Most black foods have actually been long known in Japan, but were dropped out of the modern diet or are only eaten on special occasions, such as the black soybean – by many Japanese this is consumed only once a year in Osechi Ryori, the traditional New Year dish.
In fact, black soy beans were used in Chinese medicine to clear toxins from the body. Black beans are high in protein, fiber and anthocyanins and may be helpful for lowering cholesterol levels. Years ago a method was developed for roasting the beans, making it possible to eat the beans as a snack - or make black soybean tea by soaking the roasted beans in hot water. The resulting tea has the aroma of roasted beans and tastes slightly sweet. You can even eat the beans left over at the bottom of your cup as a snack!
Black soy beans have found their way into various food products as well. House Foods has brought a new type of cocoa drink to the market, “Black Bean Cocoa”, to which black soybeans from the Tanba region in Western Japan have been added. This has been a hit, adding the polyphenols of the cocoa to the anthocyanins of the black soybeans.
Kobe-based food manufacturer Fujicco has developed Black Beans Tea, there is Black Bean Coffee, and black beans are even added to soymilk drinks. There is also Black Beans Natto (if you can stomach that).
Another black ingredient are Black Sesame Seeds, which are a source of calcium and seem to be good for the kidney and liver. They also have high amounts of protein, iron, and magnesium. Black sesame seeds too, are added to all kinds of foods and drinks – there is also a soymilk drink with black sesame seeds, not to speak of black sesame biscuits and cereals.
Black Vinegar Drinks or “Kurosu” have also been around for some time now on the health foods market. Black vinegar is aged vinegar made from rice, barley and sometimes brown rice. It is aged for 3 months to a year in ceramic pots. The dark liqid is rich in citric acid, vitamins and minerals. It is said to help lowering blood pressure and cholesterol, amongst other benefits. This, too, is a huge market. Most manufacturers come from Kagoshima in southern Kyushu, such a Sakamoto Breweries that has 70% of the market.
Black Rice or Kurokome is so rare and high in nutrition that in China only the imperial house was allowed to eat it - it was therefore also called "forbidden rice." It is again rich in anthocyanins. It is not very common in Japan and you will probably have to to visit a health store to get it. The best way to eat it is to mix a spoonfull through your "ordinary" rice.
Blueberries have for some time been a popular ingredient in for example yogurt as they are believed to improve eyesight. That may be a myth, but these deeply hued berries are indeed high in antioxidants.
Black mushrooms such as shiitake are often eaten in Japan and also thought to be good for fighting loose radicals. Shiitake do not go well with Western food, but can be eaten separately as tempura. In Japan, you find them often in stews and soups.
Finally, we have Chinese Black Tea or Puaru (Pu-erh) tea that has also boomed in Japan. Chinese black tea is of the green tea family, but has undergone a fermenting process of many, many years – sometimes as long as twenty years (although three is more normal)! This leads to a very rich aroma. The tea is thought to possess detoxificating and antibacterial properties. It also helps to slim down.
In short, black is healthy. The market for black foods in Japan is huge – it is estimated to easily surpass the $500 million mark. Of course these foods are not a cure-all and some health claims are rather based on folklore than on solid scientific research. But being high in proteins and other nutritients, they will never be bad for you!
[Technical details gleaned from Japan's Nutraceuticals Today, an article by Paul Yamaguchi on the NPI Center website]