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A few decades ago, "microbiome" drew blank stares outside research labs. Now the word pops up in startup pitches, with everyone from wellness influencers to venture capitalists convinced that gut bacteria hold the keys to health, happiness, and maybe immortality. Some of it is hype that is not backed by science but rather by an insatiable need to sell probiotics and supplements. But behind the hype, science has been assembling real evidence on how gut microbes really do influence human health. A sweeping review published in Nature Reviews Gastroenterology & Hepatology has sifted through hundreds of studies and delivered the clearest verdict yet: your gut microbes aren't just along for the digestive ride. They're finicky co-eaters of every meal, transforming food into biological signals that ripple out to your immune system, metabolism, and brain. "The gut microbiome has an undeniable role in mediating the health effects of the diet," the authors of the review conclude, in the declarative tone that science reserves for accepted wisdom. Why is microbiome having a moment right now? Technology is part of the answer. Sequencing costs have collapsed dramatically; analyzing your gut microbiome now often runs in the low thousands of rupees, down from lakhs just a decade ago. Failed drug trials have also nudged pharmaceutical companies to focus on the microbes inside us, while the "food as medicine" industry has exploded with startups promising microbiome-tailored diets and investors betting on personalized nutrition as the next gold rush. There's also a return to Ayurveda, with its emphasis on the qualities of food, in India as well. But hang on. Gut microbes may help explain why one diet works wonders for one person and fails for another. But we still don't have a probiotic prescription pad yet. The American Gastroenterological Association advises against routine probiotics for most digestive conditions, noting that evidence remains thin outside specific areas such as Clostridioides difficile infection. Even so, progress is tangible. Large studies called "PREDICT" in the UK, which tracked thousands of people eating consistent meals while wearing glucose monitors, show that personal characteristics including the gut microbiome explain much of the variation in how blood sugar and fat levels spike after eating. Genetics adds only modest predictive power, and in some cases microbiome data outperforms calorie and nutrient counts alone. Your microbes, it turns out, may know you more intimately than your DNA does. The U.S. Food and Drug Administration has now approved two microbiome-based therapies for preventing recurrent C. difficile infection. These treatments work by transplanting healthy bacterial communities, evidence that harnessing microbes can work. The mechanisms are coming to light too. Gut bacteria ferment plant fibers into short-chain fatty acids like butyrate and propionate- compounds that don't just vanish after they're made. They help seal the gut barrier, reduce inflammation, and can trigger the release of hormones that control appetite and blood sugar. It's a virtuous cycle: what you eat today shapes the microbial community that will process tomorrow's meals. Suddenly, longstanding nutritional puzzles make more sense. Why do people on identical diets experience wildly different health outcomes? Because each of us harbors a unique community of microbes. Some are especially skilled at making anti-inflammatory compounds, others are expert at wringing energy from starches, and a few are unfortunately proficient at manufacturing toxins. We are learning more about proteins as well. The ratio of protein to fiber may matter more than total protein quantity. Plant proteins usually arrive bundled with their own microbial fuel: the fiber and polyphenols that feed beneficial bacteria. Animal proteins on the other hand, especially from processed sources, often push microbial machinery toward pathways that generate compounds like TMAO, which is linked to heart disease. Even meal timing matters. Gut microbes keep their own biological clocks, synchronized with cycles of eating and fasting. Late dinners, practically a ritual in some Indian cities, can disrupt host and microbial circadian rhythms, with negative effects on metabolism and immune signaling. The implications ripple outward in ways we're only beginning to map. Microbial signals travel to the brain via the vagus nerve and immune messengers, helping explain why fiber-rich diets correlate with better mood and cognition. They influence metabolism by tweaking bile acids and releasing hormones. They even affect how much energy we extract from meals. Food companies are taking notice too. Some are reformulating products around gut health principles, adding resistant starches and developing fermented product lines. Others simply sprinkle a bit of fiber onto ultraprocessed food and slap "gut-friendly" on the label. What does this mean practically? Here is a useful rule of thumb: aim for different plant foods to support microbial diversity. Push fiber intake toward 35-45 grams daily and switch to whole grains. Pair proteins with plants in combinations. Include fermented foods like dahi and idli, since trial data shows gains in microbiome diversity and reduced inflammatory markers. Read food labels and be cautious with ultra-processed foods containing emulsifiers and some non-nutritive sweeteners; emerging research suggests they can alter the microbiome and, in some contexts, gut health and blood sugar control. Try eating earlier and more consistently to support microbial rhythms. In short, the goal is to build a healthy relationship with our gut microbiome through food. Our health is inextricably linked to trillions of microbial partners whose survival depends on our daily choices. Think of it this way. There's a microbial garden inside you. Every meal is an act of ecological conservation. All of this is new science but also feels suspiciously intuitive: more plants, more variety, more fermented foods, fewer factory products. It's a thali your grandmother would recognize. Anirban Mahapatra is a scientist and author, most recently of the popular science book, When The Drugs Don't Work: The Hidden Pandemic That Could End Medicine. The views expressed are personal.