The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice

Journal of Complementary Therapies in Health ISSN 2975-9323 |eISSN 2975-9552 Journal of Complementary Therapies in Health 2026:4(1). doi:10.5281/zenodo.17964221 institutoptc.com/journal-complementary-therapies Review The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice. Jussara Araújo Barros1*, Sandra Sampaio1, João Veiga1, and Marta Peixoto1. 1 IPN – Portuguese Institute of Naturology, Porto, Portugal. * Correspondence: [email protected] Abstract This study aims to explore the role of the vagus nerve (VN) and heart rate variability (HRV) a central physiological markers for maintaining homeostasis and for naturopathic clinical practice. The literature review allowed us to understand the functional anatomy of the VN and its relevance as an integrative axis of the gut-brain and heart-brain connections, highlighting its influence on the digestive, metabolic, and immune systems, as well as emotional and behavioural regulation. HRV analysis has emerged as a non-invasive method for assessing autonomic balance, demonstrating that higher levels of vagal activity are associated with greater resilience to stress, better emotional selfregulation, and a lower risk of chronic diseases. Conversely, reduced HRV values are associated with autonomic dysfunction and greater pathological vulnerability. Within Naturopathy, practices such as conscious breathing, meditation, exercise, stress management, sleep hygiene, and a balanced diet reveal potential for stimulating vagal tone and improving HRV, reinforcing the holistic and preventive approach of this therapeutic field. The integration of HRV monitoring devices also constitutes an innovative resource for clinical assessment and intervention, promoting a more evidencebased practice. In this way, the articulation between NV, HRV and Naturopathy constitutes a promising contribution to the promotion of integral health, although further research is required to deepen the application of these strategies in a naturopathic context, in order to consolidate their effectiveness and sustainability. Keywords: Vagus Nerve; Heart Rate Variability; Homeostasis; Naturopathy. 1. Introduction The Autonomic Nervous System (ANS) is fundamental in regulating involuntary bodily functions, including heart rate, digestion, and respiration 1. Within the ANS, the VN stands out as the main component of the parasympathetic system, responsible for promoting states of rest, recovery, and the maintenance of physiological homeostasis 2. In recent years, interest in the action of the VN and Naturopathic therapeutic approaches has grown across various healthcare areas. These practices value the balance between physiological and emotional systems as a basis for promoting integral health, aligning with the principle of treating the person as a whole and with homeostatic self-regulation 3-5. Evidence from clinical trials and systematic reviews indicates that naturopathic interventions (especially when combined with techniques such as yoga and controlled breathing) can improve HRV, reduce anxiety symptoms, and promote greater well-being 6,7. HRV analysis constitutes a non-invasive method to infer the functional balance between the sympathetic and parasympathetic branches of the ANS. Evidence indicates that higher levels of vagal activity, reflected in greater HRV, are associated with better selfCitation: Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice. Journal of Complementary Therapies in Health. 2026;4(1) 10.5281/zenodo.17964221 Academic Editor: Jorge Rodrigues Received: 7 November 2025 Reviewed: 28 November 2025 Revised: 14 December 2025 Accepted: 16 December 2025 Published: 17 December 2025 Publisher’s Note: IPTC stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: ©2026 by the authors. Submitted for open access publication under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Journal of Complementary Therapies in Health 2026: 4(1). 2 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 regulation in cognitive, emotional, social, and health domains, as well as greater adaptive capacity and resilience to stress 8,9. Naturopathy aims to stimulate the body’s natural healing mechanisms and promote integral well-being. Thus, understanding vagal function and HRV as markers of autonomic regulation becomes crucial. Recent evidence indicates that integrative interventions, including guided meditation (Heart Rhythm Meditation), breathing practices (such as Sudarshan Kriya Yoga), relaxation techniques, and aromatherapy, can increase vagal activity, reflected in an increase in HRV. These effects are associated with greater autonomic balance, resilience to stress, and better physiological well-being. Furthermore, mantra meditation practices are shown to dynamically modulate cardiac-neural interaction, reinforcing the relevance of these approaches for the maintenance of integral health 10-13. The use of devices, such as the chest heart rate monitor, combined with mobile applications and specialised software, has been widely validated for the precise monitoring of HRV and assessment of sympato-vagal balance in clinical and research contexts 14-16. Given this context, this review proposes to highlight the applicability of the VN and HRV as relevant physiological markers in naturopathic practice, emphasising their potential therapeutic application and role in promoting integral health. 2. Anatomical and Physiological Role of the Vagus Nerve in Systemic Homeostasis 2.1. Functional Anatomy of the Vagus Nerve The VN is one of the main constituents of the parasympathetic division of the ANS. It is composed of 80% afferent sensory fibres (which send sensory information from the body to the Nucleus Tractus Solitarius (NTS)—located in the brainstem) and 20% efferent motor fibres, which carry information from the brain to the body, innervating important peripheral organs and regulating vital physiological functions, such as heart rate and gastrointestinal motility. All branches of the VN with visceral efferent fibres also contain afferent sensory fibres, which makes it a highly sensitive nerve. The NTS acts as an integrating centre, coordinating autonomic, neuroendocrine, and immunological responses 1,2,8. Despite vagal neurons constituting only a small proportion of the nervous system, they play an essential role in overseeing a wide range of vital functions 17, representing the main bidirectional communication pathway between the Central Nervous System (CNS) and various peripheral organs, thereby playing a crucial role in maintaining systemic homeostasis 2. Also known as the “wandering nerve,” the VN is the main cranial nerve responsible for the connection between the brain and organs located in the neck, thorax, and abdomen (Figure 1). 2.2. Interconnection between Interoception, the Vagus Nerve, and Heart Rate Variability Interoception refers to the capacity of the nervous system to perceive, integrate, and interpret signals originating from internal organs, including the heart, lungs, gastrointestinal system, and other visceral systems. This information is essential for maintaining homeostasis and for behavioural adaptation to the body's physiological needs 17. Through interoception, the brain continuously monitors the internal state of the body, adjusting autonomic, hormonal, and behavioural responses according to internal demands and the external environment 19,20. The VN plays a central role in this process, functioning as an essential communication pathway between the organs and the brain. It transports visceral signals to the NTS and, from there, to regions like the hypothalamus and the insular cortex, which modulate behaviour and physiological state 17. Vagal sensory neurons are highly specialised, detecting stimuli such as gastric distension, the chemical composition of food, and inflammatory signals, allowing the VN to function as an "internal language" of the body 21. Journal of Complementary Therapies in Health 2026: 4(1). 3 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 Figure 1. Vagus nerve network as illustrated by Berthoud et al. 18. In the brainstem, the NTS organises these signals in a similar way to the processing of external senses. Specific maps distinguish signals from the gastrointestinal system and the respiratory tract, reinforcing the VN’s role as a "sixth sense" 22. Furthermore, the VN also transmits information about immune states, detecting inflammatory molecules and Journal of Complementary Therapies in Health 2026: 4(1). 4 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 adjusting physiological and behavioural responses, such as loss of appetite or fatigue during infections 17,23,24. HRV is a central indicator of autonomic activity and reflects the heart’s ability to respond flexibly to physiological and emotional changes. Vagal activity is one of the main modulators of HRV, with greater variability indicating greater resilience to stress and better autonomic adaptation 25. Interoception provides precise information about the body's internal states, allowing for adjusted autonomic responses that directly influence HRV. Reciprocally, techniques that increase HRV, such as biofeedback or transcutaneous auricular VN stimulation (taVNS), can improve interoceptive perception, creating a positive feedback loop that promotes physiological balance and psychological well-being 26-28. In summary, the VN acts as a vital bridge between the organs and the brain. It ensures the maintenance of internal balance and contributes to the perception of physiological states, influencing emotions, behaviour, and overall health. The integration between interoception, the VN, and HRV opens up new therapeutic perspectives for clinical conditions involving autonomic, cardiovascular, digestive, and immunological dysfunctions, reinforcing strategies that promote homeostasis, mental health, and general well-being 17,19,20. 2.3. The Vagus Nerve as an Integrating Axis for the Gut-Brain and Heart-Brain Axes The maintenance of homeostasis in situations of immunological challenge requires the adequate integration and transmission of signals from different body systems to the brain, allowing for the coordination of appropriate physiological and behavioural responses 29. This communication is mediated by complex networks that link peripheral organs to the CNS, highlighting the gut-brain and heart-brain axes. In both, the VN assumes a central role as a bidirectional connection pathway, modulating cognitive, emotional, and autonomic functions essential for adaptive behaviour and mental health 30-32. In the gut-brain axis, the interaction between the brain and the gut microbiota occurs via multiple complementary pathways: neural, predominantly through the VN and spinal cord; endocrine, via the hypothalamic-pituitary-adrenal (HPA) axis; immunological, via cytokines; and metabolic, involving molecules such as short-chain fatty acids and tryptophan 33. Neuroactive compounds produced by bacteria, such as gamma-aminobutyric acid (GABA), serotonin, dopamine, and acetylcholine (ACh), act mainly on the enteric nervous system, but some reach the brain through the bloodstream, circumventricular organs, or directly via the VN. These mediators influence not only digestive and inflammatory processes but also psychological states, affecting anxiety, mood, and stress response. Travagli et al. 34 highlight that the detection of bacterial metabolites and gastrointestinal hormones by vagal afferent fibres results in the integration of these signals into central neuroendocrine circuits, particularly in the hypothalamus and amygdala. Interventions such as vagal stimulation have demonstrated benefits in neural plasticity, memory, and emotional selfregulation, reinforcing the therapeutic potential of this pathway for psychophysiological conditions 35. Adequate vagal regulation is essential for emotional expression, the formation of social bonds, and flexible adaptation to internal and external demands 36,37. Complementarily, the heart-brain axis represents another critical bidirectional communication pathway, equally dependent on the VN for the integration of physiological signals. Changes in cardiac activity, such as those observed in HRV, directly influence cerebral processes related to attention, stress perception, and emotional regulation 38. High vagal activity is associated with the reduction of systemic inflammation, improved cardiovascular function, and stress modulation, confirming the VN's role as a mediator between emotional and cardiovascular states 31. Thus, more than a simple conductor of nerve impulses, the VN constitutes an integrating element that sustains physiological adaptations essential for survival and adaptive behaviour, making it a promising target for therapeutic approaches in cardiac dysfunctions, emotional disorders, and axis imbalances 39. Journal of Complementary Therapies in Health 2026: 4(1). 5 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 2.4. Central Role of Vagal Pathways in the Digestive, Metabolic, and Immune Systems The ANS, and particularly the VN, plays a central role in integrating digestive, metabolic, and immunological functions, ensuring the maintenance of homeostasis and the body's adaptive response to internal and external challenges. In the digestive context, the VN regulates satiety through afferent fibres that transmit gastric distension signals to the NTS, modulating hypothalamic nuclei responsible for appetite control and promoting the suppression of food intake 40. Furthermore, vagal stimulation promotes gastrointestinal motility, including gastric emptying and pyloric sphincter relaxation, restoring normal slow-wave patterns in conditions of gastric rhythm disorders 41,42. Vagovagal reflexes exemplify the functional interface between the enteric nervous system and the brain, with circuits that include the NTS and the Dorsal Motor Nucleus of the Vagus (DMV), responsible for gastric relaxation and the modulation of acid and histamine secretion 43,44. In addition to digestive function, the VN participates in glycaemic regulation, stimulating insulin secretion and improving metabolic control, with recent evidence pointing to the participation of FGF3, a signalling protein produced by vagal sensory neurons, in optimising insulin secretion in situations of metabolic stress 45,46. From an immune-neuroendocrine perspective, the sensory neurons of the VN can detect invading pathogens and inflammatory signals before or simultaneously with immune cells, relaying information to the CNS which modulates local and systemic immune responses 47,48. The activation of vagal afferent circuits can positively modulate the HPA axis, promoting the release of CRH, ACTH, and cortisol, which contributes to the regulation of the stress response and the reduction of systemic inflammation 49. The cholinergic anti-inflammatory pathway, mediated by the VN, acts on α7 receptors on immune cells, inhibiting the release of pro-inflammatory cytokines such as TNFα, IL-1β, and IL-6, being crucial in controlling inflammatory responses in chronic and acute diseases 50. The integration between enteric neurons, epithelial cells, and immune cells in the intestinal mucosa highlights the relevance of vagal pathways in neuroimmune coordination, constituting promising targets for therapeutic interventions in metabolic and inflammatory contexts 48. Thus, the VN functions as an integrating element that coordinates digestive, metabolic, and immunological functions, allowing for efficient adaptive responses and the maintenance of homeostasis 51. This view highlights its therapeutic potential in conditions such as digestive disorders, metabolic dysfunctions, and chronic inflammation, consolidating the central role of vagal pathways in the neurophysiological integration of the body 52,53. 3. Heart Rate Variability HRV refers to the physiological variation in heart rate caused by autonomic innervation, reflecting fluctuations in the time intervals between consecutive heartbeats (R-R intervals), measurable through electrocardiograms or equivalent devices 54. It is considered an indirect marker of physiological and mental well-being 55 and presents itself as an important biomarker not only of the autonomic state but also of stress and overall health, extending beyond mere cardiac function 56. According to Shaffer et al. 9, HRV reflects the regulation of autonomic balance, blood pressure, gas exchange, and intestinal, cardiac, and vascular tone. Polyvagal Theory, proposed by Porges 57, emphasises the central role of the vagal pathway in regulating social behaviour and physiological state, suggesting that higher HRV (an index of vagal modulation) is associated with greater emotional self-regulation and resilience to stress. This hypothesis has been confirmed in several studies, which indicate that individuals with higher HRV values exhibit better adaptive capacity when faced with emotional and physiological challenges 9,58. Vagal influences on the heart act as an attenuation mechanism for sympathetic responses to stress, promoting behavioural states of calmness and self-regulation. Vagal tone, in this sense, assumes a protective function, preventing vulnerability to states of apprehension and anxiety. Journal of Complementary Therapies in Health 2026: 4(1). 6 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 Higher HRV levels are consistently associated with better health indicators and reflect an autonomic state characterised by self-regulation, adaptability, and resilience. Conversely, reduced values are interpreted as signs of diminished adjustment capacity, reflecting a dysregulated cardiac autonomic function and predictive of worse clinical outcomes 54,55. This autonomic imbalance manifests as sympathetic predominance and vagal hypoactivity. Increased sympathetic tone tends to decrease HRV, while vagal predominance increases it 9,36. It is also important to note that HRV is highly sensitive to contextual factors, such as posture, time of day, and psychological or physiological state, which reinforces the need for standardised measurement conditions 54. Additionally, HRV tends to decrease with age and differs according to gender 59,60. It is also influenced by behavioural and environmental variables, such as exercise, sleep, diet, smoking, alcohol and caffeine consumption, respiratory rate, body mass index, blood pressure, negative emotional states (stress, pain, depression), hormonal changes, medication use, and genetic or familial factors 27,61. Regarding HRV measures, SDNN and RMSSD stand out clinically. SDNN represents the overall autonomic function of the heart, reflecting the joint sympathetic and parasympathetic modulation, while RMSSD predominantly reflects the vagal modulation of heart rate. It is observed that RMSSD progressively decreases from the supine position to sitting, standing, and walking, reflecting the reduction in vagal activity and the increase in sympathetic activity 62. In 24-hour monitoring, SDNN values below 50 ms are classified as unhealthy; between 50–100 ms as compromised; and above 100 ms as healthy. In fact, individuals with an SDNN greater than 100 ms have a mortality risk 5.3 times lower compared to those exhibiting values below 50 ms 37. According to Rubik 56, increases in both SDNN and RMSSD reflect a reduced stress response and/or a more adjusted autonomic balance. 24-hour recordings constitute the gold standard for clinical HRV assessment, given their greater predictive power relative to short-duration measurements. However, brief recordings (60 seconds to 5 minutes), in a sitting or supine position, have been widely used and considered reliable, currently representing the most studied methodology due to its accessibility 15,63. These assessments can be performed using validated portable devices, such as the Polar H10 chest heart rate monitor, which has demonstrated excellent agreement with the electrocardiogram (ECG) at rest and during physical exercise. GilgenAmmann et al. 64 confirmed the validity of the Polar H10 for R-R interval detection across a wide range of intensities. More recently, Schaffarczyk et al. 15 compared the Polar H10 with a 12-lead ECG, finding no significant differences when using the Kubios HRV software for analysis. Data can be transmitted via Bluetooth to mobile applications, such as Elite HRV, which stores the recordings and provides real-time feedback 14,58,64. In addition to its value as a general physiological marker, HRV is also associated with various clinical dysfunctions. The decrease in vagal activity and sympathetic predominance can favour the development of diabetes 65. Recent evidence demonstrates that the reduction in HRV can precede the clinical manifestation of metabolic and cardiovascular diseases, functioning as an early risk marker 65-67. Wang et al. 67 found that decreased HRV in initially healthy individuals is associated with a greater risk of type 2 diabetes, suggesting that autonomic dysfunction may precede detectable metabolic changes. Complementarily, Yu et al. 65 showed that high levels of plasma glucose and the presence of diabetes are negatively correlated with HRV, reinforcing its usefulness in the early detection of metabolic changes and cardiovascular risk. Also in this field, Hajdu et al. 66 identified determinants of HRV in individuals with type 1 diabetes, highlighting the importance of continuous monitoring of this parameter in different diabetic contexts. The literature also evidences the association between HRV and chronic pain. Tracy et al. 68 showed, in a meta-analysis, that patients with persistent pain have significantly reduced HRV values, indicating autonomic dysfunction marked by a reduction in vagal activity. In parallel, Yuan et al. 69 demonstrated that colonic motor patterns are directly Journal of Complementary Therapies in Health 2026: 4(1). 7 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 related to autonomic activity, reflecting in HRV parameters. Such results support the relevance of HRV as an indicator of gut-brain dysfunction. Ali et al. 70 reinforce this evidence by demonstrating correlations between changes in colonic motility and changes in HRV. Finally, Ying-Chih et al. 71 identified, through a systematic review, that individuals with functional somatic syndromes, such as irritable bowel syndrome, exhibit significantly lower HRV values, especially in vagal components, compared to healthy individuals. These changes in gut-brain communication can translate clinically into gastrointestinal disorders, such as hardened stools, or hyper-responsivity to environmental stress 68-71. For Wareing et al. 27, although RMSSD and SDNN measures do not directly index interoception, if an individual's autonomic activity is optimal in a given context, then it may be that they are capable of detecting, integrating, and adequately responding to interoceptive afferents. Supporting this assumption, a higher resting RMSSD positively correlates with interoceptive accuracy, while lower SDNN was observed in medicated and non-medicated individuals with conditions in which interoceptive deficits have been implicated, including depression, anxiety, and post-traumatic stress disorder, which provides support for a relationship between greater interoceptive abilities and better autonomic regulation. 4. Naturopathy: An Integrative Approach to Global Health Globally, Naturopathy is practised in at least 98 countries with representation in all regions of the world, being widely practised in Europe (54 practising countries), Latin America (51 practising countries), Africa (47 practising countries), and the Western Pacific (37 practising countries). Estimates from the World Naturopathic Federation (WNF) suggest there are between 75,000 and 100,000 naturopaths currently in clinical practice worldwide 72. Recognised by the National Institutes of Health (NIH) and the World Health Organization (WHO) as a distinct system of complementary and integrative healthcare, it is an existing model of integral health service delivery 73. Naturopathy is configured as an integrative health approach that emphasises the organism's natural capacity to maintain and restore balance and well-being 74 and is taught and practised according to a globally consistent set of fundamental philosophies and principles. Holism and vitalism are the core naturopathic philosophies; Holism is founded on the recognition that "the spiritual, psychological, functional, and structural aspects of an individual act interdependently and are influenced by external, environmental, social, and other factors." Human health and the manifestations of disease are understood by naturopathic practitioners as expressions of the close and complex interactions between a series of internal systems and external factors demonstrated by the naturopathic multi-system approach 75. This holistic view of the human being recognises the intrinsic interconnection between body, mind, and spirit, highlighting the importance of treating the individual as a whole, considering their uniqueness and context 76. This holistic principle implies that treatment is not limited to resolving isolated symptoms but focuses on identifying and correcting underlying imbalances that compromise the organism's homeostasis, a central concept in VN-mediated regulation and HRV modulation 77. The principles of Naturopathy act as a solid foundation for a patient-centred clinical practice, promoting integral health and sustainable prevention, and respecting the complexity and uniqueness of each individual (Bradley et al., 2019). The incorporation of naturopathy into a primary care model could increase the focus on health promotion and disease prevention 4,73. The philosophy, theory, and principles are translated into clinical practice through a variety of therapeutic modalities. The WNF identified seven main modalities: (1) clinical nutrition and diet modification/counselling; (2) applied nutrition (use of food supplements, traditional medicines, and natural health products); (3) herbal medicine; (4) lifestyle counselling; (5) hydrotherapy; (6) homeopathy; and (7) physical modalities (based on the treatment modalities taught and permitted in each jurisdiction, including yoga, naturopathic manipulation, and muscle release techniques) 5. Journal of Complementary Therapies in Health 2026: 4(1). 8 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 According to Myers et al. 5 and Steel et al. 72, Naturopathy is a system of traditional medicine supported by seven principles of practice (the healing power of nature; treat the person as a whole; treat the cause; first, do no harm; naturopath as teacher; health promotion and disease prevention; and wellness). Other defining principles of naturopathic practice are patient-centeredness and individualisation, with naturopaths typically resorting to a range of therapeutic interventions to best meet the patient's health needs and preferences. In line with these principles, Naturopathy has, as one of its major cornerstones, the emphasis on prevention, which aims to anticipate and avoid the emergence of pathologies, promoting interventions that reinforce the body's natural defence mechanisms. Unlike conventional medicine, which often focuses on symptom suppression, Naturopathy prioritises long-term health promotion through the restoration of physiological and emotional balance 78,79. Recent studies show that naturopathic techniques, such as meditation and breathing exercises, positively influence HRV, improving autonomic regulation and resilience to stress, demonstrating the VN's modulating function in homeostasis and psychophysiological well-being 17,80. This preventive orientation is supported by scientific evidence that highlights the importance of early and sustained interventions for the improvement of immune and neuroendocrine response 81. However, patient education and empowerment assume a central role in the naturopathic therapeutic process. Through information and active involvement, the individual is empowered to autonomously manage their health, developing habits that support longterm physical and emotional balance 79. This partnership between therapist and patient constitutes a fundamental basis for more effective and lasting therapeutic outcomes 82. The recognition of lifestyle as one of the main determinants of health constitutes another fundamental pillar. Interventions that promote healthy eating, regular physical exercise, effective stress management, quality sleep, and solid social relationships demonstrate a positive impact on ANS modulation, the reduction of systemic inflammation, and the promotion of hormonal balance 83. These naturopathic practices optimise vagal activity, favouring interoception, gut-brain and heart-brain communication, and promoting a balanced and resilient physiological state 20,31. Thus, Naturopathy promotes not only the treatment of diseases but the transformation of lifestyle as a preventive and therapeutic measure, reinforcing the organism's resilience 12. Another fundamental principle is ‘primum non nocere’, or “first, do no harm”. This dictates that therapeutic choices must be safe, natural, and minimally invasive, thus respecting the patient's physiological processes 84. This approach values the reinforcement of natural self-healing capacities, minimising adverse effects and promoting sustainable recovery. Recent studies corroborate that naturopathic interventions positively influence HRV 80, because naturopathic treatments can control persistent inflammation, maintain immunological homeostasis, and reduce disease activity, thus leading to better health outcomes and better quality of life in patients with or at risk of chronic conditions, including cardiovascular diseases, type 2 diabetes/obesity, chronic pain, anxiety, multiple sclerosis, hepatitis C, and menopausal symptoms 5,6,85,86. Furthermore, improvements in blood glucose levels and insulin sensitivity have been observed in studies on diabetes, which may corroborate the role of naturopathy in the management of metabolic disorders 87. In this context, it becomes particularly relevant to consider the integration of VN function and HRV, as these mechanisms offer the neurophysiological support for the observed effects. Studies have demonstrated that vagal modulation is associated with reduced inflammation, autonomic balance, and better cardiovascular outcomes 88,89. Additionally, interventions that increase HRV show a positive impact on stress control, emotional regulation, and psychophysiological resilience 90. This perspective not only reinforces the effectiveness and durability of naturopathic interventions but also establishes a bridge between clinical practice and advances in biomedical science, highlighting the consistency and relevance of this approach for promoting integral health. Journal of Complementary Therapies in Health 2026: 4(1). 9 of 14 Barros J.A., Sampaio S., Veiga J., Peixoto M. The Vagus Nerve and Heart Rate Variability: Physiological Markers in Naturopathic Practice doi:10.5281/zenodo.17964221 5. Conclusion In conclusion, the evidence presented underscores the critical role of the VN as the fundamental architect of systemic homeostasis, functioning as the essential bridge between the central nervous system and the body's vital organs. Through the complex integration of the gut-brain and heart-brain axes, the VN regulates crucial metabolic, immune, and emotional processes, while HRV serves as a quantifiable and reliable biomarker of this autonomic resilience. The scientific validation of these mechanisms confirms that high vagal tone and optimal HRV are not merely indicators of cardiac function, but comprehensive markers of an individual's capacity for self-regulation, adaptability to stress, and overall physiological well-being. Furthermore, the convergence of neurophysiology and Naturopathy offers a robust framework for promoting integral health. By recognising the VN and HRV as central targets for therapeutic intervention, Naturopathic practice gains a measurable physiological basis for its multimodal approaches, such as mind-body techniques, nutritional adjustments, and lifestyle counselling. Ultimately, bridging the gap between biomedical science and holistic principles validates the efficacy of Naturopathy in preventing chronic disease and fostering resilience, reinforcing the importance of treating the person as a whole to achieve a sustainable state of balance and health. Credit author statement: Conceptualization: J.A.B.; Investigation: J.A.B.; Writing, reviewing and editing: J.A.B., S.S., J.V., and M.P. All authors have read and agreed to the published version of the manuscript. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Conflict of Interest: The authors declare that there are no conflicts of interest. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author. References 1. Barkhudaryan A, Doehner W, Jauert N. Autonomic dysfunction after stroke: an overview of recent clinical evidence and perspectives on therapeutic management. Clin Auton Res. 2025;35(4):553-63. doi: https://doi.org/10.1007/s10286-025-01120-0 2. Alrosan AZ, Heilat GB, Alrosan K, Aleikish AA, Rabbaa AN, Shakhatreh AM, et al. Autonomic brain functioning and agerelated health concerns. Curr Res Physiol. 2024;7:100123. doi: https://doi.org/10.1016/j.crphys.2024.100123 3. Fleming SA, Gutknecht NC. Naturopathy and the primary care practice. Prim Care. 2010;37(1):119-36. doi: https://doi.org/10.1016/j.pop.2009.09.002 4. Bradley R, Harnett J, Cooley K, McIntyre E, Goldenberg J, Adams J. Naturopathy as a Model of Prevention-Oriented, PatientCentered Primary Care: A Disruptive Innovation in Health Care. Medicina [Internet]. 2019; 55(9):[603 p.]. doi: https://doi.org/10.3390/medicina55090603 5. Myers SP, Vigar V. The State of the Evidence for Whole-System, Multi-Modality Naturopathic Medicine: A Systematic Scoping Review. J Altern Complement Med. 2019;25(2):141-68. doi: https://doi.org/10.1089/acm.2018.0340