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Examining the Legitimacy of Functional Medicine

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Published By: Dr. Jeffrey Mark
Date: March 01, 2024

Functional Medicine has gained popularity in recent years, but skepticism about its legitimacy persists. This blog aims to dispel myths and provide evidence supporting the validity of Functional Medicine.

We'll delve into key principles, present case studies illustrating successful outcomes, analyze research studies, address common criticisms, and compare Functional Medicine with conventional approaches.

Functional Medicine has gained traction as a holistic approach to healthcare, but doubts about its legitimacy linger. In this blog, we'll debunk myths and provide compelling evidence to affirm the validity of Functional Medicine.

Let's delve into the essence of Functional Medicine, explore its guiding principles, showcase real-life success stories, dissect research findings, address common concerns, and compare it with conventional medical practices.

Is functional medicine legit?

Functional Medicine stands out for its personalized approach, focusing on the individual needs of each patient. Unlike conventional medicine, which often follows standardized protocols, Functional Medicine recognizes that each person is unique and requires tailored care.

Example: Consider two individuals with identical symptoms of fatigue. While conventional medicine might prescribe the same medication for both, Functional Medicine would delve deeper into each person's lifestyle, genetics, diet, and environmental factors to uncover the root cause of their fatigue and develop personalized treatment plans accordingly.

Functional Medicine adopts a systems biology perspective, understanding that the body operates as an intricate network of interconnected systems. Rather than isolating symptoms and treating them in isolation, Functional Medicine considers how imbalances in one area can affect other bodily systems.

Example: A patient with eczema may find relief not just from topical treatments but also from addressing underlying gut health issues, as the gut-skin connection is well-established in Functional Medicine. By addressing gut imbalances and reducing inflammation internally, improvements in skin health can be achieved.

Furthermore, Functional Medicine emphasizes the importance of identifying and addressing the root causes of illness, rather than merely alleviating symptoms. This proactive approach aims to foster long-term healing and prevent the recurrence of health issues.

Example: Instead of solely prescribing pain medication for a patient with chronic headaches, Functional Medicine would investigate potential triggers such as food sensitivities, hormonal imbalances, or stress, aiming to address these underlying causes and provide lasting relief.

In summary, Functional Medicine offers a patient-centered, holistic approach that delves into the root causes of illness, considers the interconnectedness of bodily systems, and empowers patients to take control of their health.

Through this blog, we'll showcase the legitimacy of Functional Medicine through real-world examples, research evidence, and comprehensive analysis.

I have written a dedicated post comparing Functional Medicine vs Conventional Medicine. If you want to their differences, this article might help you for sure.

Key Principles of Functional Medicine:

Functional Medicine is grounded in principles that guide its approach to patient care. These principles include personalization, a systems biology perspective, root cause analysis, biochemical individuality, and patient empowerment.

Understanding these principles is crucial to appreciating the legitimacy of Functional Medicine.

Functional Medicine operates on foundational principles that shape its unique approach to patient care. Here's a breakdown of these principles, accompanied by clear examples to illustrate their significance:

1. Personalized and Patient-Centered Care:

Personalized and Patient-Centered Care:

Functional Medicine prioritizes individualized care, recognizing that each person has a unique genetic makeup, environmental exposures, lifestyle habits, and health goals.

Rather than adopting a one-size-fits-all approach, Functional Medicine doctors tailor treatment plans to address the specific needs and preferences of each patient.


  • Patient A may present with digestive issues stemming from food sensitivities, while Patient B may struggle with hormonal imbalances contributing to fatigue. Both have inflammation which can be manifest in different ways. Each would need a distinct treatment plan integrating dietary modifications, supplementation, and lifestyle interventions based on their unique circumstances.

2. Systems Biology Approach:

While functional medicine advocates assert it is a science-based systems biology approach, critics argue there is a lack of scientific evidence for many functional medicine practices like chiropractic manipulation, making it seem more like pseudoscience than traditional medicine.

Functional Medicine views the body as an interconnected network of systems that influence each other. It recognizes the complex interactions between various biological processes, organs, and systems, understanding that imbalances in one area can manifest as symptoms elsewhere in the body.


  • An individual with chronic inflammation may experience symptoms not only in their digestive system but also in their joints or skin. Functional Medicine doctors investigate the underlying causes of inflammation, considering factors such as gut health, diet, stress levels, and immune function to address the root cause comprehensively.

3. Root Cause Analysis:

Instead of merely managing symptoms, Functional Medicine seeks to identify and address the underlying root causes of illness. By digging deeper and uncovering the factors driving disease processes, Functional Medicine doctors aim to promote long-term healing and wellness.


  • Traditional approaches to managing high cholesterol may involve prescribing statin medications to lower cholesterol levels. In contrast, Functional Medicine doctors would investigate the reasons behind elevated cholesterol, such as poor dietary choices, sedentary lifestyle, stress, or underlying metabolic imbalances, and develop a treatment plan targeting these root causes.

4. Biochemical Individuality:

Biochemical Individuality

Functional Medicine acknowledges that each person is biochemically unique, with distinct genetic predispositions, nutritional requirements, and responses to environmental factors and therapies.

What works for one individual may not necessarily work for another, emphasizing the importance of personalized approaches to care.


  • Two individuals with the same diagnosis of irritable bowel syndrome (IBS) may require different treatment strategies. While one may benefit from dietary modifications focused on eliminating trigger foods and restoring gut health, the other may require additional support for stress management or addressing underlying microbial imbalances.

5. Patient Empowerment:

Functional Medicine empowers patients to take an active role in their own health and well-being. By providing education, support, and tools for self-care, Functional Medicine doctors empower patients to make informed decisions, implement lifestyle changes, and become partners in their healthcare journey.


  • In Functional Medicine,  doctors educate patients about the impact of diet, stress, sleep, and physical activity on their health outcomes. They work collaboratively with patients to develop achievable goals and strategies for implementing sustainable lifestyle changes, fostering a sense of empowerment and accountability in the healing process.

By adhering to these key principles, Functional Medicine doctors offer a comprehensive and personalized approach to healthcare that addresses the root causes of illness and promotes optimal wellness for each individual patient.

Don't get confused with functional medicine and naturopath as both are different. We have discussed functional medicine and naturopath in detail to clear your doubts. I have also discussed Whether all functional medicine doctors are MDS in a detailed article.

Functional Medicine in Action:

Case studies showcase the tangible impact of Functional Medicine on patients' lives. We'll explore real-life transformations in digestive health, hormonal balance, and the reversal of chronic fatigue syndrome, providing concrete examples of Functional Medicine's effectiveness.

Functional Medicine isn't just a theory; it's a practical approach that yields real results for patients.

Here, we'll delve into some real-life examples (names and some circumstances have been modified due to HIPPA) of Functional Medicine in action, showcasing its effectiveness in addressing a range of health concerns and improving overall well-being.

Case Study 1: Digestive Health Transformation

Digestive Health Transformation

Meet Susan, a 35-year-old woman experiencing chronic digestive issues, including bloating, gas, and irregular bowel movements. Conventional medical treatments provided temporary relief but failed to address the root cause of her symptoms.

Frustrated and desperate for answers, Susan turned to Functional Medicine for help.

After conducting a comprehensive assessment, including a detailed medical history, dietary analysis, and functional testing, Susan was found to have underlying imbalances in her gut microbiome (dysbiosis) and food sensitivities contributing to her symptoms.

Susan’s treatment plan included dietary modifications to eliminate trigger foods, such as gluten and dairy, along with targeted supplementation to support gut healing and restore microbial balance.

Additionally, stress management techniques, such as mindfulness meditation and yoga, were incorporated to address the impact of stress on digestive function.

Over the course of several months, Susan diligently followed her treatment plan and experienced significant improvements in her digestive symptoms. Bloating and gas decreased, bowel movements became regular, and overall gut health improved.

Through personalized care and addressing the root cause of her symptoms, Functional Medicine transformed Susan's digestive health and restored her quality of life.

Case Study 2: Hormonal Imbalance Resolution

Hormonal Imbalance Resolution

Consider Mark, a 45-year-old man struggling with symptoms of hormonal imbalance, including fatigue, low libido, and mood swings. Despite seeking help from various healthcare providers, including traditional endocrinologists, Mark's symptoms persisted, leaving him feeling frustrated and discouraged.

Through Functional Medicine, Mark underwent a thorough evaluation, including hormone testing, nutritional assessment, and lifestyle analysis. The results revealed imbalances in Mark's adrenal and thyroid hormones, as well as deficiencies in key nutrients necessary for hormone production and metabolism.

Mark's treatment plan involved a multifaceted approach aimed at restoring hormonal balance naturally. This included dietary changes to support hormone production, targeted supplementation with vitamins and minerals essential for hormone synthesis, and lifestyle modifications to reduce stress and improve sleep quality.

As Mark implemented these interventions under the guidance of his Functional Medicine doctor, he began to notice significant improvements in his energy levels, mood stability, and libido. Over time, his hormonal balance was restored, and he regained a sense of vitality and well-being that had eluded him for years.

Case Study 3: Chronic Fatigue Syndrome Reversal

Imagine Lisa, a 40-year-old woman struggling with debilitating fatigue, brain fog, and muscle pain for several years. Conventional medical treatments offered little relief, leaving Lisa feeling frustrated and hopeless. Determined to find answers, she turned to Functional Medicine for a different approach.

Through a comprehensive assessment, including in-depth testing and analysis of Lisa's medical history, lifestyle factors, and environmental exposures, she was found to have underlying imbalances contributing to her chronic fatigue syndrome.

Lisa's treatment plan focused on addressing the root causes of her symptoms, which included optimizing her diet to reduce inflammation and support energy production, implementing targeted supplementation to address nutrient deficiencies, and incorporating stress management techniques to improve her resilience and coping mechanisms.

As Lisa committed to her personalized treatment plan and made lifestyle changes guided by her Functional Medicine assessments, she experienced a gradual but significant improvement in her symptoms.

Fatigue diminished, mental clarity improved, and muscle pain subsided, allowing Lisa to reclaim her life and engage in activities she had once thought impossible.

These case studies illustrate the transformative power of Functional Medicine in addressing a variety of health concerns and improving overall well-being. By identifying and addressing the root causes of illness, Functional Medicine empowers patients to achieve lasting improvements in their health and quality of life.

Research Studies Supporting Functional Medicine:

A critical examination of peer-reviewed research studies bolsters the legitimacy of Functional Medicine. Here are some recent publications with patient outcomes, demonstrating the evidence-based foundation of this approach.

  1. One of the more recent studies is found in an investigational study published in the Journal of the American Medical Association (JAMA) Open. (1).  It was found that functional medicine may have the ability to improve global health in patients.  The study was entitled “Association of the Functional Medicine Model of Care With Patient-Reported Health-Related Quality-of-Life Outcomes.”

It is the first retrospective cohort study of the functional medicine model and Cleveland Clinic researchers found that functional medicine was associated with improvements in health-related quality of life.

The study was published today in the Journal of the American Medical Association Network Open.

A cohort of 7252 patients was examined (1595 from a functional medicine center; 5657 from a family health center) and exhibited significantly larger improvements in Patient-Reported Outcome Measurement Information System (PROMIS) Global Physical Health at 6 months than propensity-matched patients at a family health center (398 matched pairs).

PROMIS® is an NIH-validated questionnaire. PROMIS provides a measure of patients’ global physical and mental health that can be monitored over time, measuring factors like fatigue, physical function, pain, gastrointestinal issues, and emotional well-being.

Approximately 31% of patients seen by the Center for Functional Medicine improved their PROMIS global physical health scores by 5 points or more, which is a clinically meaningful change and a noticeable effect on daily life. Twenty-two percent of primary care patients improved their scores by 5 points or more.  

  1. There is not a single approach to the delivery of functional medicine. One common appointment in functional medicine is the shared medical appointment or “group visit.” In the British Medical Journal, a study was published comparing the outcomes and costs associated with functional medicine-based care delivered in a shared medical appointment (SMA) to those delivered through individual appointments (2).

The study “Patient outcomes and costs associated with functional medicine-based care in a shared versus individual setting for patients with chronic conditions: a retrospective cohort study” reached the conclusion that SMAs deliver functional medicine-based care that improves outcomes more than care delivered in individual appointments and is less costly to deliver.

  1. There were 3 other studies demonstrating the legitimacy and benefits of Functional Medicine to stop and reverse hypertension, obesity, and heart disease, effectiveness in combination with complementary approaches including meditation, acupuncture, herbal medicine, and use of natural products with cost savings.
  • A study by the British medical journal Lancet Oncology found that Functional Medicine was able to stop and reverse hypertension, obesity, heart disease, and prostate cancer. (3)
  • A study by the Institute of Medicine found that scientifically proven conventional treatments, combined with meditation, yoga, acupuncture, and herbal medicine, proved to be both medically and cost-effective. (4)
  • The National Institutes of Health conducted a meta-analysis entitled "Health Cost Effectiveness of Natural Health Products: A Systematic Review of Randomized Clinic Trials" and found positive health outcomes with cost savings of up to 73 percent for natural products, compared to conventional treatments. (5)

Addressing Criticisms and Concerns:

Despite its growing popularity, Functional Medicine is not without its critics. Let's address some common criticisms and concerns raised about Functional Medicine and provide insights into how these issues are navigated within the field.

1. Lack of Standardization:

One criticism of Functional Medicine is the perceived lack of standardization in diagnostic and treatment protocols. Critics argue that without standardized guidelines, there's a risk of variability in care quality and inconsistency in patient outcomes.

Response: Functional Medicine acknowledges the complexity of individual health and emphasizes personalized care tailored to each patient's unique needs.

While there may not be rigid standardized protocols, Functional Medicine practitioners undergo extensive training and follow evidence-based guidelines to develop personalized treatment plans.

By addressing the root causes of illness and considering the individuality of each patient, Functional Medicine aims to achieve optimal outcomes.

2. Limited Insurance Coverage:

Another concern is the limited insurance coverage for Functional Medicine services. Since many Functional Medicine interventions, such as nutritional counseling and mind-body therapies, may not be covered by insurance plans, patients may face financial barriers to accessing care.

Response: While it's true that some Functional Medicine services may not be covered by insurance, many patients find the investment worthwhile due to the personalized care, comprehensive assessments, and long-term health benefits they receive.

Additionally, some insurance plans may offer partial coverage for certain Functional Medicine services, and flexible payment options or health savings accounts (HSAs) can help make care more accessible.

3. Integration with Conventional Medicine:

Critics argue that Functional Medicine operates outside the mainstream medical system and may not integrate well with conventional medical practices. Concerns are raised about potential conflicts between Functional Medicine and conventional treatments, as well as communication gaps between practitioners.

Response: Functional Medicine advocates for an integrative approach to healthcare, recognizing the value of combining the best of conventional medicine with evidence-based complementary therapies.

Functional Medicine practitioners often collaborate with other healthcare providers, such as primary care physicians, specialists, and allied health professionals, to ensure coordinated and comprehensive care for patients.

By fostering open communication and mutual respect between practitioners, Functional Medicine can complement conventional treatments and enhance overall patient care.

4. Lack of Regulation and Oversight:

Critics point out the lack of regulatory oversight and standardized training requirements in Functional Medicine, raising concerns about practitioner competence and patient safety.

Response: While it's true that Functional Medicine is not regulated in the same way as conventional medicine, many Functional Medicine practitioners undergo rigorous training and certification through reputable organizations.

By seeking care from qualified practitioners with appropriate credentials, patients can mitigate concerns about competence and safety.

Additionally, professional organizations such as the Institute for Functional Medicine (IFM) provide guidelines and standards to uphold professional integrity and ensure the delivery of high-quality care.

By addressing these criticisms and concerns, Functional Medicine continues to evolve and refine its approach to patient care, emphasizing personalized, integrative, and evidence-based practices aimed at promoting optimal health and wellness.

Functional Medicine vs. Conventional Medicine:

Functional Medicine and conventional medicine represent two distinct paradigms in healthcare, each with its own approach to diagnosis, treatment, and patient care. Let's compare and contrast these two approaches to gain a better understanding of their differences and similarities.

1. Philosophical Approach:

  • Functional Medicine: Functional Medicine takes a holistic and patient-centered approach, focusing on identifying and addressing the root causes of illness rather than just managing symptoms. It views the body as an interconnected system and emphasizes the importance of individualized care tailored to each patient's unique needs.
  • Conventional Medicine: Conventional medicine tends to focus on disease diagnosis and treatment based on standardized protocols and guidelines. It often employs pharmaceuticals and procedures to alleviate symptoms without always addressing underlying imbalances or lifestyle factors.

2. Diagnostic Methods:

  • Functional Medicine: Functional Medicine utilizes a comprehensive array of diagnostic tools, including specialized lab tests, genetic testing, and functional assessments, to identify underlying imbalances and dysfunctions in the body's systems.
  • Conventional Medicine: Conventional medicine relies primarily on standard diagnostic tests, such as blood tests, imaging studies, and physical examinations, to diagnose and monitor diseases and conditions.

3. Treatment Approaches:

  • Functional Medicine: Functional Medicine emphasizes personalized treatment plans tailored to address the specific root causes identified in each patient. Interventions may include dietary and lifestyle modifications, targeted supplementation, stress management techniques, and mind-body therapies.
  • Conventional Medicine: Conventional medicine typically employs pharmaceuticals, surgical procedures, and other conventional treatments to manage symptoms and control disease progression. While these treatments can be effective for acute conditions and emergencies, they may not always address underlying root causes or promote long-term wellness.

4. Patient-Practitioner Relationship:

  • Functional Medicine: Functional Medicine fosters a collaborative and empowering patient-practitioner relationship, with patients actively involved in their own care decisions. Practitioners spend more time listening to patients' concerns, addressing their questions, and educating them about their health.
  • Conventional Medicine: Conventional medicine often involves shorter patient visits and less emphasis on patient education and empowerment. The practitioner-patient relationship may be more hierarchical, with the practitioner primarily responsible for making treatment decisions.

5. Integration with Other Modalities:

  • Functional Medicine: Functional Medicine embraces an integrative approach to healthcare, combining the best of conventional medicine with evidence-based complementary therapies. It encourages collaboration between practitioners from different disciplines to provide comprehensive and holistic care.
  • Conventional Medicine: While some conventional healthcare providers may incorporate complementary therapies into their practice, the integration is often less systematic, and there may be resistance to alternative approaches that deviate from established medical norms.

In summary, Functional Medicine and conventional medicine represent two distinct approaches to healthcare, each with its strengths and limitations.

While conventional medicine excels in acute care and emergency situations, Functional Medicine shines in its personalized and holistic approach to chronic disease management and preventive care.

By recognizing the value of both approaches and fostering collaboration between practitioners, patients can access a more comprehensive and integrative healthcare experience tailored to their individual needs and preferences.

References and Resources:


  1. Beidelschies M, Alejandro-Rodriguez M, Ji X, Lapin B, Hanaway P, Rothberg MB. Association of the Functional Medicine Model of Care With Patient-Reported Health-Related Quality-of-Life Outcomes. JAMA Netw Open. 2019;2(10):e1914017. doi:
  2. Beidelschies M, Alejandro-Rodriguez M, Guo N, et alPatient outcomes and costs associated with functional medicine-based care in a shared versus individual setting for patients with chronic conditions: a retrospective cohort study BMJ Open 2021;11:e048294. doi: 10.1136/bmjopen-2020-048294
  3. Thompson, Dennis. "Healthy Lifestyles May Reverse Cellular Aging, Study Suggests." Health Day. September 16, 2013. (Originally from the Sept. 2013 online issue of The Lancet Oncology.)
  4. "Relieving Pain in America: a Blueprint for Transforming Prevention, Care, Education, and Research" Institute of Medicine of the National Academics. June 29, 2011.
  5. Kennedy, Deborah A., Hurt, Jason, Seely, Dugald, "Health Cost Effectiveness of Natural Health Products: A Systematic Review of Randomized Clinical Trials," Evidence-Based Complement Alternative Medicine, September 6, 2009: 297-304.

Functional Medicine Organizations: Gain access to educational resources, professional development opportunities, and networking events by engaging with reputable Functional Medicine organizations. These organizations provide guidance, support, and standards for practitioners and patients alike.

  • Institute for Functional Medicine (IFM)
  • American Academy of Anti-Aging Medicine (A4M)


Functional Medicine represents a transformative approach to healthcare that prioritizes personalized, holistic, and patient-centered care. As we conclude our exploration of Functional Medicine's legitimacy, let's recap key insights and reaffirm the value of this innovative paradigm in promoting health and wellness.

Throughout this journey, we've witnessed how Functional Medicine goes beyond symptom management to address the underlying root causes of illness. By taking a comprehensive and integrative approach, Functional Medicine empowers patients to achieve lasting improvements in their health and well-being.

Moreover, we've seen how Functional Medicine bridges the gap between conventional and alternative therapies, offering a synergistic approach to healthcare that combines the best of both worlds.

As we reflect on the evidence supporting Functional Medicine's effectiveness, from clinical trials to patient testimonials, it's clear that this approach offers tangible benefits for individuals seeking optimal health and wellness.

In conclusion, Functional Medicine stands as a beacon of hope and empowerment in the realm of healthcare, offering a path to healing that honors the complexity of the human body and the individuality of each patient.

As we embrace the principles of Functional Medicine—personalization, root cause analysis, and patient empowerment—we embark on a collective journey toward a future where health is not merely the absence of disease, but a state of vibrant vitality and well-being for all.

Let us continue to explore, learn, and advocate for Functional Medicine, as we strive to create a world where personalized, integrative, and holistic care is accessible to everyone, empowering individuals to thrive and flourish in body, mind, and spirit.

Take Care, Stay Healthy, 

Jeffrey Mar, M.D.

The Real Gut Doctor

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Dr. Jeffrey Mark
With over thirty years of experience, Dr. Mark is a leading expert in holistic gut health. His integrative approach combines conventional medicine, functional and regenerative medicine, and advanced therapies to heal the gut and transform patient health. Holding 5 board certifications, Dr. Mark offers the comprehensive expertise of five medical specialists during each patient visit. He is dedicated to optimizing wellbeing by addressing the gut-related root causes of chronic health issues.
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