We’re always hearing extreme results from nutritional research.
Ranging from the “dangers” of coconut oil and eggs to completely contradictory statements, like that a low-carb diet shortens lifespan and also increases it, we are bombarded with confusing information that can make deciding what to eat totally overwhelming.
But with the right knowledge and resources, we can learn to decipher dietary studies to get the real truth.
Starting with the basics, it’s important to identify what type of study is used. Often with studies on nutrition we see the use of observational data, which unfortunately has many limitations and can’t prove that particular factors are responsible for a particular outcome. These types of studies are better suited for generating a hypothesis as a basis for further research.
Observational studies get us into big trouble when it comes to nutrition because they only show us correlations which are often misinterpreted as causes—two very different things.
My guest on last week’s episode of The Doctor’s Farmacy, Chris Kresser, is an expert in Functional Medicine and a leader in nutritional research. He gives a great example of how broad and misleading correlations can be, “Per capita consumption of margarine in the United States and the divorce rate in the state of Maine are correlated at 99.3 percent.”
Is that good enough to say that the national consumption of margarine causes divorce in Maine? I don’t think so, yet this is exactly the model many nutrition studies are following, leading to the dramatic dietary headlines we so often see.
Instead, randomized-controlled trials (RCTs) yield much more reliable results. The short summary of RCTs is that they use a randomly assigned placebo group to compare the treatment group to, helping to avoid conscious and subconscious bias from researchers and providing a clearer picture of the risks or benefits an intervention does or does not have. There are additional stipulations to producing a valid RCT, like matching participants for age, sex, ethnicity, smoking status, etc. but you can get the idea.
Other important aspects of finding valid research include looking at who funds it and considering other types of conflicts of interest, as well as things like the number of participants. Unfortunately, there are times when an RCT isn’t necessarily ethical, which is one obstacle for dietary research.
If you’re curious to learn more about nutritional research and break down the myths that have become so widespread, be sure to check out my podcast interview with Chris Kresser. He is the guy I trust for accurate research and the doctor I go to for my own healthcare. I hope you’ll tune in.
Wishing you health and happiness,
Mark Hyman, MD