Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods.

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.

Quality prediction of whole-grain rice noodles using backpropagation artificial neural network.

BACKGROUND: Whole-grain rice noodles are a kind of healthy food with rich nutritional value, and their product quality has a notable impact on consumer acceptability. The quality evaluation model is of great significance to the optimization of product quality. However, there are few methods that can establish a product quality prediction model with multiple preparation conditions as inputs and various quality evaluation indexes as outputs. In this study, an artificial neural network (ANN) model based on a backpropagation (BP) algorithm was used to predict the comprehensive quality changes of whole-grain rice noodles under different preparation conditions, which provided a new way to improve the quality of extrusion rice products. RESULTS: The results showed that the BP-ANN using the Levenberg-Marquardt algorithm and the optimal topology (4-11-8) gave the best performance. The correlation coefficients (R2) for the training, validation, testing, and global data sets of the BP neural network were 0.927, 0.873, 0.817, and 0.903, respectively. In the validation test, the percentage error in the quality prediction of whole-grain rice noodles was within 10%, indicating that the BP-ANN could accurately predict the quality of whole-grain rice noodles prepared under different conditions. CONCLUSION: This study showed that the quality prediction model of whole-grain rice noodles based on the BP-ANN algorithm was effective, and suitable for predicting the quality of whole-grain rice noodles prepared under different conditions. © 2024 Society of Chemical Industry.

Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism.

Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.

Chitosan-glucose Maillard reaction products and their preservative effects on fresh grass carp (Ctenopharyngodon idellus) fillets during cold storage.

BACKGROUND: A decreasing freshness occurrs in Ctenopharyngodon (C.) idellus during post-mortem storage. In the present study, chitosan-glucose Maillard reaction products (CG-MRPs) were prepared by heating chitosan and glucose at different reaction temperatures and then used for preserving the freshness and quality of C. idellus fillets during cold storage (4 °C). RESULTS: High temperature enhanced the chitosan-glucose Maillard reaction and promoted the accumulation of melanoidins and intermediate compounds. The reducing power of CG-MRPs increased with an increasing reaction temperature. CG-MRPs inhibited the microbial growth rate and retarded the oxidation of proteins, lipids and nucleotides in C. idellus fillets by suppressing total bacterial count, total volatile basic nitrogen, thiobarbituric acid reactive substances and K values during cold storage. Furthermore, CG-MRPs prolonged shelf-life. The fillets treated with the CG-MRPs prepared at 120 °C showed an especially longer shelf-life (7 days). The preservative effect of CG-MRPs on fillets was the result of antibacterial components (melanoidins, reductone and furfural) in CG-MRPs and a reducing power against the oxidative degradation of proteins, nucleotides and lipids in C. idellus fillets. CONCLUSION: The present study demonstrates that, for C. idellus fillets, treatment with CG-MRPs prepared at 120 °C for 40 min could be a feasible approach for maintaining the freshness of C. idellus fillets and prolonging shelf-life during cold storage. © 2018 Society of Chemical Industry.

Adenosine A2A receptor deficiency attenuates the somnogenic effect of prostaglandin D2 in mice.

Prostaglandin D2 (PGD2) is one of the most potent endogenous sleep promoting substances. PGD2 activates the PGD2 receptor (DPR) and increases the extracellular level of adenosine in wild-type (WT) mice but not DPR knockout (KO) mice, suggesting that PGD2-induced sleep is DPR-dependent, and adenosine may be the signaling molecule that mediates the somnogenic effect of PGD2. The aim of this study was to determine the involvement of the adenosine A2A receptor (A2AR) in PGD2-induced sleep. We infused PGD2 into the lateral ventricle of WT and A2AR KO mice between 20:00 and 2:00 for 6 h, and electroencephalograms and electromyograms were simultaneously recorded. In WT mice, PGD2 infusion dose-dependently increased non-rapid eye movement (non-REM, NREM) sleep, which was 139.1%, 145.0% and 202.7% as large as that of vehicle-treated mice at doses of 10, 20 and 50 pmol/min, respectively. PGD2 infusion at doses of 20 and 50 pmol/min also increased REM sleep during the 6-h PGD2 infusion and 4-h post-dosing periods in WT mice to 148.9% and 166.7%, respectively. In A2AR KO mice, however, PGD2 infusion at 10 pmol/min did not change the sleep profile, whereas higher doses at 20 and 50 pmol/min increased the NREM sleep during the 6-h PGD2 infusion to 117.5% and 155.6%, respectively, but did not change the sleep in the post-dosing period. Moreover, PGD2 infusion at 50 pmol/min significantly increased the episode number in both genotypes but only enhanced the episode duration in WT mice. The results demonstrate that PGD2-induced sleep in mice is mediated by both adenosine A2AR-dependent and -independent systems.

Understanding the structural disorganization of starch in water-ionic liquid solutions.

Using synchrotron X-ray scattering analyses and Fourier transform infrared spectroscopy, this work provides insights into the solvent effects of water : [C2mim][OAc] solutions on the disorganization of a starch semi-crystalline structure. When a certain ratio (10.2 : 1 mol/mol) of water : [C2mim][OAc] solution is used, the preferential hydrogen bonding between starch hydroxyls and [OAc](-) anions results in the breakage of the hydrogen bonding network of starch and thus the disruption of starch lamellae. This greatly facilitates the disorganization of starch, which occurs much easier than in pure water. In contrast, when 90.8 : 1 (mol/mol) water : [C2mim][OAc] solution is used, the interactions between [OAc](-) anions and water suppress the solvent effects on starch, thereby making the disorganization of starch less easy than in pure water. All these differences can be shown by changes in the lamellar and fractal structures: firstly, a preferable increase in the thickness of the crystalline lamellae rather than that of the amorphous lamellae causes an overall increase in the thickness of the semi-crystalline lamellae; then, the amorphous lamellae start to decrease probably due to the out-phasing of starch molecules from them; this forms a fractal gel on a larger scale (than the lamellae) which gradually decreases to a stable value as the temperature increases further. It is noteworthy that these changes occur at temperatures far below the transition temperature that is thermally detectable as is normally described. This hints to our future work that using certain aqueous ionic liquids for destructuration of the starch semi-crystalline structure is the key to realize green processes to obtain homogeneous amorphous materials.

Structural features of rice starch-protein system: Influence of retrogradation time and quick-freezing temperature.

This work investigated the effect of retrogradation time (0 h, 2 h, 4 h, 6 h, 8 h) and freezing temperature (-20 °C, -32 °C, -80 °C) on the muti-scale structures of the rice starch-protein system of quick-frozen wet rice noodles. The Relative crystallinity and porosity of the rice starch-protein system increased with increasing retrogradation time. However, while longer retrogradation does lead to an improvement in relative crystallinity, it also results in significant damage to the microstructure. When the retrogradation time was 6 h, the microstructure of the rice starch-protein system was less damaged and the quality was better. The mass fractal dimension and relative crystallinity of the rice starch-protein system exhibited an increase as the freezing temperature was decreased from -20 to -80 °C. Additionally, the retrogradation degree of starch decreased, the size of ice crystals decreased, and the disruption of microforms was reduced. The muti-scale structures of the rice starch-protein systems were similar when quick-frozen at temperatures of -32 and -80 °C. Therefore, the optimal treatment method for practical production is to quick-freeze at -32 °C and age for 6 h to obtain high-quality quick-frozen wet rice noodles.

Effect of Thermal Processing on Food Allergenicity: Mechanisms, Application, Influence Factor, and Future Perspective.

Thermally processed foods are essential in the human diet, and their induced allergic reactions are also very common, seriously affecting human health. This review covers the effects of thermal processing on food allergenicity, involving boiling, water/oil bath heating, roasting, autoclaving, steaming, frying, microwave heating, ohmic heating, infrared heating, and radio frequency heating. It was found that thermal processing decreased the protein electrophoretic band intensity (except for infrared heating and radio frequency heating) responsible for destruction of linear epitopes and changed the protein structure responsible for the masking of linear/conformational epitopes or the destruction of conformational epitopes, thus decreasing food allergenicity. The outcome was related to thermal processing (e.g., temperature, time) and food (e.g., types, pH) condition. Of note, as for conventional thermal processing, it is necessary to control the generation of the advanced glycation end products in roasting/baking and frying, and the increase of structural flexibility in boiling and water/oil bath heating, autoclaving, and steaming must be controlled; otherwise, it might increase food allergenicity. As for novel thermal processing, the temperature nonuniformity of microwave and radio frequency heating, low penetration of infrared heating, and unwanted metal ion production of ohmic heating must be considered; otherwise, it might be the nonuniformity and low effect of allergenicity reduction and safety problems.

Research progress in ultrasound and its assistance treatment to reduce food allergenicity: Mechanisms, influence factor, application and prospect.

Food allergy is a serious public health problem, which is mainly induced by food allergens (mainly allergenic proteins). Ultrasound can change protein structure, suggesting its potential to decrease food allergenicity. The review concluded the mechanism and influence factors of ultrasound to reduce food allergenicity. The effects of ultrasound alone on some major allergenic foods such as tree nuts, shellfish, fish, egg, soy, milk, and wheat were also discussed. Moreover, ultrasound pre- and post-treatments were combined with heating, glycation, germination, hydrolysis, fermentation, irradiation and polyphenol treatment for reducing food allergenicity were also evaluated. It was found that ultrasound induced structural changes even degradation of protein to reduce the allergenicity mainly due to cavitation effects. The reduction of allergenicity through ultrasound alone was affected by ultrasound power, time, frequency and food types, while, apart from these factors, it was affected by ultrasound order and the assisted technologies conditions during ultrasound-assisted technologies. Compared to ultrasound alone treatment, the ultrasound-assisted technology exhibited high efficiency of allergenicity reduction because ultrasound treatment caused protein unfolding to accelerate allergen modification of the assisted technologies for masking and disrupting more epitopes. Thus, ultrasound treatment, especially ultrasound-assisted technologies under appropriate conditions, was promising for producing hypoallergenic foods.

Effect of the Combined Ultrasound with Other Technologies on Food Allergenicity: Ultrasound before, under, and after Other Technologies.

Food allergies are a main public health disease in the world. Ultrasound is an environmentally friendly technology that typically leads to protein unfolding and loss of protein structure, which means it has the potential to be combined with other technologies to achieve a great reduction of allergenicity in foods. This review concludes the effects of the combined ultrasound with other technologies on food allergenicity from three combinations: ultrasound before other technologies, ultrasound under other technologies, and ultrasound after other technologies. Each combination affects food allergenicity through different mechanisms: (1) as for ultrasound before other technologies, ultrasound pretreatment can unfold and lose the protein structure to improve the accessibility of other technologies to epitopes; (2) as for ultrasound under other technologies, ultrasound can continuously affect the accessibility of other technologies to epitopes; (3) as for ultrasound after other technologies, ultrasound further induces structural changes to mask and disrupt the epitopes. The reduction of allergenicity is related to the ultrasound/other technologies conditions and food types/cultivars, etc. The comparison of ultrasound before, under, and after other technologies to decrease food allergenicity should be further investigated in the future. The combination of ultrasound with other technologies is promising to produce hypoallergenic foods.

Ion presence during thermal processing modulates the performance of rice albumin/anthocyanin binary system.

Thermal processing with salt ions is widely used for the production of food products (such as whole grain food) containing protein and anthocyanin. To date, it is largely unexplored how salt ion presence during thermal processing regulates the practical performance of protein/anthocyanin binary system. Here, rice albumin (RA) and black rice anthocyanins (BRA) were used to prepare RA/BRA composite systems as a function of temperature (60-100 °C) and NaCl concentration (10-40 mM) or CaCl2 concentration (20 mM). It was revealed that the spontaneous complexing reaction between RA and BRA was driven by hydrophobic interactions and hydrogen bonds and becomes easier and more favorable at a higher temperature (≤90 °C), excessive temperature (100 °C), however, may result in the degradation of BRA. Moreover, the salt ion presence during thermal processing may bind with RA and BRA, respectively, which could restrict the interaction between BRA and RA. Additionally, the inclusion of Na+ or Ca2+ at 20 mM endowed the binary system with strengthened DPPH radical scavenging capacity (0.95 for Na+ and 0.99 for Ca2+). Notably, Ca2+ performed a greater impact on the stability of the system than Na+.

Mechanism for the synergistic gelation of konjac glucomannan and κ-carrageenan.

The synergistic interaction gels (SIGs) can be created by blending konjac glucomannan (KGM) and κ-carrageenan, and have been applied to modify and improve the rheological and texture properties of food system. However, the assembly behaviors between them are still unclear. This work revealed that the presence of KGM promoted phase transition of nearby κ-carrageenan molecules probably by contributing to entropy increment. Subsequently, the rest of κ-carrageenan transformed into helical structure, assembled into a series of laterally arranged trigonal units and formed a three-dimensional network. In KGM/κ-carrageenan SIGs, the size of high density domains (Ξ) in aggregates and the distance of these high density domains (ξ) were narrowed firstly and then enlarged as increasing of KGM content. These nano-scale structure features were responsible for the relative higher gel strength for KGM/κ-carrageenan SIGs with proportion ratios of 1:9 (K1C9) and 3:7 (K3C7). This study serves to facilitate the design and production of SIGs with the requisite performance characteristics.

Including protein hydrolysates during thermal processing mitigates the starch digestion of resulted starch-based binary matrix.

Staple foods with starch and protein components are usually consumed after thermal processing. To date, how including protein hydrolysates (with varied hydrolysis degrees) tailors the structure and digestion features of starch-based matrix with thermal processing has not yet been sufficiently understood. Here, corn starch (CS), soy protein isolate (SPI), and soy protein isolate hydrolysates (SPIH) with different hydrolysis time (5-60 min) were used to prepare starch-based binary matrices. With the addition of SPI or SPIH during thermal processing, the resultant binary systems exhibited higher thermal stability (breakdown visibility was increased by 1.9-10.8 times), denser networks, and fewer short-range orders (R995/1022 was decreased by up to 15.3 %). These structural changes allowed an inhibited starch digestion within the binary system, especially with increased SPI or SPIH content. Compared with CS, the content of resistant starch (RS) for CS-SPI binary complex (10:3 w/w) increased from 9.89 % to 16.69 %. Compared to SPI, SPIH inclusion displayed a stronger inhibitory effect on starch digestion since the reduced molecule size of SPIH probably enhanced its interplays with starch or amylase. For instance, the 10:3 w/w starch-SPIH 60 binary matrix possessed the highest RS content (19.07 %).

Towards superior biopolymer gels by enabling interpenetrating network structures: A review on types, applications, and gelation strategies.

Gels derived from single networks of natural polymers (biopolymers) typically exhibit limited physical properties and thus have seen constrained applications in areas like food and medicine. In contrast, gels founded on a synergy of multiple biopolymers, specifically polysaccharides and proteins, with intricate interpenetrating polymer network (IPN) structures, represent a promising avenue for the creation of novel gel materials with significantly enhanced properties and combined advantages. This review begins with the scrutiny of newly devised IPN gels formed through a medley of polysaccharides and/or proteins, alongside an introduction of their practical applications in the realm of food, medicine, and environmentally friendly solutions. Finally, based on the fact that the IPN gelation process and mechanism are driven by different inducing factors entwined with a diverse amalgamation of polysaccharides and proteins, our survey underscores the potency of physical, chemical, and enzymatic triggers in orchestrating the construction of crosslinked networks within these biomacromolecules. In these mixed systems, each specific inducer aligns with distinct polysaccharides and proteins, culminating in the generation of semi-IPN or fully-IPN gels through the intricate interpenetration between single networks and polymer chains or between two networks, respectively. The resultant IPN gels stand as paragons of excellence, characterized by their homogeneity, dense network structures, superior textural properties (e.g., hardness, elasticity, adhesion, cohesion, and chewability), outstanding water-holding capacity, and heightened thermal stability, along with guaranteed biosafety (e.g., nontoxicity and biocompatibility) and biodegradability. Therefore, a judicious selection of polymer combinations allows for the development of IPN gels with customized functional properties, adept at meeting precise application requirements.

Controlling sodium chloride concentration modulates the supramolecular structure and sol features of wheat starch-acetylated starch binary matrix.

The sol performance of wheat starch (WS) matrix incorporating acetylated starch (AS) is crucial for the processing and quality features of wheat products. From a supramolecular structure view, how regulating salt (sodium chloride) concentration modulates the sol features, e.g., pasting, zero-shear viscosity (ZSV) and thixotropy of WS-AS binary matrix was explored. Compared to the salt-free counterpart, the saline matrices exhibited a delayed pasting profile and a decreased viscoelasticity. Thereinto, the sol at 0.02 M NaCl exhibited the smallest ZSV (23,710 Pa·s) and the greatest in-shear recovery ratio (33.7 %). Such variations could be attributed to the weakened coil-helix, nematic-smectic and isotropy-anisotropy transitions from a side-chain liquid-crystalline perspective. Meanwhile, the correlation length (ξ) and radius of gyration (Rg) obtained from small angle X-ray scattering analysis were increased by 5.2 and 9.6 Å respectively, which disclosed a restrained entanglement and an enhanced chain mobility. These results would provide a reference for the design of fluid/semisolid products with optimized qualities.

Incorporating ions during thermal processing tailors the microstructure and practical features of rice starch/anthocyanin binary system.

Understanding the interplay among salt ions, anthocyanin and starch within food matrices under thermal conditions is important for the development of starch-based foods with demanded quality attributes. However, how salt ions presence influences the microstructure and properties of starch/anthocyanin binary system remains largely unclear. Herein, indica rice starch (IRS) and rice anthocyanin (RA) were used to construct an IRS-RA binary system, with thermal treatment under different concentrations of Na+ (10-40 mM) and types of salt ions (Na+ and Ca2+). The incorporation of salt ions induced the formation of a porous gel matrix, and destroyed the hydrogen bond between starch and anthocyanin through electrostatic interactions, reducing the storage modulus and radius of gyration of the binary system, and increasing the relative crystallinity (from 1.08 % to 1.51 % (20 mM Na+) and 1.69 % (20 mM Ca+)) of the IRS-RA binary system at 90 °C. Also, the DPPH radical scavenging ability of the binary system at 90 °C was enhanced upon incorporating salt ions (0.93 for Na+ condition and 0.94 for Ca2+ condition at 20 mM ion concentration). It is noteworthy that Ca2+ inclusion had more significant effects than the case for Na+ presence, presumably due to the increased charge density.

Changing the ionic strength can regulate the resistant starch content of binary complex including starch and protein or its hydrolysates.

Ionic strength condition is a crucial parameter for food processing, but it remains unclear how ionic strength alters the structure and digestibility of binary complexes containing starch and protein/protein hydrolysates. Here, the binary complex with varied ionic strength (0-0.40 M) was built by native corn starch (NS) and soy protein isolate (SPI)/hydrolysates (SPIH) through NaCl. The inclusion of SPI and SPIH allowed a compact network structure, especially the SPIH with reduced molecule size, which enriched the resistant starch (RS) of NS-SPIH. Particularly, the higher ionic strength caused the larger nonperiodic structures and induced loosener network structures, largely increasing the possibility of amylase for starch digestion and resulting in a decreased RS content from 19.07 % to 15.52 %. In other words, the SPIH hindered starch digestion while increasing ionic strength had the opposite effect, which should be considered in staple food production.

Incorporating edible oil during cooking tailors the microstructure and quality features of brown rice following heat moisture treatment.

While brown rice (BR) has numerous nutritional properties, the consumption potential of which is seriously restricted since the poor cooking quality and undesirable flavor. Here, edible oils (pork lard and corn oil, 1-5 wt%) were incorporated during the cooking of BR following heat moisture treatment. Incorporating corn oil rather than lard significantly ameliorated the texture properties (e.g. hardness, cohesiveness, and chewiness) and sensory properties of cooked BR. Both lard- and corn oil-incorporated cooked BR showed obvious structural changes accompanied by the formation of amylose-lipid complexes during cooking. It was confirmed that the incorporation of lard and corn oil allowed a higher degree of short-range molecular order, more V-type starch crystallites, and elevated nano-structural arrangements. Additionally, a decreased hardness (from 559.04 g to 424.18 g and 385.91 g, respectively) and enriched resistant starch (RS) were also observed, the highest RS content (15.95 % and 16.32 %, respectively) was observed when 1 wt% of lard and corn oil were incorporated.

Enhancing thermal stability and mechanical resilience in gelatin/starch composites through polyvinyl alcohol integration.

In practical scenarios, destabilizing the physical attributes of natural polymers such as gelatin and starch occurs readily when exposed to specific moisture levels and heat. In this context, this work was carried out to assess the impact of PVA addition (up to 13 wt%) on the structure and physical properties of a 6:4 (w/w) gelatin/starch blend. The inclusion of PVA unfolded the molecular chains of gelatin and starch, thereby disrupting gelatin α-helices and impeding biopolymer crystallization. This facilitated hydrogen-bonding interaction between PVA and the two biopolymers, enhancing the stability of the molecular network structure. Rheological results indicate that composites (added with 4 % or 7 % PVA) with good compatibility exhibited excellent mechanical properties and deformation resistance. The addition of PVA elevated the gelling temperature (Tgel) of the composites from 41.31 °C to 80.33 °C; the tensile strength and elongation at break were increased from 2.89 MPa to 3.40 MPa and 341.62 % to 367.56 %, respectively; and the thermal stability was also apparently improved, signifying the effective enhancement of the physical properties of gelatin/starch-based composites and the broadening of their application scope. This work could provide insights into the development of biodegradable natural/synthetic polymer composites with application-beneficial characteristics.

Ingesting retrograded rice (Oryza sativa) starch relieves high-fat diet induced hyperlipidemia in mice by altering intestinal bacteria.

High-fat diet is a risk factor for many chronic diseases, whose symptoms are probably regulated by ingesting food ingredients such as resistant starch. For cooked rice stored in cold-chain, the starch component can retrograde to generate ordered structures (helices and crystallites) and become resistant. However, the role of retrograded starch in managing hyperlipidemia symptoms is insufficiently understood. Here, compared to the normal high-fat diet, ingesting retrograded starch reduced the triglyceride and low-density lipoprotein cholesterol levels of high-fat diet mice by 17.69% and 41.33%, respectively. This relieved hyperlipidemia could be linked to the changes in intestinal bacteria. Retrograded starch intervention increased the relative abundance of Bacteroides (2.30 times higher), which produces propionic acid (increased by 8.26%). Meanwhile, Bacteroides were positively correlated with butyric acid (increased by 98.4%) with strong anti-inflammatory functions. Hence, retrograded starch intervention may regulate the body's health by altering intestinal bacteria.