Composition, food, and feed for promoting microplastic excretion from body

Abstract

An object of the present invention is to provide a composition, a food, and a feed capable of promoting the discharge of small-sized microplastics from the body.SOLUTION: A composition according to the present invention is a composition for promoting excretion of microplastics from a body, the composition containing chitosan having an average molecular weight of 650,000 or more as an active ingredient. In the composition according to the present invention, the chitosan has an average molecular weight of 800,000 or more and 4 million or less. The composition according to the present invention has a viscosity of not less than 30mPa·s and not more than 2000mPa·s in 0.5% by weight of the composition. In addition, the food and feed according to the present invention are for promoting the discharge of microplastics containing the composition from the body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composition, food, and feed that promote the excretion of microplastics from the body. [Background technology]

[0002] As global environmental problems become more serious, interest in marine plastic waste is rapidly increasing. In particular, with the improvement of analytical technology, it has become possible to detect tiny microplastics that had previously been overlooked, and the adverse effects of microplastics are becoming apparent in a variety of fields. For this reason, various technologies related to microplastics have been proposed.

[0003] For example, Patent Document 1 discloses a water treatment method for recovering microplastics from water to be treated that contains microplastics and carbon dioxide, and for immobilizing carbon dioxide, the water treatment method comprising the steps of causing algae having the ability to adsorb and recover microplastics to be present in the water to be treated, recovering the microplastics from the water to be treated, and immobilizing carbon dioxide from the water to be treated within the algae. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-61957 Summary of the Invention [Problem to be solved by the invention]

[0005] Currently, there are reports that tiny microplastics are contained in various foods that humans consume on a daily basis, such as table salt and mineral water, and that microplastics are also present in human feces. In other words, it is clear that microplastics have an impact not only on the aquatic environment surrounding living organisms, as cited in Patent Document 1, but also on the in vivo environment, such as inside living organisms.

[0006] The inventors thought that if they could create a technology that could promote the excretion of microplastics from the body in order to eliminate microplastics that have been ingested into living organisms, it would help to eliminate (or reduce) the adverse effects of microplastics on living organisms.

[0007] Furthermore, microplastics generally refer to plastics with a diameter of 5 mm or less, but the smaller the size, the more difficult it is to detect and eliminate them from various environments (aquatic environments, biological environments, etc.). Therefore, the inventors wanted to create a technology that can target even extremely small microplastics with a diameter of around 50 μm.

[0008] Therefore, an objective of the present invention is to provide a composition, food, and feed that can promote the excretion of small microplastics from the body. [Means for solving the problem]

[0009] The above problems can be solved by the following means. (1) A composition for promoting the excretion of microplastics from the body, containing chitosan with an average molecular weight of 650,000 or more as an active ingredient. (2) The composition for promoting the excretion of microplastics from the body described in 1 above, wherein the average molecular weight of the chitosan is 800,000 or more and 4,000,000 or less. (3) The composition for promoting the excretion of microplastics from the body described in 1 above, wherein the viscosity of a 0.5 wt% solution of the chitosan is 30 mPa·s or more and 2000 mPa·s or less. (4) A food for promoting the excretion of microplastics from the body, containing the composition described in any one of 1 to 3. (5) A feed for promoting the excretion of microplastics from the body, comprising the composition described in any one of 1 to 3. [Effects of the Invention]

[0010] The composition, food and feed according to the present invention can promote the excretion of small microplastics from the body. [Brief explanation of the drawings]

[0011] [Figure 1] The graph shows the results of changes in rat weight in four groups: control group (group C), low molecular weight chitosan group (group L), medium molecular weight chitosan group (group M), and high molecular weight chitosan group (group H). [Figure 2] The results show the cumulative food intake of rats in the four groups. [Figure 3] Figure 1 shows the results of tissue weights of rats in the four groups. [Figure 4] The results show the cumulative fecal weight of rats in the four groups. [Figure 5] The results show the MP excretion rate in the feces of rats in the four groups. [Figure 6] The results show the MP residual rate in the gastrointestinal tract of rats in the four groups. [Figure 7] The results show the percentage of precipitated MP in the artificial digestive fluid. [Figure 8A] 1 shows the results of microscopic observation showing chitosan agglomerating MPs. [Figure 8B] 1 shows the results of microscopic observation showing chitosan agglomerating MPs. [Figure 8C] 1 shows the results of microscopic observation showing chitosan agglomerating MPs. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments (present embodiments) for carrying out the composition, food, and feed according to the present invention will be described.

[0013] [Composition] The composition according to this embodiment is a composition containing chitosan having an average molecular weight of a predetermined value or more as an active ingredient, and is a composition for promoting the excretion of microplastics from the body. Each component of the composition according to this embodiment will be described in detail below.

[0014] (Chitosan) Chitosan is an insoluble dietary fiber that is purified by deacetylation, which removes the acetyl groups from chitin extracted from shrimp and crab shells. The inventors conducted a detailed study of chitosan's effect of promoting the excretion of microplastics from the body and discovered that molecular weight has a significant impact on the effect (the effect of promoting the excretion of microplastics from the body), leading to the creation of the present invention.

[0015] (Chitosan: average molecular weight) The average molecular weight of chitosan used as an active ingredient is preferably 650,000 or more, more preferably 660,000 or more, 670,000 or more, 700,000 or more, 750,000 or more, 800,000 or more, 1,000,000 or more, 1,300,000 or more, 1,500,000 or more, or 1,800,000 or more. When the average molecular weight of chitosan is a predetermined value or more, the effect of promoting the excretion of microplastics from the body can be more reliably exhibited. On the other hand, the upper limit of the average molecular weight of chitosan used as an active ingredient is not particularly limited, but is, for example, 4 million or less, 3 million or less, 2.5 million or less, 2 million or less, or 1.9 million or less. In this specification, the average molecular weight specifically refers to the weight average molecular weight (Mw).

[0016] (Chitosan: Measurement of average molecular weight) The average molecular weight of chitosan can be determined by comparison with pullulan (standard reagent) in GPC (gel permeation chromatography) analysis. Specifically, 10 mg of chitosan to be measured and 10 mg of standard reagent P-38 (pullulan prepared for each molecular weight range) (Showa Denko) were dissolved in 50 mL of acetate buffer prepared as follows to prepare the sample. The following acetate buffer is used as the mobile phase: Acetic acid buffer can be prepared by dissolving 20.5 g of sodium acetate (Kanto Chemical, special grade) in ultrapure water, adding 15 g of acetic acid (Kanto Chemical, special grade) and bringing the volume to 1 L in a measuring flask. 100 μL of the sample was applied to a column (TOSOH TSKgel G6000PW) at 40°C. XL -CP+G3000PW XL The chitosan and P-38 spectra can be obtained by injecting the chitosan into a CP (Pullulan column) and running it with acetate buffer at a flow rate of 0.5 mL / min. Because P-38 is pullulan prepared for each molecular weight, a pullulan calibration curve can be created. The average molecular weight of chitosan can be calculated based on the pullulan calibration curve.

[0017] (Chitosan: Viscosity) The viscosity of chitosan used as an active ingredient is preferably 30 mPa·s or more, more preferably 50 mPa·s or more, 100 mPa·s or more, 150 mPa·s or more, 300 mPa·s or more, 500 mPa·s or more, 1000 mPa·s or more, or 1500 mPa·s or more. By ensuring that the viscosity of chitosan is above the specified value, the effect of promoting the excretion of microplastics from the body can be more reliably achieved. On the other hand, the upper limit of the viscosity of chitosan used as an active ingredient is not particularly limited, but is, for example, 2000 mPa·s or less, 1500 mPa·s or less, or 1000 mPa·s or less.

[0018] (Chitosan: Viscosity Measurement) The viscosity of chitosan is a value measured using a Brookfield viscometer in a solution of a given concentration. Specifically, 1.5 g of the chitosan to be measured was dispersed in 297 g of deionized water, 1.5 g of acetic acid was added, and the mixture was stirred at room temperature for 3 hours to prepare a 0.5 wt % chitosan solution. The viscosity of the solution (0.5 wt % chitosan solution) adjusted to 20°C was then measured using a Brookfield viscometer.

[0019] (For promoting the excretion of microplastics from the body) The use of the composition according to this embodiment is to promote the elimination from the body of microplastics that have been ingested into the body, that is, to "promote the excretion of microplastics from the body." The fact that the composition according to this embodiment can be used for the above-mentioned purposes is supported by the results of the examples described below. In addition, since the composition of this embodiment exerts the desired effect (the effect of promoting the excretion of microplastics from the body) when taken into the body of an organism (oral ingestion), it is preferable to include the composition in food or feed as described below.

[0020] [Food] The food product according to this embodiment is a food product containing the above-described composition, and is a food product for the aforementioned purpose of "promoting the excretion of microplastics from the body." Foods are foods eaten by humans, and there are no particular limitations on the type of food form, such as solid, fluid, emulsion, liquid, or powder, as long as they can contain the above-mentioned composition.

[0021] [feed] The feed according to this embodiment is a feed containing the above-described composition, and is a feed for the aforementioned purpose of "promoting the excretion of microplastics from the body." Feed is food given to animals kept in captivity, such as pets, livestock, poultry, and seafood. As with the form of food, the type of form of the feed is not particularly limited as long as it can contain the above-mentioned composition.

[0022] (Other ingredients) The composition, food, and feed according to this embodiment may contain, in addition to the chitosan described above, common materials contained in conventionally known compositions, foods, and feeds (for example, excipients, binders, etc. in the case of supplements). The composition according to this embodiment may be composed of chitosan alone.

[0023] [method] The method according to this embodiment is a method (excluding methods for treating humans) for promoting the excretion of microplastics from the body by orally administering to an organism a composition containing, as an active ingredient, chitosan having an average molecular weight and viscosity equal to or greater than a predetermined value. The subjects of oral administration in the method according to this embodiment are organisms other than humans, such as domesticated animals such as pets, livestock, poultry, and seafood. The amount and timing of oral administration of the composition to animals can be determined appropriately depending on the amount of microplastics ingested into the body.

[0024] [Method of producing composition, etc.] The method for producing the composition, food, and feed according to this embodiment may be any general production method. For example, in the case of food, the composition may be added to the ingredients of the food during the process of producing the food. Although commercially available chitosan may be used, it can be produced by a conventional method. For example, first, hydrochloric acid is added to the shells of crabs, shrimp, etc. to remove calcium as calcium chloride. Then, the protein is heated with sodium hydroxide solution to decompose and remove it, producing chitin. The order of the hydrochloric acid treatment and sodium hydroxide treatment can be reversed. Then, chitin is heated with concentrated sodium hydroxide solution to perform a deacetylation treatment, producing chitosan. After that, the chitin is washed with water as needed to remove the sodium hydroxide, and then dried. In addition, when producing chitosan having a large average molecular weight or viscosity, it can be produced by adjusting the temperature during the deacetylation treatment in the above production. [Example]

[0025] The present invention will be described more specifically with reference to examples. [Preliminary test: Addition recovery test] First, rat feces (40 mg) were weighed and a predetermined amount of microplastics (30–50 pieces) was added. The feces after microplastic addition were then added to 200 mL of a 30% HO solution (Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred at 60°C for 48 hours using a hot stirrer (AS ONE Corporation, RSH-1DN). The microplastics remaining on a 10 μm pore PTFE membrane were then collected by suction filtration, and the number of microplastics was counted using a microscope. The recovery rate in the feces was then calculated based on the ratio (number of collected microplastics / number of added microplastics x 100). This procedure was carried out three times, and the average recovery rate in the feces was calculated.

[0026] The digestive tract was separated from rats, the contents were collected, and a predetermined amount of microplastics (30–50 pieces) was added. The digestive tract after the addition of microplastics was then added to 200 mL of 10% KOH solution (Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred at 60°C for 24 hours using a hot stirrer (AS ONE Corporation, RSH-1DN). The solution was then subjected to suction filtration to collect the microplastics remaining on a PTFE membrane with a 10 μm pore size, and the number of microplastics was counted using a microscope. The recovery rate in the digestive tract was then calculated based on the number of collected microplastics divided by the number of added microplastics × 100. This procedure was carried out three times, and the average recovery rate in the digestive tract was calculated.

[0027] The microplastics (referred to as "MP" where appropriate) used in the preliminary test were blue-colored polyethylene particles manufactured by Cospheric, with a particle size of 45-53 μm (average particle size approximately 50 μm), a particle density of 1.075-1.085 g / cc, and a number density of 1.623 × 10 7 It was 1 / g. Table 1 below shows the results of recovery rates in feces, and Table 2 shows the results of recovery rates in the digestive tract.

[0028] [Table 1]

[0029] [Table 2]

[0030] [Pre-test: Review of results] As shown in Tables 1 and 2, the recovery rate of microplastics was high. Therefore, it was confirmed that microplastics can be properly recovered using the recovery method used in the preliminary test, even when targeting small microplastics with an average particle size of approximately 50 μm.

[0031] [Animal experiment: Test contents] First, the experimental animals, rats (24 animals), were acclimatized for five days using feed containing AIN-93M (the feed for the control group in Table 3 below, without the addition of microplastics). After a five-day acclimation period, the 24 rats were divided into four groups of six rats each: control group (group C), low molecular weight chitosan group (group L), medium molecular weight chitosan group (group M), and high molecular weight chitosan group (group H). After that, rats in each group were fed the MP-containing feed shown in Table 3, in which 0.0113 g (approximately 183,400 pieces) of microplastics were added per 1 kg of feed, once a day for four days, for a total of four times.Every day (around 10:00 AM), the weight, food intake, and water intake of each rat were measured, and feces were collected and frozen for storage. After a 4-day feeding period with the MP-containing diet, a 1-day fasting period was set up. On the 6th day, the day of measurement and dissection, dissection was performed under isoflurane anesthesia, and organs (heart, digestive tract (from the esophagus to the anus), liver, kidneys, and fat (epididymal fat and perirenal fat)) were removed, weighed, and frozen for storage. The 4-day feeding period with the MP-containing diet, the 5th day of fasting, and the 6th day of measurement and dissection are collectively referred to as the "main test period." For the animal testing (four-day feeding period), rats were housed in metabolic cages under an environment of room temperature 23±1°C, humidity 35±5%, and a 12-hour light-dark cycle (light period: 8:00 am to 8:00 pm). They were given paired feeding of MP-containing feed and ultrapure water ad libitum.

[0032] [Animal experiments: Test animals, feed, etc.] The experimental animals used were 24 male Sprague-Dawley rats aged 9 weeks, manufactured by Japan SLC Co., Ltd. The MP-containing feed used was the AIN-93M feed composition published by the US National Institute of Nutrition as the reference feed. Specifically, the feed used for acclimation was the MP-containing feed shown in Table 3 for the control group, but without the addition of microplastics. The MP-containing feed used in the animal testing was prepared by adding 0.0113 g (approximately 183,400 pieces) of microplastics to approximately 1 kg of feed, as shown in Table 3. The MP-containing feed used for the control group was prepared by replacing a portion of the cornstarch with a specified material, as appropriate. The microplastics used were the same as those used in the preliminary test described above. The low molecular weight chitosan used was Koyo Chitosan FL-80 from Koyo Chemical Co., Ltd., a lot with an average molecular weight of about 83,000 and a viscosity of about 3 mPa·s. The medium molecular weight chitosan used was Koyo Chitosan FM-80 from Koyo Chemical Co., Ltd., a lot with an average molecular weight of about 673,000 and a viscosity of about 20 mPa·s. The high molecular weight chitosan used was Koyo Chitosan FH-80 from Koyo Chemical Co., Ltd., a lot with an average molecular weight of about 1,877,000 and a viscosity of about 130 mPa·s. The average molecular weight and viscosity of chitosan were measured by the measurement methods described in the above embodiment.

[0033] Table 3 shows the composition of the MP-containing feed given to rats in each group.

[0034] [Table 3]

[0035] [Experimental results: weight change] The results of the weight changes in rats in each group are shown in FIG. The results of the weight change show the change in the average weight (average value of the measurements at 10 AM) of the six rats in each group during the test period. In Figure 1, the start date of this test period is designated as day 1 (first day).

[0036] [Experimental results: cumulative food intake] The cumulative food intake of rats in each group is shown in FIG. This cumulative food intake is the average cumulative food intake of six rats in each group during the four-day feeding period of the MP-containing diet.

[0037] [Experimental results: tissue weight] The results of the tissue weights of rats in each group are shown in FIG. The tissue weights were the average weights of the organs excised from six rats in each group on the final day of the study, expressed as the weight of each organ per 100 g of rat body weight (g / 100 g). As mentioned above, the five organs are the heart, digestive tract (from the esophagus to the anus), liver, kidneys, and fat (epididymal fat and perirenal fat).

[0038] [Experimental results: feces weight] The cumulative fecal weight of rats in each group is shown in FIG. The cumulative fecal weight results are the average cumulative fecal weight of the six rats in each group. For example, the cumulative feces weight from 0 to 72 hours in Figure 4 is the cumulative feces weight collected up to 72 hours after the start of the test period.

[0039] [Experimental results: MP excretion rate in feces] The results of MP excretion rate in feces for each group are shown in FIG. First, the amount of microplastics (MPs) in feces was calculated as follows. After freezing and thawing feces, 40 mg of feces was weighed and collected. This was then added to 200 mL of 30% HO solution (Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred at 60°C for 48 hours using a hot stirrer (AS ONE Corporation, RSH-1DN). The microplastics in the solution were then collected on a 10 μm pore PTFE membrane by vacuum filtration. After drying the membrane in a clean bench, the number of microplastics (in 40 mg) was counted using an LCD digital microscope (Alpha Mirage Co., Ltd., MRS-T5.1). The number of microplastics in the feces was calculated as follows: number of MPs counted × fecal weight (mg) / 40 (mg)). Next, the "number of microplastics ingested by the rats" by a given time was calculated based on the amount of food consumed by the rats by that time. The "MP excretion rate in feces" was calculated by dividing the number of microplastics in the feces from 0 to 120 hours by the number of microplastics ingested by the rat from 0 to 120 hours x 100, for example, when calculating the 120-hour value for Group C in Figure 5. The number of microplastics ingested by rats from 0 to 120 hours was calculated by multiplying the cumulative amount of food ingested from 0 to 120 hours by the weight ratio of microplastics in the food (0.0113 / (1000+0.0113)), and then multiplying it by the number density of 1.623×10 7 The number was calculated by multiplying by the number of particles / g.

[0040] [Experiment results: MP residual rate in the gastrointestinal tract] Figure 6 shows the residual rate of microplastics in the digestive tract (from the esophagus to the anus) (MP residual rate in the digestive tract) for each group. After natural thawing of the frozen digestive tract, the sections (stomach, small intestine, and large intestine) were separated and added to 200 mL of 10% KOH solution (Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred at 60°C for 24 hours using a hot stirrer (AS ONE Corporation, RSH-1DN). The microplastics in the solution were then collected on a PTFE membrane with a 10 μm pore size by suction filtration. After drying the membrane in a clean bench, the number of microplastics was counted using an LCD digital microscope (Alpha Mirage Co., Ltd., MRS-T5.1). The "MP residual rate in the digestive tract" was calculated by dividing the number of microplastics present in the digestive tract (the number of MPs measured using the method described above) by the number of microplastics ingested by the rats x 100.

[0041] [Animal Experiments: Review of Results] First, the results in Figure 2 confirmed that the daily food intake of each rat was approximately 17.4 g / day / rat, and that the daily MP intake of each rat was approximately 3,200 / day / rat (≒ 183,400 × 17.4 / 1,000). Furthermore, the results in Figure 4 confirmed that the cumulative feces weight was higher in the three groups: the low molecular weight chitosan group (group L), the medium molecular weight chitosan group (group M), and the high molecular weight chitosan group (group H) compared to the control group (group C). Furthermore, compared to the control group (group C), the low molecular weight chitosan group (group L), the medium molecular weight chitosan group (group M), and the high molecular weight chitosan group (group H) showed significantly higher values. Furthermore, the results in Figure 5 confirmed that the excretion rate of microplastics in feces was higher in the three groups - the low molecular weight chitosan group (group L), the medium molecular weight chitosan group (group M), and the high molecular weight chitosan group (group H) - compared to the control group (group C).Furthermore, compared to the control group (group C), the medium molecular weight chitosan group (group M) and the high molecular weight chitosan group (group H) showed significantly higher values. Furthermore, the results in Figure 6 confirmed that the residual rate of microplastics in the digestive tract was lower in the three groups - the low molecular weight chitosan group (group L), the medium molecular weight chitosan group (group M), and the high molecular weight chitosan group (group H) - compared to the control group (group C).Furthermore, compared to the control group (group C), the medium molecular weight chitosan group (group M) and the high molecular weight chitosan group (group H) showed significantly lower values. To summarize these results, it was confirmed that among chitosans, medium molecular weight chitosan and high molecular weight chitosan are effective ingredients that contribute to promoting the excretion of microplastics from the body (high molecular weight chitosan in particular is very effective).

[0042] [Agglutination test using artificial digestive fluid 1: Test details] First, artificial gastric juice (50 mL, pH 1.21) was placed in a 100 mL beaker, and 1.3 mg of microplastics or 1.3 mg of microplastics and 900 mg of medium-molecular-weight chitosan was added. The mixture was then stirred at 37°C for 2 hours. Then, artificial intestinal fluid (200 mL, pH: 6.86) and the artificial gastric fluid containing the microplastics were placed in a 500 mL beaker, and the pH was adjusted to either 7.0, 7.5, or 8.0 using sodium hydroxide. The mixture was stirred at 37°C for 22 hours, and then left to stand at 37°C for 24 hours. After standing, the sediment was filtered and the number of microplastics in the sediment was measured.

[0043] [Agglutination test 1 using artificial digestive fluid: artificial digestive fluid used] The artificial gastric juice and artificial intestinal juice used were prepared as follows in accordance with the 12th revised Japanese Pharmacopoeia. Artificial gastric juice was prepared by adding 2.0 g of weighed sodium chloride (Wako Pure Chemical Industries, special grade) and 7.0 mL of hydrochloric acid (Wako Pure Chemical Industries, for hazardous metals) to a 1000 mL measuring flask and diluting to 1000 mL using distilled water. To prepare the artificial intestinal fluid, 27.2 g of potassium dihydrogen phosphate (Wako Pure Chemical Industries, special reagent grade) was weighed out and diluted to 1000 mL with distilled water to prepare a 0.2 M potassium dihydrogen phosphate solution. Next, 4.0 g of sodium hydroxide (Wako Pure Chemical Industries, special reagent grade) was weighed out and diluted to 500 mL with distilled water to prepare a 0.2 N sodium hydroxide solution. Finally, 250 mL of the 0.2 M potassium dihydrogen phosphate solution and 118 mL of the 0.2 N sodium hydroxide solution were added to a 1000 mL volumetric flask and diluted to 500 mL with distilled water to prepare the artificial intestinal fluid. The microplastics used were blue-colored polyethylene particles from Cospheric, with particle sizes of 180–212 μm (average particle size approximately 200 μm), particle densities of 0.99–1.01 g / cc, and number densities of 2.54 × 10 5 It was 1 / g. The medium-molecular-weight chitosan used was the same as that used in the animal experiment.

[0044] [Flocculation test 1 using artificial digestive fluid: Percentage of precipitated MP] The proportion of microplastics in the sediment at each pH is shown in Figure 7. The "proportion of microplastics in the sediment" was calculated by dividing the number of microplastics in the sediment by the number of microplastics added x 100.

[0045] [Agglutination test using artificial digestive fluid 1: Examination of results] Based on the results in Figure 7, it can be inferred that the mechanism by which chitosan promotes the excretion of microplastics is due to the aggregation of chitosan with microplastics.

[0046] [Agglutination test using artificial digestive fluid 2: Test details] First, artificial gastric juice (30 mL, pH 1.21) was placed in a 50 mL beaker, and 100 mg each of microplastics and chitosan (low, medium, or high molecular weight chitosan) was added. The mixture was then stirred at room temperature (approximately 25°C) for 30 minutes. Then, artificial intestinal fluid (100 mL, pH: 6.86) and the artificial gastric fluid containing the microplastics and chitosan were placed in a 200 mL beaker, the pH was adjusted to 7.0-8.0 using sodium hydroxide, and the mixture was stirred at 37°C for 22 hours, and then left to stand at 37°C for 24 hours. After standing, the precipitated aggregates were filtered, and the recovered amount (dry weight) of the aggregates was measured.

[0047] [Agglutination test 2 using artificial digestive fluid: artificial digestive fluid used] The artificial gastric juice and artificial intestinal juice used were the same as those used in the agglutination test 1 using the artificial digestive juice described above. The microplastics used were the same as those used in the preliminary test described above. The medium-molecular-weight chitosan and high-molecular-weight chitosan used were the same as those used in the animal experiments described above. The low-molecular-weight chitosan used was Koyo Chitosan FL-80 from Koyo Chemical Co., Ltd., a lot with an average molecular weight of about 49,000 and a viscosity of about 2 mPa·s.

[0048] [Flocculation test using artificial digestive fluid 2: Amount of recovered aggregates and microscopic observation] The recovered amount of aggregate is shown in Table 4. The results of microscopic observation showing how chitosan aggregates microplastics in the collected aggregates are shown in Figures 8A to 8C. Figure 8A shows the results of observation at low magnification (60x), Figure 8B shows the results at medium magnification (180x), and Figure 8C shows the results at high magnification (1000x).

[0049] [Table 4]

[0050] [Agglutination test using artificial digestive fluid 2: Examination of results] Based on the results in Table 4 and Figures 8A-C, similar to the results of flocculation test 1 using artificial digestive fluid, it can be inferred that the mechanism by which chitosan promotes microplastic excretion is due to the flocculation of chitosan with microplastics. Furthermore, the results in Table 4 also confirmed that, compared to low molecular weight chitosan, medium molecular weight chitosan and high molecular weight chitosan have a stronger ability to aggregate microplastics.

Claims

1. A composition for promoting the excretion of microplastics from the body, containing chitosan with an average molecular weight of 650,000 or more as an active ingredient.

2. 2. A composition for promoting the excretion of microplastics from the body according to claim 1, wherein the average molecular weight of the chitosan is 800,000 or more and 4,000,000 or less.

3. 2. A composition for promoting the excretion of microplastics from the body according to claim 1, wherein the viscosity of a 0.5 wt% solution of the chitosan is 30 mPa·s or more and 2000 mPa·s or less.

4. A food for promoting the excretion of microplastics from the body, comprising the composition according to any one of claims 1 to 3.

5. A feed for promoting the excretion of microplastics from the body, comprising the composition according to any one of claims 1 to 3.

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