It’s sticky, pungent, slimy, and – let’s be honest – somewhat off-putting. But is has been a breakfast staple in Japan for over a thousand years, and now, natto is making its way to the other side of the world.

By now, most of us know that our gut matters. We’ve swapped diet coke for kombucha, started taking daily probiotics, and can (almost) say Lactobacillus acidophilus without flinching. The UK’s probiotic market is now worth nearly $2 billion and is projected to reach $2.43 billion by 2031, and globally, food and drink launches with a gut-health claim jumped 61% between 2024 and 2025 alone. Gut health ranks as one of the top physical health concerns for consumers worldwide in 2026.

We’re also getting more discerning. The days of swallowing a random probiotic capsule and hoping for the best are fading. In their place: a generation of consumers who read ingredient labels, want the science explained, and are genuinely curious about where their fermented foods come from. So let’s welcome natto to the super powder chat – a traditional Japanese food that has been doing what kombucha and kefir only partially manage, for centuries.

What even is natto?

If you’ve never encountered natto, you’re likely not alone. Made from whole soybeans fermented with Bacillus subtilis var. natto, it’s characterised by a sticky, stringy texture, a deeply savoury smell, and a flavour that’s been described as nutty, earthy, and – by the uninitiated – thoroughly alarming. In Japan, it’s typically served for breakfast over rice, seasoned with soy sauce and a little mustard.

But natto’s reputation in the wellness world has nothing to do with aesthetics and everything to do with what it does inside your body. Because unlike most fermented foods, natto is what scientists call a synbiotic – a food that delivers both probiotics (live beneficial bacteria) and prebiotics (the dietary fibre that feeds them) in a single, whole-food source.

“Natto is unique because it naturally combines live beneficial bacteria (probiotics) with soluble and insoluble dietary fiber (prebiotics), which serve as premium nourishment for the gut microbiome,” explains Emi Hidaka, the founder of sonomono, a Japanese natto powder brand now available in the UK through Living Alpha.

“Dairy products such as yogurt and kefir can supply beneficial bacteria, but they contain very little dietary fiber to feed those bacteria. As a result, people often need to add separate ingredients such as bananas or oligosaccharides to help support bacterial growth in the gut. Natto, on the other hand, is made by fermenting whole soybeans. This means it can deliver both natto bacteria and soluble and insoluble dietary fiber to the gut simultaneously in a single food.”

But what does the science say?

For a long time, natto’s health benefits were mostly passed down through tradition rather than clinical evidence. That’s changing rapidly. A 2025 randomised, double-blind, placebo-controlled trial published in Food & Nutrition Journal found that just four weeks of natto powder intake led to measurable improvements in bowel movements, mood, fatigue levels, and sleep quality in healthy adults.

Further research found that Bacillus natto altered the composition of the gut microbiome in ways that reduced fat accumulation and metabolic disruption in high-fat diet models – early evidence that natto’s benefits may extend well beyond digestion.

Then there’s nattokinase, an enzyme produced during natto’s fermentation process that has attracted significant attention from researchers. High natto consumption has been linked to lower rates of heart disease mortality in Japan, and studies suggest nattokinase may play a role in supporting healthy blood flow and arterial health.

But there’s a clear distinction between nattokinase-only supplements and the whole-food approach.“Many products sold internationally as ‘natto supplements’ are actually nattokinase supplements, which contain only a specific enzyme extracted from natto,” he explains.

“Our product differs fundamentally in both its purpose and its approach. sonomono Natto Capsules are a ‘whole food’ made from traditional raw natto, with only the water removed. Rather than focusing on cardiovascular support, our primary focus is on the gut environment, which we consider the foundation of overall health.”

Why has it taken so long for natto to reach us?

Given all this, it seems strange that natto hasn’t broken through in the West sooner. The reasons, it turns out, are entirely practical.

“There are four main reasons why natto has struggled to gain widespread acceptance in the West,” Emi tells us. “First is the difference in food culture. Research suggests that people who dislike natto often show a strong aversion to its appearance and smell even before tasting it — and even after trying it, those impressions are not significantly altered by the taste or texture.”

Then there’s the logistics. Being a ‘living fermented food,’ fermentation continues at room temperature, causing quality to deteriorate rapidly. Maintaining frozen or low temperatures across the entire supply chain – from domestic transport to retail in Europe – adds significant technical complexity and cost.

Import regulations present a further layer of complexity – the sauces and mustard sachets that accompany natto in Japan may contain additives not permitted in European markets, requiring reformulation. And finally, timing.

“In recent years, research into gut health and the microbiome has advanced rapidly around the world. Now that the foundations for accepting natto are finally in place, what may have been missing was simply a more convenient and accessible way to incorporate it into everyday life.”

For sonomono, that accessible way comes in capsule form – freeze-dried natto that bypasses the cold chain problem entirely, while preserving the full nutritional profile of the whole food.

But does a capsule actually work as well as the real thing?

Our stomachs are highly acidic environments – typically pH 1–2 – designed to neutralise pathogens. The problem is that this acidity also kills many of the beneficial bacteria we’re trying to deliver to the gut. Lactic acid bacteria and bifidobacteria, found in yogurt, kefir, and kimchi, are generally considered vulnerable to stomach acid and often don’t survive the journey.

Natto bacteria, however, have a survival mechanism. “When exposed to harsh conditions, they switch from an active state into a defensive state,” Emi explains. “In this defensive state, they form highly resilient structures known as spores that function like an exceptionally durable protective shell, making natto bacteria far less susceptible to stomach acid and increasing the likelihood that they reach the intestines alive.”

Once in the gut, these spore-form bacteria get to work. “Natto bacteria are believed to help suppress harmful bacteria while creating conditions that support the growth of other beneficial microbes such as lactic acid bacteria, dynamically influencing the intestinal environment.”

The freeze-drying process used in the capsules concentrates this further. Because the process removes only water without applying heat, both the nutritional value and the density of live natto bacteria are preserved.

So should you be taking it every day?

Yes – and consistently. Natto bacteria are what’s known as transient bacteria: they don’t permanently colonise the gut. They do their work and then naturally leave the body within a few days to a week. That means regular intake matters.

“Our gut environment is highly influenced not only by what we eat, but also by factors such as stress, exercise, and sleep,” Emi says. “The role of a gut-health supplement is fundamentally different from that of a medicine designed to suppress temporary symptoms. Instead, it serves as a daily tool for helping to maintain and regulate the intestinal environment.”

Emi compares taking a supplement for only a short period and then stopping to “watering a field just after you have begun cultivating it, only to stop halfway through.” The gut lining itself renews over several months – which means lasting results require lasting habits.

Rather than thinking of natto as a short-term fix, Emi encourages a more considered, long-term relationship with gut health – thinking of it as a trusted long-term companion that supports their health months and years into the future.

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