High-Fructose/High-Fat Diet Is One-Two Punch to Health
The Western diet tends to be relatively high in fat. That's not necessarily bad for health, provided your daily intake of calories is in line with daily caloric expenditures. Experts no longer believe, for instance, that saturated fat in the diet is linked to high cholesterol levels. But when you add abnormally large amounts of sugar, too, health inevitably suffers. Specifically, say scientists from Italy, a diet high in fructose and fat is especially bad for the liver, and may be expected to trigger changes consistent with the development of type 2 diabetes and other troubling diseases.
To arrive at this conclusion, researchers fed rats one of two diets. Half got a high-fat diet for two weeks. The other half received a high-fat/high-fructose diet for two weeks. The rats stood in for sedentary humans in the study. Even though the lab animals ate this way for just two weeks, evidence of metabolic dysfunction developed rapidly.
Alarmingly, the Western style high-fat/high-fructose diet triggered significantly more damage, more rapidly, than the high-fat diet alone. The livers of rats fed the fructose/fat combination showed signs of insulin resistance and increased inflammation. In humans this is the first step towards the onset of type 2 diabetes. Added sugar in any form is now suspected of being essentially toxic. But it's interesting that the animals in this study fared especially poorly when they were fed a diet high in fructose.
Fructose is a simple sugar found in fruits and other plant foods. It's also present in most soft drinks. Manufacturers primarily use high-fructose corn syrup to sweeten their products, although some have switched to sucrose, in response to pressure from concerned consumers. Proponents of high-fructose corn syrup, which is also included in numerous prepared foods, argue that the body handles table sugar (sucrose, cane sugar, etc.) exactly the same as fructose.
But multiple lines of research indicate that this is not quite true. Nevertheless, the fact remains: added sugar is bad for you, your liver and your metabolism, especially when it's part of a high-fat diet. Chief investigator, Dr Susanna Iossa, of the University of Naples, said: "This result points to the harmful effect of adding fructose to the usual western, high-fat diet and, together with other related findings, should stimulate the discussion on the use of fructose and fructose-containing sweeteners in beverages and packaged foods."
Crescenzo R1, Bianco F1, et al. Fructose supplementation worsens the deleterious effects of short term high fat feeding on hepatic steatosis and lipid metabolism in adult rats.Exp Physiol. 2014 Jun 27. [Epub ahead of print]