Sunday, November 29, 2015

Nutrition Science is Controversial, but That's OK

Nutrition/diet science is a pretty controversial field.  At times it can seem a bit ridiculous, but that’s probably each of us perceives at least one of the controversies to be a non-issue and/or clearly resolved by the current body of evidence

But for the average person, who appears to have both low nutrition and scientific literacy, this can be quite confusing.  For this reason people may decide to opt out of engaging with nutrition science altogether or use that as a cover to justify to themselves and/or others why they are continuing to eat a diet that they understand to be probably not all that good

Achieving a consensus in nutrition was the aim of a recent conference by Oldways, which set out to find a common ground between diet advocates and nutrition scientists with some differing views

I’m sympathetic to the idea of a consensus, or a list of things almost all people agree on.  My rationale for this is that at the end of day I imagine almost everyone agrees that whole minimally processed foods are almost always superior to highly refined/processed foods regardless of macronutrient composition/etc and that getting sufficient micronutrients is also very important.  And then when we look what the average person eats (with 40% of calories coming from ‘extras’ [1]) and their nutrient intakes [2] it’s clear that this should be the first step and that engaging the average person with even a basic level of nutrition science will be a good thing

But the problem with nutrition science/dietary guidelines is that so much of the evidence is based on mechanisms and observational studies rather than randomised controlled trials.  As a result nutrition science is often quite speculative.  If someone asked ‘is it healthier to eat oats or eggs for breakfast’ there is enough evidence to have an intelligent conversation, but I don’t think we are close to answering that question definitively.  Even if we had a meta-analysis of long term RCTs there’s a component of individual variation as well and ignoring this can lead to the argument that ‘if X work for you, then you didn’t do X properly’ (the no true Scotsman fallacy).  All of this would be ok if there was an intelligent conversation and acknowledgment of the limitations of the evidence, but this doesn’t tend to happen

Furthermore, what this ‘consensus’ looks like and the lengths people went to fit this consensus (see Boyd Eaton’s presentation) is also a problem.  The consensus is essentially the dietary guidelines, a Mediterranean diet and a vegetarian diet, which wasn’t surprising considering the people involved.  I don’t subscribe to the idea that the dietary guidelines made us fat and sick, but I think they can be improved

To some extent the presence of a consensus can lead to dogma and also be used to shut down discussion of how current dietary guidelines can be improved.  While this seems to be a greater issue in more politicised topics, it still happens in nutrition science (for example).  In this respect the controversial nature of nutrition science can be seen as advantage over other more stagnant fields

The internet opens the doors to huge number of viewpoints on a wide range of issues, some of which may not necessarily be as simple as being right or wrong.  Some parts of nutrition science are simple and usually these are the areas with a lot of agreement (whole foods > processed foods, and adequate nutrition), while other parts of the nutrition science are complex and these are often the areas of controversy (diet and disease relationships).  Particularly as we’re living in the information age, we should stop telling people what to think, but rather how to think, so they can then go engage with the information out there and be better able to identify which are the logical arguments backed by evidence and which aren’t 

I also recommend reading George Henderson’s post on this topic

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