Colonic Delivery of DIM and Perilla Oil on Gut Hormones and Food Intake in Obesity

This study evaluates whether a targeted combination of naturally derived food supplements delivered to the lower gut can stimulate the release of appetite-regulating hormones and reduce food intake in adults with obesity. Specialised nutrient receptors in the colon can trigger the release of hormones involved in appetite control when activated by specific nutrients. This study tests a new capsule formulation designed to deliver selected nutrients to the lower intestine to activate these receptors.

The study uses a randomised, double-blind, placebo-controlled crossover design. Twenty adults with obesity (BMI 30-40 kg/m²) will complete two study visits separated by a washout period. At each visit, participants will receive either the active supplement formulation or matched placebo capsules.

At each visit, participants attend after an overnight fast. Blood samples are collected at regular intervals to measure circulating gut hormones including PYY, GLP-1, and ghrelin. Standardised breakfast and lunch meals with known calorie content are provided, and food intake is measured. Participants also complete repeated visual analogue scale questionnaires to assess hunger, fullness, and desire to eat.

The active formulation contains diindolylmethane (DIM) and perilla oil and is delivered using coated capsules designed for lower-gut release. The placebo capsules are visually identical and contain inactive material (methylcellulose). The crossover design allows each participant to receive both treatments for within-subject comparison.

The results will help determine whether targeted nutrient delivery to the colon can safely enhance appetite-regulating hormone responses and reduce food intake, supporting the development of non-drug approaches for appetite control in obesity.

• Colonic-delivered DIM + Perilla oil (Dietary supplement): A single-capsule formulation delivering DIM (GPR84 agonist) and Perilla oil (ALA, FFA4 agonist) to the colon, designed to stimulate satiety hormone release (PYY and GLP-1) from colonic L-cells. Active treatment significantly increased circulating PYY and GLP-1 compared to placebo, with concomitant reduction in caloric intake observed in female volunteers at lunch. The formulation allows synergistic activation of GPR84 and FFA4, improving hormone release compared to previous multi-ingredient delivery methods.
• Dietary Supplement: Colonic-delivered Placebo (Dietary supplement): A single-capsule formulation containing inactive methylcellulose, designed to reach the colon without pharmacological activity. It serves as a control to compare against active treatment, which significantly increased circulating PYY and GLP-1 and reduced caloric intake. Unlike the active formulation, the placebo does not stimulate GPR84 or FFA4, and therefore does not enhance hormone release.

Primary outcomes

• Change in circulating levels of appetite-regulating gut hormones (PYY, GLP-1, ghrelin) [Single day during each study visit (Visit 1 and Visit 2), with measurements every 30 minutes from 08:00 to 16:00.]: Blood samples will be collected every 30 minutes from 08:00 to 16:00 on each study visit. The levels of peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and ghrelin will be measured to assess the effect of targeted lower-gut nutrient delivery on appetite-regulating hormones in participants with obesity.

Secondary outcomes

• Subjective hunger and appetite ratings using visual analogue scales (VAS) [Baseline and during each study visit (Visit 1 and Visit 2), every 30 minutes from 08:00h to 16:00h.]: Participants will complete hunger and satiety questionnaires using VAS at baseline (day -7) and every 30 minutes from 08:00h to 16:00h during each study visit. This will assess perceived appetite and satiety changes in response to active versus placebo supplementation.

Other outcomes

• Safety and tolerability of lower gut-targeted nutrient capsules [During each study visit and for 24 hours post-capsule ingestion.]: Adverse events, gastrointestinal discomfort, and overall tolerability of the nutrient capsules will be monitored and recorded throughout the study to ensure safety of the intervention.

Sex: All, ages: 18 Years to 60 Years

Inclusion Criteria:

* Obese but otherwise healthy volunteers aged between 18 and 60 years, of either sex
* Body Mass Index (BMI) of 30-40 kg/m²
* Agreement to eat the scheduled meals
* Ability to understand the study information sheet and instructions in English, and able to provide informed consent

Exclusion Criteria:

* Not meeting any of the inclusion criteria above
* Major gut surgery involving removal of any part of the gastrointestinal tract
* Known major bowel disease
* Currently taking medication for diabetes (Type 1 or Type 2)
* Currently taking medication for weight loss