Diabetes research focuses on local foods

YOGYAKARTA (JP): The 30-year-old man gave up rice three months ago after the doctor told him that he was diabetic. Now, like many diabetic patients, he has boiled potatoes for his meals as he believes that the diet is good for him.

The fact is, potatoes provides the same glucose levels in blood as rice does.

"It is often suggested that diabetic persons eat potatoes instead of rice. That's not quite right because both boiled potatoes and rice increase the human blood glucose level," said nutrition specialist Y. Marsono, who is also deputy director of Inter University Center's Food and Nutrition department at Gadjah Mada University, Yogyakarta.

After spending two years researching Indonesian starchy foods, including tubers, Marsono discovered that a tuber locally known as uwi (Dioscorea alata) was the best alternative starch source for diabetic patients. Such patients are usually required to carefully control their starch intake.

"Uwi is indeed a promising source of starch for diabetic patients, as relatively, it doesn't cause an increase of the blood glucose level," Marsono said, adding that other promising tubers included gembili (Dioscorea aculeata LINN) and gadung (Dioscorea hispida DENNST).

Marsono started his research in April 1997 and completed it only last month. With financial support from the University Research for Graduate Education, Jakarta, the research was mainly conducted to provide the glycemic index of various kinds of Indonesian starchy foods.

"I want to make a list of the glycemic index of local Indonesian starchy foods that physicians and hospitals could use as a reference when giving medical advice to their diabetic patients," Marsono said.

The glycemic index of particular foods indicates the level of the tendency of the foods toward increasing glucose in human blood. It is usually stated in percentages in relation to particular foods used as measuring standards in the research.

Such an index, according to Marsono, is very important, especially because Indonesians -- mostly Javanese, who are known to love sweet foods -- are said to be vulnerable to diabetes. It is predicted that 3.8 million Indonesians will suffer diabetes in 2020.

Other starchy foods that Marsono examined includes sorghum, banana, breadfruit (sukun), rice, cassava, and uwi. For the research, Marsono used bread as the reference food (as a standard). Bread was given the glycemic index of 100.

Eleven volunteers, aged between 20 and 39 years, were involved in the research. They had to undergo night fasting, of about 10 hours, before tests were performed on them the following morning.

Blood samples were taken before they took the examined foods, and once every half hour, for four occasions. The amount of food given was equal to 50 grams of starch.

Based on this data, the glycemic indexes of the foods were then measured. The measurement was determined by an increase in blood glucose levels. The higher the increase, the higher the glycemic index of the food.

The research revealed that out of seven starchy foods examined, uwi was rated the lowest influence for an increase in blood glucose levels. With bread as the reference food (given the glycemic index of 100), the research revealed that the glycemic index of the examined foods varied from 160 (sorghum) to 73 (uwi). The glycemic index of baked potatoes was 135, red rice 131, banana 92, breadfruit 90, rice 83 and cassava 78.

"Sorghum, banana and breadfruit, therefore, are not good enough to substitute rice for diabetic patients," said Marsono who obtained his Ph.D from Flinders University, South Australia, in 1995.

It is not difficult to find uwi in a tropical country like Indonesia. In some parts of the country uwi is often served as the main meal, replacing rice, which has become unaffordable for many people. It sometimes has different names in different places. The Sundanese call it huwi, while Madurese and Balinese call it ubi. It is called lame by the Bugis in Ujungpandang, lutu in Banda, heli or hitu in Ambon and gusao in Halmahera.

This year Marsono plans to continue his research but at his own expense. This time he would like to focus his project on local tubers, including kimpul, suweg, gembili and gadung. If everything goes as planned, Marsono is convinced he will be able to complete his glycemic index list by the end of the year.

"If I'm not mistaken, it would be the first glycemic index of Indonesian local foods," Marsono said, adding that the glycemic index was first introduced in 1981 by the Australians Jenkins and associates.

"Information about 'safe foods' for diabetic patients is urgently needed. Unfortunately, a list of the glycemic indexes of foods is not available in many developing countries, including Indonesia," Marsono said. (swa)