Forbidden Rice (aka Black Rice): Does It Really Have Health Benefits?

Introduction

Forbidden rice (aka black rice, the Emperor’s rice, Oryza sativa L. indica) has been consumed for centuries in Asia and is now gaining popularity as a functional superfood globally. Black rice is a special cultivar of rice which contains a high content of phytochemicals (including anthocyanins) in the aleurone layer.

It is purported to detoxify, improve digestive health, prevent diabetes and reduce heart disease. In general, an all round superfood. However, not everyone loves black rice. Black rice is considered to be nutritionally inferior to other rice types in Laos.

Time to do some sleuthing to see what modern science can tell us about this age-old food.

What Is Forbidden Rice?

Rice is a food staple for three billion people living in over one hundred countries worldwide. Epidemiological studies suggests that people living in rice consuming countries experience lower rates of cancer and heart disease which is thought to be due to the antioxidant content of rice (1).

Rice is classified depending on the color of its bran fraction into four main groups: black, brown, red and purple. Brown bran fractions are classified as non-pigmented rice, while the bran fractions of black, purple and red rice are classified as pigmented rice. The extracts from pigmented rice are used as natural food colorants in bread, ice cream and liquor.

Rice is also classified into two sub-species: indica and japonica. Indica species (like black rice) grow best in tropical zones while japonica grows best in temperate zones.

Black rice has been consumed for centuries in Asian countries such as China, Japan and Korea. Black rice contains a relatively high content of bioactive compounds such as anthocyanins, phenols and terpenoids. It is considered a ‘tonifier’ in Traditional Chinese Medicine.

There is some confusion over the origins of the terms ‘forbidden’ or ‘emperors’ rice. It is correct to say that black rice was reserved for use by the ruling class in China. However, many popular bloggers assume that this relates to the nutritional superiority of black rice over white rice. In fact, the general public was ‘forbidden’ from eating black rice because it was rare and not nutritionally superior. Black rice is not a wild rice but is actually a domesticated strain that arose from natural cross-breeding (2).

There are a similar number of black and white rice products or derivatives for sale on Amazon (about 2000 of each). On average, black rice is twice as expensive as white rice. Organic American white rice costs on average 0.14 cent per ounce as compared to 0.30 cents per ounce for organic black.

Is it worth it?

Is There Any Research?

There are a total of 6,000 published studies on black rice and only three of these studies are human clinical trials.

To put this into context, maize has 40,000 studies including 872 clinical trials.

Black rice might be marketed as a superfood but it is not super well researched.

Is It High In Antioxidants & Does That Matter?

Antioxidants are organic molecules that protect human cells from free radical and reactive oxygen damage (3). The molecules with antioxidant activity contained in rice include phenolic acids, flavonoids, anthocyanins, proanthocyanidins, tocopherols, tocotrienols, γ-oryzanol, and phytic acid (4). Black rice has the highest antioxidant content of all rice types (4). In fact, black rice bran has higher antioxidant activity and higher content of phenolics, flavonoids, and anthocyanins when compared to white rice bran (4).

Anthocyanins are a class of brightly colored antioxidants that confer anti-inflammatory, anticancer and possibly cardio-protective benefits (5)

A 2010 presentation at the American Chemical Society is widely quoted in support of black rice (6). The presentation claimed that black rice contains more anthocyanins than blueberries and with the added benefit of having a lower sugar load of blueberries.

A clinical study in Guangzhou, China, randomly allocated 60 patients with coronary heart disease to dietary supplementation with either white or black rice (7). Analysis at the six month time point showed a statistically significant increase in total antioxidant capacity in the patients allocated to black rice. However the study participants were not followed prospectively to see if this translated into any clinically significant benefits

It is worth noting that not all black rice is created equally. Studies show that the anthocyanin content of black rice differs amongst different types of black rice (1).

Bottom Line: Black rice has been shown to improve surrogate markers of anti-oxidation but it is not been established whether this translates into any meaningful clinical benefits.

Does It Improve Heart Health?

Rodent studies have shown that black rice reduces platelet hyperactivity, hypertriglyceridemia, reduces body weight gain and facilitates optimal platelet function in dyslipidemic rats (8).

Other rodent studies have confirmed the lipid lowering benefits of black rice (9,10).

The study in Guangzhou, China mentioned earlier was specifically designed to assess the effect of black rice in coronary heart disease (7).The study randomly allocated 60 patients with coronary heart disease to dietary supplementation with either white or black rice. Analysis at the six month time point showed a statistically significant increase in total antioxidant capacity and a reduction in c-reactive protein  (CRP which is a measure of inflammation) in the black rice group.

The authors concluded that black rice could have cardio-protective benefits by modulating antioxidant and anti-inflammatory profiles. However, as discussed above, the study did not follow the patients to see if this translates into actual clinical benefit for patients.

Bottom line: There is pre-clinical and clinical data to support the fact that black rice has a favorable impact on known risk factors for heart disease. There are no studies proving that black rice actually improves outcomes in patients with heart disease.

Does It Help With Weight Loss?

A study in 40 overweight Korean women evaluated white rice versus a mixture of brown and black rice (11). Meal replacement with mixed rice was shown to be superior to white rice in terms of weight reduction. However this level did not reach the level of statistical significance.

Bottom line: A single clinical study showed that black rice resulted in a non statistically significant reduction in weight.

Does It Help Detoxify?

There are no studies evaluating the ability of black rice to detoxify.

Bottom line: There is no science to support the claim that black rice helps detoxify.

Is It A Good Source Of Fiber?

Black rice has a higher content of fibre as compared to white rice (12).

To put this into context, black rice has an average of 2.2 gm of fibre per 100gms of rice, while all bran cereals have 32gms of fibre per 100 gm serving (13).

Bottom line: Black rice has relatively more fibre than white rice but less than would be sourced from an equivalent serving of commercially available bran cereals.

Does It Help Prevent Diabetes?

Studies in diabetic rats showed that germinated back rice reduced plasma glucose, cholesterol, triglyceride levels, insulin resistance and was comparable in efficacy to the oral diabetic drug metformin (14).

Black rice also improves hepatic lipid accumulation in obese and diabetic model mice but was no better than brown rice in this experiment (15).

Finally, black rice was shown to improve retinal damage produced by photochemical stress and so may have some clinical utility in diabetic eye disease (16).

There are no human clinical studies looking at black rice in the prevention or treatment of diabetes.

Bottom line: Animal studies suggest that black rice may offer some benefits in diabetes but there are no human clinical studies to date.

Other Uses

There are some other emerging possible roles for black rice but again none of these have been tested in the clinical arena.

Early preclinical studies suggest that black rice may induce apoptosis (cell death) and suppress angiogenesis (blood vessel formation) in breast cancer cells (17).

Animal studies show that black rice is showing promise in the management of osteoporosis (18)

Finally there is interest in a possible role for black rice in reducing alcohol withdrawal and alcohol toxicity (19, 20).

Is Forbidden Rice Safe?

There are no case reports of toxicity related to black rice.

It is worth noting that rice in general is considered to be nutritionally deficient in bioavailable vitamins, minerals, essential fatty acids and other phytonutrients and attempts are underway to genetically bio-fortify back rice (21). There are also efforts underway to produce back rice noodles (22)

Conclusion

Based on current research, it is reasonable to conclude that black rice is a good source of key antioxidants such as anthocyanins. I would not exactly agree with the people of Laos that black rice is inferior to other rice.

However, given the fact that there are only three clinical studies on black rice, it is a complete overstatement to consider it to be a ‘functional superfood’.

So why does this blog differ so much to other blogs on black rice?

This is an entirely reasonable question and one that I asked myself too.

Some popular blogs on black rice claim that it deserves the status of superfood. At first glance, these blogs look well referenced. However, on closer examination, these blogs are not actually referencing any original source data on black rice. (They could not do so as there are only three human clinical studies).

The references in these blogs actually relate to either other blogs on their own websites or general articles on diabetes or heart disease etc. However , the presence of references gives the blog an undeserved air of authority. Reader, beware!

Researchers from Brussels have just published a comprehensive review summarizing the recent developments on black rice bioactivities (23). The paper was published this month so is totally up to date.

The authors of the paper conclude that ‘black rice should be considered as a promising source of health-promoting functional foods targeting a large set of noninfectious diseases. However, more clinical studies are needed to support the findings highlighted in this review’.

Whew, just as I was beginning to doubt my own sanity!

References

  1. Zhang MW, et al. Phenolic profiles and antioxidant activity of black rice bran of different commercially available varieties. J Agric Food Chem. 2010
  2. Oikawa T, et al The Birth of a Black Rice Gene and Its Local Spread by Introgression. Plant Cell. 2015
  3. Kumar S, et al. Review on antioxidants and evaluation procedures. Chin J Integr Med. 2017
  4. Goufo P, et al. Rice antioxidants: phenolic acids, flavonoids, anthocyanins, proanthocyanidins, tocopherols, tocotrienols, γ-oryzanol, and phytic acid. Food Sci Nutr. 2014
  5. Yousuf B, et al. Health Benefits of Anthocyanins and Their Encapsulation for Potential Use in Food Systems: A Review. Review article Crit Rev Food Sci Nutr. 2016
  6. https://www.acs.org/content/acs/en/pressroom/newsreleases/2010/august/black-rice-rivals-pricey-blueberries-as-source-of-healthful-antioxidants.html
  7. Wang Q, et al. Supplementation of black rice pigment fraction improves antioxidant and anti-inflammatory status in patients with coronary heart disease. Randomized controlled trial Asia Pac J Clin Nutr. 2007
  8. Yang Y, et al. Anthocyanin extract from black rice significantly ameliorates platelet hyperactivity and hypertriglyceridemia in dyslipidemic rats induced by high fat diets. J Agric Food Chem. 2011
  9. Um MY, et al. Hypolipidaemic effects of cyanidin 3-glucoside rich extract from black rice through regulating hepatic lipogenic enzyme activities. J Sci Food Agric. 2013
  10. Salgado JM, et al The role of black rice (Oryza sativa L.) in the control of hypercholesterolemia in rats. J Med Food. 2010
  11. Kim JY, et al. Meal replacement with mixed rice is more effective than white rice in weight control, while improving antioxidant enzyme activity in obese women. Randomized controlled trial Nutr Res. 2008
  12. https://ndb.nal.usda.gov/ndb/foods/show/9494?fgcd=&manu=&lfacet=&format=&count=&max=50&offset=&sort=default&order=asc&qlookup=black+rice&ds=Branded+Food+Products&qt=&qp=&qa=&qn=&q=&ing=
  13. https://ndb.nal.usda.gov/ndb/foods/show/90304?manu=&fgcd=&ds=Branded%20Food%20Products
  14. Chaiyasut C, Sivamaruthi BS, Pengkumsri N, Keapai W, Kesika P, Saelee M, Tojing P, Sirilun S, Chaiyasut K, Peerajan S, Lailerd N Germinated Thai Black Rice Extract Protects Experimental Diabetic Rats from Oxidative Stress and Other Diabetes-Related Consequences. Pharmaceuticals (Basel). 2016 Dec 28;10(1). pii: E3. doi: 10.3390/ph10010003.
  15. Felix AD, et al. Extracts of black and brown rice powders improve hepatic lipid accumulation via the activation of PPARα in obese and diabetic model mice. Biosci Biotechnol Biochem. 2017
  16. 16. Jia H, et al. Black rice anthocyanidins prevent retinal photochemical damage via involvement of the AP-1/NF-κB/Caspase-1 pathway in Sprague-Dawley rats. Randomized controlled trial J Vet Sci. 2013
  17. Hui C, Bin Y, Xiaoping Y, Long Y, Chunye C, Mantian M, Wenhua L. Anticancer activities of an anthocyanin-rich extract from black rice against breast cancer cells in vitro and in vivo. Nutr Cancer. 2010;62(8):1128-36. doi: 10.1080/01635581.2010.494821.
  18. Jang WS, et al. Black rice (Oryza sativa L.) extracts induce osteoblast differentiation and protect against bone loss in ovariectomized rats.Effect of GABA Food Funct. 2015
  19. Hou Z, et al. Effect of anthocyanin-rich extract from black rice (Oryza sativa L. Japonica) on chronically alcohol-induced liver damage in rats. J Agric Food Chem. 2010
  20. Effect of GABA Extract of Black Sticky Rice with Giant Embryo on Alcohol-Related Indices After Acute Alcohol Intake in Social Drinkers. Randomized controlled trial Jung WY, et al. Alcohol Clin Exp Res. 2015
  21. Birla DS, et al. Progress and challenges in improving the nutritional quality of rice (Oryza sativa L.). Review article Crit Rev Food Sci Nutr. 2017
  22. Kong S, et al. Black rice bran as an ingredient in noodles: chemical and functional evaluation. J Food Sci. 2012
  23. Dias ALS Recent advances on bioactivities of black rice. Curr Opin Clin Nutr Metab Care. 2017
Summary
Forbidden Rice (aka Black Rice): Does It Really Have Health Benefits?
Article Name
Forbidden Rice (aka Black Rice): Does It Really Have Health Benefits?
Author
Healthy But Smart

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