To assess the effect of rice bran oil emulsified formulation (EMF) on cooked rice, a single-arm open clinical trial and in vitro testing for digestion and glycemic response were performed. Fifteen Japanese men consumed 200 g of packed rice, cooked with or without EMF. Blood samples were collected 0, 30, 60, and 120 min post-consumption and analyzed for glucose, insulin, and triglyceride levels. Continuous glucose monitoring (CGM) and sensory evaluation were also performed. A two-step in vitro digestion test, simulating gastric and small intestinal digestion was conducted. EMF-added rice group showed higher insulin response levels at 60 min than the placebo group. Stratification of participants with HbA1c ≥ 5.6 or an insulinogenic index ≤ 0.4 revealed a significant reduction in C_max glucose levels. A significant correlation was observed between venous and CGM blood glucose levels and no significant sensory differences were observed. The in vitro test revealed significantly lower C_∞, equilibrium starch concentrations, with EMF. Clinical trial suggests that EMF may stimulate insulin secretion and reduce blood glucose levels in participants with lower insulin responses. In vitro tests suggest that EMF inhibits glycemic digestion. This trial was registered at the UMIN Center (UMIN000053495; registered 31 January 2024).

Objective This study aimed to evaluate the effect of simultaneous consumption of vegetables and bread on postprandial serum glucose concentration. In total, 15 healthy men were given meals (bread vs. bread with vegetable salad) after a night of fasting. At 0, 15, 30, 45, 60, 90, and 120 min following the consumption of the test meal, blood samples were collected to determine the serum levels of glucose, insulin, glucose-dependent insulinotropic polypeptide, and triglycerides. Results Results revealed that serum glucose and insulin levels were significantly lower after 45 and 60 min in participants who consumed bread with vegetable salad than in those who only consumed bread. This emphasizes the potential benefit of simultaneously consuming vegetables and bread as an effective dietary strategy for preventing postprandial blood glucose elevation. Trial registration: UMIN Clinical Trials Registry (UMIN-CTR), UMIN000053931, registered on March 22, 2024.

We used a prototype of packaged cooked rice based on white rice using an emulsified formulation (EMF) containing γ-oryzanol, a compound with various biological activities. We compared the bioaccessibility of γ-oryzanol after in vitro digestion and its subsequent uptake by Caco-2 intestinal model cells. γ-Oryzanol bioaccessibility was higher in cooked EMF rice and cooked white rice than in cooked brown rice. Because EMF contains phospholipids, which influence the bioaccessibility and intestinal absorption of fat-soluble components, we examined their effects on uptake. Lysophospholipids enhanced γ-oryzanol uptake by the cells. Rice oil was added to cooked EMF rice to adjust its γ-oryzanol content to that of cooked brown rice. Cooked EMF rice showed greater γ-oryzanol bioaccessibility than cooked brown rice. The bioaccessible γ-oryzanol fraction was diluted and applied to cells using a combined model of in vitro digestion and cellular uptake. Cellular uptake of γ-oryzanol from the bioaccessible fraction was greater when the fraction was derived from cooked EMF rice than from cooked brown rice. Finally, the biological activities of γ-oryzanol constituents were estimated using online computer simulations. The results suggested that free ferulic acid and ferulic acid esters, as well as the free triterpene alcohols, may exhibit biological activity.