Yakult Knowledge
Login

Latest News

Gut Health and Metabolic Syndrome

Metabolic syndrome (MetSy) is an alarming precursor to type 2 diabetes and cardiovascular disease, affecting a growing number of Australian adults.¹ 

While diet, physical inactivity, and lifestyle factors are well-known contributors, emerging research points to another key player: the gut microbiome. Could supporting gut health be the missing link in reducing metabolic risk?

What is metabolic syndrome?

Metabolic syndrome is characterised by a cluster of interrelated cardiometabolic risk factors:²

  • Excess abdominal (central) adiposity
  • Atherogenic dyslipidaemia – elevated triglycerides and/or reduced HDL cholesterol
  • Hypertension
  • Impaired glucose regulation or elevated fasting glucose

These factors share a common underlying mechanism: insulin resistance associated with central adiposity. MetSy development is further influenced by:³

  • Genetic and early life factors: intrauterine environment, early growth patterns
  • Lifestyle behaviours: physical inactivity, poor sleep, unhealthy dietary patterns

Linking Metabolic Syndrome and Gut Health

Emerging evidence suggests that the gut microbiome may play a significant role in the development and progression of metabolic syndrome. The trillions of microbes in the gastrointestinal tract interact with host metabolism, influencing glucose regulation, lipid metabolism, inflammation, and energy balance.4 For healthcare professionals, understanding these mechanisms can inform dietary strategies to complement conventional metabolic management. 

Figure 1. Overview of the gut–metabolism connection, illustrating how diet, lifestyle, and therapeutic interventions influence the gut microbiome and highlighting potential microbiome-targeted treatment strategies.

Key gut–metabolic mechanisms include:

  1. Energy harvest and adiposity: 

Certain bacteria, such as gram-positive Firmicutes, extract more calories from dietary substrates, potentially contributing to weight gain and central adiposity. Firmicutes increased the fermentation of otherwise indigestible carbohydrates into short-chain fatty acids (SCFAs), which were then absorbed and utilised for gluconeogenesis and lipogenesis.5 The Firmicutes/Bacteroidetes (F/B) ratio has been extensively studied as a potential biomarker for obesity and metabolic diseases, but the findings remain inconsistent.6 

  1. Short-chain fatty acids (SCFAs): 

Produced from fibre fermentation, SCFAs like acetate, propionate, and butyrate support insulin sensitivity, modulate appetite, and maintain gut barrier integrity.3

  1. Bile acid metabolism: 

Gut microbes convert primary bile acids to secondary bile acids, enhancing local intestinal immunity and limiting pathogenic growth.7

  1. Metabolic endotoxaemia: 

Dysbiosis and increased intestinal permeability may allow lipopolysaccharides (LPS) to enter circulation, promoting systemic low-grade inflammation and insulin resistance.3

Diet, Gut Microbiome, and Metabolic Risk

Diet is the most powerful modulator of gut microbiota:⁸

  • Animal-based diets increase bile-tolerant species and microbial metabolites such as trimethylamine (TMA), which the liver converts to Trimethylamine-N-oxide (TMAO), a compound associated with atherosclerosis and cardiovascular risk.
  • Plant-based, fibre-rich diets promote beneficial taxa (Bifidobacterium, Lactobacillus) and enhance butyrate and propionate acid production, improving insulin sensitivity and lipid metabolism.

No single diet fits all individuals, so personalised approaches remain essential. However, the Mediterranean diet was shown to have positive effects on lipid profile, glycaemic control and blood pressure.9 When combined with increased physical activity, it offers a sustainable approach to managing metabolic syndrome.10 

Gut Microbiome and Pharmacotherapy

Treatments for metabolic diseases, include metformin and statins, and faecal microbiota transplantation (FMT) can interact with gut microbiota, and the microbiome may in turn influence treatment efficacy:

  • Metformin alters microbial communities linked to bile acid metabolism and gas metabolism. Baseline microbiome profiles can affect therapeutic response.11, 12
  • Statins (e.g., rosuvastatin) may work more effectively in individuals with higher abundance of Lactobacillaceae and Bifidobacteriaceae.12
  • Faecal Microbiota Transplantation (FMT): effective for recurrent Clostridioides difficile infection, but evidence for metabolic improvements is mixed.⁹

Gut Microbiota and Therapeutic Opportunities

Recent research highlights the potential of modulating the gut microbiota to support metabolic health. Certain probiotic strains have shown promising results:

  • Lactobacillus gasseri SBT2055 and Bifidobacterium breve have been associated with reductions in body mass and improvements in lipid metabolism by promoting beneficial changes in the gut microbiome.13
  • The Lacticaseibacillus paracasei Shirota (LcS) strain, unique to Yakult, has been shown to reduce glycoalbumin levels compared to controls, suggesting it may help improve metabolic markers in obese prediabetic individuals. Further research is needed to fully understand how LcS influences these outcomes.14

Prebiotics such as inulin, particularly oligofructose-enriched forms, have been linked to reductions in weight, BMI, waist circumference, and diastolic blood pressure in people with diabetes.15

Synbiotics, which combine probiotics with prebiotic dietary fibre from fruits and vegetables, can also support metabolic health. Studies have shown benefits such as lower fasting glucose and triglycerides, increased HDL-cholesterol, and reductions in BMI and body fat mass.16

While these findings are encouraging, further research is needed to clarify the underlying mechanisms, long-term effects, and how individual microbiome differences influence outcomes. Moving toward personalised, evidence-based therapies will require interdisciplinary collaboration, standardised research methods, and large-scale clinical trials to translate these promising insights into routine practice.

Take-home messages:

  • MetSy and gut health are linked: Gut microbiota influences metabolism, inflammation, and energy balance.
  • Diet matters: Fibre-rich, plant-based, or Mediterranean-style diets support beneficial gut microbes and metabolic health.
  • Targeted interventions help: Probiotics, prebiotics, and synbiotics could improve weight, glucose, and lipid outcomes, but effects are strain- and individual-specific.
  • Personalisation is key: Combine diet, lifestyle, and conventional therapies for optimal, patient-centred results.

References:

  1. Australian R. RACGP – The metabolic syndrome. Racgp.org.au. Published 2017. https://www.racgp.org.au/afp/2013/august/the-metabolic-syndrome/
  2. Wutthi-in M, Cheevadhanarak S, Yasom S, et al. Gut Microbiota Profiles of Treated Metabolic Syndrome Patients and their Relationship with Metabolic Health. Scientific Reports. 2020;10(1). doi:10.1038/s41598-020-67078-3
  3. Sabitha Sasidharan Pillai, Gagnon CA, Foster C, Ashraf AP. Exploring the gut microbiota: Key insights into its role in obesity, metabolic syndrome, and type 2 diabetes. The Journal of Clinical Endocrinology & Metabolism. 2024;109(11). doi:10.1210/clinem/dgae499
  4. Emmanuel Henry Ezenabor, Aishat Abimbola Adeyemi, Oluyomi Stephen Adeyemi. Gut Microbiota and Metabolic Syndrome: Relationships and Opportunities for New Therapeutic Strategies. Scientifica. 2024;2024(1). doi:10.1155/2024/4222083
  5. Shetye B, Hamilton FR, Bays HE. Bariatric surgery, gastrointestinal hormones, and the microbiome: an Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022. Obes Pillars. 2022;2:100015. doi: 10.1016/j.obpill.2022.100015.
  6. Boulangé CL, Neves AL, Chilloux J, Nicholson JK, Dumas ME. Impact of the gut microbiota on inflammation, obesity, and metabolic disease. Genome Med. 2016;8(1):42–422. doi: 10.1186/s13073-016-0303-2.
  7. Oliphant K, Allen-Vercoe E. Macronutrient metabolism by the human gut microbiome: major fermentation by-products and their impact on host health. Microbiome. 2019;7(1):91.
  8. Qureshi W, Dar MA, Rather MY. New therapy for metabolic syndrome: Gut microbiome supplementation. World J Diabetes. 2024 Sep 15;15(9):1833-1836. doi: 10.4239/wjd.v15.i9.1833. 
  9. Horvath A, Zukauskaite K, Hazia O, Balazs I, Stadlbauer V. Human gut microbiome: Therapeutic opportunities for metabolic syndrome-Hype or hope? Endocrinol Diabetes Metab. 2024 Jan;7(1):e436. doi: 10.1002/edm2.436. 
  10. Scaglione S, Di Chiara T, Daidone M, Tuttolomondo A. Effects of the Mediterranean Diet on the Components of Metabolic Syndrome Concerning the Cardiometabolic Risk. Nutrients. 2025;17(2):358. doi:10.3390/nu17020358
  11. Diaz-Perdigones CM, Munoz-Garach A, Alvarez-Bermudez MD, Moreno-Indias I, Tinahones FJ. Gut microbiota of patients with type 2 diabetes and gastrointestinal intolerance to metformin differs in composition and functionality from tolerant patients. Biomed Pharmacother. 2022;145:112448. doi:10.1016/j.biopha.2021.112448
  12. Liu Y, Song X, Zhou H, et al. Gut microbiome associates with lipid-lowering effect of Rosuvastatin in vivo. Front Microbiol. 2018;9:530. doi:10.3389/fmicb.2018.00530
  13. Oudat Q, Okour A. The Role of Probiotics in Modulating Gut Microbiota and Metabolic Health for Weight Management: A Mini Review. Acta Microbiologica Hellenica. 2025;70(1):5. doi:10.3390/amh70010005
  14. Naito E, Yoshida Y, Kunijiro S, et al. Effect of Lactobacillus casei strain Shirota-fermented milk on metabolic abnormalities in obese prediabetic Japanese men: a randomised, double-blind, placebo-controlled trial. Bioscience of Microbiota, Food and Health. 2018;37(1):9-18. doi:https://doi.org/10.12938/bmfh.17-012
  15. Dehghan P, Farhangi MA, Tavakoli F, Aliasgarzadeh A, Akbari AM. Impact of prebiotic supplementation on T-cell subsets and their related cytokines, anthropometric features and blood pressure in patients with type 2 diabetes mellitus: A randomized placebo-controlled Trial. Complementary Therapies in Medicine. 2016;24:96-102. doi:10.1016/j.ctim.2015.12.010
  16. Lauw S, Kei N, Po Lam Chan, et al. Effects of Synbiotic Supplementation on Metabolic Syndrome Traits and Gut Microbial Profile among Overweight and Obese Hong Kong Chinese Individuals: A Randomized Trial. Nutrients. 2023;15(19):4248-4248. doi:10.3390/nu15194248