The nutritional and medical world is abuzz about the trendiest part of the digestive system, the gut microbiome. Studies show that the bacterial residents of your gut biome are correlated with weight, inflammation, various diseases, and even mental health. So why not give your gut a “makeover” for your health? At first I fell right for the hype couched in science, and was preparing myself for Jeannette Hyde’s four week plan, The Gut Makeover.
I found Hyde’s work in a peer-reviewed journal article as I was researching the gut biome; I was hoping to discover clinical findings that might translate into concrete dietary advice to improve my own and my clients’ gut biomes. And I thought I’d found it. Hyde’s article “Microbiome restoration diet improves digestion, cognition and physical and emotional wellbeing”, where I originally came across it for some reason didn’t include a giant retraction notice as does the link above.
Not knowing the firestorm of criticism surrounding the “study”, I eagerly purchased Hyde’s book, The Gut Makeover and was surprised to find that strict plan in her one-month diet went far beyond the protocol described in the journal article. I’d read diet advice such as chewing every bite twenty times, fasting for 12 hours, and avoiding snacks between meals in other places. Indeed these techniques seem to have some connection to the gut such as giving the digestive system a chance to work better by slowing down eating and do its “clean up” work between meals. The advice also correlated with weight loss in some studies. So I swallowed these points and my questions and kept reading.
It was when I begin preparing for the actual diet that real skepticism crept in. I thought I’d start in the new year, after the holidays because the diet is so strict I wouldn’t be able to have a glass of champagne at midnight on New Year’s Eve or a cup of coffee the next morning. As I was detoxing from caffeine withdrawal symptoms (I’ll write about caffeine in a future post), I started to wonder How is caffeine related to gut health at all? and Why am I torturing myself?
Hyde’s rationale for avoiding all caffeine (even decaf tea and decaf coffee!) rests on two assumptions. One, that caffeine affects the central nervous system, which she suggests interferes with digestion. Two that caffeine also causes a release of sugar into the blood stream, which she states without explanation of why this might be harmful to the gut. Try as I might, I couldn’t find any studies that suggested that caffeine disrupts digestion or harms the gut. In fact, I found a study published in the American Journal of Gastroenterology that showed that a higher intake of caffeine increased specific types of beneficial gut bacteria and decreased one harmful type.
Immediately I went back to my 16 ounces of coffee a day habit. I still thought I’d go through with the rest of Hyde’s diet, however, which seemed reasonable in its focus on consuming a wide variety of vegetables. I went back to find the original research again, and thought I’d stick closer to her research findings. I figured I might still benefit from parts of the diet while ignoring what advice in her book appeared to be simply Hyde’s “gut instincts” about what ought to be good for the gut.
That’s when I found the version of the paper with the giant red box of retraction. That’s a big step for an academic journal to take–to retract an article that it had published. The journal cited a host of problems in the study which rendered the results essentially no better than guesswork based on self-reported anecdotes. Some of these reports were from her own clients.
My gut was telling me that something was amiss when the book cited individual success stories of the outcomes of the four week plan and no scientific data other than basically “feeling better” and having (reportedly) lost an average of 7 pounds in four weeks. (The weight loss was not measured by experiments but rather by subjects.) Further, she didn’t even mention longer term outcomes. What happened after four weeks? The weight loss was not a surprising short term results for any restrictive diet. Feeling better after eating lots of vegetables and cutting out processed food is also underwhelming evidence that people’s guts actually changed.
In fact, this last problem is the point that many critics made: no evidence was given in the study that the gut microbiome had changed at all. It would have been interesting if the “researchers” tested samples of fecal bacteria before and after the four week “trial”. If there were more good bacteria and fewer harmful bacteria, that would’ve been some persuasive evidence that the diet protocol made a difference in the gut biome. Instead, there’s little scientific proof that her diet had any effect. All the participants knew how they were supposed to feel at the end, and half were sold on the dietary changes as clients of Ms. Hyde. Thus a strong possibility of placebo effect, in addition to no control group, no double or single blind study, and all self-reported changes.
Then I also found a Buzzfeed article describing the approximately $3000 Gut Makeover retreat Hyde was selling (and is still selling on her website), in addition to the book sales of the diet book and the follow up recipe book.
Bottom line: This book is a lot of hype with some common sense diet advice. There is little to no data backing up the plan as a whole or for its individual recommendations for restoring one’s gut biome, or indeed for improving gut health at all.
In future posts I’ll examine what we do know about diet and gut health from reputable (non-retracted) studies.