MEAL TICKET. Gut reaction

Fermented foods are bubbling over these days: Kimchi, sauerkraut, pickles, and sourdough, the holy grail of hipsters. Everyone’s a fan, from Lindsay Lohan to Vladimir Putin. Kombucha, a tea drink, and kefir, a milk beverage, can be spotted at restaurants in Indian metros. The drinks can be also ordered online — from outlets such as Bombucha, Zen Tiger and Mo’s Superfoods in Mumbai, and Khukrain’s Kombucha, Atmosphere and Bhu-Living in Delhi. Meanwhile, in cities such as New York, San Francisco and London, kombucha has snuck into cocktail bars. Bon Appétit magazine advises mixing it with Campari and gin, or making kombucha highballs.

This isn’t a new trend, though. Fermentation is sped-up, controlled rotting — the transformation of the sugars in food to preserve it, or make it tastier or healthier. People have been fermenting things for millennia: Bread, cheese, wine, kimchi, idli, dosa batter, cured meats, pickles, soy sauce and coffee are all fermented foods that boost the variety of bugs in our bodies. (The microbes in bread are dead, while gochujang (red chilli paste) or sauerkraut have live cultures.)

It may seem counterproductive to introduce bacteria into our systems, but we’re already mostly bacteria; our bodies contain 10 times as many microbial cells as our cells. Many are vital to human health. Scientists have identified several species that maintain immune and gut health in return for a hospitable place to live, like helpful tenants. But how they do it is unclear.

Wellness trends have propelled a renewed interest in foods with live cultures, as seen in the success of books such as The Art of Fermentation by fermentation’s big cheese Sandor Ellix Katz. While some studies say certain probiotics — currently being touted as a panacea for everything from acne to AIDS — and their cousins, prebiotics, may modulate immune responses and allergies, skin and digestive problems, others disagree. Even food writer Katz is wary of these claims. A spate of studies this summer caused consternation among fermenting fanatics when they concluded that probiotics were unable to colonise the guts of many test subjects, and thus had no long-lasting effect. Since our ecosystem tends to resist newcomers, probiotics are likely beneficial, but not very helpful unless the original system is weakened. And commercial, pasteurised probiotic products may not contain live bacteria at all.

Diverse gut bacteria is good for everyone, though. Live cultures are probably most useful to people on strong medication, whose digestive systems are decimated. But if you want live cultures in your ferments, you might have to grow them yourself. Homemade fermented foods contain varied strains of microorganisms, specific to neighbourhood air and soil.

A kefir starter has been passed among my family and friends for years now, beginning with the original presentation of a jar of the nubbly white grains from our friend Joanna. Kefir, considered one of the few ferments capable of repopulating the gut, is a fermented milk drink from the Caucasus Mountains, runnier and more tart than yoghurt. As it’s slightly bubbly and can contain up to three per cent of alcohol, fervent fermenters call it “the champagne of milks”. Unlike yoghurt, it grows from over 30 strains of bacteria that band together into rubbery clumps like nano-cauliflowers, and it can be used to make coconut or soy milk kefirs as well.

This strain has bounced from kitchen to kitchen, having taken several long-distance flights in the process. It takes about 24 hours to culture, and the grains reproduce endlessly, doubling every three weeks (though not as prolifically as viili , a Finnish cultured dairy product that has a cement-like consistency and if left unattended, can explode out of the bowl overnight). Every day’s batch has a different flavour and consistency, depending on the weather, humidity, and the bacteria’s mood (Mondays are tough).

The kefir really proved its worth when it brought my insides back to health after a full year of medication and antibiotics. Our relationship was symbiotic: Every day I rinsed the nubbly kefir grains, refilled the jar with warm milk, and found it a warm nap spot. On winter days when we had the heat on only in the bedroom, I’d rest it on a radiator, a chubby jar wrapped in a tea towel like a pet with rheumatism. One afternoon, a friend came by to find both me and the kefir on the couch, swaddled in blankets, watching Downton Abbey (I thought Game of Thrones would be too upsetting for the sensitive little critters).

I’m still on the fence about kombucha, that sweet tea fermented with the help of scoby. Despite what it sounds like, a scoby is not the name of a cartoon dog detective, but an acronym for “symbiotic culture of bacteria and yeast,” similar to the “mother” used to make vinegars. The rubbery, jelly-like mass floats atop the liquid as its bacteria and yeasts snack on the sugar, turning the tea into a fizzy, tangy, slightly alcoholic drink.

The jury’s still out on the scientific results for both, which may burst the bubble of fermented foods entirely — but until then, they’re not going anywhere.

Naintara Maya Oberoi is a food writer based in New Delhi;

Twitter: @naintaramaya