The colour brown

It’s not just the fibre and vitamins; wholegrain brown rice has a compound that may protect you from high blood pressure and cardiovascular disease.

Replacing that familiar mound of white on your plate with a brown variety may do a world of good to your heart. Nutritionists have known for a while that brown rice is healthier, and been exhorting rice eaters to choose the wholegrain brown type instead of polished white ones. Brown rice, they said, is rich in certain minerals and vitamins and dietary fibre, which are lost in white rice following milling and polishing.

But that’s not the end of its goodness, it now emerges. A recent study by a team of US and Japanese scientists points to the “clinical significance” of brown rice. The researchers have found that brown rice contains a compound — which is, however, yet to be isolated and identified — that offers protection against high blood pressure and cardiovascular ailments. The compound is located in a layer surrounding the grain, called subaleurone layer, which is stripped off when the milled grain is polished to a shine. This layer lies between the white centre of the grain and the brown fibrous outer layer, and is abundant in certain beneficial carbohydrates and dietary fibre. It also accounts for a good measure of nutrients such as magnesium and iron, and vitamins like niacin, vitamin B1 and vitamin B6.

More significantly, the scientists found that a new milling process developed by a Japanese firm three years ago allows the rice to retain the subaleurone layer. Thisrice, available only in Japan, has a golden tinge and appears similar to brown rice, but tastes more like white rice as it is not tough and chewy like the other.

The scientists, led by Satoru Eguchi of the Cardiovascular Research Center at the Temple University School of Medicine in Philadelphia, found that when an extract of subaleurone compounds dissolved in ethyl acetate was applied to vascular smooth muscle cells cultured in a dish, it inhibited the activity of angiotensin II, a hormone strongly implicated in hypertension and atherosclerosis. Vascular smooth muscle cells are typical cells found in the walls of blood vessels. Their contraction and relaxation in tune with the local blood pressure and blood volume is responsible for the distribution of blood to different organs in the body. Excessive constriction of smooth muscle cells in normal blood vessels leads to hypertension, while in the case of heart muscles it leads to a hardening of the arteries.

“We strongly believe the compound may be present in all rice varieties (including those consumed in India), even though its strength may vary,” says Eguchi.

The researchers say that the compound apparently inhibits the production of angiotensin II by interfering with the body’s signalling mechanism that orders its conversion from angiotensin I, which is relatively harmless. Many modern drugs for blood pressure already target enzymes that trigger the production of angiotensin II.

“Our research suggests that there is a potential ingredient in rice that may be a good starting point for looking into preventive medicine for cardiovascular diseases,” says Eguchi. Such health benefits may accrue if half-milled or brown rice is included in the diet, he adds.

“Studies in the past have only partly answered what the mechanism behind this is. The particular compound which offers the benefit is yet to be identified,” Eguchi told KnowHow. The Japan-born scientist, who has been studying the beneficial effects of the subaleurone layer of rice for the last three years, says work is on to identify the compound and elucidate its chemical composition.

“This is an interesting find,” says Kanwaljit Chopra, associate professor at the University Institute of Pharmaceutical Sciences, Punjab University, Chandigarh. “The study indicates the possibility of a promising drug molecule from rice for cardiovascular protection.” Chopra herself has worked on a compound called tocotrienol, which is abundant in rice and oil palm and has shown that it may have potential benefits for people suffering from diabetes-related kidney problems.

“Angiotensin II is a big villain when it comes to atherosclerosis,” she says. The Punjab University professor, however, feels there is a need for the scientists to identify the compound and repeat similar results in animals and humans before claiming that the study is a success.

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Another study by a team of researchers from the Harvard School of Public Health last year had shown that eating two servings of brown rice every week lowered the risk of type 2 diabetes by about 16 per cent. The research, led by Qi Sun — who subsequently moved to the Brigham and Women’s Hospital in Boston — showed that dietary fibre, found abundantly in brown rice, helps deter diabetes by slowing the rush of sugar into the blood stream.

White rice comparison:
Brown rice and white rice have similar amounts of calories, carbohydrates, and protein. The main differences between the two forms of rice lie in processing and nutritional content.

When only the outermost layer of a grain of rice (the husk) is removed, brown rice is produced. To produce white rice, the next layers underneath the husk (the bran layer and the germ) are removed, leaving mostly the starchy endosperm.

Several vitamins and dietary minerals are lost in this removal and the subsequent polishing process. A part of these missing nutrients, such as vitamin B1, vitamin B3, and iron are sometimes added back into the white rice making it “enriched”, as food suppliers in the US are required to do by the Food and Drug Administration (FDA).

One mineral not added back into white rice is magnesium; one cup (195 g) of cooked long grain brown rice contains 84 mg of magnesium while one cup of white rice contains 19 mg.

When the bran layer is removed to make white rice, the oil in the bran is also removed. Rice bran oil may help lower LDL cholesterol.

Among other key sources of nutrition lost are small amounts of fatty acids and fiber.

You may click to see:Neutrition facts & analysis of brown rice

This leaves no room for doubt that brown is better.

Source : The Telegraph ( Kolkata, India)

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