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| Fermented bean curd (腐乳) is highly associated with gastric cancer. |
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Fermentation is a process in which food is modified by the bacteria growing on it. In lacto-fermentation, the bacteria consume sugar or starch in the food and produce lactic acid. |
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The acid in turn kills the bacteria and prevents them from continuing to proliferate. Therefore fermentation has been used for centuries in preserving food. Adding certain yeasts in the fermentation of grapes or rice produces alcohol. |
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Traditionally, fermented foods have been touted as healthy foods because the bacteria (also called lactobacilli) make the food more digestible after fermentation, as well as promoting the growth of beneficial bacteria in the gut. |
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However, a recent research found that fermented food contains a carcinogenic by-product called ethyl carbamate (urethane). |
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| Common fermented foods include: |
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Food Category |
Examples |
| 1. |
Fermented milk products |
Cheese, yogurt |
| 2. |
Fermented soy products |
Soy sauces, fermented bean curd (腐乳), fermented tofu (臭豆腐), soy bean paste, miso, tempeh, and natto etc. |
| 3. |
Fermented grapes / rice (with or without yeast) |
Alcohol in wine, vinegar |
| 4. |
Fermented vegetable |
Sauerkraut, Korean kimchi |
| 5. |
Fermented tea |
Black and red teas are fermented. Oolong tea is semi-fermented. (Re: green tea is not fermented.) |
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| Research on the link between fermented food and cancer |
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| In a research conducted by the Queen's University in Canada, it was found that common fermented food and alcoholic beverages contain trace amounts of a carcinogen called ethyl carbamate (urethane). These include wine, cheese, yogurt and bread. |
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| Ethyl carbamate (urethane) is a by-product of fermentation. The scientists found that urethane would cause DNA modification and mutations, leading to abnormal cell growth and lung cancer. The research report was published in the March 2007 issue of the journal Carcinogenesis. (Related News: Mar 7, 2007) |
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| Urethane has been labeled as a potential human carcinogen by both the World Health Organization and the International Agency for Research on Cancer. |
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| Fermented food is common in both Asian and Western culture |
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| Miso soup, made from fermented soybean paste (麵士), is very popular in Japan. |
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Sauerkraut (sour cabbage) is a common dish in Germany. Photo: sausages in sauerkraut |
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| Fermented black beans (photo) and soy sauces are used for cooking in many Chinese dishes. |
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Korean kimchi is made of fermented cabbage. |
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| Fermented duck egg is a common ingredient in Chinese congee. |
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Cheese and yogurt are popular in western meals. |
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| Fermented bean curd is famous for its pungent smell. It is a favourite snack in certain parts of China. |
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Alcohol is a product of anaerobic fermentation with yeast. Drinking wine or beer is common in many places. |
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