Dr. John Gannage, MD

Dr. John Gannage, MD Dr. John Gannage is a Leader in Integrative Medicine to Restore Health and Prevent Disease

MARKHAM INTEGRATIVE MEDICINE is a clinic specializing in Integrative Medicine (integrating conventional and complementary/functional medicine) located in the City of Markham’s heritage district. DR. JOHN GANNAGE, MD is a leading provider of Integrative Medicine, offering health services as a licensed medical doctor to the Greater Toronto Area since 1992.

Stress is supposed to be temporary. Your body responds to a stressor, mobilizes energy, and then returns to balance. But...
09/05/2026

Stress is supposed to be temporary. Your body responds to a stressor, mobilizes energy, and then returns to balance. But when stress becomes chronic, that alarm can stay activated, affecting far more than how you feel mentally.

Chronic stress can influence the nervous system, hormones, immune function, digestion, sleep, metabolism, cardiovascular health, mood, and cognitive function. Over time, these systems can begin to influence one another, creating a cycle of poor sleep, inflammation, digestive changes, fatigue, and reduced resilience.

The good news is that supporting stress resilience is about more than simply trying to “relax.” A functional and integrative approach looks at the bigger picture and considers what your body needs to regulate, recover, and become more resilient.

If stress is affecting your energy, sleep, digestion, hormones, or overall wellbeing, it may be time to look deeper. Comment CHRONIC STRESS and we'll send you the blog to learn more about why stress may be making your histamine symptoms worse.

09/02/2026

One of the biggest misconceptions in health is that if something is good, more must be better.

In reality, the body thrives within a relatively narrow range of balance.

Too much exercise can become a stressor. Too little movement creates its own challenges. The same is true for nutrition, supplementation, fasting, sleep, and even recovery.

Our job isn’t to chase extremes. It’s to understand what your body actually needs.

When we identify the right inputs, in the right amounts, at the right time, the body becomes much better at regulating itself. Energy feels steadier.

Symptoms become less unpredictable. Progress becomes sustainable instead of temporary.

The goal isn’t perfection. It’s finding the sweet spot where your body can consistently function at its best.

Stress isn't just affecting your mind. It can influence your histamine levels, too.If your histamine symptoms seem to fl...
08/25/2026

Stress isn't just affecting your mind. It can influence your histamine levels, too.

If your histamine symptoms seem to flare during busy seasons, periods of poor sleep, illness, or emotional stress, food may not be the whole story.

Chronic stress affects the nervous system, activates mast cells, disrupts gut function, and can make it harder for your body to regulate and break down histamine. The result? More headaches, congestion, brain fog, anxiety, digestive symptoms, skin reactions, and food sensitivities, even if your diet hasn't changed.

That's why a functional medicine approach goes beyond simply eliminating high-histamine foods. We look at the bigger picture by supporting nervous system regulation, improving gut health, identifying underlying triggers, and helping your body restore its natural ability to manage histamine.

If you've been chasing symptoms without finding lasting answers, it may be time to look beyond your plate.

Comment "STRESS" below to learn how we approach this in practice.

08/22/2026

If regulating your nervous system were as simple as taking one supplement, life would be a lot easier.

The truth is, your nervous system responds to the inputs it receives every single day. Poor sleep, unstable blood sugar, chronic inflammation, gut dysfunction, ongoing stress, nutrient deficiencies, and environmental exposures can all keep your body stuck in a constant state of “fight or flight.”

That’s why a functional medicine approach focuses on supporting the whole system, not just managing symptoms.

Simple habits like nourishing your gut, balancing blood sugar, prioritizing quality sleep, moving your body regularly, spending time outdoors, practicing breathwork, addressing inflammation, correcting nutrient deficiencies, reducing toxin exposure, and managing stress all work together to help your body become more resilient.

Healing your nervous system isn’t about finding one magic solution. It’s about consistently giving your body the support it needs to shift from survival mode toward balance.

Which of these has made the biggest difference for you? Let us know in the comments below.

08/17/2026

Most people associate iron with making red blood cells, but iron plays a much bigger role in the body than many realize.

Low iron can influence energy, attention, behavior, and healthy brain development. In some children, it may even contribute to pica, a condition where non-food items are repeatedly chewed or eaten.

This behavior isn’t simply a habit. It can be an important clue that something deeper deserves attention.

In functional medicine, we don’t just ask whether a child has anemia. We also look at whether their iron stores are truly optimal. One marker we often evaluate is ferritin, which reflects the body’s stored iron. Even when hemoglobin is normal, low ferritin may indicate that iron reserves are inadequate.

The next question becomes why iron is low.

In some cases, children aren’t consuming enough iron-rich foods because of highly selective eating patterns. In others, poor absorption, gut inflammation, or microbiome imbalances may be limiting the body’s ability to utilize iron effectively.

Certain gut bacteria can even compete with the body for available iron.

Rather than simply replacing iron, it’s important to understand what is contributing to the deficiency in the first place. Identifying and addressing the underlying cause can support not only healthy iron levels, but also improvements in energy, attention, behavior, and overall wellbeing.

If your child has ongoing fatigue, restricted eating, attention challenges, or pica behaviors, it may be worth taking a closer look at their iron status and gut health through a comprehensive functional medicine evaluation.

I’m honored to be presenting once again on the international stage, this time as part of the International Nutrition Med...
08/14/2026

I’m honored to be presenting once again on the international stage, this time as part of the International Nutrition Medicine Symposium 2026 in Japan.

For this recorded presentation, I’ll be discussing biological stratification in pediatric neurodevelopment, with a focus on folate receptor autoimmunity within a systems-based orthomolecular framework. I’ll also be available to answer questions afterward, which provides an opportunity to continue the conversation and explore the clinical considerations in greater depth.

I’m grateful for the opportunity to share this work with an international audience and to contribute to conversations around more personalized, systems-based approaches to pediatric neurodevelopment.

I’ll also be speaking for Exceptional ND, an educational platform focused on clinical excellence and community, where I’ll be discussing ASD assessment and where leucovorin may fit within a functional medicine approach.

It’s always a privilege to connect with clinicians who are committed to looking deeper, asking better questions, and continuing to advance evidence-informed approaches to patient care.

08/10/2026

When we think about fertility, we often focus on hormones, ovulation, or s***m count. But there’s another factor that’s frequently overlooked: environmental exposures.

One example is mycotoxins, toxic compounds produced by certain molds. Their role in nature is to help mold survive, but when humans are exposed, these compounds can place additional stress on the body’s detoxification systems.

One of the ways mycotoxins may influence fertility is by increasing oxidative stress. As the body works to process and eliminate these compounds, it can generate reactive oxygen species (ROS). When oxidative stress becomes excessive or when the body’s detoxification pathways aren’t functioning optimally then it may contribute to cellular damage that can affect both egg quality and s***m quality.

For some individuals, genetic differences in detoxification pathways may also make it more difficult to efficiently clear environmental toxins, increasing the body’s overall burden.

This doesn’t mean mycotoxins are the cause of every fertility challenge. However, if you’ve addressed more common factors and are still searching for answers, it may be worth taking a deeper look at your environment and your body’s ability to manage toxic exposures.

Functional medicine aims to understand the bigger picture by investigating underlying contributors that may be affecting overall health including fertility.

Comment FERTILITY if you’d like to learn more about how environmental exposures may impact reproductive health.

Stress doesn't just affect how kids feel. It can influence how they grow, learn, sleep, and regulate their emotions.Duri...
08/04/2026

Stress doesn't just affect how kids feel. It can influence how they grow, learn, sleep, and regulate their emotions.

During childhood and adolescence, the body is constantly developing. Chronic stress activates the body's stress response system, increasing cortisol production. While cortisol is essential in the short term, prolonged elevations can affect hormone balance, growth, metabolism, focus, and emotional wellbeing over time.

That's why supporting adrenal health isn't about eliminating stress altogether. It's about helping the body respond to stress more effectively.

Simple habits like prioritizing sleep, eating balanced meals, spending time outdoors, moving regularly, and creating opportunities for rest can all help support healthy cortisol rhythms and build resilience. For some children, a deeper functional medicine evaluation may also help identify underlying factors contributing to fatigue, anxiety, attention challenges, or other signs of chronic stress.

When we support the body's stress response early, we're not just helping kids feel better today. We're investing in their long-term health and development.

Swipe through to learn how stress impacts hormones in children and teens, and what you can do to help support healthy growth, resilience, and overall wellbeing.

Antibiotics can be lifesaving, but they don't just eliminate harmful bacteria they also reduce many of the beneficial mi...
07/27/2026

Antibiotics can be lifesaving, but they don't just eliminate harmful bacteria they also reduce many of the beneficial microbes your gut depends on.

For some people, that temporary disruption resolves on its own. For others, it may contribute to digestive issues, changes in the gut microbiome, chronic inflammation, bacterial or yeast overgrowth, and symptoms that persist long after the infection is gone.

That's why recovery shouldn't end when you finish your prescription.

Supporting your gut after antibiotics may include eating a nutrient-dense, anti-inflammatory diet, replenishing beneficial bacteria, feeding your microbiome with prebiotic fiber, prioritizing quality sleep, managing stress, and addressing any underlying imbalances that may have developed.

A healthy gut plays a role in far more than digestion, it influences your immune system, metabolism, brain health, and overall resilience.

If you've taken antibiotics recently or find yourself needing them frequently, don't overlook the importance of supporting your microbiome during recovery.

Comment GUT if you'd like to learn more about restoring your gut microbiome after antibiotics.

07/07/2026

When I started medical school over 40 years ago, we learned anatomy, muscles, nerves, and how the body was structured.

What we didn’t learn was the important role fascia plays in movement, flexibility, and chronic pain.

Fascia is the connective tissue that surrounds and links muscles, joints, and organs throughout the body. When it becomes restricted after injury, inflammation, surgery, or repetitive strain, it can contribute to stiffness, reduced mobility, and pain that seems to spread beyond one specific area.

This is one example of how our understanding of the body continues to evolve. It’s also why functional medicine is built on looking beyond symptoms and considering the many systems that influence health including areas that weren’t emphasized in traditional medical training.

If you’ve been living with chronic pain, persistent stiffness, or a body that simply doesn’t move the way it used to, it may be worth exploring whether fascial restrictions are part of the picture. Working with a skilled physiotherapist, osteopath, chiropractor, or manual therapist who understands fascial release may help restore movement and support your recovery.

Pain isn’t always just about the muscles. Sometimes the connective tissue deserves a closer look.

Comment PAIN if you’d like to learn more about fascia, chronic pain, and the role it may play in your recovery.

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