Composition for suppressing blood glucose elevation and its uses

Abstract

This invention provides a new type of blood glucose elevation suppression composition that can be manufactured at low cost using novel plant materials as raw materials and exhibits excellent efficacy. [Solution] The composition for suppressing blood glucose elevation is composed of mulberry leaf extract and exfoliation extract of plants of the Trapa natans family as active ingredients.

Description

Technical Field

[0001] The present invention belongs to the technical field of biochemistry, and particularly relates to a composition for suppressing blood glucose level increase derived from plants.

Background Art

[0002] In modern society, due to the Westernization of eating habits and the development of transportation means, unbalanced lifestyle habits such as a high-fat diet and lack of exercise tend to continue chronically, the risk of hyperglycemia is high, and the number of people suffering from diabetes accompanied by an increase in blood glucose level and various complications is increasing, becoming a social problem.

[0003] It is expected to prevent lifestyle-related diseases by suppressing the increase in blood glucose level that promotes lifestyle-related diseases.

[0004] Many compositions for suppressing blood glucose level increase with excellent preventive and inhibitory effects against lifestyle-related diseases have been proposed so far. In particular, those using natural products (especially plants) as raw materials have the advantage of higher safety during handling than synthetic compounds using petroleum as a raw material, and compositions for suppressing blood glucose level increase derived from plants have been actively developed.

[0005] For example, mulberry leaves, although being natural-derived substances, are known to have various health-promoting effects, among which the effect of suppressing blood glucose level increase is also known. Furthermore, research has been conducted to obtain a characteristic composition for suppressing blood glucose level increase by mixing mulberry leaves with other materials.

[0006] Such conventional compositions for suppressing blood glucose elevation include, for example, a composition for suppressing postprandial blood glucose elevation containing tea flower extract, mulberry leaf extract, and chitosan as active ingredients (see, for example, Patent Document 1). Also known is a composition for suppressing blood glucose elevation containing indigestible dextrin and at least one plant material selected from the group consisting of lemongrass, rosehip, and mulberry as active ingredients (see, for example, Patent Document 2). A composition for suppressing blood glucose elevation is known that is characterized by containing indigestible dextrin and at least one plant material selected from the group consisting of lavender, lemongrass, houttuynia cordata, rosehip, and mulberry as active ingredients (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-105094 [Patent Document 2] Japanese Patent Publication No. 2017-88621 [Patent Document 3] Japanese Patent Publication No. 2017-1965 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, conventional compositions for suppressing blood sugar spikes often have high raw material costs because they use multiple expensive plants already sold for consumption, such as herbs, or plants that cannot be harvested in large quantities. Furthermore, there are cases where raw materials cannot be reliably obtained, which has hindered their practical application as blood sugar spike suppressing compositions. In addition, the health-enhancing effects unique to mulberry leaves may be diluted when mixed with other raw materials, potentially reducing the inherent blood sugar spike suppressing effect of mulberry leaves.

[0009] Furthermore, while conventional blood glucose elevation-suppressing compositions have been studied from the perspective of their blood glucose elevation-suppressing effect using mulberry leaves, if a multi-functional blood glucose elevation-suppressing composition that also possesses other health-promoting functions such as anti-aging could be realized, it would not only promote disease prevention but also active beauty effects, and it is thought that this would increase the satisfaction of health-conscious consumers. However, currently, no such excellent multi-functional blood glucose elevation-suppressing composition is known.

[0010] The objective of the present invention is to solve the above-mentioned problems and to provide a new type of blood glucose elevation suppression composition that can be manufactured at low cost by using novel plant materials as raw materials and exhibits excellent efficacy. [Means for solving the problem]

[0011] As a result of diligent research, the inventors focused on the existence of certain plant materials that are largely unused, and discovered that by combining these plant materials with mulberry leaves, it is possible to produce a product that can suppress blood sugar level increases while also possessing antioxidant properties. This led to the completion of the present invention.

[0012] Thus, according to the present invention, a composition for suppressing blood glucose elevation is provided, comprising mulberry leaf extract and water chestnut plant exoskeleton extract as active ingredients. Since the water chestnut exoskeleton has so far had no particular use and is largely unused, the blood glucose elevation suppressing composition according to the present invention can be manufactured at low cost and is also beneficial from the viewpoint of effective resource utilization. [Brief explanation of the drawing]

[0013] [Figure 1] The experimental results regarding the DNJ content in mulberry tea according to Example 1 of the present invention are shown below. [Figure 2] The results of the analysis of water chestnut polyphenols in the outer skin of water chestnut, which is the raw material for the water chestnut tea according to Example 1 of the present invention, are shown. [Figure 3] The experimental results regarding the antioxidant activity of mulberry leaf tea according to Example 1 of the present invention are shown below. [Figure 4] The experimental results regarding the maltase inhibitory activity of mulberry tea according to Example 1 of the present invention are shown below. [Figure 5] The experimental results regarding the sucrase inhibitory activity of mulberry tea according to Example 1 of the present invention are shown below. [Figure 6] The experimental results regarding the change in Δglycemic levels after ingesting a load food in a human clinical trial of Kuwabishi Tea according to Example 2 of the present invention are shown (*** P<0.001). [Figure 7] The experimental results comparing the area under the blood glucose elevation curve (ΔIAUC) from before intake of the load food to 120 minutes after intake in a human clinical trial of Kuwabishi Tea according to Example 2 of the present invention are shown (*** P<0.001). [Figure 8] The experimental results regarding the change in Δinsulin (insulin change) after intake of a loading food in a human clinical trial of Kuwabishi Tea according to Example 2 of the present invention are shown (** P<0.01, *** P<0.001). [Figure 9] The experimental results comparing the area under the insulin elevation curve (ΔIAUC) from before intake of the loading food to 120 minutes after intake in a human clinical trial of Kuwabishi Tea according to Example 2 of the present invention are shown (*** P<0.001). [Modes for carrying out the invention]

[0014] The blood glucose level elevation suppression composition according to this embodiment is composed of mulberry leaf extract and exfoliation extract of plants of the Trapa natans family as active ingredients.

[0015] The Trapa species used in this embodiment are not particularly limited as long as they belong to the Trapa family (commonly known as water chestnuts), and examples include Trapa japonica, Trapa natans, Trapa bicornis, and Trapa incisa.

[0016] Water chestnut is an annual aquatic plant that grows wild in ponds, marshes, and creeks scattered in rural areas. Its thorny fruits adhere to the bottom of the water and overwinter, sprout in spring, and bear fruit in autumn. The fruits of water chestnut are rich in starch, can be boiled and the inside can be used for food, can be decocted and drunk as a folk medicine or tea, and are even used as a raw material for shochu. However, the outer skin of water chestnut has no current utilization value and most of it is discarded.

[0017] The mulberry used in the mulberry leaf extract according to this embodiment is a plant belonging to the genus Morus of the family Moraceae. The place of origin of the mulberry is not particularly limited. For example, mulberry produced in Kanzaki City, Saga Prefecture, which is a special production area of mulberry, can be used. The mulberry leaf extract is obtained by extracting the leaf part.

[0018] As the extraction method, in consideration of safety in food use, it is preferable to perform hot water extraction by stirring the mulberry leaf extract and the outer skin of the water chestnut family plant in hot water. The mulberry leaf extract and the outer skin of the water chestnut family plant can be extracted with hot water at the same time, or they can be mixed after being extracted with hot water separately.

[0019] Hot water refers to water heated to 60°C to 100°C and can be, for example, 90°C. Also, when stirring, ultrasonic vibration can be applied, whereby the extraction is efficiently performed. By extracting with hot water in this way, there is no irritation to the human body (such as stabbing pain) caused by the remaining alcohol in the alcohol extraction method and the peculiar pungent smell of alcohol, and it is easy to handle, and a blood sugar level increase inhibitory composition that is also friendly to the human body can be obtained.

[0020] The blood glucose elevation-suppressing composition of this embodiment is not particularly limited in its form of use and can be used in any form such as powder, tablet, granule, capsule, or syrup. If used in powder form, for example, a total of 3 g of powder containing 2.85 g of dried mulberry leaf powder and 0.15 g of water chestnut peel (weight ratio of 95:5) can be packaged in a stick-shaped bag (1 sachet) and used for manufacturing and sales, and can be easily consumed by purchasers simply by dissolving it in water. Furthermore, the blood glucose elevation-suppressing composition of this embodiment can be used as a Food for Specified Health Uses, a Food with Function Claims, a Supplement, a Pharmaceutical, or a Quasi-drug.

[0021] The blood glucose elevation-suppressing composition of this embodiment can be manufactured by known methods, with the addition of other components besides the orally permissible active ingredient as needed. For example, it can be used in combination with pharmaceutically acceptable carriers, diluents, activators, excipients, fillers, penetration enhancers, thickeners, flavorings, emulsifiers, dispersing aids, or binders.

[0022] The extract obtained in this manner has been confirmed in human clinical trials to have the effect of suppressing the rise in blood glucose levels, which is deeply related to lifestyle-related diseases (see the examples described below). Furthermore, it has been confirmed that the synergistic effect with mulberry leaf extract and the outer bark extract of water chestnut plants results in superior efficacy compared to these extracts alone.

[0023] The weight ratio of mulberry leaf extract to the bark extract of the Trapa natans plant is not particularly limited, but it is preferable that the weight ratio of mulberry leaf extract to the bark extract of the Trapa natans plant is in the range of 20:80 to 95:5 on a dry weight basis (mulberry leaf extract:bark extract of the Trapa natans plant), as it can significantly suppress the rise in blood glucose levels. Furthermore, it is more preferable that the ratio is in the range of 30:70 to 70:30, as it can also easily exhibit excellent antioxidant effects at the same time (see the examples described below).

[0024] The blood glucose level-inhibiting composition according to this embodiment can suppress the rise in blood glucose levels and can be used as an active ingredient for the prevention or treatment of diseases, including diabetes, in which symptoms are prevented or improved. Furthermore, it also exhibits excellent antioxidant activity, suppressing the rise in blood glucose levels and providing an anti-aging effect through oxidation of cell membranes in the body.

[0025] The blood glucose-lowering composition according to this embodiment is not limited to pharmaceutical applications. For example, it can be used as an ingredient (additive) in processed foods such as tea, somen noodles, sake, soft drinks, milk, powdered dairy products, yogurt, ice cream, coffee, jelly, cookies, chocolate, cakes, rice crackers, or snack foods by mixing, dissolving, or kneading it in. However, it is not limited to these uses and can also be used in other food products and beverages. In this case, for example, tea mixed with this blood glucose-lowering composition can be called Hishikuwa tea, sake mixed with this blood glucose-lowering composition can be called Hishikuwa sake, and somen noodles, milk, or powdered dairy products can be kneaded with this blood glucose-lowering composition. The resulting processed foods can be consumed in daily life, offering the convenience of easily improving health.

[0026] The following examples illustrate the features of this embodiment in more detail, but this embodiment is not limited to these examples.

[0027] (Example 1) (1) Preparation of mulberry tea sample and hot water extract As a blood glucose level elevation suppressing composition according to Example 1, a powder was produced that can be dissolved in water or hot water and consumed as tea (Kuwabishi tea).

[0028] As raw materials for the blood glucose elevation suppression composition according to Example 1, mulberry leaves and the outer shell of water chestnut (Trapa Japonica) were sourced from Kanzaki-cho, Kanzaki City, Saga Prefecture, and were dried and finely powdered using a pulverizer. The fine powders of mulberry leaves and water chestnut shells were mixed to create the blood glucose elevation suppression composition (mulberry water chestnut tea powder) according to Example 1, with mulberry leaf extract content at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, and 100%. 500 mg of mulberry water chestnut tea powder was accurately weighed and placed in a 50 ml disposable centrifuge tube. 30 ml of pure water was added and heated in boiling water for 30 minutes. After cooling, the solution was filtered through filter paper (No. 1, manufactured by Advantec Co., Ltd.) and diluted to a final volume in a 50 ml volumetric flask with pure water. Further centrifugation was performed, and the supernatant was filtered through a membrane filter (0.45 μm) to obtain the sample solution.

[0029] (2) Component analysis Below, in order to analyze the characteristics of the components of the obtained mulberry leaf tea powder (hereinafter also simply referred to as mulberry leaf tea), we performed an analysis of the total polyphenols, 1-deoxynojirimycin, and hishi polyphenols contained in the mulberry leaf tea.

[0030] (2-1) Determination of total polyphenols The total polyphenol content was determined by the Forin-Ciocalt method. 100 μl of the sample solution or a gallic acid solution of known concentration and 100 μl of phenol reagent were placed in a microcentrifuge tube, stirred, and allowed to stand for 3 minutes. Then, 100 μl of 10% sodium carbonate was added, mixed well, and allowed to stand for 60 minutes. Centrifugation (3000 rpm, 15 minutes) was performed, and the supernatant was collected and the absorbance (750 nm) was measured. A calibration curve for gallic acid standard solutions was created, and the amount of gallic acid per 100 g of sample was determined by substituting the values ​​into the following formula.

[0031] Total polyphenol content (g / 100g) = x × A / 100 × 100 / w × 1000 × 1 / 1000 × dilution ratio x = Concentration of gallic acid from the calibration curve (mg / 100ml) A: Volume (ml) when the sample is extracted. w = sample volume (mg)

[0032] The total polyphenol content of each type of water chestnut tea is summarized in the table below. The total polyphenol content showed an extreme peak when mulberry leaf extract and water chestnut peel extract were mixed, with 30% to 50% water chestnut peel extract (70% to 50% mulberry leaf extract), compared to when only mulberry leaf extract or only water chestnut peel extract was used.

[0033] [Table 1]

[0034] (2-2) Determination of 1-deoxynojirimycin Mulberry, the raw material for Example 1, is known to contain 1-deoxynojirimycin (DNJ) as a unique component. Therefore, the 1-deoxynojirimycin (DNJ) contained in the mulberry tea of ​​Example 1 was analyzed as follows.

[0035] 0.5 ml of the sample solution or DNJ standard solution was placed in a sample tube, and 2.4 ml of 30 mM borate buffer solution and 100 μl of 5 mg / ml 4-fluoro-7-nitrobenzoflazan solution were added and mixed. The mixture was heated in 60°C constant temperature water for 40 minutes. It was immediately cooled, 2 ml of 1N hydrochloric acid was added, and the mixture was filtered through a membrane filter (0.45 μm) and subjected to HPLC. The HPLC instrument used was a Prominence LC-20AT (Shimadzu Corporation), and the column was a CAPCELLPAK C18 UG120 φ4.6 × 250 mm particle size 5 μm (Shiseido Co., Ltd.). The mobile phase was solution A: 0.05% phosphoric acid, and solution B: methanol:5% phosphoric acid (99:1), and gradient elution was performed from 0 min (100% solution A) to 45 min (95% solution A, 5% solution B). The flow rate was set to 1 ml / min and the column temperature to 40°C. Fluorescence intensity was detected using a fluorescence detector (Ex 470 nm, Em 530 nm). A calibration curve for DNJ standard solutions was created, and the content per 100 g of sample was determined.

[0036] Figure 1 shows the results of an investigation into the DNJ content in Kuwabishi tea. DNJ began to be detected at a mulberry leaf extract concentration of 20%, and the DNJ content increased as the concentration of mulberry leaf extract increased.

[0037] (2-3) Analysis of Hishi polyphenols Three characteristic polyphenols contained in the outer shell of the water chestnut used in the blood glucose elevation-suppressing composition (mulberry tea) according to Example 1—eugenin, 1,2,3,6-tetra-O-galloyl-D-glucopyranose (Tetra-GG), and trapine—were analyzed. A Prominence LC-20AT HPLC system (Shimadzu Corporation) was used, and a CAPCELL PAK C18 UG120 column (length 250 mm × inner diameter 4.6 mm, particle size 5 μm, Shiseido) was used. The column temperature and flow rate were set to 40°C and 1 ml / min, respectively. A 0.1% formic acid / acetonitrile eluent was used, and linear gradient elution was performed from 95 / 5% (v / v) at the start to 70 / 30% (v / v) after 30 minutes. Detection was performed using a UV-Vis detector at a wavelength of 280 nm.

[0038] Figure 2 shows the results of an analysis of water chestnut polyphenols (eugenin, tetra-GG, trapane) contained in the outer shell of the water chestnut. When the mulberry leaf extract content was 70% or higher, water chestnut polyphenols were below the detection limit, but the higher the content of water chestnut shell extract, the more water chestnut polyphenols were present.

[0039] (3) Efficacy analysis Below, in order to analyze the efficacy of the obtained Mulberry Tea, we performed analyses of its antioxidant activity, α-glucosidase inhibitory activity, 1-deoxynojirimycin, and hishi polyphenols.

[0040] (3-1) Measurement of antioxidant activity The antioxidant activity of Kuwabishi tea was investigated using the DPPH radical scavenging activity method. 50 μl of the sample solution or a known concentration of Trolox solution (for calibration) was placed in a 98-well microplate. 150 μl of DPPH mixture (400 μM DPPH:MES-NaOH buffer solution (pH 6):ethanol = 2:1:2) was added, and after standing at room temperature for 20 minutes, the absorbance at 520 nm was measured. A calibration curve for the Trolox standard solution was created, and the DPPH units per gram of sample (DPPH radical scavenging ability equivalent to 1 μmol of Trolox) were determined by substituting the values ​​into the following formula.

[0041] DPPH radical scavenging activity of the sample (μmolTE / g) = x × A / 1000 × 1 / w × 1000 × dilution ratio x: Molar concentration (μM) from the calibration curve w: Sample volume (mg), A: Volume after sample extraction (ml)

[0042] Figure 3 shows the results of investigating the antioxidant activity of the water chestnut tea from Example 1 using DPPH radical scavenging activity. A higher content of water chestnut peel tended to indicate higher antioxidant activity. In the range of 20% to 70% mulberry leaf extract content, the high antioxidant activity was likely due to the high polyphenol content mentioned above.

[0043] (3-2) α-glucosidase inhibitory activity 80 μl of substrate solution (dissolved in 50 mM maleate buffer (pH 6.0) to obtain 74 mM maltose or 74 mM sucrose) was added to 20 μl of sample solution. 30 μl of 50 mM maleate buffer (pH 6) was added and mixed, then preheated at 37°C for 3 minutes. 40 μl of enzyme solution (1 g of rat small intestine acetone powder was mixed with 9 ml of 50 mM maleate buffer (pH 6.0), stirred in an ultrasonic cleaner on ice, and centrifuged at 3000 rpm at 4°C for 10 minutes. The supernatant was used as the crude enzyme solution for sucrase, and a 3-fold diluted crude enzyme solution was used for maltase) was added and mixed, and the enzymatic reaction was carried out at 37°C for 30 minutes. 640 μl of distilled water was added, and the enzymatic reaction was stopped by heating in boiling water for 2 minutes. After cooling, 50 μl was taken, 750 μl of colorimetric reagent (Lab Assay™ Glucose, Fujifilm Wako Pure Chemical Corporation) was added, and the mixture was heated at 37°C for 5 minutes. The absorbance at a wavelength of 505 nm was measured using a microplate reader. The α-glucosidase inhibitory activity was determined by substituting the values ​​into the following formula.

[0044] α-glucosidase (maltase, sucrase) inhibitory activity (%) = 100 - 100 × (DC) / (BA) A: Absorbance of the control (water) blank (no enzyme) B: Absorbance of control (water) C: Absorbance of sample blank (without enzyme) D: Absorbance of the sample Acarbose (10 μg / ml) and 1-deoxynojirimycin (10 μg / ml) were used as positive controls.

[0045] (3-2-1) Maltase inhibitory activity Maltase is an enzyme that breaks down maltose into two glucose molecules, and the stronger the activity of this enzyme, the higher the blood glucose level. In other words, inhibiting maltase activity can suppress a rapid rise in blood glucose levels. Figure 4 shows the results of the maltase inhibitory activity of Kuwabishi tea. Acarbose and DNJ are standard solutions at 10 μg / ml each.

[0046] While 14% inhibitory activity was observed with 100% water chestnut bark extract, high inhibitory activity of over 70% was observed with mulberry leaf extract at a concentration of 10% or more. These levels were higher than those of the positive control acarbose (10 μg / ml). High inhibitory activity was also observed at concentrations of mulberry leaf extract below 90%, suggesting that this is due to a synergistic effect between components other than DNJ in the mulberry leaf extract and components contained in the water chestnut bark extract.

[0047] (3-2-2) Sucrase inhibitory activity Sucrase is an enzyme that breaks down sucrose into glucose and fructose. Inhibiting sucrase activity can prevent an increase in blood glucose levels. Figure 5 summarizes the results of investigating the sucrase inhibitory activity of mulberry leaf tea. Acarbose and DNJ are standard solutions at 10 μg / ml each. Extracts from only the outer bark of the water chestnut tree showed almost no activity, but when the mulberry leaf extract was added at concentrations of 10% and 20%, 47% inhibitory activity was observed. Furthermore, when the mulberry leaf extract was added at a concentration of 30% or more, approximately 60% inhibitory activity was observed. This was higher than the inhibitory activity of the positive control acarbose (10 μg / ml).

[0048] When the sucrase inhibitory activity of the DNJ standard solution (10 μg / ml) was examined, it showed an inhibitory activity of 57%. It was found that the inhibitory activity was higher when the mulberry leaf extract was added at a concentration of 30% or more than the DNJ standard solution. This result suggests that it is higher than the maltase inhibitory activity previously observed. This sucrase inhibitory activity is also thought to be due to DNJ. In mulberry leaf extract tea with a content of 90% or less, high inhibitory activity was observed even at a lower concentration than the DNJ standard solution (10 μg / ml), which is presumed to be due to a synergistic effect with components contained in mulberry leaves and water chestnut peel.

[0049] Based on the results above, analysis of the functional components (polyphenols and DNJ) contained in the Kuwabishi tea of ​​Example 1 confirmed that functional components such as polyphenols and DNJ were significantly present after hot water extraction, confirming that both safety for consumption and high functionality are achieved. Regarding DNJ, it was confirmed that the amount of DNJ present increased with a higher proportion of mulberry leaf extract.

[0050] Furthermore, regarding the antioxidant activity of the mulberry leaf tea according to Example 1, contrary to the DNJ content, it was confirmed that when the mulberry leaf extract content was high, at 80% to 100% or more, the antioxidant activity was low. Moreover, as is clear from Figure 3, it was confirmed that the antioxidant activity was extremely low, especially when the mulberry leaf extract content was 80% to 95%. On the other hand, the mulberry leaf tea according to Example 1, when combined with water chestnut peel extract at a mulberry leaf extract content of 20% to 70% (water chestnut peel extract content of 30% to 80%), exhibited significantly higher antioxidant activity than mulberry leaf extract alone. In other words, the mulberry leaf tea according to Example 1 obtained antioxidant activity that could not be obtained with mulberry leaf extract alone.

[0051] Furthermore, regarding the carbohydrate-degrading enzyme (α-glucosidase) inhibitory activity of the mulberry leaf tea according to Example 1, while the blood glucose elevation-suppressing effect inherently possessed by the active ingredient DNJ in the mulberry leaf extract alone was reduced by mixing it with the water chestnut peel extract, it was confirmed that the carbohydrate degradation ability was equivalent to or higher than that of the mulberry leaf extract alone, even though the DNJ content decreased. In particular, regarding sucrase inhibitory activity, extremely high activity exceeding that of the mulberry leaf extract alone was confirmed when the mulberry leaf extract content was 40% to 95% (the water chestnut peel extract content was 5% to 60%).

[0052] Thus, it was confirmed that the Kuwabishi Tea of ​​Example 1, by mixing mulberry leaf extract and water chestnut peel extract, obtained a blood glucose level-suppressing effect that also possessed antioxidant activity not obtained with mulberry leaf extract alone. From the above, it was confirmed that the Kuwabishi Tea of ​​Example 1 is a new type of blood glucose level-suppressing composition that prevents a rapid rise in postprandial blood glucose levels, contributing to the prevention of diabetes and the alleviation of hyperglycemia, while also exhibiting excellent antioxidant activity and offering the potential for anti-aging effects through oxidation of cell membranes in the body. Such Kuwabishi Tea can be used in stick-type powder form, allowing for easy daily intake of a blood glucose level-suppressing composition.

[0053] (Example 2) As described above, the Kuwabishi tea produced in Example 1 can be used in stick-type powder form. Therefore, in this example, a human clinical trial was conducted using the stick-type powder form of Kuwabishi tea on individuals with elevated blood glucose levels to investigate the effect of Kuwabishi tea consumption on raising human blood glucose levels.

[0054] (1) Experimental method (1-1) Subjects The subjects were adults (male or female) aged 20 to 65 years residing or working in Kanzaki City, who did not meet the exclusion criteria and had elevated blood glucose levels. The selection criteria for subjects were a fasting blood glucose level of approximately 100 mg / dL to less than 126 mg / dL or a hemoglobin A1c value of approximately 5.6% to less than 6.5%. The exclusion criteria for subjects were: <1> Those who do not meet the aforementioned participation criteria (place of residence or work, age), <2> Individuals whose blood glucose levels and hemoglobin A1c levels indicate diabetes (fasting blood glucose level of 126 mg / dL or higher, hemoglobin A1c level of 6.5% or higher), <3> Those undergoing continuous drug treatment, <4> Individuals who regularly consume pharmaceuticals, foods for specified health uses, foods with functional claims, or health foods that may potentially affect the test results. <5> Individuals with a history of serious illness affecting the heart, liver, kidneys, digestive system, etc. <6> Those who have consumed excessive amounts of alcohol, <7> Those with irregular lifestyles, such as shift workers and night shift workers, <8> People with allergies to medicines and food, <9> Pregnant women or those who may be pregnant, <10> Breastfeeding women, <11> In addition, any person deemed unsuitable as a subject by the physician in charge of the study, <12> Participants who requested to discontinue the study (those who submitted a withdrawal of consent form were excluded at any time) were included.

[0055] Thirty individuals who met the above criteria were selected as subjects and randomly assigned to Group A and Group B, taking into account age, sex, fasting blood glucose levels, etc. The characteristics of the subjects are shown in the table below.

[0056] [Table 2]

[0057] (2) Test method (2-1) Test Foods The test food used was Kuwabishi tea, made from dried, crushed, roasted, and powdered mulberry leaves and water chestnut peels from Kanzaki City. Each test food (1 packet) contained 3 g of powder, including 2.85 g of mulberry leaves and 0.15 g of water chestnut peel, in a stick-shaped bag. The 1-deoxynojirimycin and total polyphenol content in 3 g of the test food was 5.1 mg and 87.3 mg, respectively. The placebo food was made similar to the test food by adding corn flour and coloring agents. Subjects were given either the test food or the placebo food after mixing it well with 200 ml of hot water. In addition, 200 g of cooked rice (Sato's Rice, Sato Foods Co., Ltd.) (300 kcal of energy, 68.8 g of carbohydrates), heated in a water bath, was used as a load food.

[0058] (2-2) Examination Design The study was a randomized, placebo-controlled, double-blind, crossover comparative trial. In the first trial, Group A received the test food and Group B received a placebo. After a break of approximately one week, in the second trial, Group A received the placebo and Group B received the test food. First, blood was drawn from an empty stomach, followed by the consumption of 200 ml of either the test food or a placebo. Immediately afterward, 200 g of rice (the load food) was consumed within 10 minutes. Blood was then drawn again at 30, 60, 90, and 120 minutes to measure blood glucose and insulin levels. Participants were prohibited from consuming anything other than water from 9 PM the day before the study until the end of the study. Furthermore, participants were instructed not to significantly change their lifestyle habits, such as diet and exercise, from before the study during the study period.

[0059] (2-3) Ethical considerations This human clinical trial was approved by the Ethics Committee of Nishikyushu University in accordance with the Declaration of Helsinki (Approval Number: 21BIQ03). Applicants for this study were given a joint information session where the research objectives, methods, and handling of information were thoroughly explained, and the study was conducted only after obtaining the participants' voluntary consent. Personal information was kept strictly confidential through ID management.

[0060] (2-4) Statistical analysis All data are presented as mean ± standard deviation. For statistical significance testing, interaction was confirmed using a two-way ANOVA with repeated exposures. Post-hoc tests were then performed, including paired tests for group differences and Dunnett's method for time-course differences. All statistical analyses were performed using SPSS Statistics Version 22 (IBM Japan, Ltd.), with a significance level of p<0.05 for two-tailed tests.

[0061] (3) Results and Discussion (3-1) Blood sugar level Figure 6 shows the change in Δglycemic levels after ingesting the stress food. Δglycemic level is the change in blood glucose level, with the blood glucose level before ingesting the stress food (0 minutes) set to 0. In both the placebo and test food groups, Δglycemic levels increased after ingesting the stress food, reaching a maximum at 60 minutes, and then gradually decreasing until 120 minutes. At 30 and 60 minutes, the test food group showed significantly lower values ​​compared to the placebo group (P<0.001). Figure 7 shows a comparison of the area under the blood glucose elevation curve (ΔIAUC) from before stress food intake to 120 minutes after intake. The results showed that the test food group had significantly lower values ​​compared to the placebo group (P<0.001). In other words, a significant effect of suppressing blood glucose elevation by Kuwabishi tea in this example was observed.

[0062] (3-2) Insulin Figure 8 shows the change in insulin levels after ingesting the test food, with the insulin level before ingesting the test food set to 0 (Δinsulin). (** P<0.01, *** P<0.001). The results showed that the Δinsulin levels for both the placebo and test foods increased after ingesting the test food. However, at all time points, the test food showed significantly lower values ​​than the placebo food. Figure 9 also shows a comparison of the area under the insulin elevation curve (ΔIAUC) from before ingesting the test food to 120 minutes after ingestion. The results showed that the test food had significantly lower values ​​than the placebo food (P<0.001). In other words, a significant insulin secretion-inhibiting effect of Kuwabishi tea in this example was observed.

[0063] These results are thought to be due to the superimposed increase in the inhibitory activity of carbohydrate-degrading enzymes (α-glucosidase) by DNJ contained in mulberry leaves and polyphenols contained in water chestnut bark. It is presumed that the synergistic action of these components suppressed the rapid rise in blood glucose levels after meals more effectively than when mulberry leaf extract or water chestnut bark extract were used individually, resulting in less unnecessary insulin secretion.

[0064] (4) Summary To investigate the effect of consuming Kuwabishi tea according to this embodiment on postprandial blood glucose levels, a randomized, placebo-controlled, double-blind, crossover comparative trial was conducted on individuals with elevated blood glucose levels or hemoglobin A1c. The results showed that consumption of Kuwabishi tea according to this embodiment significantly suppressed the rise in postprandial blood glucose levels and insulin after consuming a load food compared to a placebo.

[0065] Based on these results, it was confirmed that the consumption of Kuwabishi tea according to this embodiment suppressed the rise in blood glucose levels after meals, and consequently suppressed insulin secretion, thereby reducing the risk of developing diabetes.

Claims

1. It is composed of mulberry leaf extract and water chestnut plant bark extract as active ingredients. The weight ratio of mulberry leaf extract to the outer bark extract of the Trapa natans plant (mulberry leaf extract: outer bark extract of the Trapa natans plant) is 80:20 to 95:

5. It is characterized by suppressing the rise in blood glucose levels, at least through sucrase inhibitory activity. A composition for suppressing the rise in blood glucose levels.

2. The blood glucose level elevation suppression composition according to claim 1, wherein the weight ratio of mulberry leaf extract to the bark extract of a plant in the Trapa natans family (mulberry leaf extract: bark extract of a plant in the Trapa natans family) is 80:

20.

3. The blood glucose level elevation suppression composition according to claim 1 or 2, wherein the embodiment is in the form of a powder, tablet, granule, capsule, or syrup.

4. A composition for suppressing blood glucose elevation according to claim 3, which is a Food for Specified Health Uses, a Food with Function Claims, a Supplement, a Pharmaceutical, or a Quasi-drug.

5. A food product comprising the blood glucose level-suppressing composition described in any one of claims 1 to 4, which is tea, somen noodles, sake, soft drinks, milk, powdered dairy products, yogurt, ice cream, coffee, jelly, cookies, chocolate, cakes, rice crackers, or snack foods.

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