Cutting down on white rice may not in itself lower a person's risk of getting diabetes, two new studies have found.
The risk depends on what the rice is substituted with and the overall quality of a person's diet, said Professor Koh Woon Puay, director of the Centre for Clinician-Scientist Development at Duke-NUS Medical School, a co-author of the studies.
Both studies used data from the ongoing Singapore Chinese Health Study, which was started in 1993 by the National University of Singapore (NUS).
This comes after a series of previous studies that linked white rice to diabetes. In 2016, Singapore's Health Promotion Board cited studies by the Harvard School of Public Health in the United States which showed that each plate of white rice eaten daily on a regular basis raises the risk of diabetes by 11 per cent in the overall population.
In one study, researchers from NUS and Duke-NUS Medical School found no link between the quantity of white rice consumed and the risk of Type 2 diabetes when controlled for other variables like age, sex and body mass index (BMI), and various other food intakes.
Type 2 diabetes is related to weight management and is a result of blocked or reduced insulin receptors. Over 90 percent of diabetics suffer from Type 2 diabetes.
"Even over a relatively wide range of rice intakes, from half a bowl to several bowls a day, we didn't see much of an increase in the risk of diabetes," said Professor Rob Martinus van Dam, domain leader of epidemiology at the Saw Swee Hock School of Public Health in NUS and one of the study's co-authors.
Prof van Dam said the study showed that a person who eats less rice is likely to eat more of something else to maintain the same calorie intake.
But people who ate different foods in place of rice were affected differently.
For example, a person may choose more noodle dishes, which are often cooked in sauces that are high in salt and oil, he said. Others may eat more meat to feel full.
These increase their risk of diabetes.
Substituting rice with whole grains, on the other hand, decreases the risk.
Another study, also involving Prof van Dam and Prof Koh, used established diet quality indices to determine the overall "quality" of a person's dietary pattern.
They then measured the link between diet quality and diabetes risk.
A list of 165 food items and beverages were identified, covering an estimated 90 percent of what is commonly eaten by the population in Singapore.
It is the first such study to examine local food specifically.
The researchers said the study found that whole grains, fruits, vegetables, nuts and a moderate amount of dairy were associated with lower risks of cancer, diabetes, heart disease and stroke, in line with other established dietary studies from mostly Western countries.
Sugar-sweetened drinks, processed meat and red meat - including beef, pork and even the darker portions of poultry like chicken thigh meat - were found to be associated with higher risks of the same diseases.
The items were scored according to the Dietary Approaches to Stop Hypertension (Dash) diet index.
The proportion of each item as a part of a consistent dietary pattern was found to be more important than the absolute intake, said Prof Koh, who is also the principal investigator in the Singapore Chinese Health Study.
This means one does not have to cut out unhealthy foods like red meat entirely, as long as they are eaten in moderation, she added.
About 45,400 Chinese Singaporeans who did not have diabetes, cancer or cardiovascular diseases were recruited between 1993 and 1998 for the Singapore Chinese Health Study.
Details about their diets were collected through questionnaires during two follow-up interviews. Over an average of 11 years, more than 5,200 developed diabetes.
This data was then used in the two recent studies.
The participants' diets were ranked according to how often and how much of a given food they ate on average.
Those who ate relatively more whole grains, low-fat dairy, nuts, seeds, legumes, fruits, and vegetables were given higher scores.
Those who had more processed and red meats, sugary drinks and sodium in their diets were given lower scores.
Other foods like fish and refined grains, including white rice, were not scored under the Dash index.
The researchers found that the top 20 percent of the participants, who had relatively "higher quality" diets, were nearly 30 percent less likely to develop diabetes compared to the bottom 20 percent.
Dr Annie Ling, group director of policy, research and surveillance at the Health Promotion Board, said the studies are timely given the findings of the recent National Nutrition Survey 2018.
The survey showed gradual improvements in Singaporeans' dietary habits but highlighted areas for improvement.
She said: "While Singaporeans are consuming more whole grains, fruits and vegetables, high sugar and sodium intake remains a cause for concern.
"It is important to continue encouraging Singaporeans to pay attention to the foods they choose and the quality of their diets."