A 56-year-old university professor with psoriatic arthritis goes to see a doctor because his condition is worsening. Psoriatic arthritis is a disease where your immune system rebels against you, creating patches of abnormal skin and aching joints. Does the man leave the doctor’s office with a prescription for a better medication than what he was on? No.
Instead, he is told to completely change his diet and avoid gluten, dairy, yeast, and eggs; he is given a high-dose multivitamin and mineral supplement, as well as additional vitamin pills like D3, B6, B12, and folic acid; he is told to take capsules of gut bacteria; and he is prescribed an antifungal drug.
Why?
Because he was seen by a functional medicine practitioner.
This case was published in the reference tome on the subject, Textbook of Functional Medicine. Make no mistake: functional medicine is not a specialty of medicine. It is a slippery slide that moves healthcare providers into alternative medicine. Under the seductive luster of marketing verbiage, its goal is clear: test for as many things as possible and load the patient up with dietary supplements.
It is a philosophy that runs counter to modern medicine while pretending to be its salvation.
Test until you find something that could be wrong
On two major websites for functional medicine, a paper is referenced that apparently shows that this discipline can improve health better than conventional medicine! I’m sure most readers would like to know more. After all, the practice of modern medicine is riddled with long wait times and short visits, and the management of chronic conditions can be challenging. This triumphant paper, though, is anything but. Patients who went to family health centres were compared to those who went to a functional medicine centre, and while the patients themselves were similar enough, the ones in the latter group also got to see a registered dietitian and a health coach! Their functional medicine practitioner even gave them 60 to 75 minutes! No wonder they felt better. This is not functional medicine; it is functioning medicine.
The marketing campaign for functional medicine, however, has a lot more to unpack. Websites speak of imbalances. Health and disease are placed on a spectrum, with declining function in the middle. No one is ever truly healthy, which means everyone can be sold supplements.
And conventional medicine, you will be reminded ad nauseam, only treats symptoms. Functional medicine is revolutionary because, for the first time, its doctors will investigate the root cause of what makes you ill. As Andrea Love, who has a doctorate in microbiology and immunology, pointed out recently, this alluring falsehood is rampant in alternative medicine and wellness circles—even FDA Commissioner Marty Makary himself repeated it despite being a physician. The root cause of type 1 diabetes is the death of beta cells in the pancreas; that of smallpox is an infection by the Variola virus; and phenylketonuria (PKU) is due to mutations in the PAH gene that hamper a protein in the body from metabolizing the amino acid phenylalanine. To accuse medicine of being incurious with regards to true disease causes is unfounded, but it will feel right to aggrieved patients looking for an alternative.
What these patients will be confronted by when they seek out functional medicine is a massive battery of tests, “five times more testing than most physicals” according to one prominent website. But as much as we would all like to get tested for cancer every five minutes, the main problem with medicine is not that doctors don’t test people enough. Every test is imperfect: it will generate the occasional falsely positive result. Test enough people and you get a lot of false positives, which generate anxiety, more invasive tests, and sometimes unnecessary treatments. That’s why cancer screening recommendations are age-specific, and why the Choosing Wisely campaign exists. It reminds physicians not to carelessly order tests but to consider whether they really are needed and if their results will be informative.
Functional medicine practitioners are even more slapdash than simply ordering unneeded tests: they also fudge the results. “In the functional medicine work-up,” we read in chapter 35 of Textbook of Functional Medicine, “the clinician often looks to lab not only for signs of pathological change [meaning changes that indicate the presence of a disease] but also to assess more subtle signs of imbalance or dysfunction.” This encourages people to approach blood and urine test results with the thought that there must be something wrong with them and to thus interpret them very generously.
Once something has been flagged as wrong—and there is always something “wrong”—the solution is simple: throwing expensive spaghetti at the wall to see what sticks.
First, open your wallet. Then, open your mouth
Elimination diets are a hallmark of functional medicine. Why? Because modernity is apparently slowly killing us, a sentiment echoed throughout the wellness industry. “In the early 21st century,” we read in the functional medicine textbook, “as society has increasingly been exposed to toxic compounds in the air, water, and food,” our ability to detox “is of critical importance to overall health.” Disregard the fact that the U.S.’s food supply is the safest it has been in history. Functional medicine says we need to purge.
A two-day water fast is often recommended—“consume water, lemon water, and herbal tea only”—followed by a slow reintroduction of certain foods. Then come the supplements.
The general prescription strategy taught in the functional medicine textbook might as well include the kitchen sink. Future disciples are invited to give their patients antioxidants to protect their cells; amino acids to help with the detox; bile stimulants; probiotic bacteria; molecules that repair intestinal permeability; vitamins and minerals; antiparasitics; and laxatives. Toxins, they are taught, are everywhere: their textbook even has a section titled “A broader definition of detoxification,” which helps identify (or create from whole cloth) even more problems than conventional doctors would.
This idea that the body cannot function without 50 different pills is a hypochondriac’s wet dream. The body’s resilience and buffers are dismissed; what it needs is a perpetual molecular rescue operation, and this all-hands-on-deck salvage comes with an eye-watering bill.
Supplements don’t grow on trees
Mark Hyman has become the poster child for functional medicine. The idea behind the discipline is said to have originated in 1990, followed a year later by the foundation of the Institute for Functional Medicine by a biochemist, his wife, and a physician. But it’s Hyman—an American who received his medical degree from the University of Ottawa and who is now president of clinical affairs for the Institute—who embodies the movement itself and provides it with far-reaching legitimacy.
Like Joe Mercola, Mark Hyman sells just about any dietary supplement you can think of: roughly 500 products, in fact, spread over 12 pages of results. Supplements are bundled into a confusion of stacks: collections for gut health, for COVID-19, for female hormones, with stacks you should take when building muscles and other stacks for “fitness and performance.” I wonder if the confusing overlap is meant to invite you to book a paid consult so you can get oriented.
Indeed, Hyman and his staff also offer a program called Function Health—“no insurance involved”—as well as an in-person clinic in Massachusetts named the UltraWellness Center. It’s not wellness and it’s not superwellness; it’s ultrawellness, a level of wellness few dare to dream. To be ultrawell, though, you may need to be ultrawealthy. The Center sells about a dozen intravenous infusions with a price tag between 150 and 450$ a shot. You don’t need these IVs, but if your wallet is feeling heavy, you can simply open wide.
And while Hyman’s Function Health revolution promises to integrate cutting-edge technologies—“omics, biosensors, big data, and AI”—to deliver personalized care, functional medicine as a whole can’t help but embrace not-so-new boogeymen and disproven cures. Its textbook claims that “it is likely that at least 25% of the United States population suffers to some extent from heavy metal poisoning,” which would be front-page news if true. No source is listed. If we look at lead, it is true that 25% of Canadians aged 6 or older (and I suspect Americans as well) used to have blood lead concentrations above what was recommended… in the 1970s. Since then, we have phased out leaded gasoline and paints, and the percentage dropped to below 1%.
Meanwhile, the Institute for Functional Medicine warns us against the evils of extremely low-frequency electromagnetic radiation, like cell phones and Bluetooth, recommending vitamin C to mitigate the alleged harm. And, of course, functional medicine flirts heavily with anti-vaccine views: Hyman himself wrote that he is “pro-vaccine-safety” (a code word often used publicly by anti-vaccine activists) but noted that “vaccines may affect susceptible children through different mechanisms,” leading to autism.
I saw a lot of autism pseudoscience while looking into Mark Hyman, the Institute for Functional Medicine, and the Textbook of Functional Medicine. Hyman’s recommended “treatment” is indistinguishable from any of functional medicine’s cure-alls: remove gluten and allergens and prescribe anti-fungals, antibiotics, probiotics, enzymes, vitamins, minerals, and omega-3s. Functional medicine frees doctors from the algorithms and protocols of evidence-based medicine and gives them an unlimited supply of unproven and disproven supplements to play with—and these supplements are not infrequently contaminated and adulterated. Because care is personalized, nobody knows which supplements will benefit a patient, so the practitioner is free to improvise, recommending stack upon stack until the patient says they’re feeling better.
Speaking of these practitioners, you may associate “alternative medicine” with chiropractors and acupuncturists—people who are typically not MDs. The twist with functional medicine is that it often attracts professionals with legitimate healthcare degrees. The Institute for Functional Medicine’s current certification is open to medical doctors, osteopathic physicians (which in the U.S. are extremely similar to MDs), nurse practitioners, physician assistants… and naturopaths. With the exception of the latter, it is a funnel encouraging genuine healthcare providers to embrace woo. It’s where disillusioned doctors meet disillusioned patients. See Surgeon General nominee Casey Means, a former surgical resident turned functional medicine influencer.
But the Institute’s certification program will be broadening in 2026, accepting applications from acupuncturists, chiropractors, naprapaths, dentists, optometrists, psychologists, and many others. And you don’t need certification to offer functional medicine services: after all, it’s not like functional medicine has a professional order. Here, in Montreal, the Institute lists 55 functional medicine practices and they exemplify the wide web of people who get caught up in this philosophy: physicians and naturopaths, yes, but also pharmacists, physical therapists, health coaches, and Traditional Chinese Medicine providers.
The 1,000-page Textbook of Functional Medicine, released by the Institute for Functional Medicine, begins with this disclaimer: “… this book is not intended to be used as a clinical manual recommending specific treatments for individuals patients.”
A fair warning, perhaps even an invitation to close the book and put it back on the shelf.
Take-home message:
- Functional medicine is not a specialty of medicine but rather a way to move conventional healthcare providers into the alternative medicine space
- Practitioners will order a large number of unneeded medical tests, leading to many potential false positive results, and are encouraged to interpret results loosely by not just looking for signs of disease but for anything that might indicate “imbalance”
- The solutions they propose include restrictive diets for no good reason, as well as many dietary supplements that have often never been shown to work
