Fructose is the Villain, But Not So Easy to Avoid

Animal studies have shown that fructose, compared with glucose, causes raised lipid levels and insulin resistance. Fructose is used to sweeten most soft drinks in the USA usually in the form of high-fructose corn syrup, a mixture of fructose and glucose. So it’s not surprising that clinical studies have investigated the possible harm from consuming too much high-fructose corn syrup.

One such study has been reported in the Journal of Clinical Investigation. Overweight volunteers were given glucose- or fructose-sweetened drinks that provided 25% of their calorie requirements, for 10 weeks. Both groups had similar weight gain during the study, but the visceral adipose tissue (i.e. belly-fat) was significantly increased only in the fructose drinkers. Most of the weight gain in the glucose drinkers was subcutaneous, i.e. beneath the skin. There were increased total cholesterol, low-density lipoprotein cholesterol (LDL-C), and insulin resistance in the fructose-drinking group – findings consistent with the metabolic syndrome.

Clearly the findings after obtaining calories from fructose differed, and were more unhealthy, than those after glucose consumption. However, high-fructose corn syrup is not the bad character it’s sometimes painted. Found in most soft drinks and even cereals, it contains about 55% fructose and 45% glucose, while table sugar has roughly a 50/50 ratio of fructose to glucose. The ‘excess’ fructose in high-fructose corn syrup is insufficient to label the substance a risk factor for cardiovascular disease or diabetes. However, the findings in the study should encourage nutritionists to look more closely at the fructose content of foods . . .