This fixed-sequence, three-period crossover study demonstrates that acute supplementation with TRPTI™ produced a dose-dependent enhancement of incretin responses in healthy adults. Treatment effects were observed under both post-prandial and fasting conditions, suggesting that TRPTI™ potentially augments enteroendocrine signalling as well as altering basal hormone secretion. The 300 mg TRPTI™ dose showed the most consistent biological activity, particularly for serum GLP-1, GIP and DPP-4 concentrations, with no significant treatment-related changes in glucagon.

TRPTI™ exhibited an immediate basal hormone secretion as well as early and sustained post-prandial change between treatments. At 15 minutes post-dose, placebo participants demonstrated a reduction from baseline (−6.4%) and the 150 mg TRPTI™ group displayed a larger reduction (−24.4%), whereas the 300 mg TRPTI™ dose produced a statistically significant increase (+13.6%), corresponding to approximately a 20% elevation relative to placebo. This early difference persisted following the second standardised meal (4 h), with placebo remaining slightly below baseline (−4.6%), the 150 mg TRPTI™ group suppressed (−17.5%), and the 300 mg TRPTI™ group maintaining an elevated GLP-1 response (+20.5%), equating to roughly a 25% greater response than placebo at that timepoint. The consistency of this pattern across repeated meal exposures supports a nutrient-dependent mechanism rather than a transient fluctuation.

The prandial-period AUC analyses provide a framework for interpreting these effects. It should be noted that significant between-group effects were not uniformly driven by differences between 300 mg TRPTI™ and placebo. Rather, several AUC windows reflected lower responses in the 150 mg treatment condition, whereas direct differences between 300 mg TRPTI™ and placebo were evident in only certain periods. Significant between-group differences during the earliest window (0–30 min, pre-prandial) indicate that the 300 mg dose exerted a direct, nutrient-independent stimulatory effect on incretin secretion, consistent with OEA acting via GPR119 on intestinal L- and K-cells prior to meal arrival. The sustained and significant differences during the first post-prandial period (45 min–2.5 h) suggest that TRPTI™ potentiates the meal-stimulated incretin response, amplifying the normal GLP-1 and GIP secretory burst triggered by breakfast. Significant differences during the 3–4 h pre-prandial window and the 5–6 h post-lunch period further indicate that the effect is not confined to a single meal exposure but recurs across repeated nutrient stimuli, consistent with ongoing GPR119 engagement throughout the gastrointestinal transit of the dose. The persistence of between-group differences into the 7–8 h window for GIP, but not GLP-1, may reflect differential rates of clearance or L- versus K-cell sensitivity across the distal gut. Collectively, the prandial-period AUC pattern supports a model in which TRPTI™ primes enteroendocrine cells for enhanced secretion both independently of and in concert with nutrient ingestion.

GLP-1 is secreted from intestinal L-cells in response to macronutrient exposure and enhances glucose-dependent insulin secretion whilst modulating gastric emptying and satiety (13–15). Preclinical evidence identifies OEA as an activator of both PPAR-α and GPR119, mechanisms linked to enteroendocrine signalling and incretin secretion (16–18). The present study extends this mechanistic framework by demonstrating that acute oral TRPTI™ augments meal-stimulated GLP-1 responses under controlled feeding conditions.

Clinical trials of other natural supplements have often shown inconsistent effects on GLP-1. Obese individuals supplemented with resveratrol did not significantly alter fasting or post-prandial GLP-1 despite mechanistic rationale (18), and systematic evaluations of dietary supplements report limited evidence for robust GLP-1 enhancement (19). In this context, the timepoint-specific GLP-1 augmentation observed with TRPTI™, particularly during post-prandial periods, represents a meaningful biological signal.

GIP responses paralleled GLP-1 dynamics. The 300 mg dose produced greater positive deviations from placebo during early and later post-prandial periods, with percentage differences generally ranging from ~15–25% at peak timepoints. GIP, co-secreted with GLP-1 from enteroendocrine K- and L-cells, contributes to post-prandial insulin secretion and metabolic homeostasis (10, 20). The coordinated enhancement of both incretins suggests a generalised potentiation of nutrient-responsive enteroendocrine activity rather than an isolated hormonal fluctuation.

DPP-4 concentrations were relatively stable over time but demonstrated late-phase concentration changes in the 300 mg TRPTI™ group (approximately 10–20% relative to placebo at key timepoints). Studies have shown that pharmacological DPP-4 inhibition enhances incretin bioavailability and improves glycaemic control in type 2 diabetes (13, 21). Although robust human evidence for meaningful modulation of DPP-4 through nutritional intervention remains limited and is largely derived from preclinical or in vitro work (19), the directionally consistent reductions in circulating DPP-4 concentrations observed here suggests that TRPTI™ may influence DPP-4 regulation. However, the functional significance of these changes remains to be established. Accordingly, the present findings should be interpreted as evidence of altered circulating DPP-4 concentrations rather than direct evidence of altered DPP-4 activity or incretin hormone degradation. Future studies incorporating direct DPP-4 activity measures or active hormone kinetics will be required to confirm functional relevance.

Glucagon followed expected post-prandial dynamics and did not differ consistently between treatments. The absence of over-suppression or dysregulation of glucagon indicates that TRPTI’s™ incretin modulation does not perturb counter-regulatory hormonal balance in healthy adults. Prior supplementation trials (e.g., resveratrol) have also demonstrated negligible effects on glucagon despite broad metabolic interest (18).

Both insulin and glucose concentrations exhibited similar temporal patterns across all groups, with no significant between-group differences at any timepoint, indicating no change despite modulation of upstream incretin signalling. This observation suggests that although TRPTI™ influenced GLP-1, GIP, and DPP-4 responses, the magnitude and duration of incretin stimulation achieved following a single dose was insufficient to produce measurable changes in downstream glycaemic regulation under the conditions of the present study. Importantly, this study was designed as an acute pharmacodynamic investigation to determine whether TRPTI™ could engage incretin-related pathways, rather than to evaluate clinical efficacy or glycaemic outcomes. Given the transient nature of the observed hormonal responses and the healthy metabolic status of the study population, the absence of changes in insulin or glucose is not unexpected. Whether repeated administration can amplify or sustain these endocrine effects sufficiently to influence metabolic outcomes remains to be determined in longer-duration studies.

Pre-lunch satiety scores assessed by visual analogue scale were comparable across groups, but both TRPTI™ groups consumed a lower percentage of the standardised meal compared with placebo, particularly at lunch. Although differences were modest and subjective ratings were similar, the directional reduction in energy intake aligns with rodent and limited human evidence implicating OEA pathways in satiety and feeding regulation (16, 22). In animal models, OEA administration reduces meal size and prolongs inter-meal intervals via PPAR-α–mediated pathways and vagal sensory signalling (22, 23), although translation to human appetite regulation is less consistently reported and a direction for future studies.

TRPTI™ was well tolerated, with gastrointestinal symptoms reported in fewer than 5% of participants and no meaningful between-group differences. Routine clinical chemistry parameters, including liver function tests (LFTs), remained within normal reference ranges throughout the study, with only minor timepoint-specific fluctuations and no evidence of clinically significant treatment-related changes. These findings are consistent with the safety profile observed in prior human incretin and lipid signalling studies, where short-term nutritional modulation of enteroendocrine pathways did not produce adverse hepatic or systemic laboratory changes (18, 20, 24). The absence of acute adverse signals supports tolerability of single-dose TRPTI™ administration at both tested doses.

Although the present study provides mechanistic insight into acute incretin modulation, several limitations warrant consideration. Significantly elevated pre-dose GLP-1 and GIP concentrations were observed at the 150 mg visit relative to both the placebo and 300 mg visits. Because all analyses were baseline-adjusted by subtracting the 0 h value, a higher pre-dose starting point mathematically compresses the post-dose trajectory relative to placebo, and in several prandial windows produced an artefactual suppression pattern in which the 150 mg group appeared to perform below placebo. This is most likely attributable to period or order effects inherent to the fixed-sequence design, in which all participants received treatments in the same predefined order, rather than a genuine pharmacological suppression of incretin secretion by the 150 mg dose. The study adopted this design because the absorption profile and duration of action of TRPTI™ had not previously been characterised in humans, and therefore the potential for carryover effects could not be confidently excluded during study planning. A minimum 6-day washout was incorporated between treatment periods to minimise carryover, but because the absorption and elimination profile of TRPTI™ had not been previously characterised in humans, residual biological or physiological carry-in effects between the placebo and 150 mg visits cannot be entirely excluded. Consequently, the apparent underperformance of the 150 mg dose relative to placebo should be interpreted cautiously and does not necessarily reflect the true pharmacological potential of this dose. Circulating DPP-4 concentrations were measured rather than enzymatic activity, and total rather than active incretin fractions were assessed, limiting mechanistic specificity. Consequently, the functional significance of the observed reductions in DPP-4 concentration on incretin preservation cannot be determined from the present study and warrants further investigation. Therefore, longer-duration trials incorporating enzymatic activity measures and validated appetite assessments are warranted.

Standardised meals were provided at each visit, and participants consumed this food ad libitum to avoid introducing bias associated with compulsory overconsumption. Consequently, the absolute quantity of food consumed may have varied both between study visits within the same participant and/or between participants for the same visit. However, meal composition and timing were identical across treatment visits, and the change in consumption volumes is unlikely to alter incretin hormones significantly. Additionally, the observed reductions in food intake following TRPTI™ administration are themselves consistent with the proposed satiety-related mechanisms of OEA. Therefore, whilst variation in meal quantity cannot be completely excluded as a contributing factor, it is unlikely to fully account for the consistent treatment-related differences observed in the incretin hormone responses.

The primary outcome of GLP-1 AUC analyses demonstrated significant between-group differences across all five meal-related windows, with time-course analyses providing further characterisation of the temporal pattern of these effects. Together, these findings demonstrate rapid and measurable incretin modulation following a single dose of TRPTI™, providing preliminary proof-of-mechanism. Although the magnitude of the acute hormonal response was insufficient to influence insulin or glucose concentration in the current study. Chronic incretin modulation strategies such as GLP-1 receptor agonists and DPP-4 inhibitors have produced substantial metabolic benefits in obesity and type 2 diabetes (13, 25). The observable timepoint-specific endocrine effects following a single 300 mg TRPTI™ dose provides rationale for longer-duration supplementation studies to determine whether repeated administration amplifies effect magnitude, prolongs duration, or translates into improvements in glycaemic regulation, appetite control, or metabolic health.

Future investigations should determine whether repeated administration of TRPTI™ amplifies effect magnitude, prolongs post-prandial GLP-1 and GIP elevation, modulates DPP-4 levels, or translates into clinically meaningful improvements in glycaemic regulation, appetite control, body weight, or metabolic health. Given that incretin responsiveness and DPP-4 dynamics differ in individuals with insulin resistance or impaired glucose tolerance, extending this work to metabolically at-risk populations may be of particularly interest.