Strategies altering dietary nutrient composition, such as the addition of appropriate essential amino acids or phytochemicals, are effective in addressing the adverse effects of heat stress (HS) under rising temperatures. The new food ingredient L-theanine (LTA), a natural non-protein amino acid found in tea, showed a promising effect in alleviating HS. However, systematic studies on the mechanisms by which LTA mitigates HS are scarce. Here, we evaluated the mechanisms by which LTA alleviates HS both in vivo and in vitro. The results showed that LTA suppressed HS-induced decreases in cell viability, antioxidant enzyme activity, mitochondrial membrane potential and ATP content. It reduced reactive oxygen species levels and apoptosis in heat-stressed BRL-3A cells. In addition, LTA affected the expression of heat shock proteins, ribosomal proteins and apoptosis-relate genes during HS and HS recovery (HSR) process. Similar results were observed in heat-stressed rats. Mechanistically, the alleviating effect of LTA on HS may be mediated by heat shock factor 1 (Hsf1). Specifically, at the initiation of HS, LTA promoted the binding of Hsf1 to the promoter of heat shock protein family H member 1 (Hsph1), which facilitated Hsph1 transcription and accelerated the response to HS. Following the end of HS treatment, LTA repressed the expression of Hsph1, thus restoring intracellular homeostasis. Taken together, these results suggest that LTA effectively regulates the transcription of Hsph1 via Hsf1, thereby mitigating HS-induced hepatic injury. This provides scientific evidence supporting the potential of LTA, a promising anti-HS phytochemical that deserves further development.

High-protein diets (HPDs) have the potential to reduce body weight, yet excessive protein intake can induce hepatic metabolic dysregulation and insulin resistance. L-theanine (LTA), a unique amino acid abundantly present in tea leaves, regulates protein metabolism under HPD conditions. However, its influence on glucose and lipid metabolism remains unclear. In this study, Sprague-Dawley rats were fed either a standard maintenance diet (20% of energy from protein) or HPDs containing 30%, 40%, or 50% of energy from protein, and were administered LTA at different doses (0, 100, 200, or 400 mg kg-1·body weight-1) for 40 days. A combination of physiological and biochemical assessments, metabolomics, proteomics, and Western blot techniques was used to investigate the regulatory effects and mechanisms of LTA on glucose and lipid metabolism under HPD conditions. The 30% HPD did not cause notable metabolic changes, whereas the 40% and 50% HPDs led to hyperinsulinemia and hepatic lipid accumulation by enhancing gluconeogenesis and fatty acid synthesis while inhibiting fatty acid β-oxidation. LTA alleviated insulin elevation, hepatic steatosis, and lipid droplet accumulation caused by the 40% and 50% HPDs. Mechanistically, LTA enhanced peroxisome proliferator-activated receptor alpha (PPARα) expression and increased acyl-CoA dehydrogenase medium chain (ACADM) expression to promote mitochondrial fatty acid β-oxidation, while decreasing acetyl-CoA carboxylase alpha (ACACA) and phosphoenolpyruvate carboxykinase 1 (PCK1) expression, thereby suppressing lipid synthesis and gluconeogenesis. These findings highlight the potential of LTA to mitigate HPD-associated metabolic alterations, supporting its application as a functional food ingredient for metabolic health management.

ABSTRACT The global incidence of diabetic kidney disease (DKD) due to type 2 diabetes is rising and is becoming one of the most threatening complications. Excessive sugar intake accelerates DKD progression, highlighting safe, low‐calorie sugar substitutes as potential intervention. This study aimed to elucidate the effects of different sugar substitutes on DKD and explore their underlying mechanisms. We established a mouse model of DKD using a high‐fat diet and streptozotocin and systematically compared the effects of Mogroside V (MOG), stevioside (ST), sucralose (TGS), erythritol (ERT), and sucrose (SUC). DKD mice exhibited typical renal injury characteristics along with increased renal oxidative stress and inflammatory responses. MOG and ST interventions significantly improved insulin levels; reduced blood urea nitrogen, serum creatinine, and urinary microalbumin levels; restored renal tissue structure; and alleviated oxidative‐inflammatory damage in DKD mice. ERT and TGS also mitigated oxidative‐inflammatory damage but had weaker effects, whereas SUC failed to improve DKD. Combined metabolomics, quantitative polymerase chain reaction, and western blot analyses indicated that different sugar substitutes exert comprehensive metabolic protection by regulating glycerophospholipid metabolism, linoleic acid metabolism, AMPK, MAPK signaling pathways, and FcεRI signaling pathways. Specifically, MOG significantly alleviated oxidative stress and inflammatory responses in DKD mouse kidneys by suppressing the mRNA expression of Alox5 , Pla2g4 , Raf1 , Hras , Ma2pk1 , Mapk1 , and Cysltr1 , as well as p‐ERK and 5‐lipoxygenase protein expression. These findings provide scientific evidence supporting the nutritional value of sugar substitutes in DKD.

Summer black tea typically lacks the floral-fruity aroma and high catechin oligomer content of premium black tea, limiting consumer acceptance and resource utilization. We aimed to enhance the aroma and taste quality of summer black tea by introducing vibratory withering (VW), piling fermentation (PF), and their combination process (CP) into traditional processing (CK). Traditional (CK), VW, PF, and CP treatments were compared using sensory evaluation, physicochemical analysis, and integrated LC-MS, untargeted metabolomics, and HS-SPME/GC-MS volatile profiling. Our results demonstrated that CP considerably improved sensory quality, elevating theaflavins, theasinensins, and floral/fruity volatiles (e.g., geraniol, linalool, geranylacetone, β-ionone, α-ionone, nonanal, and trans-linalool oxide (furanoid), hexanal, 1-nonanol, citral, and benzaldehyde). VW activated the jasmonic acid pathway, promoting terpene biosynthesis and catechin oxidation, while PF enhanced carotenoid degradation and LOX pathway activity. The CP process improved the quality and levels of bioactive compounds in summer black tea, enhancing its sensory appeal and commercial value.

Epigallocatechin-3-gallate (EGCG), a major catechin in green tea, exhibits potent antioxidant and disease-preventive properties, but its application is limited by poor stability and bioavailability. This study aimed to address these challenges by preparing and characterizing three EGCG-loaded nanoparticles: chitosan-EGCG-tripolyphosphate nanoparticles (CE-NPs), β-cyclodextrin-EGCG (BE-NPs), and EGCG-nanostructured lipid carriers (NE-NPs). BE-NPs exhibited the highest loading performance and retention rate under thermal environment (89.78 % after 10 h at 80 °C). NE-NPs had the highest EGCG stability in alkaline condition (45 % after 4 h at pH 7.4). Compared to free EGCG, all NPs significantly improved in vitro bioaccessibility following incubation in simulated gastrointestinal digestion for 4 h; BE-NPs enhanced oral bioavailability by 1.71 times in vivo. Additionally, CE-NPs and NE-NPs increased the relative abundance of Faecalibaculum, Erysipelotrichaceae, and Bifidobacterium in the colons of Sprague-Dawley rats. These findings suggest that BE-NPs are a promising nano-delivery system for enhancing EGCG stability and bioavailability in healthy organisms.

Peanut oils, which are rich in unsaturated fatty acids (UFAs), offer significant health benefits, but are susceptible to oxidative rancidity during storage, resulting in a degraded nutritional value and potential health risks. Epigallocatechin gallate (EGCG), a potent natural antioxidant found in tea, exhibits promise for mitigating the oxidation of such oils; however, its poor lipophilicity limits its direct application in oil-based systems. EGCG was encapsulated using nanostructured lipid carriers (NLCs), and its effectiveness in preserving the quality and oxidative stability of peanut oil during storage was compared with a natural antioxidant, α-tocopherol. The EGCG-NLCs, with an average particle size of 156.7 ± 12.9 nm, exhibited encapsulation and loading efficiencies of 99.79 ± 0.00% and 6.74 ± 0.02%, respectively. Compared to the free EGCG, the EGCG-NLCs exhibited a superior radical scavenging activity and an improved lipophilicity. After 180 d storage under natural light, the EGCG-NLCs inhibited color changes in the peanut oil, increased the relative UFA content, and demonstrated reduced oxidative stability indices, with an optimal dose of 400 mg/kg. Compared to α-tocopherol, the EGCG-NLCs demonstrated a superior performance in preserving the oxidative stability and overall quality of peanut oil, highlighting their potential for use in food oil preservation applications.

ABSTRACT Heat stress (HS) induces intestinal inflammation and dysbiosis, and Bifidobacterium exhibits anti‐HS roles in the intestinal tract. l‐theanine (LTA) increases intestinal Bifidobacterium abundance in HS‐exposed mice and may modulate Hsf1 to alleviate HS‐mediated intestinal immune injury; however, the underlying mechanism remains unclear. This study found that LTA alleviated HS‐induced MODE‐K cell inflammatory injury by modulating Hsf1, and this effect was absent when Hsf1 expression was inhibited. In heat‐stressed Hsf1 knockout (KO) mice, LTA failed to regulate colon immunity and the expression of Hsf1 and its target proteins Hsp70 and Hsph1. Bifidobacterium longum (BL) ameliorated HS‐induced intestinal injury in pseudo‐germ‐free mice and inhibited the expression of Hsf1 and its target proteins, indicating its potential against HS; LTA in combination with BL was more effective than BL or LTA alone in modulating the above indices. Compared to the BL group, 200 µM LTA intervention using an in vitro co‐culture system increased BL abundance. Moreover, the co‐culture supernatant increased MODE‐K cell viability and IL‐10 and sIgA secretion under HS conditions, and this effect was not conspicuous following the targeted inhibition of Hsf1. These findings suggest that LTA mediates Hsf1 modulation of intestinal immunity by increasing the abundance of B.longum to alleviate HS. These findings provide scientific evidence for the development of anti‐HS functional foods and the extensive application of LTA.

Ulcerative colitis (UC) is closely related to impaired intestinal barrier function and imbalanced gut microbial communities. l-theanine shows great potential in maintaining intestinal integrity and regulating the gut microbiota and associated short-chain fatty acids (SCFAs). However, whether l-theanine can alleviate UC by repairing the intestinal barrier through these regulatory processes remains unclear. In this study, l-theanine was used to optimize the gut microbiota, and the restorative effect and mechanism of l-theanine in UC by repairing the gut barrier through the gut microbiota and SCFAs were investigated via fecal microbiota transplantation. The findings revealed that l-theanine regulated the gut microbiota structure, increased SCFA contents, and promoted gut barrier repair in UC mice. Moreover, l-theanine upregulated the protein and mRNA expression of G-protein-coupled receptor 43 (GPR43), AKT, and phosphatidylinositide 3-kinase (PI3K). These results indicated that l-theanine alleviates UC by repairing the gut barrier via regulating the gut microbiota and SCFAs through the GPR43/PI3K/AKT signaling pathway activation. This study provides a method of preventing and treating UC via l-theanine as a safe food dietary supplement.

Excessive alcohol consumption over a short period can result in acute alcohol-induced brain injury (AIBI), characterized by brain inflammation, oxidative stress imbalance, and cognitive impairment, such as a 20 % increase in TNF-alpha. L-Theanine (LTA), a unique non-protein amino acid found in tea leaves, is known to mitigate alcohol-induced immune disorders and oxidative stress. However, its protective role against AIBI is poorly understood. This study aimed to investigate the protective effects and underlying mechanisms of LTA in AIBI. We administered different doses of LTA (100, 200, 400 mg kg(-1)d(-1)) to mice for 28 days and established an AIBI model by feeding them a 5 % ethanol Lieber-DeCarli diet followed by an 8-day acute alcohol binge. LTA significantly reduced autonomic behavioral disorders, brain tissue damage, inflammatory factor release, oxidative stress imbalance, and neurotransmitter disorders caused by AIBI, with the 400 mg kg(-1)d(-1) dose being the most effective. Tandem mass tag proteomic analysis revealed that LTA primarily involves the cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) pathway. Quantitative PCR and western blotting confirmed that key proteins in this pathway, such as PKG(up arrow 1.5-fold, P < 0.01), PI3K (up arrow 1.2-fold, P < 0.01), p-AKT (up arrow 1.4-fold, P < 0.01) and p-CREB (up arrow 1.3-fold, P < 0.01) were significantly upregulated, whereas IP3R(down arrow 0.6-fold, P < 0.01) and MCU (down arrow 0.5-fold, P < 0.01) were downregulated. These results suggest that LTA alleviates acute alcoholic brain injury by activating the cGMP-PKG signaling pathway, offering a potential nutritional intervention strategy for AIBI protection.

Alcohol exposure induces kidney oxidative stress and inflammatory responses. L-theanine (LTA) can protect the kidneys through its antioxidant and immunomodulatory effects; however, its role and underlying mechanisms in alleviating alcoholic kidney injury remain unclear. In this study, LTA significantly ameliorated alcohol-induced kidney tissue structural damage, excessive release of inflammatory factors, and oxidative stress imbalance, with the 400 mg kg-1 day-1 dose group showing the most effective intervention. LTA inhibited the sphingolipid metabolism-S1PR2-JNK signaling pathway, reduced sphingosine levels, downregulated the S1PR2 proinflammatory receptor, blocked S1PR2 signal transduction, and subsequently suppressed JNK phosphorylation and AP-1 activity. Additionally, LTA activated the PPAR alpha and steroid synthesis pathway, promoting the production of endogenous anti-inflammatory steroids. These results indicate that LTA alleviates alcohol-induced kidney injury by inhibiting the sphingolipid metabolism-S1PR2-JNK pathway and activating the PPAR alpha and steroid synthesis pathways, providing a safe and effective nutritional intervention strategy for alcoholic kidney injury.

Sugar substitutes that maintain the homeostasis of glucose, lipid, and protein metabolism are important for nutritional intervention in type 2 diabetes mellitus (T2DM). However, the specific metabolic effects remain unclear. The aim of this study was to systematically compare the effects of four common sugar substitutes on a high-fat diet (HFD) combined with a streptozotocin (STZ)-induced T2DM mouse model from the perspective of hepatic glucose, lipid, and protein metabolism. In this study, based on the establishment of a T2DM mouse model induced by an HFD combined with STZ and nontargeted metabolomics, the effects of four sugar substitutes on regulating and improving sugar, lipid, and protein metabolism were systematically evaluated. The results showed that mogroside V (MOG), stevioside (ST), and erythritol (ERT) enhanced protein synthesis via the mammalian target of the rapamycin/p-P70S6K pathway. MOG and ST also improved glucose and lipid metabolism by activating the phosphor-AMP-activated protein kinase (p-AMPK) pathway and upregulating peroxisome proliferator-activated receptor alpha/carnitine palmitoyltransferase 1. Sucralose primarily improves lipid metabolism by downregulating sterol regulatory element-binding protein 1, whereas ERT increases lipid droplet accumulation in the liver. These findings provide a foundation for the application of sugar substitutes in T2DM nutritional interventions.

The disturbance of gut microbiota and its metabolites are considered to be the causes of ulcerative colitis (UC), which leads to immune abnormalities. Diet is the most important regulator of gut microbiota; therefore, it has a beneficial impact on UC. A novel food ingredient, l-theanine, alters the gut microbiota, thereby regulating gut immunity. However, whether l-theanine prevents UC by altering the gut microbiota, as well as the underlying mechanisms, remains unknown. Here, l-theanine was used to optimize the gut microbiota and its metabolites. Furthermore, to explore the mechanism by which l-theanine prevents UC, an l-theanine fecal microbiota solution was used to prevent dextran sulfate sodium-induced UC via fecal microbiota transplantation. Improvements in the colonic structure, colon histology scores, immune factors (IL-10), and inflammatory factors (IL-1β) demonstrated the preventive effect of l-theanine on UC. The 16S rDNA and metabolomic results showed that tryptophan-, short chain fatty acid-, and bile acid-related microbiota, such as Muribaculaceae, Lachnospiraceae, Alloprevotella, and Prevotellaceae were the dominant. Flow cytometry results showed that l-theanine decreased helper T (Th)1 and Th17 immune responses, and increased Th2 and T-regulatory immune responses via regulation of antigen-presenting cell responses, such as dendritic cells and macrophages. Therefore, l-theanine regulated the immune response of colon CD4 + T cells to dendritic cell and macrophage antigen presentation via tryptophan-, short chain fatty acid-, and bile acid-related microbiota, thereby preventing dextran sulfate sodium-induced UC.

Heat stress compromises the intestinal mucosal barrier, whereas bifidobacteria preserve its structural integrity. L-theanine (LTA) elevates intestinal Bifidobacterium abundance in heat-stressed mice, thereby alleviating barrier damage. This protection may occur through heat shock factor 1 (Hsf1) regulation, though the precise mechanism requires further elucidation. We investigated the mechanism for the protective effect of L-theanine against heat stress: the LTA protects the intestinal mucosal barrier to alleviate heat stress through Hsf1 and is mediated by Bifidobacterium for Hsf1 regulation. These investigations employed LTA interventions in heat-stressed MODE-K cells, Hsf1-knockout mice, pseudo-germ-free mice, and LTA-Bifidobacterium longum (BL) co-culture experiments. In heat-stressed MODE-K cells, LTA intervention significantly increased cell viability, improved mucosal barrier function, and inhibited Hsf1 and its target proteins Hsp70 and Hsph1. These effects were no longer observed in the Hsf1-inhibited cells but were enhanced in the Hsf1-overexpressing cells. Consistently, LTA failed to protect the intestinal mucosal barrier in heat-stressed Hsf1-knockout mice. In pseudo-germ-free mice and co-culture experiments, BL improved intestinal morphology, protected mucosal barrier function, and suppressed Hsf1 and its target proteins. The effects of L-theanine and BL were superior to those of BL alone. These findings indicate that L-theanine protects the intestinal mucosal barrier in a manner dependent on Bifidobacterium and the Hsf1 signaling pathway.

Mogroside V (MOG) improves type 2 diabetes mellitus (T2DM) mice gut health via PI3K/AKT and NF-κB, while stevioside (ST) mainly regulates NF-κB. Erythritol (ERT) has minimal benefits. Sucralose (TGS) and sucrose (SUC) harm colon microbiota.

Background/Objectives: Acute alcohol consumption can cause intestinal dysfunction, whereas L-theanine (LTA) has shown the potential to support intestinal health. We explored L-theanine’s ability to protect against acute alcohol-induced injury. Methods: Male C57BL/6 mice were administered LTA for 28 d and then underwent acute alcohol intestinal injury modeling for 8 days. Results: The results revealed that LTA ameliorated alcohol-induced pathological damage in the duodenum and gut permeability, improved secretory immunoglobulin A (SIgA) content, and reduced oxidative stress, inflammatory markers, and serum lipopolysaccharide (LPS) content in mice. Furthermore, LTA restored the composition of the intestinal flora, increasing the abundance of Alloprevotella, Candidatus_Saccharimonas, Muribaculum, and Prevotellaceae_UCG-001. Additionally, LTA increased beneficial metabolites, such as oxyglutaric acid and L-ascorbic acid, in the HIF-1 pathway within the enrichment pathway. Further investigation into the HIF-1 signaling pathway identified up-regulation of claudin-1, HIF-1α, occludin, and ZO-1, and down-regulation of TLR4, PHD2, p65 NF-κB, TNF-α, and IFN-γ mRNA and protein levels. Conclusions: These results suggest that LTA may enhance the intestinal barrier by activating the HIF-1 signaling pathway to regulate the TLR4/NF-κB/HIF-1α axis, thereby reducing acute alcoholic intestinal injury.

Background: Chronic alcohol intake impairs intestinal function, while L-theanine (LTA) may support intestinal health. However, the protective effects of LTA to chronic alcoholic intestinal injuries remain unclear. Methods: SD rats were administered LTA for 8 weeks and then co-administered Lieber–DeCarli liquid alcohol feed and LTA for 4 weeks to establish a chronic alcoholic intestinal injury model and investigate the mitigating influence of LTA on chronic alcoholic intestinal injury. Results: LTA alleviated duodenal pathology and intestinal permeability injury and reduced intestinal oxidative stress and inflammatory response, thereby mitigating chronic alcoholic intestinal injury. Additionally, LTA ameliorated disturbances in the gut microbiota induced by chronic alcohol intake by increasing the beneficial bacteria abundance (Ruminococcus and Odoribacter) and decreasing the harmful bacteria abundance (Enterococcus). Moreover, LTA altered the metabolic profiles associated with ethanol and linoleic (LA) and arachidonic acid (AA) metabolism. ADH6, ALDH2, and ACSS1 mRNA and protein levels were upregulated by LTA, whereas those for CYP2E1, FADS2, ALOX-5, and COX-1 were downregulated. Concurrently, LTA increased the levels of metabolites, such as acetyl-CoA, and decreased the levels of ethanol, acetaldehyde, acetic acid, LA, AA, PGE2, 13-HPODE, and LTB4. Conclusions: L-theanine mitigates chronic alcoholic intestinal injury by regulating intestinal alcohol and LA-AA metabolism. Our findings support the functional potential of the dietary supplement LTA and highlight its potential for addressing chronic intestinal injury caused by chronic alcohol intake.

L-theanine (LTA) is a key component in tea plants and is commonly used as a functional ingredient and dietary supplement. In a recent study, we investigated the potential antiaging properties of LTA using a D-galactose-induced L6 skeletal muscle aging cell model. The results showed that LTA treatment improved cell viability and antioxidant enzyme activities while reducing levels of proinflammatory factors and advanced glycation end products. Additionally, LTA demonstrated the ability to decrease senescence-associated beta-galactosidase-positive cells, lower reactive oxygen species and MDA levels, preserve mitochondrial function, inhibit apoptosis, and alleviate cell cycle arrest in the G2/M phase. These protective effects may be attributed to the activation of the p53/p21/CDK4 pathway, regulation of cell cycle-related protein expression, promotion of cell proliferation, and regulation of apoptosis-related protein expression through the p53/Bax/Bcl-2 pathway.

BACKGROUND: Chronic excessive alcohol consumption can lead to alcoholic fatty liver, posing substantial health risks. l-Theanine (LTA) and epigallocatechin gallate (EGCG) in tea exert antioxidant and hepatoprotective effects. However, the combined effects of LTA and EGCG on rats with alcoholic fatty liver, and the underlying mechanisms of such effects, remain unclear. In this study, Sprague Dawley (SD) rats were fed with alcohol for 6 weeks to induce alcoholic fatty liver. Subsequently, for another 6 weeks, the rats were administered LTA (200 mg kg(-1) day(-1)), EGCG (200 mg kg(-1) day(-1)), or a combination of LTA with EGCG (40 mg kg(-1) day(-1) l-Thea +160 mg kg(-1) day(-1) EGCG), respectively. RESULTS: The combined use of LTA and EGCG for alcoholic fatty liver disease had more significant effects than their individual administration. This combination reduced the activity of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as the levels of hepatic triglyceride (TG), malondialdehyde (MDA), and reactive oxygen species (ROS) in the rats. The combined intervention also increased hepatic superoxide dismutase (SOD) and glutathione peroxidase activity. Reductions in hepatic fat accumulation and inflammatory responses were observed. The mechanism underlying these effects primarily involved the inhibition of fatty acid synthesis and the alleviation of lipid peroxidation through the downregulation of the mRNA and protein expression of TNF-alpha, SREBP1c, and CYP2E1 and the upregulation of the mRNA and protein expression of ADH1, ALDH2, Lipin-1, PPAR alpha PPAR alpha, AMPK, and PGC-1 alpha, thereby promoting the oxidative decomposition of fatty acids and reducing the synthesis of cholesterol and glucose. CONCLUSION: L-Theanine and EGCG appear to be able to alleviate alcoholic fatty liver by modulating lipid metabolism and ameliorating oxidative stress, indicating their potential as natural active ingredients in anti-alcoholic fatty liver food products. (c) 2024 Society of Chemical Industry.

Heat stress can impair the male reproductive function. l-Theanine and dihydromyricetin have biological activities against heat stress; however, their effects on reproductive function in heat-stressed males are unclear. In this study, male mice were given l-theanine, dihydromyricetin, or a combination of both for 28 days, followed by 2 h of heat stress daily for 7 days. All interventions alleviated heat stress-induced testicular damage, improving the testicular organ index, sperm density, acrosome integrity, sperm deformity rate, and hormone levels. Treatment increased the antioxidant enzyme activity and decreased the markers of oxidative and inflammatory stress in the testes. A combination dose of 200 + 200 mg kg(-1) d(-1) showed the best protective effect. The potential mechanism involves the regulation of HSP27 and HSP70, which regulate the levels of reproductive hormones through the StAR/Cyp11a1/Hsd3b1/Cyp17a1/Hsd17b3 pathway, alleviate inflammation and oxidative stress through the P38/NF-kappa B/Nrf2/HO-1 pathway, and regulate the Bcl-2/Fas/Caspase3 apoptotic pathway. Overall, l-theanine and dihydromyricetin may play a protective role against heat stress-induced reproductive dysfunction, suggesting their potential use in heat stress-resistant foods.