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What 2 Weeks of Soda Can Do to Your Heart

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Sugary drinks are linked to obesity, heart disease, high blood pressure and diabetes -- and the more soda people drink the more likely these outcomes. The deniers keep arguing that association isn't proof that one actually causes the other, although when epidemiologic studies show a link again and again, and the mechanism of harm is plausible, it is actually pretty damning evidence. That's how we proved smoking cigarettes caused disease (there never was a controlled study asigning people to smoking and comparing them to controls). But there's nothing like controlled experiments, especially double blind placebo controlled ones, to prove cause and effect.

It would be quite difficult to feed experimental groups a certain diet and follow them for the necessary time to see heart disease, diabetes and early death manifest -- I don't think many would sign up to eat for the sake of research for the rest of their lives no matter what the compensation. But the next best thing when you're studying heart disease is to look at markers of heart disease risk, such as LDL cholesterol, apoB, triglycerides and uric acid in the blood.

A new study led by Kimber Stanhope and published online ahead of print in the American Journal of Clinical Nutrition recruited a group of 85 people aged 18-40 and divided them into four groups. For two weeks participants drank beverages sweetened with high-fructose corn syrup (HFCS) making up 0 percent, 10 percent, 17.5 percent or 25 percent of their daily caloric requirement. The participants were blinded to their drink content, and in order to do that the 0 percent drink for the control group was sweetened with aspartame.

Within two weeks, the people who were on the HFCS drinks had higher levels of LDL, triglycerides and uric acid, and the higher the HFCS they drank, the higher the level of heart risk factors.

Although the American Heart Association and the World Health Organization recommend that people limit added sugar to no more that 5 percent of daily calories, very few people do so, and levels of added sugar in the 10-20 percent are typical of the American diet. By this study's assessment, the average American's sugar intake is enough to increase cardiac risk.

Would replacing HFCS with regular sugar (sucrose) make a difference? The fructose content in table sugar is 50 percent, compared to 55 percent in HFCS -- just a slight difference -- and since fructose is metabolized in our body in a way that promotes fat production, raises triglycerides and affects cholesterol levels, either one of these sweeteners would probably have the same negative effects; there's no reason to assume that sugar is metabolically much safer than HFCS.

Dr. Ayala

Full disclosure: I'm vice president of product development for Herbal Water, where we make organic herb-infused waters that have zero calories and no sugar or artificial ingredients. I'm also a pediatrician and have been promoting good nutrition and healthy lifestyle for many years.