The science of sugar

We explore the correlation between sugar intake and heart disease in young adults.

The latest World Health Organization data indicates that 1.9 billion people worldwide are overweight, with 600 million considered obese. Sugar, in the form of processed, high-in-sugar foods are largely to blame.

Scientists around the world are making a desperate plea to stop an epidemic of obesity. But now, new research goes beyond fat to reveal a risk that could be even greater.

TechKnow explores the science of sugar at the Department of Molecular Bioscience School at the University of California-Davis where cutting-edge research is being done. The project, headed by Dr Kimber Stanhope, put healthy young adults in their 20s on a highly controlled sugary diet for 10 weeks and then measured the effects of that added sugar.

We think of fat as fat, but actually in this study, fat isn't all the same.

by Dr John McGahan, diagnostic radiologist

Through the course of the study researchers strictly controlled the food consumed by each subject, specifically the amount of sugar and calories in their diet. The study was a single-blind study, meaning only the scientists knew who was getting what.

One group of 15 subjects were given beverages sweetened by high fructose corn syrup, the sweetener commonly found in soft drinks.

A second group was given beverages sweetened by the artificial sweetener aspartame. Two other groups were given the same drinks, but they were allowed to eat as much food as they wanted.

Stanhope’s study showed that when subjects took an increased dose of sugar intake, the risk factors for cardiovascular disease also increased. The fat-burning process in the liver is impaired because the organ has been overloaded with sugar fructose.

“This study we called our dose-response study, because we actually fed four levels of high fructose corn syrup – 0, 10 percent, 17.5 percent and 25 percent of energy requirement. We saw a perfect stair-step response for cholesterol, for triglycerides, for uric acid … What was very important was that even the 10 percent group showed significant increases [in risk factors] compared to their baseline level. That was only equivalent to handing our research subjects one and a half cans of soda a day,” explains Stanhope.

“So basically, half a can at breakfast, a half a can at lunch, half a can at dinner was the equivalent. Again a surprise, I would not have expected to see significant increases in risk factors with only a half a can per meal in two weeks. I would have believed it could have happened in six months, but I didn’t know we would see it so quickly,” says Stanhope.

The study group that drank an artificial sweetener aspartame instead of high fructose corn syrup experienced none of those risk factors.

Diagnostic radiologist Dr John McGahan explains how high fructose corn syrup affects the body by overloading the liver with fat, causing an increase in cardiovascular risk.

The patients on the fructose diets “end up actually forming more visceral fat than subcutaneous fat so that’s important to the study. And then there’s other metabolic effects that we found out about that,” says McGahan. “We think of fat as fat, but actually in this study, fat isn’t all the same… there’s a big difference between the effects of where our fat is stored and our health.”

While high fructose corn syrup appears to be behind cardiovascular disease, Stanhope says sucrose – any sugar made from sugar cane or sugar beet – may also increase liver fat. She suggests limiting intake of all types of sugars and sweeteners – brown, white or artificial. The best advice is to stick with mother nature and get your sweet fix from fresh fruit.