Tuesday, 20 March 2012

White rice-eating South Asia on the brink of a diabetic disaster

Last Thursday, the British Medical Journal reported that higher white rice intake is associated with a significantly elevated risk of type 2 diabetes, especially among Asian (Chinese and Japanese) populations.(1) According to the authors, each serving of white rice, ie nearly 160 grams a day, increases the risk by 11 per cent.

The meta-analysis and systematic review done by the Harvard School of Public Health, Boston, involved 352,384 participants, from China, Japan, the United States and Australia, with follow-up periods of four to 22 years. Though it has been known for some time now that white rice is not good for diabetic patients, the findings of various studies that examined the connection were not consistent. This study, with its large pooled data, seems to have settled the debate.

What makes white rice the wrong choice?

Let’s take a quick look at the anatomy of a grain of rice. The husk is the outer protective and inedible covering for the entire grain. Just below this is the bran which consists of layers of fibrous tissue with protein, vitamins, minerals and oil. Then, there is the germ and the endosperm. The endosperm consists of complex carbohydrates, the energy source of the germinating rice plant.

When only the husk is removed, you get brown rice. When the bran and the germ are also removed, you get white rice. Therefore, while white rice and brown rice are similar in terms of the number of calories and carbohydrates, they are very different as far as there processing and nutritional content are concerned.(2)

What this means is that white rice is rice stripped of almost all its goodness.

Double trouble

Another added complication is that unlike brown rice, polished rice has a high glycaemic index (GI), an indicator of the glucose-raising effect.

Polishing removes useful nutrients found in the bran such as insoluble fibre, magnesium (both lower the risk of diabetes mellitus), vitamins, and so on. It also pushes up the glycaemic index. A higher dietary glycaemic load is associated with increased risk of diabetes.(3)

Significance of the study for Asia

Do Asian populations who have had rice as their staple diet for millennia really need to worry? Unfortunately, they do. Earlier, our life-style protected us from various factors increasing the risk of diabetes, these protections are no longer in place. The BMJ study notes that the transition to drastically decreased activity levels and the security and variety of food has led to obesity and insulin resistance in Asian countries. Thus with this transition, we are now more susceptible to the adverse effects of white rice.

And though Westerners do not have to worry as much, the study does say that “the dose-response relations indicate that even for Western populations with typically low intake levels, relatively high white rice consumption may still modestly increase risk of diabetes.” The researchers estimate that, in the middle-aged US population, 167 cases of diabetes per 1,00,000 people would occur every year for every additional serving of white rice a day.

Diabetes - the bad news, in numbers

In its April 2004 clinical review on the “Burden of non-communicable diseases in South Asia”(4), the BMJ had reported that “the prevalence of diabetes and its adverse health effects has risen more rapidly in South Asia than in any other large region of the world”. India, it says, has the highest number of diabetic patients in the world, with the estimates ranging from 19.4 million in 1995 to 32.7 million in 2000. In Bangladesh, Sri Lanka and Nepal, diabetes imposes a huge disease burden.

The report also says that according to the projections for 2020, based on modelled estimates by WHO, the number of people with diabetes is expected to rise by 195% in India during 1995 -2025 to reach 57.2 million in 2025, while Pakistan is expected to have about 14.5 million people with diabetes by that year.

Can we make the shift?

It is difficult to say whether the South Asian nations, the ones who are most hard-hit by diabetes, will make the shift from white to brown rice. Even the educated among us who have been sensitized are, more likely than not, to stick to the centuries-old habit of eating white rice. The reasons may range from skepticism, reluctance to make the transition to a very different taste, lack of seriousness about health issues, to a very human dislike of change.

As for the poor, there is the added question of “If not white rice, then what?”. Undisclosed sources say that the public distribution system, in almost all its outlets, provides polished rice of high-yield varieties, (which has a significant GI), at a cheap rate.

A look at alternatives

Though white rice may be enriched by adding nutrients, this is not an option for developing nations. For developing nations, in order to ease the transition, parboiled white rice could be promoted as the healthier alternative to white rice.

Parboiling, ie partially boiling in the husk by soaking, steaming and drying, drives nutrients, from the bran to the endosperm. What this means is that parboiled white rice is 80% nutritionally similar to brown rice. Parboiling is a practice already followed in many parts of the world such as India, Bangladesh, Pakistan, Myanmar, Malaysia, Sri Lanka, Guinea, South Africa, Italy, Spain, Thailand, Switzerland, USA and France.(5)

Whether parboiling should be adopted as a pain-free compromise or whether the transition should be made to brown rice may be debated.

However, we can no longer sit back and ignore the writing on the wall.

1. Hu EA, Pan A, Malik V, Sun Q. White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review. BMJ. 2012 Mar 15;344(mar15 3):e1454–e1454.
2. Most, Marlene M, Most MM, T, M, L. Rice bran oil, not fiber, lowers cholesterol in humans. American Journal of Clinical Nutrition. 2005;81(1):64–8.
3. The Hindu : Health / Medicine & Research : White rice intake increases risk of Type II diabetes [Internet]. [cited 2012 Mar 20]. Available from: http://www.thehindu.com/health/medicine-and-research/article3001544.ece
4. Ghaffar A. Burden of non-communicable diseases in South Asia. BMJ. 2004 Apr 3;328(7443):807–10.
5. Miah MAK, Haque A, Douglass MP, Clarke B. Parboiling of rice. Part II: Effect of hot soaking time on the degree of starch gelatinization. International Journal of Food Science and Technology. 2002 Jun;37(5):539–45.