Role of sugar in obesity, diabetes still up for debate
It is a topic that is increasingly heard among clinicians and policymakers alike: a lack of viable solutions to the growing prevalence of obesity and diabetes among children and adults. Although the literature has confirmed that high-fructose corn syrup is a factor in the increased frequency of type 2 diabetes, many experts are still questioning how to reduce this risk and assess the urgency for less sugar-sweetened foods and beverages.
Michael I. Goran, PhD, director of the Childhood Obesity Research Center; professor of preventive medicine, physiology and biophysics, and pediatrics; and the Dr. Robert C. and Veronica Atkins Chair in childhood obesity and diabetes at USC Keck School of Medicine, told Endocrine Today that although there has been an emphasis on sugary beverages, they are not the only source of added sugar in the diet.
“The introduction of high-fructose corn syrup has changed the foodscape in the United States because it’s made food sweeter. And part of the reason is to prolong shelf life, to reduce spoilage, to improve the way it looks and improve the way it tastes. That change has occurred in the last 30 years and needs to be reconsidered in terms of what we think about with our food supply,” Goran said.
Miriam Vos, MD, MSPH, assistant professor of pediatrics in the division of gastroenterology, hepatology and nutrition at Emory University School of Medicine and research director at Health4Life Program at Children’s Healthcare of Atlanta, said the change in foodscape has progressed.
“It continues to evolve over time. The more important questions are, ‘Is the current amount of consumption good? Is it healthy?’ The average consumption and the number of those who are consuming more than average remain at unhealthy levels,” Vos told Endocrine Today.
Clinical effect of sugar
In an international analysis published in the journal Global Public Health, Goran and colleagues addressed the association between the use of high-fructose corn syrup in the Western diet and an increased risk for obesity. There were no differences in BMI or in other dietary variables, including caloric intake and total sugar intake, compared with countries that do not use high-fructose corn syrup. However, they found that indicators of diabetes were 20% higher in countries that used high-fructose corn syrup compared with those that did not.
Data indicate the trend was statistically significant for the International Diabetes Federation estimates of diabetes prevalence (P=.013) and fasting plasma glucose (P=.046). Furthermore, at a rate of 25 kg per year, the United States has the highest per capita consumption of high-fructose corn syrup. The country with the second highest per capita consumption is Hungary, with a rate of 16 kg per year.
While he was a medical resident at the University of California, San Francisco, Sanjay Basu, MD, PhD, and colleagues conducted a large epidemiological study to empirically evaluate whether changes in sugar availability could account for the divergence of diabetes prevalence rates worldwide.
Using econometric models of repeated cross-sectional data on diabetes and nutritional components of food from 175 countries, Basu and colleagues found that every 150 kcal per person, per day increase in sugar availability (which equates to about one can of soda per day) was linked to a 1.1% increased prevalence of diabetes (P<.001), according to data.
Basu, a statistician by training, is now assistant professor of medicine at the Stanford Prevention Research Center in Palo Alto, Calif. He told Endocrine Today that he accidentally stumbled upon these findings.
“I was using a dataset to understand urbanization and I kept getting this weird signal of correlation to sugar and diabetes, outweighing all of the obesity. … That’s when I talked to my endocrinologist colleagues at UCSF,” Basu said.
The most noteworthy mention from his study is that it was consistent with other studies, in that there is a possibility that calories should be investigated in further detail, he said.
“There are some [researchers] that are skeptical that we even needed trials because they say, ‘If you have calories in and calories out, then you are going to get diabetes from obesity.’ This is the first indication that maybe we should research this a little more carefully,” he said.
Basu said he is conducting a long-term clinical trial to confirm his findings from the exploratory analysis published in PLoS One.
Aside from diabetes, Vos told Endocrine Today she and colleagues have been interested in the role of sugar and fatty liver disease.
“The reason why I have become interested in it is because earlier work in animal models showed that giving [animals] fructose induced a fatty liver. We wondered if this was the case for humans, and specifically for children, because non-alcoholic fatty liver disease is now the most common liver disease happening in children and the prevalence of it is high.”
As much as one-third of overweight children will have a fatty liver, making research challenging, she said.
New, relevant research
Vos and colleagues’ most recent work aimed to determine whether reducing fructose resulted in measurable benefits over a short period of time. The data are expected to be presented at the Experimental Biology annual meeting in Boston in late April, she added.
“It does look very promising that reduction — even for as short as a month — already shows some benefits. I can tell you that the markers for cardiovascular risk already improve after just 1 month of reduction in fructose,” Vos said.
A recent study by Ruyter and colleagues struck Vos’ interest. The 18-month double blind, randomized controlled trial examined sugar-free or sugar-sweetened beverages and body weight in children.
“What was important about that study is that it was a very small beverage [8 oz] and it only provided 104 calories. Just that small amount led to a significant difference in weight gain,” Vos said.
According to data, weight increased by 6.35 kg in the sugar-free group compared with 7.37 kg in the sugar group (95% CI, –1.54 to –0.48).
“While I don’t think sugar is the only thing that we need to address for the epidemic of obesity in our country, I think it is one of the important contributors. We’re all looking for small changes that our patients can make in order to prevent gaining too much weight and to lose weight if they’re already obese. Having a moderate consumption of sugar at a healthy level is a great change that patients can make,” Vos said.
According to research presented at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism Scientific Sessions in March, sugar-sweetened beverages, sports drinks and fruit drinks may be associated with about 180,000 deaths worldwide each year.
“In the United States, our research shows that about 25,000 deaths in 2010 were linked to drinking sugar-sweetened beverages,” Gitanjali M. Singh, PhD, postdoctoral research fellow in the department of nutrition, Harvard School of Public Health, said in a press release.
Based on data collected for the 2010 Global Burden of Diseases Study, and data from 114 national dietary surveys covering more than 60% of the population, the researchers linked consumption of sugar-sweetened beverages to 133,000 deaths from diabetes, 44,000 deaths from CVD and 6,000 deaths from cancer, according to a press release. Seventy-eight percent of deaths occurred in low- and middle-income countries, compared with high-income countries.
When examined by region in 2010, sugar-sweetened beverage intake ranged from less than one serving (8 oz) daily in Chinese women aged older than 65 years to more than five servings in Cuban men aged younger than 45 years. Latin America and the Caribbean had the greatest number of deaths related to diabetes (n=38,000) due to consumption of sugar-sweetened beverages. Also, East/Central Eurasia had the greatest number of CVD-related deaths due to beverage consumption (n=11,000). Mexico, which has the highest per-capita consumption of sugar-sweetened beverages, had the highest death rate due to sugar-sweetened beverage intake — 318 deaths per million adults. Japan had the lowest death rate associated with consumption (10 deaths per million adults).
“Although there may not be clear evidence that high-fructose corn syrup is inherently dangerous when consumed in moderation, consuming too many calories in the form of sugar leads to numerous and serious health consequences over time,” Steven Driver, MD, MPH, resident physician of internal medicine at the Mayo Clinic in Rochester, Minn., told Endocrine Today. “High-fructose corn syrup is cheap, and when things are cheap and readily available, we tend to purchase more of them than we might otherwise prefer. When a 20-oz soda packs in nearly 240 calories, people end up taking in more sugar than is healthy, which has had a major impact on public health.”
According to research presented by Driver at the American College of Cardiology Scientific Sessions in March, modest financial incentives offered to overweight or obese patients were associated with significant weight loss. Driver’s research interests are in the fields of preventive cardiology and behavioral economics.
“The obesity epidemic itself has been a major challenge for patients, employers and their physicians. Traditional therapies are not working for many individuals, so people are looking for creative ways to help people lose weight and keep it off. Financial incentives can help us stick with the kind of healthy behaviors we wish we would [stick to] more often. In our study, this meant losing more weight and keeping it off for a full year,” Driver said.
In October, New York City health officials voted 8-0 with one abstention in favor of Mayor Michael R. Bloomberg and his administration’s proposal to limit the size of sugary beverages sold in food service establishments to 16 oz, according to a news release. Beverages containing less than 25 calories per 8 oz and those that are more than 50% milk or 100% fruit or vegetable juice would not be affected by the new measure.
Food service establishments, including restaurants, mobile food carts, delis and concessions at movie theaters, stadiums and arenas, originally had until March 12 to adjust their menu boards, as well as cup and container sizes, to be in compliance with the regulation.
However, 1 day before the ban was to go into effect, state Supreme Court Justice Milton Tingling ruled the ban “arbitrary and capricious,” and its would-be implementation was halted. In a press release after the reversal, Bloomberg said he is confident the decision will be reversed.
Patrick M. O’Neil, PhD, current director of the Weight Management Center, professor in the department of psychiatry and behavioral sciences at the Medical University of South Carolina and past-president of The Obesity Society, released a statement after the court ruling against Bloomberg’s proposed ban.
“… Between 1977 and 1996, food portion sizes increased both inside and outside the home for all categories except pizza. The energy intake and portion size of salty snacks increased by 93 kcal (from 1.0 to 1.6 oz [28.4 to 45.4 g]), and in soft drinks by 49 kcal (13.1 to 19.9 fl oz [387.4 to 588.4 mL])…” O’Neil said in a press release. “The Obesity Society continues to support efforts by Mayor Bloomberg to reduce consumption of super-sized sugary beverages, per our statement issued in May 2012.”
Goran told Endocrine Today that the ban would have been a “stop-gap solution” and would not have had a beneficial impact on the global diabetes and obesity epidemic.
However, results from a controversial poll published in The New England Journal of Medicine in January reflect favorable votes from 1,290 clinical readers in 75 countries regarding the government regulation of sugar-sweetened beverages to reduce the prevalence of obesity. According to the report written by James A. Colbert, MD, and Jonathan N. Adler, MD, 58% of voters from the United States supported government regulation vs. 84% of voters from other countries.
“A few readers pointed out the irony of government regulation of sugar-sweetened beverages at the same time that the government is providing generous subsidies to agricultural producers of sugar and high-fructose corn syrup, the very products that are helping to fuel the obesity epidemic,” Colbert and Adler wrote.
Eric A. Finkelstein, PhD, an associate research professor at the Duke Global Health Institute at Duke University, and deputy director and associate professor in the health services research program at Duke-NUS Graduate Medical School in Singapore, and colleagues wrote in the Journal of Health Economics that a 20% price increase on sugar-sweetened beverages would result in an average weight loss of 1.6 lb during the first year of implementation and a cumulated weight loss of 2.9 lb in 10 years. They suggest the tax would have a similar effect on calories for the largest purchasers of sugar-sweetened beverages.
Vos said making sugar more expensive or less convenient to consumers could be beneficial.
“Research suggests that raising the price of cigarettes was very beneficial in combination with all of the other public health efforts to reduce smoking. I think that taxation or industry agreeing to put less sugar into products is an important part of the approach. We also need to have public health campaigns to help patients understand what is a healthy amount of sugar and to understand the benefits of the approaches,” Vos said.
However, fairness should be considered, she said. If sugar taxes were raised at the earlier industry level compared with the store or restaurant level, Vos said it could make a difference.
“It seems like that would then even the playing field for the many different stores and restaurants that depend on these products. It shouldn’t make one product more expensive than the other,” Vos said.
In an essay published in the CDC’s Preventing Chronic Disease in February, Jason Fletcher, PhD, from Yale School of Public Health, and colleagues wrote that taxes on sugar-sweetened beverages could be beneficial if the approach is broader and applies to a more comprehensive policy.
“For example, a tax combined with a subsidy for water could be more effective than a tax in isolation,” the researchers wrote. “Additionally, a recently proposed extension of a sugar-sweetened beverage tax that instead taxes all caloric sweeteners at the manufacturer level would limit consumers’ ability to easily switch to foods with caloric sweeteners or other unhealthful beverages.”
After an increasing amount of literature linking sugary drinks to the prevalence of obesity, the Coca-Cola Company launched a campaign in January to address its role in the matter, according to a press release.
The commercials, “Coming Together” and “Be OK,” broadcasted on national cable news channels in the company’s effort to highlight specific beverages and their caloric content.
“We are committed to bring people together to help fight obesity,” Stuart Kronauge, general manager of sparkling beverages at Coca-Cola North America, said in a press release. “This is about the health and happiness of everyone who buys our products and wants great-tasting beverages, choice and information. The Coca-Cola Company has an important role in this fight. Together, with willing partners, we will succeed.”
According to the press release, the company has dedicated $5 million for 100 new fitness centers in US schools during the next 5 years.
David Levitsky, PhD, professor of nutrition and psychology at Cornell University, told Endocrine Today there is a clear link between the taste of sweets and consumption of food. Levitsky specializes in obesity, weight loss and how patients inform their food choices.
“From a quantitative perspective, yes, there is a relationship. However, if you go into the physiology and chemistry of fructose, I think the data show once it gets to the liver it is handled just like any other sugar,” Levitsky said.
Levitsky said people in general have a poor memory for what is consumed. “Giving individuals the tools to cope with this ‘obesigenic’ environment that we live in,” is one solution, he said. Yet, he believes calories are the biggest issue.
“I could give you some theoretical chemical reasons to why certain sugars in food should be more fattening than others. In the end, it is just calories. Underlying this, particularly with the Coca-Cola commercials that are trying to absolve themselves of the blame, they’re not doing it in order to create pathologies, they’re doing it in order to sell more food,” Levitsky said. “It should be brought out because not many of us in nutrition are saying that this is really a war on calories. The food companies want us to eat a little more, and we’ve got to eat a little less.”
Goran said it comes down to consumers rejecting high-fructose corn syrup.
“That will be a move in the right direction. Implementing a sugar or soda tax is a good idea but the projections suggest that it’s not going to be enough to have a broad impact on obesity and/or diabetes. It comes back to the need for a shift in social norms that will promote real foods and avoid processed foods, especially foods and beverages made with high-fructose corn syrup and reducing our cultural obsession with sugar and sweet taste.” – by Samantha Costa
Is high-fructose corn syrup to blame for obesity in the United States?
Yes, but not because high-fructose corn syrup (HFCS) is metabolically different from its sister compound sucrose (ie, cane sugar, beet sugar, maple syrup, honey, agave). Rather, it is because it’s cheaper. HFCS was introduced into the American marketplace in the early 1970s. The price of sugar dropped immediately, as now there was economic competition. Initially, there was reticence on the part of the food industry to adopt the sweetener. However, Hurricane Allen in 1980 wiped out the Caribbean sugar crop, food executives saw that they needed a “home-grown” product and sales of HFCS took off, as did the obesity/diabetes (ie, metabolic syndrome) epidemic. The other necessary technological advance was the two-liter bottle, invented by DuPont in 1973, which served as the “fructose delivery vehicle.” However, HFCS is only available in the US, Canada, Japan and very limited exposure in parts of Europe. The rest of the world uses sucrose; yet because of HFCS, global sugar prices dropped, global consumption increased and global prevalence of metabolic syndrome skyrocketed.
The O-glycosidic bond of sucrose is rapidly cleaved by the intestinal enzyme sucrase to yield the fructose moiety. Thus, HFCS and sucrose similarly exert three metabolic and central actions to cause metabolic syndrome: 1) fructose is metabolized directly by liver mitochondria where excess is turned into liver fat (de novo lipogenesis), which generates hepatic insulin resistance; 2) fructose binds to proteins (the Maillard or “browning” reaction) seven times faster than glucose, generating reactive oxygen species (oxidative stress) leading to cell aging; and 3) fructose promotes increased caloric consumption through lack of suppression of ghrelin, lack of stimulation of leptin and lack of extinction of reward in the nucleus accumbens. Indeed, fructose more closely resembles ethanol than glucose.
While many food items cause weight gain (potato chips and french fries are No. 1 and No. 2), a recent meta-analysis by Te Morenga and colleagues shows that sugar/HFCS contributes to obesity as well. Our recent worldwide econometric analysis by Basu and colleagues looked at specific food availability against diabetes prevalence over the past decade. For every 150 total calories extra per day, diabetes prevalence increased just 0.1%; but if those calories were a can of soda, diabetes prevalence increased 11-fold, to 1.1%. Let me repeat: The total calories did not count. And no other “foodstuff” explained diabetes prevalence except for added sugar. Furthermore, the sugar effect evidenced: 1) dose; 2) duration; 3) directionality; and 4) precedence. And we controlled for: 5) income; 6) urbanization; 7) aging; 8) physical activity; and most importantly 9) obesity. While only randomized clinical trials can prove “scientific causation,” this natural history study reaches the level of evidence espoused by Sir Austin Bradford Hill, which implicated tobacco as causative of lung cancer in the 1960s, and provides “causal medical inference” between sugar and diabetes. Bottom line: It’s the sugar, stupid.
Robert H. Lustig, MD, is professor of pediatrics and member of the Institute for Health Policy Studies at UCSF; Masters’ candidate at UC Hastings College of the Law; author of The New York Times best-seller, Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease (Hudson Street Press, 2012); and head of the non-profit Doctors’ Food Project. He can be reached at the University of California/San Francisco, 513 Parnassus Ave., Box 0434, San Francisco, CA 94143; email: email@example.com. He has no relevant financial disclosures.
Not by itself. When all is said and done, obesity is a problem of energy balance. There are too many calories being taken in, and too few are removed. The excess intake of sugar (both high-fructose corn syrup and others) is part of that problem in two ways. First, sugar adds calories we don’t need. Second, by making food sweet, added sugar stimulates us to eat more overall.
However, it would be a mistake to think that HFCS is “the” cause of the obesity epidemic. It could be eliminated from our food supply, and we would still have all the same problems if we ate artificially sweetened doughnuts. We would have all the same problems if we replaced it with other varieties of added sugar.
We cut fat and got fatter and sicker; we cut carbohydrates and got fatter and sicker. We could cut HFCS and get fatter and sicker.
No “one” food, nutrient or ingredient caused the crisis we are in, and a focus on no one food or nutrient or ingredient will solve it. If we want to get out of these dark woods where obesity and diabetes are an epidemic, we will have to see the forest through the trees. We will have to eat well overall and exercise more. Will that entail eating less (or no) HFCS? Certainly. Will that be all there is to it? Certainly not.
David L. Katz, MD, MPH, FACPM, FACP, is director of the Yale University Prevention Research Center and of the Integrative Medicine Center at Griffin Hospital; editor-in-chief of Childhood Obesity; president-elect of the American College of Lifestyle Medicine; and president and founder of the Turn the Tide Foundation. He can be reached at the Yale University Prevention Research Center, 130 Division St., Derby, CT 06418; email: firstname.lastname@example.org. He has no relevant financial disclosures.