askST: All you want to know about rice, sugar, the glycaemic index and diabetes

A story in The Straits Times about how the Health Promotion Board (HPB) is targeting white rice in Singapore's fight against diabetes caused a furore this week. Readers have been asking about the link between diabetes and the consumption of white rice and sugar, as well as how glycaemic index comes into the picture.

Senior Health Correspondent Salma Khalik answers some frequently asked questions.

What is diabetes?

There are three types of diabetes.

•Type 1 diabetes is an autoimmune disease and affects the young.

•Type 2 diabetes is largely caused by sedentary lifestyle and a diet consisting largely of simple carbohydrates like white rice and sugary drinks. It accounts for about 90 per cent of diabetes worldwide.

•There is also gestational diabetes, which is temporary and affects one in five pregnant women here. But the effects of this is long lasting and makes them more than seven times as likely as other women to get diabetes.

The body's pancreas produces a hormone called insulin that is needed to move sugar from the blood to tissues in the body.

Diabetes happens when the pancreas has problems producing enough insulin, or when the insulin does not work properly. Type 1 diabetics do not produce insulin.

When this happens, sugar is left in the circulating blood.

Sugar blocks the flow of blood, especially in the small vessels. This makes it hard for blood to get to the organs. Over time, it can lead to damage to the eyes, heart, nerves, feet, and kidneys.

This is why diabetes is the top cause of kidney failure here, a major reason why people go blind, and accounts for two amputations a day because injuries, especially to extremities like fingers and toes, do not heal properly and can become gangrenous.

Why should I be worried about diabetes?

One in nine people in Singapore have diabetes. ST PHOTO: AZMI ATHNI

Diabetes can affect anyone at any age. One in nine people here have diabetes. Out of those with diabetes, one in three do not know they have the disease. Left uncontrolled, it can lead to lifelong health complications.

People at higher risk are those who have a parent or sibling with diabetes, have a Body Mass Index (BMI) of 23 or higher, is sedentary, have high blood pressure or cholesterol levels, is 40 years or older and for women, who have had gestational diabetes.

What is the link between food and diabetes?

Sugar is necessary as it is converted to energy for the body. But too much of it is bad.

Sugar in the blood comes from the food we eat. This includes not just sugar per se, but also carbohydrates like rice and noodles, which turn into sugar when digested.

Consuming large amounts of sugar and simple carbohydrates results in sugar spikes in the body. The pancreas then has to work extra hard to get rid of this sudden increase of sugar in the blood.

When this happens too often, the pancreas can get fatigued and produces less insulin than needed, or the insulin it produces is not able to do the work efficiently, leaving much of the sugar in the blood.

What is the link between white rice and diabetes?

A bowl of white rice. ST PHOTO: LIM SIN THAI

According to the 2010 National Nutrition Survey, white rice forms the largest intake of carbohydrates in Singaporeans' diet, accounting for a third of the calories consumed.

The more processed and the shorter the grain, the faster it is digested and turned into sugar.

This means unpolished long grain rice is the slowest to digest, while short grain white rice is the fastest.

This also means short grain white rice has a high Glycaemic Index (GI).

What is Glycaemic Index (GI)?

The GI is a measurement of how food raises the level of sugar (or glucose) in the blood. GIs of 70 or more is considered high. A GI of 55 or less is good as it means the food takes longer to digest so there is a slower rise in blood sugar, giving the body more time to cope.

Does the way we cook the food affect the GI, and how important is GI?

GI is just one measure of a healthy diet. Other considerations include eating more vegetables and less saturated and trans fat, and not eating too much.

Also, the GI measures specific food, such as rice. But what the rice is eaten with will also affect blood sugar levels.

For example, chicken rice and nasi lemak have lower GI than plain white rice because the fat in the rice slows down the digestion process. But the flip side is, such rice is rich in saturated fat, which is high in calories and is not healthy.

As a rule of thumb, wholemeal is better than white bread because it has more nutrients and fibre, and unpolished red or brown rice is better than white rice, which has had all the healthy bran and germ removed.

Who is most at risk of diabetes?

Although Type 2 is acquired, there are some risk factors that cannot be changed, such as genetic predisposition, ageing and women who had gestational diabetes when pregnant, a condition that puts them at high risk.

The other causes of diabetes come largely from unhealthy lifestyles, such as lack of exercise and poor diet. Having uncontrolled high blood pressure and high cholesterol levels also raise the risk of getting diabetes.

Isn't diabetes also a big problem in countries where people do not consume a lot of white rice?

Yes, diabetes is a big worry in Western countries. There, obesity and sugary drinks are the main causes of diabetes.

While sugary drinks are bad and also a cause of diabetes here, such drinks form only 3.5 per cent of Singaporeans' caloric intake a day. In comparison, rice makes up 33 per cent of calories here.

This is why the HPB is pushing the health benefits of eating more brown rice to lower the risk of diabetes.

The HPB says exercise lowers risk, so does that mean if I exercise, I can eat more white rice and drink sugary sodas?

A group of people exercising at the Botanic Gardens’ Palm Court. PHOTO: ST FILE

In theory yes, but we have to be careful about the amount of exercise as well as the quantity of food.

Essentially exercise lowers blood sugar as it makes insulin more effective, which means your cells are better able to use any available insulin to take up sugar during and after activity.

When your muscles contract during activity, it allows your cells to take up sugar and use it for energy, whether insulin is available or not.

Does snacking, or having smaller but more frequent meals help?

Having small but frequent meals can help to reduce sugar spikes. But snacking may not fit into everyone's lifestyle, especially those with tight work schedules.

That is why it is important to choose the foods you eat. Aim to replace your refined staples with healthier whole grain versions as it can help you feel fuller for longer.

Is there a difference between taking sugar, and taking carbohydrates that turn into sugar?

Both sugars from cane sugars and starch in staples (e.g. rice and noodles) are converted to sugars in the blood when consumed.

But for the same quantity, sugars from starchy staples trigger a higher glycaemic response than sugars from cane sugars as they are processed differently in our body.

To make matters worse, people here take nine times as much starchy staples like rice, compared to sugary drinks.

What about brown sugar, and other types of sugar - are they all created equal when it comes to warding off diabetes? Must I stop eating sugar altogether if I do not want to get diabetes?

There is no need to avoid sugar totally. In fact, sugars are found naturally in foods such as fruits. But added sugar is often a source of empty calories. Because it tastes good, it is easy to take too much.

The World Health Organisation recommends that such free sugars - sugars added to food and drinks and naturally present in honey, syrups, fruit juice, and fruit juice concentrates- be limited to 10 per cent of total energy intake. Reducing the amount to five per cent gives additional health benefits, says WHO.

Are there other 'baddies' when it comes to diabetes? What about ice cream or fatty stuff like bacon, milk and cheese?

Diabetes prevention goes beyond the quality of our carbohydrates and reducing the intake of empty calories from sugar in sweetened drinks. Overall diet needs to be balanced, and should comprise foods from the various food groups (whole grains, fruits, vegetables as well as meat and alternative proteins). Foods that are high in added sugar and saturated fat should be limited (e.g. confectioneries and fatty meats), as they are a source of excess calories. This could lead to excess weight, contributing to obesity - a risk factor of diabetes.

What is the difference between white rice, brown rice, red rice and unpolished rice?

A plate of brown rice is served at a mixed rice stall. ST PHOTO: KEVIN LIM

Most people refer to unpolished rice as brown rice. However, brown rice is just one of the many variants of unpolished rice. All unpolished rice are whole-grain rice, with the outer hull removed; white rice is the same grain after further milling and polishing to remove the bran layer and germ.

Brown rice refers to rice that is unpolished, where only the hull is removed but the germ and bran are retained. It contains almost five times the fibre and two times the iron of white rice.

The other types of rice have even more nutrients.

Compared to brown rice, red rice has six times the amount of zinc and twice the iron; black rice has three times the fibre; purple rice has four times the zinc and twice the iron; and wild rice has twice the zinc and eight times the Vitamin E.

If white rice is so bad, why is it that diabetes was not such a big problem in the past?

Rice has been a staple food in Asian countries for centuries. By the twentieth century, the advance of grain-processing technology made it possible for large scale production of refined grains.

Mechanised steel roller mills and automated sifting devices are being used to efficiently refine grains. Through refining processes, the outer bran and germ portions of intact rice grains (i.e., brown rice) is removed to produce white rice that primarily consists of starchy endosperm.

The consumption of white rice generally creates a stronger postprandial blood glucose response as measured by the GI compared with that from consuming the same amount of brown rice.

Additionally, the modern inactive lifestyle promotes excessive body fatness which predisposes people to reduced insulin sensitivity. This works in tandem with the glycaemic load from high intakes of highly refined rice which increases the risk of diabetes.

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