Lief Sosa, Medical Doctor

Functional medicine is a form of alternative medicine^[1] which proponents say focuses on interactions between the environment and the gastrointestinal, endocrine, and immune systems.^[2] Practitioners develop individual treatment plans for people they treat.^[2] Functional medicine encompasses a number of unproven and disproven methods and treatments,^[3][4] and has been criticized for being pseudoscientific.^[5]

The discipline of functional medicine is vaguely defined by its proponents.^[5] Oncologist David Gorski has written that the vagueness is a deliberate tactic which facilitates the discipline’s promotion, but that in general it centers on unnecessary and expensive testing procedures performed in the name of “holistic” health care.^[5]

Proponents of functional medicine oppose established medical knowledge and reject its models, instead adopting a model of disease based on the notion of “antecedents”, “triggers”, and “mediators”.^[6] These are meant to correspond to the underlying causes, the immediate causes, and the particular characteristics of a person’s illness respectively.^[6] A functional medicine practitioner will devise a “matrix” from these things which acts as a basis for treatment.^[6]

Treatments will generally be those not supported by traditional medical evidence.^[3] These include:

• Orthomolecular medicine ^[7]
• Detoxification of undocumented toxins.^[8]
• “Biochemical Individuality” (i.e. the notion that the nutritional needs, chemical constitution and disease states are unique for every individual;^[9] this represents a revival of the mainstream medical conception of disease common before the development of germ theory^[10])
• Organ reserve
• Diagnosis of chronic occult infections (e.g. so-called chronic Lyme disease)^[11]
• Homeopathy, including “Biopuncture”, the injection of homeopathic remedies^[12]
• Scientifically unproven nutritional interventions, including avoidance of gluten for people who do not have celiac disease or non-celiac gluten sensitivity^{[13][14][15][16]}
• Antivaccine advocacy^[5] including promotion of the discredited link between MMR vaccine and autism^[17] (the retracted Lancet paper by Wakefield et al.^[18] is cited in The Textbook of Functional Medicine)^[19]
• Leaky gut syndrome^[20][21][22]