Rice is the staple diet of South Asia, in particular, the Indian sub continent. Like India, China, Japan, the Philippines and other neighbouring South and South East Asian populations also prefer rice to wheat.
Indians prefer white rice and black rice is relatively unknown to most Indians.
In imperial China, black rice (Orayza sativa) was forbidden in China. Not because it looked poisonous because of its black colour, but because of its high nutritional value, which meant it could only be eaten by the Emperor.
For long, the nutritional value of this wild rice eluded the commoners. Black rice contains more Vitamins B and E, niacin, calcium, magnesium, iron and zinc compared to white rice. It is rich in fibre and the grains have a nutty taste. The anthocyanins not only act as antioxidants, they also activate detoxifying enzymes.
It is only in recent times that rice researchers have begun to study the sticky varieties of black rice and discovered that it has several medicinal and nutritional properties.
It has anti carcinogenic properties and its bran soothes inflammation due to allergies, asthma and other diseases. Black rice is sold in local markets for as much as Rs. 300 a kg.
Black rice is indigenous to north-east India and is extensively grown in Odisha, West Bengal and Jharkhand. It is commonly eaten in Manipur because of its medicinal value.
Called chak-hao, meaning rice (chak) which is delicious (ahaoba), black rice is eaten during traditional feasts. Chak-hao kheer is a popular pudding in these regions and the water in which black rice is boiled is used in these parts to wash hair, in the belief it makes hair strong.
Mystery surrounds its origin. Japanese researchers discovered that its genetic trait is traceable to a rearrangement in a gene called Kala4, which activates the production of anthocyanin, a water soluble pigment which might show different colours like red, purple or blue depending on the pH.
These researchers concluded that this rearrangement must have originally occurred in the tropical Japonica sub species of rice (Oryza sativa. var. Japonica) and the black rice trait was then transferred to other varieties, including those found today, by cross breeding.
The findings of the origin of black rice help explain the history of domestication of black rice by ancient humans, during which they selected desirable traits, including grain colour.