The health and wellness brigades have been fizzing over ferments for almost a decade.
In 2011, Lindsay Lohan was said to have blamed a positive alcohol test while on probation on her fondness for kombucha, a fermented tea drink.
Australian journalist and bestselling sugar-avoider Sarah Wilson urges anyone "with auto-immune issues, irritable bowel syndrome, bloating, sugar cravings or any kind of digestive or allergy issue" to give fermenting a go.
Chef Gizzi Erskine loves kimchi - a punchy Korean speciality made from cabbage, chilli and garlic - so much that she named her cat after it. Not bad for what is, essentially, just some cabbage.
Get The Straits Times
newsletters in your inbox
WHAT IT DOES
As with so many fads, fermentation is nothing new. Humans have been harnessing the natural action of microorganisms to preserve food for thousands of years.
Fermentation involves the use of micro-organisms to transform food from one state to another. In the right conditions, bacteria and yeasts will convert the natural sugars in foods into other compounds, such as alcohol or lactic acid.
This not only inhibits the growth of other more harmful bacteria, but also changes the flavour of the food, such as the distinctive tang of yogurt produced by microbes feeding on the lactose in milk.
Beer and wine are fermented foods, as are bread, sauerkraut, olives, cured meat, chocolate, miso, coffee, cheese and pickles.
The good news is that you are probably eating a few of them already. Apart from the interesting flavours, it is the microbial content that has got the health- conscious excited.
More specifically, the microbes that live happily in your gut, the make-up of which may have a significant effect on everything from your long-term weight to your current mood.
HOW IT HELPS US
Unfortunately, the modern Western menu does little to nourish this "huge alien ecosystem", as Dr Michael Moseley puts it.
But, however much we may like junk food and chemical additives, our gut bacteria do not.
Professor Tim Spector, who specialises in genetic epidemiology at King's College London, said if we "wipe out our gut microbes, our immune system goes into autodrive and starts attacking us with auto- immune diseases and allergies" .
One way of boosting your natural gut flora is to eat more of the kind of foods they thrive on. These include onions, garlic, asparagusand banana, which encourage microbe growth, said the British Dietetic Association.
The other way is the use of probiotics, foods or supplements containing beneficial bacteria that, if they make it as far as our guts, will take up residence there.
Fermented foods are considered to be an excellent source of desirable microbes. There is evidence that probiotics can prevent children on antibiotics from developing diarrhoea. They can shorten an episode caused by a stomach bug by up to a day and may help relieve the symptoms of irritable bowel syndrome and lactose intolerance too.
However, pickle evangelist Sandor Katz said: "When I hear people talk about fermented foods as a cure for diseases - eat sauerkraut to cure cancer, drink kombucha to cure diabetes - that's kind of a trigger for me," he told Radio 4. "It is not reasonable to expect that eating a particular food is going to cure a particular disease."
But, as microbes seem to be the current buzz topic, more research is likely to be forthcoming.
Prof Spector has been instrumental in the establishment of British Gut, the United Kingdom's largest open-source science project, which is investigating the microbial diversity of the human gut, running in tandem with a similar project in the United States.
For about £350 (S$623), you get an expert interpretation of your microbiome - and scientists get the benefit of your data.
WHAT TO EAT
In the meantime, there is no harm in adding fermented foods to your diet. They are easy to digest and they tend to have a distinctive, complex and challenging flavour.
Live yogurt is good, but kefir, a fermented milk drink, is better. Prof Spector said it contains at least five times as many microbial varieties.
Kombucha is another decent source, as are raw milk cheeses, sauerkraut, pickles and kimchi.
Natto, Japanese fermented soya beans, may be an acquired taste, but Indonesian tempeh is just like tofu, but nicer. Just make sure none of it has been heat-treated to increase its shelf life.
However, it might be better to prepare your own. Like other ferments, kimchi is easy to make at home with little more than a sturdy jar and a bit of patience.