The Problem with Science Discussions
It is amazing to me how much science is interpreted in multiple ways, sometimes exactly the opposite from each other. Today I want to highlight this issue using a study on dietary choline from animal sources and a substance it converts to, TMAO.
TMAO levels tend to be higher in blood and urine of people who have died from heart attacks and strokes. This has led to studies which are seeking to prove a connection between the two, in other words some form of causation and not just a correlation.
The study which is being focused on in today’s discussion is done by a group of researchers from the Cleveland Clinic. It can be accessed at this link nejm.org/doi/full/10.1056/NEJMoa1109400#t=article, so you can read it for yourself if you are so inclined.
The basic facts of the study are as follows: (1) The study showed a definite mechanism of TMAO production to be the presence of certain intestinal microflora and (2) the study showed a clear correlation between higher TMAO levels and cardiovascular disease mortality risk. The fun starts when people with a differing bias begin to interpret the study and discuss it from their individual point of view – this is why it always pays to be skeptical when you read science reporting or media.
Two views on dietary choline and TMAO risk
I have linked to two resources below with completely opposite views on the study. The first is a video posted by Dr. Michael Greger, physician, New York Times bestselling author, and internationally recognized speaker on nutrition, food safety, and public health issues. Dr. Greger publishes videos and blogs at nutritionfacts.org. The second is an article posted by Chris Kresser, functional and integrative medicine practitioner, author, premier researcher, and creator of chriskresser.com.
Dr. Greger is a resource I respect a lot – however he is a committed vegan and he brings that viewpoint to everything he discusses. Not surprisingly he looks at this study and then reports it as verifying why one should never eat animal products.
Chris started out with a website called “the Healthy Skeptic” and what has attracted me to his work is his ability to disect research extensively looking at it from a multitude of angles. Chris is an omnivore along the lines of the Paleo community, and of course he does not see this study as proving anything in terms of whether eating animal based choline is detrimental to health.
I am fascinated by how two very highly educated people can look at the same data and come to completely different conclusions as to what it means. In a sense, it shows the tendency we all have towards “confirmation bias”, which is a bias we all hold to believe things which tend to confirm what we already think and disregard things which tend to prove the opposite. Of the two, I tend to think Chris is more open to alternative explanations, but we are all human and we all have the bias.
Where do I come down? There is nothing here which has changed my current nutrition belief – I am an omnivore in moderation – in other words I eat a mostly plant-based diet with small daily amounts of eggs, fermented dairy and meat / fish to round out my nutritional profile. I believe there is enough health risk in animal based food to eat enough of it to obtain basic nutrients and no more.
Where should you land on this question? That is a matter for you to decide – I have given you two views to consider below.