What is black rice

Black rice (also known as purple rice or “forbidden rice”) is a range of rice types of the species Oryza sativa L., some of which are glutinous rice. Varieties include Indonesian black rice and Thai jasmine black rice. Black rice has been consumed for centuries in Asian countries such as China, Korea or Japan. Black rice contains health-promoting antioxidants called anthocyanins, a pigment found in the rice grain that creates its dark hue, at levels similar to those found in blueberries and blackberries ¹⁾. However, the most common sources of dietary anthocyanins remain berries, including blackberries, bilberries, chokeberries, elderberries, cranberries and raspberries. In addition there are many other highly colored fruits such as black currant, cherry, grape, strawberry, colored cabbage, eggplant and radish also known to have high levels of anthocyanins. Because anthocyanins are commonly consumed, their biological activities have been extensively studied. Notably, anthocyanins have antimicrobial, antioxidative, anti‐inflammatory, and anti‐mutagenic properties, which in turn play a role on the prevention and treatment of many chronic diseases such as metabolic disorders, cancer, eye diseases and cardiovascular ²⁾.

A team of researchers at Cornell University, including WGC Scientific Advisor Rui Hai Liu ³⁾, analyzed the phenolic content and antioxidant activity of 12 diverse varieties of black rice, and found that antioxidants were about six times higher in black rice than in common brown/white rice. The black rice bran had higher content of phenolics, flavonoids and anthocyanins.

Black rice nutrition facts

Table 1. Black rice nutrition facts

Black rice health benefits

Anthocyanins are a group of polyphenolic natural products that belong to a broad class of secondary metabolites collectively called flavonoids. Being bright in coloration, ranging red, pink, purple and blue, anthocyanins are the principal components of pigmented plant parts such as flowers and fruits. Their functions to the plant that produce them include aiding pollination and seed dispersal by attracting insects and other animals, while their antioxidant effects have been implicated to the plants survival, especially in UV prevalent high altitude environments ⁵⁾. In addition to providing vibrant colour, anthocyanins are of interest because of their known bioactivity including potent antioxidant capacity ⁶⁾ and potential to change markers of health and function of the vascular endothelium. For example, oxidative damage to endothelial cells may interfere with their ability to produce nitric oxide (NO), a powerful vasodilator, thus contributing to endothelial dysfunction ⁷⁾. Cell culture studies have demonstrated that the incorporation of anthocyanins into endothelial cells can protect against insult from oxidative stressors ⁸⁾. Anthocyanins also increase the expression of endothelial nitric oxide synthase, an enzyme that generates nitric oxide (NO) ⁹⁾. More recent research suggests that anthocyanins regulate a number of complex immune and inflammatory signalling pathways involved in maintaining vascular health ¹⁰⁾. This suggests that anthocyanin consumption may improve vascular function in humans.

Numerous intervention studies have evaluated the effect of isolated anthocyanins, anthocyanin-rich foods or their extracts on cardiovascular disease risk factors, including some markers for vascular health. In a recent meta-analysis of 22 randomised-controlled trials, Huang and colleagues ¹¹⁾ demonstrated that anthocyanin-rich berry consumption (2–12 weeks duration) significantly lowered body mass index (BMI), LDL “bad” cholesterol, fasting glucose, haemoglobin A1c (HbA1c) and tumour necrosis factor-α in both healthy and metabolically compromised participants. Similarly, a systematic review of 12 andomised-controlled trials reported that consumption of purified anthocyanins and anthocyanin rich extracts (primarily from berries; 7.35–640 mg anthocyanins/day) improved blood pressure and LDL “bad” cholesterol in post-myocardial infarction and hyperlipidemic individuals, respectively ¹²⁾.

Another mechanism for anthocyanin’s health benefit is through effects on the various functional aspects of adipocytes that is linked to insulin resistance. Anthocyanin extracts from black soybeans, which were shown to be composed of cyanidine-3-O-glucoside (68.3%), delphinidin-3-O-glucoside (25.2%), and petunidin-3-O-glucoside (6.5%), not only reduced lipid accumulation in vitro. Anthocyanins could also lower the level of circulating free fatty acids through direct effect on lipolysis in adipose tissue. In this regard, cyanidin-3-O-β-glucoside has been shown to suppress the expression of adipose triglyceride lipase in cultured 3T3-L1 adipocytes while at the same time increasing the activity of the AMPK ¹³⁾. The AMPK pathway has also been emerged as a major drug target for diabetes and related diseases given its crucial regulatory role in energy metabolism involving glucose and lipids ¹⁴⁾. The increased phosphorylation of the AMPK pathway by anthocyanin such as those from mulberry fruit extract could not only increase glucose uptake but also inhibit gluconeogenesis and stimulates glycogen synthesis ¹⁵⁾.

This study showed the effects of anthocyanins-rich food on attenuating obesity and inflammation in cells, animals, and humans ¹⁶⁾. Taken together, dietary anthocyanins may be a potential regulator of obesity-derived inflammation and its associated chronic diseases. Anthocyanin may also aid in the fight against heart disease and cancer.

Scientists at the Harvard School of Public Health ¹⁷⁾ followed 39,765 men and 157,463 women as part of the Health Professionals Follow-up Study and the Nurses’ Health Study I and II. They found that those eating several servings of white rice per week had a higher risk of Type 2 diabetes and that those eating 2 or more servings of brown rice had a lower risk. They estimate that replacing about two servings a week of white rice with the same amount of brown rice would lower diabetes risk 16%.

At the Department of Food and Nutrition at Hanyang University in Seoul, Korean researchers randomly assigned forty overweight adult women to two groups. For six weeks, one group ate meals containing white rice, while the other consumed otherwise-identical meals with a mix of black and brown rice. While both groups showed significant reductions in weight, BMI and body fat, the whole grain rice group surpassed the white rice group in all three measures. The whole grain group also saw an increase in HDL (good) cholesterol and in antioxidant activity ¹⁸⁾.

Recent findings found sterols and triterpenoids with potential anticancer properties tested in vitro (test tube studies) and in vivo (animal studies) have been isolated and identified from bran extracts of black rice ¹⁹⁾. Protection against osteoporosis has also been suggested for the first time for black rice extracts. Because of its antioxidant and anti-inflammatory properties, black rice also protects liver and kidney from injuries. One clinical study reported the interest of black rice in case of alcohol withdrawal.

S.P. Choi and colleagues from Ajou University in Suwon ²⁰⁾, South Korea showed feeding mice a standard diet with added 10% black rice bran significantly suppressed 2,4-dinitrofluorobenzene-induced allergic contact dermatitis on the skin of the mice ²¹⁾. By contrast, a nonpigmented brown rice bran extract did not inhibit the 12-O-tetradecanolylphorbol-13-acetate-induced edema and failed to significantly suppress production of pro-inflammatory biomarkers (mediators). These in vivo (animal study) findings further demonstrate the potential value of black rice bran as an anti-inflammatory and antiallergic food ingredient and possibly also as a therapeutic agent for the treatment and prevention of diseases associated with chronic inflammation ²²⁾. The scientists suggest that black rice may be a “useful therapeutic agent for the treatment and prevention of diseases associated with chronic inflammation.”

This study ²³⁾ investigates the anticancer effects of an anthocyanin-rich extract from black rice on breast cancer cells in vitro and in vivo. Oral administration of anthocyanin-rich extract from black rice (100 mg/kg/day) to BALB/c nude mice bearing MDA-MB-453 cell xenografts significantly suppressed tumor growth and angiogenesis by suppressing the expression of angiogenesis factors MMP-9, MMP-2, and uPA in tumor tissue. Altogether, this study suggests the anticancer effects of anthocyanin-rich extract from black rice against human breast cancer cells in vitro and in vivo by inducing apoptosis and suppressing angiogenesis ²⁴⁾.

Another study on anthocyanins from black rice showed that it promotes immune responses in leukemia through enhancing phagocytosis of macrophages in vivo ²⁵⁾.

This study showed black rice-derived anthocyanins inhibit HER-2-positive breast cancer epithelial cells in vitro ²⁶⁾.

This study ²⁷⁾ indicated that black rice extract acts as a potent inhibitor of the biogenesis of H. pylori virulence proteins and that black rice extract can be used to exert beneficial effects in patients with gastroduodenal diseases caused by H. pylori.

A study using rice powder extract from black and brown rice (Oryza sativa L. indica) improves hepatic lipid accumulation in obese and diabetic model mice ²⁸⁾.

How to cook black rice

Follow These Steps

• Boil water and add salt. Pour water (for every cup of rice, use 1 3/4 cups of water) into a large saucepan with a tight-fitting lid. …
• Pour in rice. Add it to the boiling water.
• Stir once, or just enough to separate the rice.
• Cover the pot and simmer.
• Fluff rice with a fork.