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Why you should add fermented foods - and their friendly bacteria - to your diet

Kimchi contains probiotics and also delivers fibre, niacin and vitamins A and C.

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If you haven't tried – let alone heard of – fermented foods, such as kimchi, kombucha or natto, consider adding them to your menu. They've been part of the human diet for nearly 10,000 years, but only recently have fermented foods become trendy in North America for their purported health benefits.

Research suggests fermented foods can help the body dampen inflammation, fend off cell-damaging free radicals and fight infection. They're seen as a boon to the gut and, as such, fermented foods may help prevent digestive problems, allergies, obesity, even mood disorders.

Traditionally used to preserve perishable foods, fermentation is a natural process in which bacteria and/or yeasts break down carbohydrates in food, creating compounds such as lactic acid that combat food spoilage from pathogens. Many scientists attribute the possible health benefits of fermented foods to the fact they're a source of beneficial bacteria, or probiotics.

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Eating probiotic-rich fermented foods helps shore up the population of friendly bacteria that live in our large intestines. These beneficial bacteria promote a barrier against germs and viruses, keep bowel function regular, produce vitamins B6, B12 and K2, help absorb minerals and communicate with cells to keep us healthy in other ways.

Don't get me wrong: Fermented foods are not magic bullets. The vast majority of research has focused on probiotic supplements; there is little evidence that fermented foods offer the same benefits. Even so, some experts contend that fermented foods, as a source of probiotics, should have the same effect.

Not all fermented foods are a source of probiotics, though. Foods that are pasteurized won't have any naturally occurring probiotics since high heat destroys them.

Several species of Lactobacillus and Bifidobacteria, Streptococcus thermophilus, Saccharomyces boulardii (a type of yeast) deliver health benefits and are therefore considered probiotics. Foods fermented with other types of microbes don't contain probiotics (read labels and ingredient lists to determine if a fermented food is a source of beneficial bacteria). That doesn't mean these foods aren't good for you. During fermentation, microbes release vitamins and minerals from carbohydrates, making them more available for absorption.

Fermented foods are also easier to digest. For instance, when milk is fermented to make yogurt or kefir, some of the lactose is broken down making it more digestible for people with a mild to moderate lactose intolerance.

If you're unfamiliar with fermented foods, try the following seven foods to add flavour, nutrients and, in some cases, a hefty dose of probiotics to your diet.

Kefir

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This yogurt-like beverage is made from milk fermented with mixture of 10 to 20 different types of probiotic bacteria and yeasts; kefir has three times the amount of probiotic cultures as yogurt. It's also a good source of protein, calcium, B vitamins and potassium.

Drink kefir, pour it over cereal and granola, or blend it with fruit to make a smoothie. Choose a brand that's low in added sugars; ideally opt for unflavoured.

Kimchi

This sour and spicy Korean side dish is made by fermenting vegetables, typically Napa cabbage, with seasonings such as scallions, ginger, garlic and fish sauce. Kimchi contains probiotics and also delivers fibre, niacin and vitamins A and C.

It's downside: salt. A one-half cup serving has almost 200 mg of sodium, so treat it as a condiment. Serve kimchi as a side dish with barbecued meat. Eat it raw over brown rice. Add kimchi to sandwiches and burgers, homemade spring rolls, stir-fries and egg dishes.

Kimchi is available in Asian food markets and many large grocery stores.

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Kombucha

This fermented tea is made by adding a probiotic bacteria and yeasts to black, green or white tea, sugar and sometimes fruit juice and other flavourings. The end product is a slightly effervescent and tart-tasting tea.

Kombucha tea contains 30 to 35 calories per 250 ml serving, mainly from the sugar, which is considerably less than sugar-sweetened soft drinks.

Many brands of kombucha tea have been pasteurized to kill off unwanted bacteria. Some companies fortify their products by adding probiotic bacteria after it's brewed. Kombucha tea is also available unpasteurized; be sure to purchase from a reputable company.

Natto

This traditional Japanese food is made by fermenting soybeans with a powdered probiotic bacterium called Bacillus subtilis. The end product is highly nutritious – it's rich in protein and is a good source of fibre, B vitamins, vitamin K, calcium, potassium, manganese and iron.

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Natto has a strong, nutty flavour, a musky smell and slippery texture. It's not for everyone. In Japan it's often served for breakfast with rice or broth and vegetables. If you're game to try natto, you'll find it in Asian markets.

Miso

Made from soybeans fermented with the fungus Aspergillus oryzae, this thick and flavourful (and salty) seasoning paste can be used in soups, sauces, marinades and salad dressings. Miso can also be used instead of butter on corn on the cob.

Some brands of miso may also contain Lactobacillus acidophilus. Keep in mind, though, that boiling miso paste in soup kills probiotic bacteria.

White, yellow and red miso products are sold refrigerated. The darker the colour, the stronger the taste.

Sauerkraut

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Made from shredded cabbage that's been fermented with lactic acid bacteria, unpasteurized sauerkraut is a source of probiotics. Naturally fermented sauerkraut is sold in the refrigerated section of the grocery store. Look for "unpasteurized" or "source of live cultures" on the label.

Like its cousin kimchi, use sauerkraut as a condiment in sandwiches, serve with grilled meat or eat raw with vegetables.

Tempeh

A traditional soy food from Indonesia, tempeh is made by fermenting soybeans with the fungus Rhizopus oligosporus, a process that binds soybeans into a patty. Some brands add beans or whole grains and spices. It's not considered a probiotic food, but tempeh is an excellent source of vegetarian protein that's easier to digest than tofu.

Tempeh is sold uncooked and frozen, or cooked and refrigerated. Add cubes of tempeh to a stir-fry or crumble it into soups, tacos, burritos and chili.

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