Why There Is So Much Conflict with Nutrition

      When I talk about this paper in this post, I'm talking about this paper. Does it look long, and you don't really feel like reading it? That's ok, I'll summarize it for you: 

·         Nutritional epidemiology is a fluid area of study kept interesting by many limitations:

o   Measurement error – inability to conclusively measure an individual’s entire diet without large margins of error

o   Confounders – sources of error due to lifestyle associations (e.g. smoking and caffeine intake) that may skew results

o   Variable effects of foods items – even in the same food, variables such as source, age, etc. can impact the actual levels of nutrients in that food

o   Variable reference groups – Because diets and lifestyles range so wildly, it is difficult to create a group to compare to, creating an inability to determine causality, only correlation

o   Interactions – many foods and nutrients consumed together change the effects they would have by themselves, changing the way the nutrients would present in different diets

o   Multiple testing – when different studies come to different conclusions, whether may a mistaken association or other bias, it can create conflict, especially in the media, on what is ‘healthy’ or not (e.g. eggs and high cholesterol)

·         Media coverage of nutritional epidemiology may exacerbate the effect of conflicting evidence on the general public.

·         Because of the variations in people, foods, and interactions between diet and lifestyle, nutritional epidemiology may always be an ever-changing subject. 

      People come to me all the time to ask what they should eat. If we're being honest, if you come at me off the street, figure out my work is in nutrition, as ask me to make a diet plan for you, I'm going to have absolutely no idea what to tell you. This isn't paint-by-numbers information. It's a trial and error mess.

      Many people absolutely can't stand that. They want real information. They want me to tell them what to eat so that they never get cancer or give them a 100% fool proof way to lose weight.

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       If it were that easy, why would anyone need me? 

      Nutritional epidemiology is such an interesting field, because there is so much variation, conflicting information, and bias. The paper (check the top if you skimmed over the italics) really lays out some of the major reason we are unable to get a firm grasp on what to eat, when to eat it, and who should eat what.

It even inadvertently reiterates how far we are from finding the ‘optimal diet’. In the conclusion, the paper recommended avoiding excess calories, substituting white for red meat, eating more fruits and vegetables, and consuming mono- and poly-unsaturated fats rather than saturated fats. Sounds pretty basic, right? Not really.

      Using red meats as an example, I have seen much conflicting evidence on the subject. I pulled a review that concluded that red meat with increased risk of heart disease (Sun, 2012), and another one in the same course that showed processed meats, not specifically red meats, as the culprit in raising our risk of heart disease (Micha, Wallace, & Mozaffarian, 2010). I found it interesting that this was an example used to show what we know so far, when there is still so much conflict surrounding just those basic ideas.

We are so limited in the field of nutritional epidemiology by our biases, confounding interactions, and inability to truly track the lifestyle of a person. We may never have a solid grasp on what we should tell everyone to eat! We can make the best recommendations that we can with the information that is available to us, and continue the trial and error experiment that is a diet plan. Good thing you have a coach that's here to help!

Micha, R., Wallace, S., & Mozaffarian, D. (2010). Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus: A Systematic Review and Meta-Analysis. Circulation, 121(21), 2271-2283. http://dx.doi.org/10.1161/circulationaha.109.924977

Sun, Q. (2012). Red Meat Consumption and Mortality. Archives Of Internal Medicine, 172(7), 555. http://dx.doi.org/10.1001/archinternmed.2011.2287