Fermented foods: The easy and delicious way to boost your health

Fermented foods have been a staple of diets worldwide for thousands of years. They're made by letting bacteria, yeast, or fungi work their magic on various foods and drinks, producing delicious tangy, sour, or fizzy results that scientists now say can boost health and even longevity.

The latest scientific research shows that eating fermented food can change the makeup of the ecosystem of trillions of bacteria, viruses and fungi living in your gut, which is collectively known as the gut microbiome.

A 2021 Stanford University study looked at how fermented foods affected healthy adults. Half of a group of 36 were told to eat more fiber-rich plant foods like fruit and veggies, while the other half started eating a lot of fermented foods. After ten weeks, the fermented food group saw big reductions in inflammatory proteins associated with diseases like diabetes and arthritis.

Unspuringly, the guts of the people eating fermented foods also began to host more diverse microbes. The same study found more fermented foods were associated with more biodiversity. However, it wasn't only that the specific probiotics consumed started growing in the intestines. Instead, the fermented foods seemed to recruit a whole array of different microbes to the gut.

While there are tons of different fermented foods, and it's a fairly new realm of study, a 2022 meta-analysis published in the journal Nutrients highlighted some of the most solid scientific evidence around the specific health effects of fermented foods so far.

A study that followed nearly 4,000 people for decades found that dairy products didn't impact the chances of developing type 2 diabetes. That's good news in itself for dairy lovers, but yogurt was even linked to a reduced risk of developing the disease.

A study that followed more than 4,500 people for a decade found that fermented dairy products like cheese, kefir or yogurt were inversely associated with overall mortality. In other words, people who consumed them more died less (during the study period).

Population studies from around the world have found that consuming fermented dairy foods like cheese and yogurt is associated with a reduced risk for cardiovascular disease, according to a 2015 paper in the British Journal of Nutrition.

A 2013 Japanese study found that a fermented milk product alleviated muscle soreness and related biological markers after high-intensity exercise in a group of healthy young men.

One study found fermented kimchi to be beneficial in a group of people with pre-diabetes, even compared to those who ate fresh kimchi. Another study found consuming fermented kimchi reduced body weight and boosted the metabolism in overweight and obese people.

In recent years, scientists have found strong links between the gut biome and mental health and cognitive performance. While studies are few, a 45-person review found people eating more fiber, prebiotics (like oatmeal) and fermented foods reported feeling less stressed than a control group on a different diet. Another 2015 study found fermented food consumption was linked to less social anxiety.

A 2020 Japanese study found that miso, a fermented soybean paste often used for soup, can lower blood pressure, decrease heart rate and calm nerve activity even though it has a high salt content. That's interesting because salt is generally known to provoke the opposite effects.

Natto is another soy-based fermented food rich in protein, vitamins and minerals. But most health benefits are found in the nattokinase enzyme produced during fermentation. Studies link it to reduced blood clots, lower blood pressure, increased bone strength, and increased nutrient absorption.

After controlling for other diet components, hypertension, diabetes, smoking, alcohol intake and other factors, scientists looking at nearly 100,000 Japanese people for 15 years found that 10% of people who ate the most fermented soy like tempeh, miso and natto compared with those in the lowest one-fifth for fermented soy intake had a 10% lower risk of death.

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Besides evidence to support the power of fermented foods in general, kombucha, a fermented tea, hasn't been deeply studied. According to the Mayo Clinic, some research suggests kombucha tea may support a healthy immune system and prevent constipation, but more evidence is needed.

These two beloved staples are both packing fiber, but they can either come with the benefits of fermented foods… or not. As a rule, if you buy them un-refrigerated, they are probably pasteurized, a heating process that kills all the probiotics. If unpasteurized pickles and sauerkraut are unavailable at the store, you can make them at home.

Pretty much any whole food can be fermented in your home on the cheap. "What I like about fermented foods is that they democratize science. They don't really cost much, and you don't have to get them from some fancy store. You can do it yourself," John Cryan, a professor of anatomy and neuroscience at University College Cork, told BBC.

Olives are one of the oldest fermented foods in the Mediterranean area. While some traditionally cured olives are available, many are often pasteurized too. That means they won't all carry the same probiotic punch as seen with other fermented foods. However, they have still been linked to numerous health benefits.

Again, studies are really just getting started, but a 2022 experiment in mice showed potential health benefits of sourdough bread, such as cholesterol reduction, inflammation alleviation, and healthy gut microbiota maintenance when compared to non-fermented but similar white bread.

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Yes, beer is fermented, but that doesn't mean that guzzling pints is good for your health. Most beers are pasteurized, which kills all bacteria, including the beneficial probiotics. However, some contain live bacteria, and studies have shown moderate consumption could boost gut microbiota. However, that must be balanced with the negative effects of alcohol.

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Wine is also made by fermenting grapes, but sulfites can inhibit the growth of beneficial probiotics. A 2019 study by Kings College London found red wine (not white) was associated with increased gut microbiota diversity, but suggested that the high levels of polyphenols, not probiotics, could be responsible for much of wine's controversial health benefits when used in moderation.

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