Fermented food is extremely popular right now, and people are turning their home kitchens into science labs in an effort to improve their health via microbes. Fermentation is an ancient form of preservation. People following a 'raw diet' were the first to pick up on the idea, but it has become mainstream with the publication of numerous books and articles praising fermented foods, perhaps most notably Wild Fermentation by Sandor Ellix Katz.
The following are popular fermented foods.
This fermented tea is characterized by a gelatinous 'mushroom' of bacteria. It is made by fermenting a mixture of yeast, bacteria, sugar, and tea.
Compared to a 'liquid yogurt', kefir was originally made from camel's milk, but today it usually is made from fermented cow's milk. It contains about 2.5% alcohol.
This is a fiery, pungent condiment made from fermented vegetables, such as cabbage or turnips. Kimchi is served at almost every Korean meal, and is made by pickling the vegetables and burying them in tightly sealed pots.
Black garlic is a South Korean delicacy prepared by fermenting raw garlic for 1 month. It is described as tasting sweet and syrupy with a licorice flavor.
Mead is a beverage made by fermenting honey, water, and yeast with flavorings such as herbs, spices, or flowers. It dates back to Biblical times.
Miso is a fermented soybean paste that is an important part of Japanese cuisine. Cooked soybeans are injected with a mold cultivated from a barley, rice, or soybean base. It is aged from 6 months to 3 years. Miso is used in sauces, soups, marinades, dips, main dishes, salad dressings, and as a table condiment. More than 200 types of miso are available.
Natto are steamed, fermented, and mashed soybeans that have a strong cheeselike flavor. Nato is very popular in Japan, and is often mixed with mustard, soy sauce, and/or chives.
Tempeh is a fermented soybean cake, similar in texture to tofu with a yeasty flavor.
Common fermented foods
Some of the more commonly known fermented foods are:
Pickled fruits and vegetables
Note: Many mass-produced varieties of these foods are pasteurized during processing and do not carry the health benefits associated with fermented foods.
It is true that consuming fermented foods may improve digestive and immune health via the probiotics that these products contain. Further, it is thought that fermented foods contain higher levels of vitamins and minerals, and that these nutrients are easier to digest because they already are broken down to some degree by the fermentation process. Many of these foods are potent sources of antioxidants.
The proposed benefits of probiotics include:
Improved digestive health
Improved urinary and genital health
Improved immune function
Improved nutrient bioavailability
Improved management of atopic allergies
Improved synthesis of vitamins (niacin, folic acid, biotin, and vitamin B6)
Decreased lactose intolerance
Decreased blood cholesterol
Many of these fermented foods are very high in sodium. Home-brewed kombucha may become contaminated with aspergillus (a fungus that produces a toxin). In 1995, the Centers for Disease Control and Prevention released a report linking kombucha to two deaths. Both women died from severe metabolic acidosis. Probiotics are sensitive to many factors including heat, humidity, pH levels, and oxygen.
The wide variety of bacteria types and viability is what makes it difficult to make broad claims regarding the health benefits of a specific food. Many of the health claims associated with these products are not validated in any studies. In fact, a study published in the online version of Carcinogenesis recently found that alcoholic beverages and fermented foods contain urethane, which is a naturally occurring carcinogen that causes DNA modification and mutations. The study was led by Dr Poh-Gek Forkert of Queen's Department of Anatomy and Cell Biology, who said, "We believe that people should not be apprehensive about consuming these foods and beverages; if consumed at low levels, they probably don't pose a risk. It might be prudent, however, to have a varied diet and to limit drinking certain alcoholic beverages."
Regulating these foods is becoming a tricky undertaking as the lines blur between food and supplement. It also is important to note that many of the herbs and raw products used in these foods can interact with medication. Many experts warn that pregnant women, people diagnosed with yeast or bacterial overgrowth, the elderly, children, and people with compromised immune function should not consume homemade fermented foods.
References and recommended readings
Brannon CA. Phoods and bepherages: the phuture of phunctionality. Today's Dietitian [serial online]. 2007;9:12. Available at:
http://www.todaysdietitian.com/newarchives/tdsept2007pg12.shtml. Accessed August 18, 2011.
Koff A. Kombucha and kefirs: hype or healthy? Available at:
Accessed August 18, 2011.
Martens C. Black garlic: the hot new color in food. Available at:
Accessed August 18, 2011.
ScienceDaily?. New link between wine, fermented foods and cancer. Available at: http://www.sciencedaily.com/releases/2007/03/070307152917.htm. Accessed August 18, 2011.
Wollan M. A strange brew may be a good thing. Available at:
http://www.nytimes.com/2010/03/25/fashion/25Tea.html. Accessed August 18, 2011.
Zelman KM. The truth about kombucha. Available at:
http://www.webmd.com/diet/features/truth-about-kombucha. Accessed August 18, 2011.
Review Date 10/11