Kimchi, Kefir and Kraut: Is Gut Health the Real Deal?

There was a time, not so long ago, when finding a jar of kimchi in a British supermarket meant a trip to a specialist Asian grocer. Now it sits proudly on the shelf between the hummus and the olives in most major chains, alongside kefir, kombucha, sauerkraut and an ever-expanding array of 'gut-friendly' yoghurts. Gut health has gone thoroughly mainstream.

The interest is not entirely misplaced. Over the past decade, research into the gut microbiome, the trillions of bacteria living in our digestive systems, has exploded, linking gut bacteria diversity to everything from digestion and immunity to mood and even, more speculatively, long-term disease risk.

"It's one of the most exciting areas of nutrition science right now, but also one of the most overhyped in terms of marketing," says Dr Sunita Rajpal, a fictional microbiome researcher at a university institute in Oxford. "The science is genuinely promising. The claims on some yoghurt pots have rather run ahead of it."

Fermented foods, in particular, have become the poster child of the gut health movement. Kimchi, sauerkraut, kefir, kombucha and live natural yoghurt all contain live bacterial cultures produced through fermentation, and there is decent evidence that regularly eating a variety of them can support a more diverse gut microbiome, which is generally considered a marker of good gut health.

"A landmark study a few years ago found that a diet rich in fermented foods increased microbiome diversity and reduced markers of inflammation over just ten weeks, more so than a diet simply high in fibre alone," notes Dr Rajpal. "That was a genuinely striking result and it's part of why interest in this area has taken off."

Case study Helena Whitfield, 37, a marketing manager from Bristol, started making her own sauerkraut and drinking kefir daily after years of bloating and irregular digestion. "I'd tried cutting out various food groups with no real improvement," she says. "Within about a month of adding fermented foods regularly, my bloating had noticeably calmed down. I can't prove it was the kimchi, but the timing lined up too well to ignore."

Helena now keeps a rotating cast of ferments in her fridge. "Kefir on my porridge, a spoonful of sauerkraut with dinner, kimchi in a stir fry. It's become such a normal part of my week that I barely think about it as a health thing any more, it's just how I eat."