| Ever since my January newsletter, I’ve become something of a gut health enthusiast: sauerkraut, kefir, kombucha — you name it. I was genuinely excited to see whether months of fermented foods and leafy greens would pay off in bacteria-diversity glory. So, back in February, I bought one of those at-home microbiome kits. Conveniently, it came with a Valentine’s Day deal, so I got one for my boyfriend too (though I’m still not sure how romantic a poop test really is). Gut health matters. The trillions of microbes in our digestive tract influence not only digestion, but also immunity, inflammation, and even mental health. Unfortunately, shortly before taking the test, I had to go on antibiotics for an infection after a wisdom tooth extraction. I knew this would likely lower my bacterial diversity because these white pills don’t just kill the bad bacteria, they also wipe out the good ones I’d been carefully cultivating for weeks. But the results were... curious. True, my gut diversity score was quite low, but I’d expected worse and it was surprisingly similar to my boyfriend’s, even though he hadn’t taken antibiotics. Even stranger, I was flagged as having a high tendency to get acne (I’ve never had it), and my enterotype — the bacterial profile linked to diet — suggested I was a meat-eater. Meanwhile, my boyfriend, who definitely consumes more meat than I do, was labeled a plant-eater. So was that worth the €120? Dirk Haller, a professor for nutrition and immunology at Technical University of Munich who’s been researching the microbiome for 25 years, is skeptical. “I’d be very cautious about drawing conclusions from this type of analysis,” he says, scrolling through my results, which indicated high risk of leaky gut syndrome, irritable bowel syndrome and of being underweight. While the underlying lab analysis — identifying bacterial strains and measuring diversity — is scientifically solid, the interpretation is where things fall apart, according to Haller. The health categories and risk predictions are “highly speculative” and “full of buzzwords.” “This kind of hype discredits serious microbiome research by pushing it into the realm of speculation,” he says. “That’s tragic — because gut health is really important. But we just don’t have solid markers for it yet.” One test alone, Haller stresses, tells you very little. Meaningful insights would require dynamic, repeated testing — something that quickly becomes expensive. These kinds of home tests are largely driven by commercial interest, he says. His advice for a healthy gut? Eat your vegetables and fruit for fiber, move more, and don’t stress about the occasional burger — he still eats them too. And while there’s no hard proof that eating fermented foods gives long-term health benefits, I’ll definitely keep brewing my own kombucha. — Sonja Wind | 
