Moderate Amounts of Fructose Consumption Impair Insulin Sensitivity in Healthy Young Men

A randomized controlled trial

http://care.diabetesjournals.org/content/early/2012/08/24/dc12-0540.abstract

OBJECTIVE Adverse effects of hypercaloric, high-fructose diets on insulin sensitivity and lipids in human subjects have been shown repeatedly. The implications of fructose in amounts close to usual daily consumption, however, have not been well studied. This study assessed the effect of moderate amounts of fructose and sucrose compared with glucose on glucose and lipid metabolism.

RESEARCH DESIGN AND METHODS Nine healthy, normal-weight male volunteers (age 21–25 years) were studied in this double-blind, randomized, cross-over trial. All subjects consumed four different sweetened beverages (600 mL/day) for 3 weeks each: medium fructose (MF) at 40 g/day, and high fructose (HF), high glucose (HG), and high sucrose (HS) each at 80 g/day. Euglycemic-hyperinsulinemic clamps with [6,6]-²H₂ glucose labeling were used to measure endogenous glucose production. Lipid profile, glucose, and insulin were measured in fasting samples.

RESULTS Hepatic suppression of glucose production during the clamp was significantly lower after HF (59.4 ± 11.0%) than HG (70.3 ± 10.5%, P < 0.05), whereas fasting glucose, insulin, and C-peptide did not differ between the interventions. Compared with HG, LDL cholesterol and total cholesterol were significantly higher after MF, HF, and HS, and free fatty acids were significantly increased after MF, but not after the two other interventions (P < 0.05). Subjects’ energy intake during the interventions did not differ significantly from baseline intake.

CONCLUSION This study clearly shows that moderate amounts of fructose and sucrose significantly alter hepatic insulin sensitivity and lipid metabolism compared with similar amounts of glucose.

COMMENT: As the authors state the metabolic effects of hypercaloric fructose have been well studied.  What this study addresses if what if you drink one 600 ml soda with either 40 grams of fructose (the amount of sugar in a typical soda, 150 calaries) for three weeks or ones with 80 grams of fructose, glucose or sucrose?  Since almost all beverages in the US are sweetened with fructose (actually corn syrup is supposed to be equally fructose and glucose, but the fructose is generally higher).  The bottom line is that the equivalent of one or two regular sodas a day can have significant metabolic effects within three weeks.  So how much of this “liquid candy” does the average American consume?  Let’s let the industry answer that: “According to the National Soft Drink Association (NSDA), consumption of soft drinks is now over 600 12-ounce servings (12 oz.) per person per year. Since the late 1970`s the soft drink consumption in the United States has doubled for females and tripled for males. The highest consumption is in the males between the ages of 12 - 29; they average 1/2 gallon a day or 160 gallons a year.”  There is significant evidence that relates soda consumption to obesity.  Whether that is a calorie effect or a fructose effect is still uncertain.