Dear Food Doc: I keep hearing about kombucha. Evidently, I have missed out on the trend. What is this stuff?
Dear Reader: Alas, you are not too late -- kombucha is likely to be around for a while. Indeed, kombucha has joined the list of other trendy foods, like kimchi, kale and quinoa that are now found everywhere, not just in hipster cafes and upscale restaurants. Heck, you can even find kombucha at Walmart.
The kombucha craze actually began decades ago. A New York Times article from 1994 refers to the fad as having "spread like a new-age chain letter" and being "the pet rock of the '90s."
The origins of kombucha go back 2,000 years ago, in China. It eventually spread throughout Asia and Europe. In the U.S., commercial kits for home-brewing kombucha became available in the early 1990s, and bottled versions soon appeared on the grocery shelves.
To answer your question, kombucha (pronounced com-BOO-chuh) is made by fermenting sweetened tea with a unique concoction of yeasts and bacteria. This culture mixture is called SCOBY, short for “symbiotic colony of bacteria and yeast." The SCOBY forms a gooey mat that can be re-used repeatedly or shared with friends.
Several factors may explain why kombucha has become so popular. First, many people like the sweet, sour, vinegary flavor. There may also be a little ethanol present, although commercial products must be below the legal limit of 0.5 percent. The fermentation yields carbon dioxide, which gives kombucha a pleasant fizziness. There are also flavored versions, containing ginger, mango or lavender. In some cafes, kombucha is even available on tap.
It’s probably the suggested health properties that are most responsible for the kombucha craze. Some blends have antimicrobial properties, which may have been valuable before antibiotics were available. However, these properties depend on the mix of microbes, which varies between brands.
Other suggested health benefits range from improved digestion to treatment of cancer and other diseases. Unfortunately, there is no scientific evidence to support these claims.
In contrast, the very acidic nature of kombucha may not sit well for some people. Microbiologists are also concerned that home-brewed kombucha could possibly contain toxin-producing fungi.
Nonetheless, there are a lot of consumers drinking kombucha. Annual sales in the U.S. are over $500 million, with double-digit growth. Millennials, in particular, love it, as half of the coveted 25-to-34 age group are kombucha drinkers. It has everything marketers like -- in addition to being hip and funky, it also has a huge social media presence.
Dear Food Doc: I am confused about which fats to avoid and which are OK to eat. Good fat, bad fat -- what’s the difference?
Dear Reader: Let’s first be careful about this notion of good versus bad. While I get the point, there are few foods that are truly bad. Obviously, foods that are moldy, rancid or otherwise spoiled would qualify. Same for foods contaminated with disease-causing bacteria or viruses.
However, even foods devoid of any nutritional attributes are not necessarily evil. The occasional glazed doughnut, brownie or potato chip will not cause irreparable harm.
The good fat versus bad fat discussion is a case in point. Since the 1970s, nutritionists began advising consumers to reduce consumption of saturated fats. These are the so-called “bad” fats found in meat, dairy products, eggs and tropical oils. The data showed that these fats raise cholesterol and increase the risk of heart disease. In contrast, unsaturated fat, found in vegetable, legume and seed oils, as well as avocados and salmon and other fish, were considered as “good” and heart-healthy.
The push toward unsaturated fat probably contributed to the popularity of margarine. One unintended consequence, however, was that the hydrogenation step used to make margarine created trans fat. These are now known to be very unhealthy. In this case, the cure was worse than the disease.
To complicate the good fat versus bad fat debate, nutrition researchers just last month published a study in the British Medical Journal that challenged the entire saturated fat hypothesis. The authors stated that “the benefits of replacing saturated fat with vegetable oils” have been overestimated.
Nonetheless, most experts recommend limiting saturated fat to less than 10-to-14 grams or about three teaspoons per day.
Of course, by the time this study was reported in the popular press, we were treated to headlines like this one from the Guardian: “Butter is no more deadly than vegetable oil, study finds." No wonder consumers are confused.
Bob Hutkins is the Food Doc. He is a professor at the University of Nebraska-Lincoln, where he teaches and conducts research in food science and food microbiology. Send your questions on any topic related to food, food safety, food ingredients and food processing to the Food Doc at firstname.lastname@example.org.