Sea-land composite dietary fiber composition and application thereof in regulating intestinal flora

Abstract

The invention provides a sea-land composite dietary fiber composition and application thereof in regulation and control of intestinal flora. The composition is prepared by mixing araboxylan and fucoidin according to a mass ratio of 1: 1. The composition is formed by mixing arabinoxylan from land plants and fucoidin from marine plants according to the mass ratio of 1: 1, the composition is proved to have remarkable nitrite adsorption capacity, growth of pathogenic bacteria is effectively inhibited in the nitrite-containing environment, meanwhile, proliferation of beneficial bacteria is promoted, and the nitrite adsorption capacity is improved. Therefore, the composition can be applied to development of prebiotic supplements and intestinal micro-ecological regulation products.

Description

Technical Field

[0001] This invention relates to the field of natural products, specifically to a marine-terrestrial composite dietary fiber composition and its application in regulating gut microbiota. Background Technology

[0002] Dietary fiber is a class of carbohydrates primarily found in plant-based foods that cannot be directly digested and absorbed by the human small intestine, but are beneficial to health. It can enter the lower intestine intact and exert various health benefits by regulating the composition and function of the gut microbiota and promoting the production of short-chain fatty acids. Because gut microbiota metabolism of dietary fiber exhibits high substrate specificity, different fiber structures can induce the expression of specific carbohydrate-active enzymes and selectively enrich corresponding microbiota. Therefore, existing studies often use single, purified dietary fiber models to analyze the causal relationship between fiber structure, gut microbiota function, and health effects. However, increasing clinical evidence suggests that single dietary fiber interventions suffer from unstable effects and significant individual variability. In recent years, research trends have gradually shifted towards synergistic intervention strategies using multiple dietary fibers, aiming to utilize the physicochemical properties of different fibers to construct synergistic mechanisms to more effectively regulate the gut microbiota and enhance host health benefits.

[0003] The stability of the gut microbiota is influenced not only by host genetics, nutrient supply, and intermicrobial interactions, but also by key microenvironmental factors such as bile acid concentration, redox potential, and nitrite levels. Studies have shown that nitrite, as a key influencing factor in the gut microenvironment, can inhibit the growth of beneficial bacteria (such as Bifidobacteria) while promoting the proliferation of pathogenic bacteria (such as Escherichia coli).

[0004] Arabicoxylan (AX) is mainly derived from the cell walls of terrestrial plants, with β-(1→4)-xylose as the main chain, linked by arabinose branches in varying proportions. Fucoidan (FUC), on the other hand, is a sulfated polysaccharide from marine brown algae, with a main chain composed of α-(1→3) or α-(1→4) linked fucose, rich in sulfate ester groups and various accessory monosaccharides. These two substances differ significantly in structure and origin, and exhibit different specificities and metabolic effects in regulating the intestinal microenvironment and flora. Currently, research on AX and FUC largely focuses on the application of single components, lacking a systematic exploration of the synergistic effects of terrestrial and marine dietary fiber complexes. However, using a single type of dietary fiber alone has significant limitations. Literature reports indicate that while AX can promote the production of beneficial short-chain fatty acids such as propionic acid in the short term, its effects are difficult to sustain in some individuals, possibly due to the metabolic adaptation of gut microbiota to specific substrates or fermentation saturation. While FUC has strong fermentation capacity and targeted proliferation of specific beneficial bacteria, its highly sulfated structure easily releases large amounts of free sulfate after degradation in the intestine, providing substrates for sulfate-reducing bacteria (such as *Desulfovibrio*), thereby promoting the production of the toxic metabolite hydrogen sulfide (HS). High concentrations of HS are cytotoxic and may damage the intestinal epithelial barrier function, exacerbating intestinal inflammation. Therefore, relying on purified dietary fiber from a single source may not only lead to unstable or transient probiotic effects but also pose safety risks due to the accumulation of metabolic byproducts. Thus, developing a composite system of terrestrial and marine dietary fibers is of great significance. Utilizing the complementary advantages of their structural characteristics, fermentation rates, and microbial targeting, it is hoped that more sustained and balanced gut microecological regulation can be achieved, while reducing the metabolic risks associated with single-fiber diets, providing a new strategy for precision nutritional intervention. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the above-mentioned technologies, namely, to provide a marine and terrestrial composite dietary fiber composition and its application in regulating intestinal flora, so as to overcome the limitations of single dietary fiber in regulating intestinal flora, and to provide a composition that adsorbs nitrite, inhibits harmful bacteria and promotes beneficial bacteria through the synergistic effect of marine and terrestrial dietary fiber.

[0006] Therefore, in a first aspect of the present invention, a marine-terrestrial composite dietary fiber composition is proposed, which is composed of arabinoxylan and fucoidan mixed in a mass ratio of 1:1.

[0007] According to an embodiment of the present invention, the marine-terrestrial composite dietary fiber composition is prepared by mixing arabinoxylan from terrestrial plants and fucoidan from marine plants in a 1:1 mass ratio. The composition has been verified to have a significant nitrite adsorption capacity and effectively inhibits the growth of pathogenic bacteria in nitrite-containing environments while promoting the proliferation of beneficial bacteria. This composition can be applied to the development of prebiotic supplements and intestinal microecological regulation products.

[0008] In a second aspect of the invention, the invention proposes the application of the above-described marine-terrestrial composite dietary fiber composition in the preparation of products that adsorb nitrite.

[0009] According to the application of the embodiments of the present invention, the adsorption rate of the marine and terrestrial composite dietary fiber composition for nitrite in a simulated gastric and intestinal environment is significantly higher than that of the single component (arabinoxylan or fucoidan), indicating that the composition exhibits a significant synergistic effect and has the ability to efficiently remove nitrite from the environment, providing a physicochemical basis for its application in the regulation of gastrointestinal function.

[0010] Optionally, the application is to adsorb nitrite in the gastrointestinal environment.

[0011] In a third aspect of the invention, the invention proposes the application of the above-described marine and terrestrial composite dietary fiber composition in the preparation of products that regulate intestinal flora.

[0012] Optionally, the application is to regulate the gut microbiota in the presence of nitrite.

[0013] Optionally, the regulation of intestinal flora involves inhibiting the growth of potentially pathogenic bacteria and promoting the proliferation of beneficial bacteria.

[0014] Furthermore, the pathogenic bacteria include Escherichia coli LF82; the beneficial bacteria include Bifidobacterium longum subsp. Longum.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] Figure 1 This invention relates to the adsorption capacity of dietary fiber for nitrite in a simulated gastrointestinal environment, according to an embodiment of the present invention; wherein, Figure 1 a shows the adsorption capacity of different dietary fiber samples for nitrite under pH=2.0 (simulated gastric acid environment); Figure 1 b shows the adsorption capacity of the same dietary fiber sample for nitrite under pH=7.0 (simulating the neutral environment of the intestine);

[0017] Figure 2 This invention relates to the effect of nitrite on the growth of *B. longum* subsp. *longum* and *E. coli* LF82 according to an embodiment of the present invention; wherein, Figure 2 a represents the growth curves of B. longum subsp. longum under conditions with and without nitrite; Figure 2 b represents the growth curves of E. coli LF82 under conditions containing / without nitrite;

[0018] Figure 3 This invention relates to an embodiment of the effect of dietary fiber treatment on the growth and activity of B. longum subsp. longum in a nitrite environment. Figure 3 a shows the plate colony counts (CFU / mL) of B. longum subsp. longum at 0, 12, and 24 h in culture systems containing (10 mM) and without (0 mM) nitrite. Figure 3 b represents a comparison of the growth rates of B. longum subsp. longum in different dietary fiber groups under nitrite conditions after 12 hours of cultivation. Figure 3 c represents the concentration of residual nitrite in the supernatant of each group after 24 hours of culture.

[0019] Figure 4 To illustrate the effect of dietary fiber treatment on the growth and activity of E. coli LF82 in a nitrite environment according to embodiments of the present invention; Figure 4 a shows the plate colony count (CFU / mL) of E. coli LF82 at 0, 12, and 24 h under different dietary fiber treatments in culture systems containing (10 mM) and without (0 mM) nitrite. Figure 4 b represents a comparison of the growth rate of E. coli LF82 in each dietary fiber group under nitrite environment after 12 hours of cultivation; Figure 4 c represents the concentration of residual nitrite in the supernatant of each group after 24 hours of incubation. Detailed Implementation

[0020] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0021] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0022] The test materials used in this invention are all common commercial products and can be purchased on the market.

[0023] Among them, arabinoxylan (AX) comes from AgriFiber Solutions LLC in the United States.

[0024] Fucoidan (FUC) is derived from Qingdao Mingyue Seaweed Group Co., Ltd., China.

[0025] The marine and land-based complex dietary fiber composition is a mixture of AX and FUC in a 1:1 mass ratio.

[0026] Escherichia coli LF82 was obtained from Shanghai Luwei Technology Co., Ltd.

[0027] Bifidobacterium longum subsp. longum was obtained from the China Industrial Microbial Culture Collection Center.

[0028] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0029] Example 1: Determination of the in vitro adsorption capacity of dietary fiber for nitrite.

[0030] (1) Simulated gastrointestinal environment: Dietary fiber adsorption of nitrite:

[0031] ① Take 0.50g of different dietary fiber samples (including AX, FUC and FAX combination) and 25mL of sodium nitrite (0.5mM) and place them in a centrifuge tube, and mix thoroughly.

[0032] ② Adjust the pH value to 2.0 (simulating the gastric environment) and 7.0 (simulating the intestinal environment) using 1M hydrochloric acid and 1M sodium hydroxide, respectively.

[0033] ③ Place the mixture in a 37℃ constant temperature shaker and shake for 120 min in the dark. Centrifuge at 5,000 r / min for 5 min at room temperature and collect the supernatant for subsequent nitrite concentration determination.

[0034] (2) Nitrite determination (Griess method):

[0035] ① Griess reagent preparation: Mix 0.1% (w / v) N-(1-naphthyl)ethylenediamine dihydrochloride with 1% (w / v) p-aminobenzenesulfonic acid (dissolved in 5% phosphoric acid solution) at a volume ratio of 1:1, and use immediately after preparation.

[0036] ② Preparation of standard curve solutions: Prepare nitrite standard solutions with concentrations of 0, 0.02, 0.04, 0.06, 0.08, 0.1, and 0.2 mM, respectively.

[0037] ③ Colorimetric reaction and detection: Add 150 μL of the supernatant sample, 20 μL of Griess reagent, and 130 μL of deionized water to each well of a 96-well plate. Mix thoroughly and incubate in the dark for 30 min. Measure the absorbance at 548 nm and calculate the residual nitrite concentration based on the standard curve.

[0038] The results are as follows Figure 1 As shown, in simulated gastric and intestinal environments, the adsorption rate of nitrite by the FAX composition was significantly higher than that of the single components AX and FUC. This result reveals that the combination of AX and FUC in a 1:1 ratio exhibits a significant synergistic effect, demonstrating the ability to efficiently remove nitrite from the environment, thus providing a physicochemical basis for its application in the regulation of gastrointestinal function.

[0039] Example 2: Determination of the effect of nitrite on the growth characteristics of B. longum subsp. longum and E. coli LF82

[0040] (1) Determination of growth curves of B. longum subsp. longum in nitrite-free environments.

[0041] ① Preparation of RCM liquid medium: Dissolve 10.0 g / L beef meal, 10.0 g / L peptone, 3.0 g / L yeast extract, 1.0 g / L soluble starch, 5.0 g / L glucose, 0.5 g / L cysteine ​​hydrochloride, 5.0 g / L sodium chloride, and 3.0 g / L sodium acetate in 300 mL of double-distilled water. Adjust the pH to 6.80 ± 0.1 and autoclave at 121 °C for 30 min. For solid medium, add 2% (w / v) agar.

[0042] ② Strain activation: The frozen B. longum subsp. longum strain was inoculated onto the surface of RCM solid medium plates and cultured at 39°C in an anaerobic environment for about 48 hours to revive and activate the strain.

[0043] ③ Bacterial Culture: Under aseptic conditions, single colonies of bacterial growth were picked and inoculated into 5 mL of RCM liquid medium. A control group without nitrite and an experimental group containing 10 mM sodium nitrite were set up. After inoculation, the cultures were placed in an anaerobic incubator at 39°C and incubated continuously for 24 hours. Samples were taken every 2 hours (0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 hours) to measure the absorbance (OD) of the bacterial culture at 590 nm. 590 Record the values ​​at each time point. Plot the culture time on the x-axis, and OD... 590 The growth curve was plotted with the values ​​on the ordinate to analyze the effect of nitrite on the growth kinetics of the bacteria.

[0044] (2) Growth curve determination of E. coli LF82 in nitrite-free environments

[0045] ① Preparation of 5% porcine mucin carbon-free E (NCE) medium: Dissolve monopotassium phosphate (3.94 g / L), dipotassium phosphate (5.9 g / L), diammonium hydrogen phosphate (4.68 g / L), and magnesium sulfate heptahydrate (2.46 g / L) in deionized water to prepare a basic carbon-free E (NCE) medium. Add sterile porcine mucin to a final concentration of 0.5% (w / v) and autoclave at 121℃ for 30 min.

[0046] ② Preparation of LB solid culture medium: Weigh 5g yeast extract, 10g tryptic peptone, and 10g sodium chloride and dissolve them in 1L deionized water. Add 2% (w / v) agar and adjust the pH to 7.0 with NaOH. Autoclave at 121℃ for 20min.

[0047] ③ Strain activation: The frozen E. coli LF82 strain was inoculated onto LB solid culture plates and cultured at 37°C under anaerobic conditions for about 24 hours to complete the strain activation.

[0048] ④ Bacterial Culture: Under aseptic conditions, single colonies of bacterial growth were picked and inoculated into 5 mL of NCE liquid medium. A control group without nitrite and an experimental group containing 2 mM sodium nitrite were established. After inoculation, the cultures were placed in an anaerobic incubator at 37°C and incubated continuously for 24 hours. Samples were taken every 2 hours (0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 hours) to measure the absorbance (OD) of the bacterial culture at 600 nm. 600 Record the values ​​at each time point. Plot the culture time on the x-axis, and OD... 600 The growth curve was plotted with the values ​​on the ordinate to analyze the effect of nitrite on the growth kinetics of the bacteria.

[0049] The results are as follows Figure 2 As shown, the growth of *B. longum* subsp. *longum* was significantly inhibited under 10 mM nitrite conditions, reaching a stationary phase after 12 hours. Conversely, for *E. coli* LF82, the growth rate was accelerated and the cell density was higher under 2 mM nitrite conditions, also reaching a stationary phase in approximately 12 hours. This suggests that nitrite may inhibit the growth of beneficial bacteria, promote the growth of potentially harmful bacteria, and disrupt the balance of the intestinal flora.

[0050] Example 3: Effects of dietary fiber treatment on the growth and activity of B. longum subsp. longum and E. coli LF82 in nitrite-containing and nitrite-free environments.

[0051] (1) The effect of dietary fiber treatment on the growth and activity of B. longum subsp. longum in the presence and absence of nitrite was determined.

[0052] ① Culture medium preparation: RCM liquid culture medium was prepared according to the method in Example 2. In the experimental group containing dietary fiber, 0.5 g / mL of the test fiber sample (including the combination of AX, FUC, and FAX) replaced glucose in the RCM basal medium as the sole carbon source; in the experimental group containing nitrite, 10 mM nitrite was added. The blank control group was a carbon-free culture medium, and the positive control group used 0.5 g / mL glucose as the carbon source.

[0053] ② Effect of dietary fiber treatment on B. longum subsp. longum under nitrite-free conditions: Activated B. longum subsp. longum bacterial culture was inoculated at a 6% (v / v) inoculation rate into 10 mL of RCM medium containing different dietary fibers as the sole carbon source and free of nitrite, and incubated at 37℃ in an anaerobic incubator. Samples were taken at 0, 12, and 24 h of culture, serially diluted, and spread onto LB agar plates. After 24 h of anaerobic incubation, colony-forming units (CFU / mL) were counted to assess the effect of each dietary fiber as a prebiotic on B. longum subsp. longum.

[0054] ③ Effect of dietary fiber treatment on B. longum subsp. longum under nitrite stress: Based on the above system, 10 mM nitrite was added to culture media containing different dietary fibers to simulate nitrite exposure. The same concentration of bacterial suspension was inoculated and cultured anaerobically at 37℃ for 24 h. Samples were taken at the same time points (0, 12, and 24 h) and plate colony counts (CFU / mL) were performed to assess the effect of dietary fiber on B. longum subsp. longum under nitrite stress.

[0055] ④ Determination of residual nitrite: After cultivation, the bacterial cultures of each group were centrifuged at 5,000 r / min for 5 min at room temperature, and the supernatant was collected. The concentration of residual nitrite in the supernatant was determined using the Griess method described in Example 1 to evaluate the effect of each dietary fiber on B. longum subsp. longum in a nitrite environment.

[0056] (2) Effects of dietary fiber on the growth and activity of E. coli LF82 in environments with and without nitrite.

[0057] ① Culture medium preparation: NCE liquid culture medium was prepared according to the method in Example 2. 0.5 g / mL of the dietary fiber sample to be tested (including a combination of AX, FUC, and FAX) was added to the experimental group culture medium as a potential functional component. For the nitrite-containing experimental group, sodium nitrite was additionally added to a final concentration of 2 mM. The blank control group used carbon-free NCE culture medium, and the positive control group used 0.5 g / mL glucose as the sole carbon source. Solid LB culture medium was used for colony counting, and its preparation method was the same as in Example 2.

[0058] ② Effect of dietary fiber treatment on E. coli LF82 under nitrite-free conditions: Activated E. coli LF82 bacterial suspension was inoculated at a 2% (v / v) inoculation rate into 10 mL of NCE liquid medium containing different dietary fibers (AX, FUC, FAX combinations) and free of nitrite, and incubated at 37℃ in an anaerobic incubator. Samples were taken at 0, 12, and 24 h at the start of incubation, serially diluted, and spread onto LB agar plates. After anaerobic incubation at 37℃ for 18-24 h, colony forming units (CFU / mL) were counted to evaluate the effect of each dietary fiber on the growth of E. coli LF82.

[0059] ③ Effect of dietary fiber treatment on E. coli LF82 under nitrite conditions: Based on the above system, 2 mM sodium nitrite was added to NCE medium containing dietary fiber to construct a nitrite stress environment. The same concentration of bacterial suspension (2% v / v) was inoculated and cultured continuously at 37℃ under anaerobic conditions for 24 h. Samples were taken at the same time points of 0, 12, and 24 h for plate colony counting (CFU / mL) to investigate the effect of dietary fiber on E. coli LF82 in the presence of nitrite.

[0060] ④ Determination of residual nitrite: After cultivation, the bacterial cultures of each group were centrifuged at 5,000 r / min for 5 min at room temperature, and the supernatant was collected. The concentration of residual nitrite in the supernatant was determined using the Griess method described in Example 1 to evaluate the effect of each dietary fiber on E. coli LF82 in a nitrite environment.

[0061] The results are as follows Figure 3 and Figure 4 ,like Figure 3As shown, in a nitrite-free environment (0 mM), AX significantly promoted the growth of *B. longum* subsp. *longum* at 12 h, with a proliferation-promoting effect superior to the positive control (glucose), FAX, FUC, and the blank control group, indicating that AX itself possesses excellent prebiotic properties. However, under stress containing 10 mM nitrite, the FAX composition exhibited significant advantages: its growth-promoting effect on *B. longum* subsp. *longum* was the most pronounced, significantly higher than AX, FUC, and other control groups, and this promoting effect was consistent with the trend of nitrite adsorption capacity of each component. Calculations of the proliferation rate revealed that the FAX-treated group showed a significantly increased proliferation rate at 12 h. Furthermore, after 24 h of culture, the residual nitrite concentration in the supernatant of the FAX group was significantly lower than that of other experimental groups, indicating that it maintained highly efficient adsorption activity in the bacterial co-culture system. The above results indicate that the FAX composition of this application can not only serve as a fermentable substrate to support the growth of B. longum subsp. longum, but also effectively reduce the concentration of nitrite in the environment, alleviating its inhibitory effect on probiotics, thereby synergistically promoting the proliferation of beneficial bacteria. This dual function reveals the potential of FAX to achieve positive regulation of the gut microbiota through a "nutrient supply + environmental purification mechanism".

[0062] like Figure 4 As shown, in a nitrite-free environment (0 mM), compared with the blank control group and the glucose-positive control group, AX, FUC, and FAX did not significantly promote the growth of E. coli LF82, indicating that these dietary fibers cannot be effectively utilized by this bacterium as a carbon source or fermentation substrate, and do not possess prebiotic properties that promote its proliferation. However, under stress containing 2 mM nitrite, the FAX composition exhibited a significant inhibitory effect: its growth inhibition effect on E. coli LF82 was the most significant, with a significantly lower total colony count than other experimental groups, and the order of inhibition intensity was FAX > FUC > AX. This trend is highly consistent with the adsorption capacity of each component for nitrite. Further analysis showed that at 12 h, the proliferation rate of the FAX-treated group was significantly lower than that of other groups; simultaneously, after 24 h, the residual nitrite concentration in the supernatant of the FAX group was also significantly lower than that of other groups, indicating that it has a sustained and efficient adsorption capacity. The above results indicate that FAX does not inhibit E. coli LF82 directly, but rather indirectly mediates the inhibition of this pathogen by efficiently adsorbing nitrite from the environment, further supporting its application value in maintaining intestinal flora balance.

[0063] In summary, according to embodiments of the present invention, the marine and terrestrial dietary fiber composition FAX exhibits excellent nitrite adsorption capacity, significantly superior to single components. In a simulated intestinal environment containing nitrite, FAX can effectively inhibit the growth of E. coli LF82 while significantly promoting the proliferation of B. longum subsp. longum, demonstrating dual biological activity. All raw materials used are of natural plant origin, safe, non-toxic, edible, and possess good biocompatibility. The formulation is simple and easy to scale up, making it suitable for prebiotic supplements and intestinal health intervention products for special medical purposes. Therefore, this application reveals for the first time a novel application of terrestrial and marine dietary fiber in synergistically regulating harmful and beneficial bacteria under nitrite stress, which has significant scientific value and broad application prospects.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A marine-terrestrial composite dietary fiber composition, characterized in that, It is made by mixing arabinoxylan and fucoidan in a mass ratio of 1:

1.

2. The marine and terrestrial composite dietary fiber composition as described in claim 1, characterized in that, The arabinoxylan is extracted from terrestrial plants, and the fucoidan is extracted from marine plants.

3. The application of the marine and terrestrial composite dietary fiber composition as described in claim 1 in the preparation of products that adsorb nitrite.

4. The application as described in claim 3, characterized in that, The application is to adsorb nitrite in the gastrointestinal environment.

5. The application of the marine and terrestrial composite dietary fiber composition as described in claim 1 in the preparation of products that regulate intestinal flora.

6. The application as described in claim 5, characterized in that, The application is to regulate the intestinal flora in the presence of nitrite.

7. The application as described in claim 5, characterized in that, The regulation of intestinal flora involves inhibiting the growth of potentially pathogenic bacteria and promoting the proliferation of beneficial bacteria.

8. The application as described in claim 7, characterized in that, The pathogenic bacteria include Escherichia coli LF82; the beneficial bacteria include Bifidobacterium longum subsp. Longum.

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