Monday, January 14, 2013

What about diet and evidence-based IBD?

IBD and Diet

Despite claims to the contrary, there is no one diet that will provide universal symptom relief for IBD.  I’d like to say that the nutritional portions of this blog present a silver bullet approach to diet and IBD, but they don't.  There is no –I repeat no – clinical evidence for a one-size-fits-all diet plan that addresses everyone with these diseases.  Additionally, traditionally recommended diets such as the BRAT diet (bananas, rice, apple sauce, toast) don’t address long-term nutritional needs and may be unnecessarily restrictive.

Much of the information presented as authoritative ranges from harmless to outright dangerous.  Well meaning individuals provide anecdotal stories as evidence (“ I don’t know – my cousin has UC and ever since he started taking fish oil pills he’s been fine”) and health care providers repeat dietary guidance that they were taught in medical school (sometimes decades earlier) that has little to no clinical basis.  Even worse, for-profit enterprises promote diets that rely on magical thinking to work and can even go so far as to claim to “cure” IBD (unfortunately, with the exception of a complete colectomy for UC, there is no known cure for IBD as of this writing).

How do we differentiate between the myriad of sources offering dietary tips (and why is this blog any different)?  Everywhere else in medicine the gold standard for evaluating treatments is a concept called science-based medicine.  Science-based medicine is the application of the scientific method to evaluate various treatment modalities.  The process is straightforward, repeatable, based on sound principles of chemistry, biologic, and physics and open to professional review and scrutiny. 

In science-based medicine, a theory is put forth regarding a specific treatment (or, in this case diet) approach.  The theory should be based on solid scientific principles to differentiate it from “magical” theories based on physical impossibilities.  The theory is then tested in a double-blind fashion against a control group.  In double-blind studies, neither the evaluator nor the subject knows which group the subject is in.  The results are published in a peer-reviewed forum, and if the treatment is found to be more effective than the control (efficacy) in an objectively measurable fashion and to have minimal harmful side effects (safety), it is adopted as a new approach.  Ideally, the studies are confirmed by other, independent researchers and on a large scale. 

Contrast this approach to the way many dietary approaches are proposed.  An individual poses a theory that may be based on scientific principles or it may not.  They try that theory on themselves (or in the case of physicians, a few patients) and ask the subjects if they believe it works.  If so, they provide it to more patients and inform them a priori that they have had success with the treatment.  In these cases, there is no way to know if the diet is effective or if the placebo effect* is responsible for the results.  Additionally, even if there is efficacy, because the diet itself hasn't been isolated as a factor there is no way of knowing if the diet is responsible for or just correlated with positive results.

This blog attempts to provide science-based guidance, including dietary advice.  The guidance is provided based on high quality, peer reviewed research.  Where there are gaps in the research and unanswered questions, these are addressed as well.  

The information provided represents the consensus of the nutrition-based evidence at the time of writing.  Because we refine our scientific understanding over time, the studies and information presented may be refined (or in some cases even overturned with substantial evidence) over time.  To address this, I'll cover in a future post the ways for you to personally evaluate new evidence as it become available and incorporate it into your own  nutritional planning.

The placebo effect is only partially people feeling better because they believe they are being treated.  The effect is, in actuality, a multi-faceted effect.  It includes the provider selectively looking for evidence to support their theories and not looking at the negative results, choosing which evidence to include, other actions taken by people being treated, and the desire to “self-report” positive effects on subjective factors.

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