February 28, 2013
Global Sugar Intake Behind The Rise In Type 2 Diabetes
Lawrence LeBlond for redOrbit.com - Your Universe Online
More than 350 million people worldwide are believed to have diabetes, and for years health experts have debated on what the exact driver of the illness has been. While sugar intake has been viewed as a culprit in many eyes, scientists have long refuted that conjecture and attributed the global health crisis to too much overall food intake and obesity.
But a new finding by three California universities — Stanford, UC-Berkeley and UCSF — suggests through compelling evidence that Type 2 diabetes is being largely driven by the rising consumption of sugary foods and drinks. This evidence comes in the form of large-scale analysis of worldwide sugar availability over the last decade. The findings have been published in Wednesday´s (Feb. 27) issue of the journal PLoS ONE.
In all, the American researchers looked at sugar intake in 175 countries, including the United States. They found increases in sugar intake account for a third of all new cases of diabetes in the US and a quarter of all cases worldwide. In the countries studied, the researchers found an average 150-calorie-per-day increase in the availability of sugar — roughly the equivalent of a can of cola. This accounts for a rise in the prevalence of Type 2 diabetes by 1.1 percent.
The team also found that, in the countries studied, an increase of 150-calories-per-day for all food, regardless of sugar content, only led to a 0.1 percent rise in the prevalence of Type 2 diabetes, adding credence to the evidence that sugar intake is a prominent driver for onset of diabetes.
The study´s lead author, Sanjay Basu, MD, PhD, an assistant professor of medicine at the Stanford Prevention Research Center, said the finding was “quite a surprise.”
"We're not diminishing the importance of obesity at all, but these data suggest that at a population level there are additional factors that contribute to diabetes risk besides obesity and total calorie intake, and that sugar appears to play a prominent role," Basu said.
While the study cannot prove that sugar alone is causing diabetes, it does confirm that the longer a population is exposed to excess sugar, the higher its diabetes rate will be after taking obesity and other factors into account. The study also found that diabetes rates waned over time when sugar availability dropped, independent of changes in consumption of other calories.
For the study, the team used food-supply data from the United Nations Food and Agricultural Organization [FAO] to estimate the availability of foods in the 175 countries included in the study. Data were also gleaned from the International Diabetes Foundation on the prevalence of diabetes among 20- to 79-year-olds.
Basu and colleagues employed new econometric statistical methods to control for factors that could provide alternate explanations for the link between sugar and diabetes. These factors included obesity, non-sugar food components, sedentary lifestyle, economic development rates, household income, urbanization, tobacco and alcohol use, and the percentage of the population 65 and older.
Senior author Robert Lustig, MD, pediatric endocrinologist at UCSF's Benioff Children's Hospital, said causation cannot be proven directly through epidemiology.
“But in medicine, we rely on the postulates of Sir Austin Bradford Hill to examine associations to infer causation, as we did with smoking. You expose the subject to an agent, you get a disease; you take the agent away, the disease gets better; you re-expose and the disease gets worse again. This study satisfies those criteria, and places sugar front and center,” he explained in a statement.
"As far as I know, this is the first paper that has had data on the relationship of sugar consumption to diabetes," said Marion Nestle, PhD, a professor of nutrition, food studies and public health at New York University.
"This has been a source of controversy forever. It's been very, very difficult to separate sugar from the calories it provides. This work is carefully done, it's interesting and it deserves attention," said Nestle, who was not involved in the study.
Basu said an important factor in the study was the fact that data was obtained over time. "Point-in-time studies are susceptible to all kinds of reverse causality“¦ For instance, people who are already diabetic or obese might eat more sugars due to food cravings."
Basu said they had to rely on food-availability data because no large-scale consumption data existed in any of the international databases. Of course, he noted, follow-up studies should be pursued to examine the possible links between diabetes and specific sugar sources, such as high-fructose corn syrup and sucrose. Future research should also evaluate the influence specific foods have on diabetes, such as soft drinks or processed foods.
Another important step in future studies would be to conduct randomized clinical trials to find a cause-and-effect connection between sugar and diabetes. Basu noted that this would be a difficult process because it is unethical to feed large amounts of sugar to people just to try and induce diabetes. However, he said researchers could put people on a low-sugar diet to see if it reduces diabetes risk.
Nestle said the evidence in this research really adds to the numerous other studies that suggest people should cut down on their sugar intake.
"How much circumstantial evidence do you need before you take action?" she said. "At this point we have enough circumstantial evidence to advise people to keep their sugar a lot lower than it normally is."
NOT EVERYONE ON BOARD
Dr. Matthew Hobbs, head of research at Diabetes UK, said caution should be taken into consideration when reading into the results.
"At the moment the evidence is not strong enough for us to be confident that sugar consumption has a direct effect on risk of type 2 diabetes," he said in an interview with The Guardian.
He said his charity recommends minimizing the consumption of all foods that are high in sugar or fat and not just sugar alone. Fatty foods drive up obesity, which in turns increases the chances that Type 2 diabetes can develop.
“Expert reviews of the scientific evidence are clear and in agreement — sugar does not cause diabetes,” said Dr. Glenys Jones, a nutrition communications manager for Sugar Nutrition UK. She pointed to a previous finding that showed a decline of 6 percent in British sugar consumption did not stop diabetes prevalence doubling during that same time.
Because the study does not directly control for all variables, Nestle said it shouldn´t be taken as a final word. For decades there has been a flip-flop on what really drives diabetes. Some scientists have maintained that too much sugar is the culprit. Others believe it´s the fatty foods. And still others say its consumption of too many calories.
“It´s really difficult to separate sugars from calories,” she said.
Nestle told Bloomberg's Elizabeth Lopatto in an interview that the data used by Lustig´s team are “notoriously unreliable.”
She did say they are good for showing trends, but that´s about all. The data is poor when it comes to giving an accurate measure on the amount of foods in the diet. The numbers show the data on all the food in the country, less exports and plus imports, “so you can imagine how difficult it is to get that information accurately,” she explained.
She said follow-up research is definitely needed to examine the links between types of foods and obesity to help clarify the observations made in the study. Only then, may we have an accurate account of the role sugar plays in the onset of diabetes.
GLOBAL HEALTH CRISIS
Dr. Walter Willett, a nutritionist and epidemiologist at Harvard School of Public Health, said Lustig´s results underestimated the role of added sugar in the development of diabetes.
He told Melissa Healy of the Los Angeles Times that because the data didn´t distinguish where the source of the sugar was coming from — be it fruit or junk foods — the role the sweetener has in the onset of Type 2 diabetes may be even more pronounced than what was shown in this study.
He said the results make it clear that sugar intake “is fueling the global epidemic of diabetes,” and reducing consumption is necessary to control the rise of the disorder.
The increasing availability of sugar over the past 50+ years has placed a huge burden on the world´s health. Most of the sugar the world now consumes comes from the US and China, vastly expanding production to meet the world´s unhealthy needs.
The result of this global need for sugar has largely driven up the number of people who have become overweight or obese. Today, more than 1.4 billion adults (nearly 18 percent of the world population) over the age of 20 have expanding waistlines, according to data from the World Health Organization (WHO). Diabetes now affects more than 300 million people worldwide and will account for nearly 6 million deaths per year by 2030.
Willett pointed to previous research that has shown similar findings to Lustig´s study. One such study tracked people for up to 20 years and found that with each daily serving of soda a person consumes the risk of developing diabetes increases by 15 to 25 percent. Soft drinks on average contain about 140 calories (mostly from sweetener) for a 12-ounce serving.
With studies like this in the books, politicians and health experts have proposed measures to reduce the consumption of soda. Measures have included instating soda taxes, reducing size limits on fountain drinks in restaurants and concession stands, and even banning them, such as a recent proposal by NYC Mayor Michael Bloomberg.
However, the beverage industry, which generates billions of dollars in sales worldwide from their soft drinks, has fought hard to keep such measures from making headway.
Lustig said that in light of his study´s findings, beverage companies can no longer reasonably argue that their products are safe for consumption.
But the American Beverage Association [ABA] says otherwise.
Lustig´s study, nor do any studies, show “that consuming sugar causes diabetes,” the group said in a statement.
“The study's conclusions on sugar and diabetes should be viewed cautiously given that the underlying model failed to consider the potential impact of solid fats – such as butter, cheese and lard – or factor for family history," it added.
The Sugar Association also found fault with Lustig´s study, saying it failed to separate the effects of “natural sugar” and high-fructose corn syrup.
Of interesting note, as some might infer, Lustig´s study was rejected from nearly every journal before being picked up by PLoS ONE.