WHILE many people, some health professionals included, believe that consuming too much sugar causes diabetes, the American Diabetes Association and the scientific community at large have been trying for years to set the record straight. Sugar and other carbohydrates must be limited once a person develops diabetes, they say, but sugar itself doesn't cause the disease; excess weight and physical inactivity are the big lifestyle culprits.
Now comes a report that makes the scientific consensus look incorrect and the commonly held "myth" look like reality. In yet another look at tens of thousands of women participating in the Nurses' Health Study, researchers at Harvard have found that those who drank at least one sugary soft drink a day, including fruit punch (as opposed to actual fruit juice) were at about twice the risk for developing adult onset, or type 2, diabetes as those who drank soda pop and other sweetened beverages less often than once a month.
The media immediately picked up on it. "Study Links Sugar-Sweetened Soft Drinks and Diabetes" was the way the headline read in the Wall Street Journal. Other news outlets took a similar tack.
Is it true? Does sugar, sweet soft drinks in particular, lead to diabetes development?
The answer is yes, but no. As the. investigators themselves point out, the women who drank the most soda pop, specifically, those who increased their non-diet soda pop consumption over time, gained significantly more weight than women for whom soda was not a dietary mainstay. They put on more than 10 pounds in 4 years. In other words, much of the increase in diabetes risk came from weight gain rather than sugary beverages per se.
Comments Karmeen Kulkarni, MS, RD, president-elect for Health Care and Education for the American Diabetes Association, "we have to look at the whole picture rather than teasing out one piece. We need to pay attention to the total calories. We cannot label one food over another as causing diabetes." Indeed, the women who drank a lot of soda tended not only to gain more weight than others but also tended to be relatively inactive and more likely to smoke and have unhealthful lifestyles in general.
How one of the researchers sees it
JoAnn E. Manson, MD, a Harvard investigator who worked on the study, differs from Ms. Kulkarni, but only by degree. She says it's "biologically plausible" that the type of carbohydrate in soda pop (a sugary sweetener called high fructose corn syrup) increases the risk for diabetes beyond its effect on weight gain. Dr. Manson points to the fact that when a lot of sugar enters the bloodstream quickly, as it does when people consume soft drinks, the pancreas has to secrete large amounts of the hormone insulin for the sugar to be removed from the blood and taken to the body's tissues. But over time, with repeated soda pop sugar rushes, the pancreas might not be able to keep up with the demand for insulin, and sugar levels in the bloodstream may remain high for too long--the hallmark of diabetes.
But, Dr. Manson says, while evidence for such a mechanism is mounting, this study only "points to a possibility" and is "not the final word." In addition, she explains, compared to other risk factors for diabetes--weight gain and a sedentary life-style--a relatively large amount of sugar from sweetened beverages is "not tremendously important." It "shouldn't be over-emphasized," she says. "There's more evidence for unrefined whole grains and a high-fiber diet preventing diabetes than for sugar-sweetened beverages causing it."
Our own take on soda pop
Is soda pop off the hook, then? Until more research comes in, is it basically okay to drink as much as you want as long as you keep down your weight and stay physically active?
No. From a nutrition standpoint, soda contributes nothing to the diet other than sugary calories (look at all the zeroes on the Nutrition Facts label). Moreover, research has indicated that people don't perceive liquid calories the way they feel calories from solid foods. Drinking a 150-calorie can of soda won't make you less apt to consume 150 fewer calories at some other point in the day, as a solid 150 calories would, because it doesn't appear to trigger any satiety mechanism. Thus, those calories are particularly apt to lead to excess pounds--and thus can be said to lead to diabetes indirectly.
Finally, sugar-sweetened soft drinks contribute more than 7 percent of Americans' calories, making them the largest single source of calories in the US diet. In a nation where a lot of people get at least 20 percent of their calories from sugar but treat fruits, vegetables, and whole grains as condiments, keeping soda pop a dietary staple is not nutritionally sound.