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Fermented foods—why and how to eat them

In my last post I talked about how our emphasis on wiping out microorganisms from our environment is impacting our health in a negative way. We can give up sanitizing our environment and overreliance on antibiotics, but in order to replace the beneficial bacteria in our digestive systems we need fermented foods. There are many ways to include these healthful traditional foods in our diet. Before the advent of refrigeration fermentation was used to preserve food for later use and also to enhance its nutritional content. The organisms that do the fermenting produce alcohol, lactic acid and acetic acid, which can be called “bio-preservatives”, as they not only prevent spoilage but also enhance nutrition by breaking foods down into more easily digestible forms and adding certain B vitamins to the food (1). Even more importantly, they provide living beneficial microorganism to maintain our own bacterial communities.

All cultures used some type of alcoholic fermentation, but these beverages were brewed with naturally occurring yeasts and retained many of the nutrients contained in the starting materials. Beer is brewed from fermented grain and contains many of the B vitamins of the grain and yeast if it has not been refined and filtered. Wine is fermented fruit juice, usually grape, but any untreated fruit juice will ferment. Wine, particularly red wine, has been shown epidemiologically to have health benefits when consumed regularly in small quantities; the mechanism for the benefit is still being researched. Distilled alcohol has lost any health benefits inherent in fermented beverages, containing only very strong alcohol.

Other fermented beverages add beneficial bacteria to the diet without the alcohol content. Kombucha is a sour tonic beverage made from either black or green tea which has been brewed, sweetened, and cultured with a SCOBY, or symbiotic colony of bacteria and yeast. The SCOBY turns the sugar into lactic acid for a pleasant fizzy drink containing live microorganisms. Fruit juices can also be fermented using the SCOBY. Natural sodas such as ginger ale can be made using fresh grated ginger, sugar and water and allowing it to ferment. Since the sugar in these beverages has been largely converted to lactic acid it does not raise insulin levels the way regular sodas do (2).

I have already blogged about the virtues of sourdough bread, which is leavened via a fermentation process in which the acids produced by bacteria called Lactobacilli give it the sour taste, and wild yeasts cause the dough to rise. Other starchy foods are also traditionally fermented to improve their nutrition and keeping qualities. Familiar here in Hawaii is poi, a pasty starch made from cooked, mashed and fermented taro corms. It is the staple food of Polynesian cultures and manifests probiotic properties from the Lactococcus and Lactobacillus lactic acid producing bacteria that it contains (3). Certain varieties of another starchy staple, cassava-widely eaten in tropical South America, Africa and Asia, must be fermented to remove cyanide and render the starch edible.

Asian cuisines contain an abundance of fermented foods. Thousands of years ago people living in this region learned that nutrients from the soybean could be made available for human consumption by fermenting the plant in various forms. Most of these foods are eaten in small quantities, as they still contain antinutrient substances. Such condiments as soy sauce and tamari are used as flavorings; miso makes a nutritious soup, especially when combined with fish; natto, tempeh and traditional tofu supply protein. Fish, especially small fish from rice paddies, are fermented in an earthen jar with water and salt to make fish sauces and pastes. Vegetables are often pickled, a form of fermentation, to preserve them. Kim chee is made of salted won bok or other vegetables which is then combined with spices and buried in earthen jars for the winter. Japanese and Korean cuisines contain many different traditionally fermented vegetable dishes served in small quantities. Many of these foods are highly salted and as such are eaten as condiments. Even a small amount can supply a big dose of beneficial microorganisms.

Western culture, too, contains its fermented dishes. Sauerkraut and pickles are ways of preserving the cabbages and cucumbers that are so abundant during summer. Traditionally, these vegetables are brined in salt water to which the appropriate spices are added and allowed to ferment for several weeks in a crock, usually in a cool basement. I remember the delicious dill pickles my mother made every winter. They had a flavor far superior to the overheated, overprocessed varieties available on supermarket shelves. Actually, any vegetable can be preserved by fermenting, and often the nutrient content is improved. Captain Cook kept his crew free of scurvy on his discovery trip to Hawaii by feeding them sauerkraut.

Dairy products are extremely perishable. Since humans first began keeping cows and goats for milk they had a problem with spoilage. However, they discovered that fresh raw milk will ferment, after which it is much more stable and long-lasting. Today, with refrigeration we do not need to ferment milk products but we have grown to relish such fermented dairy products as yogurt, cheese, buttermilk, sour cream, kefir, etc. All of these products in their traditional forms contain live bacterial cultures that convert the lactose in milk to lactic acid. Therefore, even those with lactose intolerance can enjoy them. Be sure to look for yogurt and related products that say on the label “contains live cultures”. Some of the concoctions now being sold as yogurt are not only loaded with sugar but microbially dead.

To give an old adage a new twist—a fermented food a day keeps the doctor away. Enjoy the pleasures of these foods. Your gut will love you for it!

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