What is functional nutrition and diseases and underlying causes

What Is Functional Nutrition?

Functional Medicine Iceberg 1024x682 - What Is Functional Nutrition?


If you’re like most people, you’ve never heard of functional medicine let alone functional nutrition and that’s OK.


You’ve never heard of it because it’s not talked about by most health care professionals including medical doctors and dietitians.


That’s because they were never taught it. It’s just not talked about, and unfortunately often dismissed and sometimes ridiculed.


What is Functional Medicine?

It all starts with functional medicine. Functional nutrition is one aspect of the functional medicine model of health care that some doctors use to address the root cause of disease.


Functional medicine does take an integrative approach to patient care understanding that all bodily systems are interconnected (1). This interpretation of “integrative” is a different compared to conventional medicine.


In “mainstream” medicine, integrative care usually means considering all of a person’s needs.This is why there are interdisciplinary teams with doctors, dietitians, social workers, pharmacists, physiotherapists etc. A person may get help from all of those disciplines but they are basically operating separately but in parallel to each other.


They don’t consider a truly integrative approach. Yes they talk to each other about their care plans but a psychiatrist isn’t thinking about the role of diet on a patient’s gut bacteria and how the health of the gut is influencing a patient’s mind and mood via the gut-brain axis. A pharmacist isn’t thinking about the impact of an acid-reducing medication on the risk for small intestinal bacterial overgrowth (SIBO).


None of the body’s different systems (digestive, circulatory, nervous etc) are separated. They are inextricably INTEGRATED.


Functional medicine understands that disorders and diseases arise from dysfunction which has a basis at the cellular, molecular and metabolic level (2, 3). Dysfunction in one system will impact another because of integrative nature of the human body and therefore health and disease (4).


How Functional Medicine differs from Conventional Medicine

There are important differences between functional medicine and conventional medicine.


Conventional medicine on the other hand is more reactive in nature.


Once symptoms fall within a treatable range, an intervention is given. It’s geared towards treating a symptom without meaningful regard for the underlying cause.


Pre-diabetes example

Whereas a conventional medicine doctor wouldn’t react to a slowly increasing fasting blood sugar for example, functional medicine would try to understand why? Maybe they had low vitamin D levels, poor intake of magnesium, chromium or vitamin K2 (5, 6, 7, 8)


A person might have a fasting blood sugar that falls within the normal range of 4 to 6 mmol for years but which is slowly increasing.  I see this all the time. A person tells me their blood sugar increased from 4.5 mmol, to 5.2 mmol,  to 5.8 mmol over an 8 year period but was told “everything is fine”.


The problem is, that person was ALREADY insulin resistant. The resistance was simply getting worse by no one asked why? Not only that, nothing was done about it because there is no established medical (e.g. drug) to treat it until it falls in the ‘”official” pre-diabetic range (6.1 to 6.9 mmol).


Once in this range of 6.1 mmol or higher, a pharmaceutical treatment exists: metformin.


Sadly, the best time to have intervened would have been during the 6 to 10 years before the type 2 diabetes diagnosis, during the early stages of insulin resistance when there was a greater chance for prevention. This is where functional medicine and functional nutrition therapy is different.


Conventional medicine really is about symptom management, disease progression management. Functional medicine aims to get at true healing or what’s referred to as “upstream interventions”. Getting to the problem proactively before things get really bad.


What is Functional Nutrition?

Using this example, the functional medicine and functional nutrition viewpoint is that anyone who is experiencing this kind of blood sugar change is not ‘functionally’ optimal [i.e. at a cellular or metabolic level].


Despite looking & feeling fine, not having any outward symptoms, nor meeting any criteria for a medical diagnosis, there is clear metabolic derangement.


It’s true, this person IS NOT at the tipping point. However, there are several underlying causes that are driving this progressive insulin resistance. 


It could a functional [or sub-clinical] nutrition deficiency; a state where there isn’t an overt, full-blown nutrient deficiency but one where the underlying physiology or cellular fitness is not functioning at its best.


There could be a sub-clinical deficiency of magnesium, vitamin D, chromium, thiamine [B1], or omega-3 fatty acids since all of these are involved in regulating insulin and carbohydrate metabolism (9). Perhaps the insulin resistance is due to poor sleep quality and chronic stress; known risk factors for insulin resistance and diabetes (10, 11).


Functional medicine and functional nutrition want to know !!


IBS example

I’ve been at this long enough to remember that if a patient had IBS, they were told in get more fiber in their diet and to reduce stress. Fast forward to today and someone who’s been diagnosed with diarrhea-prominent irritable bowel syndrome (IBS-D) will be approached differently (thankfully).


The non-functional approach is still in play and might include giving a patient a handout and telling them to avoid high FODMAP foods. Or it might be that and telling them how to identify and avoid trigger foods, plus advising how to prevent dehydration.


More and more doctors and dietitians are using a structured low FODMAP approach including both the restriction phase and a proper reintroduction/challenge phase. But then once a patient’s FODMAP trigger(s) is found, simply be told to limit their intake of that problematic FODMAP.


A functional approach, on the other hand, would involve functional investigation for other possible underlying contributors, like SIBO, gut dysbiosis, food sensitivities, allergies, or intolerances and a thorough evaluation of lifestyle and health history (1213).  Perhaps the patient has a histamine intolerance or mast cell activation syndrome (14, 15).


This is because gut irritation and inflammation can be caused by many other things [other dietary components, foods, medications, supplements, stress] not considered in the non-functional approach.


Using Functional Nutrition in Practice

Functional medicine and functional nutrition therapy gets to the underlying cause of disease-promoting dysfunction.


Practitioners follow appropriate clinical practice guidelines but also focus on a patient’s unique clinical picture. In this sense it is more personalized.


Functional nutrition practitioners aim to get to as many underlying issues early on by supporting normal physiology, biology and metabolism.


Integrative Model David Allen MD - What Is Functional Nutrition?


It uses a systems-oriented approach which engages the patient and the practitioner in a therapeutic partnership by focusing on the whole person [not the symptom of the day]. See the patient care matrix below


Institute of Functional Medicine Patient Care Matrix


Functional medicine understands that disease and dysregulation don’t ‘just happen’ or ‘come out of nowhere’; but rather are in the making for years.


A functional nutritionist looks at the foundational way that food & nutrients affect the body on the cellular level and goes beyond simply assessing what you’re eating as compared to a model such as Canada’s Food Guide or Choose My Plate.


Functional nutrition therapy is not your grandmother’s nutrition. It’s not about making generic statements about ‘balance, variety or moderation’ nor is it a myopic view on just grams of protein, fat and carbs.


A ‘generally healthy diet’ will not hit the mark; rarely to never will it address optimal functionality since nutrient guidelines are designed to prevent overt deficiencies; not to ensure optimal metabolism. Being your best self and having best health requires a more holistic and comprehensive approach.


Three main focuses of functional nutrition therapy

Patient-centered care

Its truly listening to the patient and learning his or her story. The practitioner includes the patient in the discovery process and tailors the treatment that address’s the individual’s unique needs taking into account the physical, psychological, environmental and not just what the patient is eating.


Evidence-based and integrative

It integrates all the variables that make up the complex web of interactions that influence the patient’s health such as medical history, medication & supplement use, physiology, social supports, lifestyle, physical and social environment, and unique genetic make-up.



It goes beyond just traditional treatment of symptom management but strives for true prevention. It does this by being proactive and getting to the root cause of disease to promote true healing (12).


For more, see Dietitians in Integrative & Functional Medicine – a practice group of the Academy of Nutrition & Dietetics


Doug Cook RDN is a Toronto based integrative and functional dietitian nutritionist with a focus on digestive, gut, mental health.  Follow me on FacebookInstagram and Twitter.


Photo credit: CKNC Wellness, The Joint , David Allen MD