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.
Q What is diabetes?
A There are three types of diabetes.
•Type 1 diabetes is an autoimmune disease and affects the young.
•Type 2 diabetes is largely caused by a 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 effect is long lasting and makes those who have it 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 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.
Q Why should I be worried about diabetes?
A Diabetes can affect anyone at any age. One in nine people here has diabetes. Out of those with diabetes, one in three does not know he or she has 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 of 23 or higher, are sedentary, have high blood pressure or cholesterol levels, are 40 years or older and, for women, those who have had gestational diabetes.
Q What is the link between food and diabetes?
A 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.
Q What is the link between white rice and diabetes?
A 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.
Q What is glycaemic index (GI)?
A The GI is a measurement of how food raises the level of sugar (or glucose) in the blood. GIs of 70 or more are 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.
Q Does the way we cook the food affect the GI, and how important is GI?
A 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 foods, such as rice. But what the rice is eaten with will also affect blood sugar levels.
For example, chicken rice and nasi lemak have a lower GI than plain white rice because the fat in the rice slows down the digestion process. But the flip side is that 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.
Q Who is most at risk of diabetes?
A 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 raises the risk of getting diabetes.
Q Isn't diabetes also a big problem in countries where people do not consume a lot of white rice?
A 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.
Q The HPB says exercise lowers risk, so does that mean if I exercise, I can eat more white rice and drink sugary sodas?
A 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.