Nutrition science is challenging. In its own way, it is the most challenging of the sciences. But also the greatest.
Could it possibly be argued otherwise?
This difficulty comes from the fact that we are deeply biased about the act of eating, in a few ways:
Psychological. We are emotional about the act of eating, and we crave certainty about how we do it. We all eat, and eating is one of our most primary life functions. We form strong emotional attachments to the habits that fulfill primary life functions: food, sex, work, family, etc. When the emotional attachments to such habits of life–in this case, our eating habits–are challenged, we respond emotionally. The tendency to respond emotionally to biases our interpretation of the objective facts about nutrition. We also develop polarized thinking. Good-bad, right-wrong, natural-unnatural. Emotional, polarized thinking leads to a desire for certainty: if something so important is either good or bad, then we need it to be clearly one or the other, since making a mistake about something so important has serious implications. And yet…
Scientific. The objective facts of nutrition science, i.e. how we should eat, are unclear. Our strong emotions and craving for certainty about food are frustrated by the fact that the objective facts in nutrition science are incomplete and cannot fulfill these desires. We do not and will not have randomized controlled trials testing many of the most important hypotheses in nutrition science for the foreseeable future. Instead, we rely on surrogate or indirect tests of most of the hypotheses of nutrition science. Because these surrogate or indirect tests are many but also flawed, with different methods giving contradictory results, the results of many or most of these tests are debatable on the grounds that they do not and cannot provide the certainty that we psychologically crave. In fact, nutrition science does the very opposite and assures us that we can know little. What nutrition science can offer us (very little of certainty) is in direct conflict with deep-felt psychological needs (that is, a desire for certainty). This causes us to impute into nutrition science what is not there, or alternatively to become frustrated when definitive, practicable answers are not forthcoming–and to seek alternative sources of certainty, in the form of gurus, anecdotes, knowledge-through-self-knowledge, etc.
Politico-economic. The government and diet industry make authoritative but seriously conflicting recommendations. This leads to group identity and financial conflicts of interest. Because eating is one of our primary life functions, how we eat is important for health. To promote health, the government makes recommendations. Because we desire certainty and simplicity, they provide these recommendations in a simplified and authoritative form. Because these broad recommendations are not detailed, individualized, or explained well, an industry of practical advice has sprung up to provide more detailed, individualized, and better communicated recommendations. Because the advice of these authorities is conflicting, an emotionally charged conflict over food choices emerges. Shared feelings about food lead to the formation of groups of like-feeling people, in turn creating a sense of group identity. This sense of group identity further biases the way we receive the already fragmentary and difficult to interpret objective facts. Furthermore, because there are livelihoods to be made in this industry, financial conflicts of interest further bias the communication of the objective facts.
How should we evaluate and understand nutrition science so as to minimize these challenges and the impact of our biases on the interpretation of the facts? Is there any method or approach that is most reasonable that we can systematically follow to achieve this?
I think there might be. In evaluating this chapter, I hope to articulate the outlines of what that might look like. This systematic approach to the evidence will not enable us to fulfill our psychological desire for certainty about what we eat, but it might help people who want to understand how nutrition scientists think and work and where nutrition recommendations come from. Not much if anything of what I will write here will be new. It will only communicate what I have learned from my reflections on what nutrition scientists have told me and what I have read as a nutrition scientist-in-training.
But what I want to point out here is that nobody seems yet to be popularly endorsing or communicating a systematic approach for looking at nutrition science. That is part of the problem, and part of what this series is going to try to do.
For those who have followed this, I want this to be something bigger and more serious than just Diet Wars, or polyunsaturated or saturated fats, etc. That kind of argument is simply not interesting to me. I agreed to look at the chapter itself. So let us look at the chapter. And take it very seriously.