabdominal pain. People who experience symptoms have a greater risk ofdeveloping complications. The main treatment for symptomatic gallstones ischolecystectomy. Traditionally, a low-fat diet has also been advised to managegallstone symptoms, but there is uncertainty over the evidence to support this.

Objectives

To evaluatethe benefits and harms of modified dietary fat intake in the treatment ofgallstone disease in people of any age.

Search methods

We searchedthe Cochrane Hepato-Biliary Group Controlled Trials Register, the CochraneCentral Register of Controlled Trials in the Cochrane Library, MEDLINE ALLOvid, Embase Ovid, and three other databases to 17 February 2023 to identifyrandomised clinical trials in people with gallstones. We also searched onlinetrial registries and pharmaceutical company sources, for ongoing or unpublishedtrials to March 2023.

Selectioncriteria

We includedrandomised clinical trials (irrespective of language, blinding, or status) inpeople with gallstones diagnosed using ultrasonography or conclusive imagingmethods. We excluded participants diagnosed with another condition that maycompromise dietary fat tolerance. We excluded trials where data fromparticipants with gallstones were not reported separately from data from participantswho did not have gallstones. We included trials that investigated otherinterventions (e.g. trials of drugs or other dietary (non-fat) components)providing that the trial groups had received the same proportion of drug orother dietary (non-fat) components in the intervention.

Data collectionand analysis

We intended toundertake meta-analysis and present the findings according to Cochranerecommendations. However, as we identified only five trials, with dataunsuitable and insufficient for analyses, we described the data narratively.

Main results

We includedfive trials but only one randomised clinical trial (69 adults), published in1986, reported outcomes of interest to the review. The trial had four dietaryintervention groups, three of which were relevant to this review. We assessedthe trial at high risk of bias. The dietary fat modifications included amodified cholesterol intake and medium-chain triglyceride supplementation. Thecontrol treatment was a standard diet. The trial did not report on any of theprimary outcomes in this review (i.e. all-cause mortality, serious adverseevents, and health-related quality of life). The trial reported on gallstonedissolution, one of our secondary outcomes. We were unable to apply the GRADEapproach to determine certainty of evidence because the included trial did notprovide data that could be used to generate an estimate of the effect on thisor any other outcome. The trial expressed its finding as "no significant effectof a low-cholesterol diet in the presence of ursodeoxycholic acid on gallstonedissolution." There were no serious adverse events reported. The includedtrial reported that they received no funding that could bias the trial resultsthrough conflicts of interest. We found no ongoing trials.

Authors'conclusions

The evidenceabout the effects of modifying dietary fat on gallstone disease versus standard diet is scant. We lack results from high-quality randomised clinical trialswhich investigate the effects of modification of dietary fat and other nutrientintakes with adequate follow-up. There is a need for well-designed trials thatshould include important clinical outcomes such as mortality, quality of life,impact on dissolution of gallstones, hospital admissions, surgicalintervention, and adverse events.