Sauerkraut, blue cheese and pickles hardly sound like the route to wellbeing. But fermented foods – left to age for anything from a few days to weeks before they’re eaten – are the new health craze.
It comes from the U.S. of course, where it’s become fashionable to ferment vegetables and drink kombucha – a fizzy, fermented tea drunk for centuries in China.
Now the science appears to back it up. Last week Cambridge University researchers reported that regular consumption of fermented low-fat dairy foods, such as yoghurt, fromage frais and cottage cheese, could reduce the risk of developing type 2 diabetes by 25 per cent over 11 years.
Fermented foods could stimulate bacteria that help with immunity, helping cold sufferers
When certain foods are left to ferment, they are ‘pre-digested’ by good bacteria and yeast found naturally on the surface of the food. These microbes eat the food before you do, breaking down the sugars and starches and making the nutrients easier for the body to absorb.
Some also release lactic acid, a natural preservative, which acidifies the environment in the gut, stimulating the growth of good bacteria. The fermented food effectively becomes a natural probiotic supplement.
Bacteria’s role in health has attracted much attention in recent years and experts welcome the new interest in ‘living’ foods, as fermented food is also known.
‘Between 70 and 80 per cent of our immune cells are in the gut,’ says Alison Clark, of the British Dietetic Association. ‘Fermented foods stimulate bacteria that help with immunity.
‘So for someone who suffers with lots of coughs and colds, they could help. We also know that a food that’s high in probiotics could help control the symptoms of things such as Irritable Bowel Syndrome, bloating, and flatulence.’
Respected U.S. food writer Michael Pollan has embraced fermentation, pointing out that in the body, microbes outnumber human cells ten to one.
A study found yoghurt could protect the immune system, and against diarrhoea
‘Much of public health has been obsessed with bacteria as the enemy,’ he says. ‘But 99.9 per cent are benign, and a great number of are also in a symbiotic relationship with us. They help us, and we need them.’ The proponents of fermented food – ‘fermentos’ – claim that antibiotics and antibacterial cleansing products have depleted our levels of gut bacteria to the detriment of health.
They recommend a wide variety of fermented foods, including cured olives, meats and cheeses, to boost immunity, fight allergies and even help you lose weight -because they aid digestion, helping you feel full.
But those that seem to make a real difference are rich in Lactobacillus, which release lactic acid during fermentation.
A study in Critical Reviews in Microbiology in 2011 found that lactic acid bacteria can help, among other things, the immune system, protect against diarrhoea (yoghurt and fermented milk may be particularly protective for young children) and stomach ulcers, and may help reduce allergies.
Vegetables are a rich source of these bacteria – hence the sudden interest in sauerkraut and pickles.
But increasingly popular is kefir, a fermented milk that originated in Russia and Eastern Europe, and kombucha – these both contain lactic acid. Sourdough bread is enjoying a comeback, too. Made in the traditional way, the dough is left for several hours, fermented by ‘wild’ yeasts and bacteria found naturally on the grain.
One hundred and fifty years ago, all bread was made this way, but most modern loaves are now made by adding yeast to speed up the process. Donna Schwenk, author of Cultured Food For Life, first came across kefir in a book from a health food store.
At the time she was desperately worried about her ten-month-old baby, Holli, who was born prematurely and suffered from frequent colds as well being underweight. ‘I began to add one or two teaspoons of kefir to Holli’s bottles,’ says Donna. ‘In one month she gained four pounds.’
Donna, too, started drinking kefir every day and claims it’s reduced her blood pressure, while tests show her blood sugar levels have dropped, too – her type 2 diabetes was starting to reverse.
Inspired, she started feeding her whole family kefir, kombucha and cultured vegetables, and claims the diet has eased her daughter’s wheat intolerance and her own allergies.
Research is starting to bear out the benefits of a fermented diet.
A study by immunologists at Spain’s University of Granada – published in 2006 in the Journal of Dairy Research – looked at people who ate at least five portions of yoghurt and cheese, and three other fermented foods such as cured meats and olives, each week.
When they were deprived of these for two weeks, the levels of good bacteria in their gut dropped, as did markers of a healthy immune system. After two weeks, they started eating yoghurt again, but their immunity didn’t return to its original levels until they resumed eating a wide variety of fermented foods.
Cheese is said to boost immunity, fight allergies and even help you lose weight
Then in November last year researchers writing in Letters in Applied Microbiology suggested that suguki – a Japanese pickled turnip – could protect against flu.
But not everyone is convinced by fermented foods. Peter Whorwell, gastroenterologist at Wythenshawe Hospital, Manchester, says there’s not enough proof.
He adds: ‘How do we know these foods give a sufficient dose of bacteria? How do we know which types of bacteria they carry?’
And one worrying piece of research suggests that fermented foods – specifically, pickles – could be harmful. In 2011 the World Health Organisation classified pickled vegetables as ‘possibly carcinogenic’.
This came after research showed high rates of throat and stomach cancer in parts of Asia where populations rely heavily on pickles.
Importantly, this link has only been found with pickles made the traditional way – fermented in their own brine.
Gherkins from supermarkets or served up in your hamburger are likely to have been made with vinegar, which kills all bacteria.
What’s more, the correlation was only found in populations who ate almost no fresh vegetables.
Intuitively, it seems better to consume friendly bacteria through food than a tablet, but Glenn Gibson, professor of food microbiology at the University of Reading, urges caution.
He says: ‘My worry is that the bacteria cultures in fermented foods are more complex, while in probiotic supplements the strains have been tested and the health benefits unravelled.’
One thing all agree on, however, is that when it comes to friendly bacteria, the more the merrier – there’s no such thing as a harmful amount.
Source: Daily Mail
