Synergistic effects of fructose and glucose on lipoprotein risk factors for cardiovascular disease in young adults

Abstract

Background: Fructose consumption increases risk factors for cardiometabolic disease. It is assumed that the effects of free sugars on risk factors are less potent because they contain less fructose. We compared the effects of consuming fructose, glucose or their combination, high fructose corn syrup (HFCS), on cardiometabolic risk factors.

Methods: Adults (18-40 years; BMI 18-35 kg/m²) participated in a parallel, double-blinded dietary intervention during which beverages sweetened with aspartame, glucose (25% of energy requirements (ereq)), fructose or HFCS (25% and 17.5% ereq) were consumed for two weeks. Groups were matched for sex, baseline BMI and plasma lipid/lipoprotein concentrations. 24-h serial blood samples were collected at baseline and at the end of intervention. Primary outcomes were 24-h triglyceride AUC, LDL-cholesterol (C), and apolipoprotein (apo)B. Interactions between fructose and glucose were assessed post hoc.

Findings: 145 subjects (26.0 ± 5.8 years; body mass index 25.0 ± 3.7 kg/m²) completed the study. As expected, the increase of 24-h triglycerides compared with aspartame was highest during fructose consumption (25%: 6.66 mmol/Lx24h 95% CI [1.90 to 11.63], P = 0.0013 versus aspartame), intermediate during HFCS consumption (25%: 4.68 mmol/Lx24h 95% CI [-0.18 to 9.55], P = 0.066 versus aspartame) and lowest during glucose consumption. In contrast, the increase of LDL-C was highest during HFCS consumption (25%: 0.46 mmol/L 95% CI [0.16 to 0.77], P = 0.0002 versus aspartame) and intermediate during fructose consumption (25%: 0.33 mmol/L 95% CI [0.03 to 0.63], P = 0.023 versus aspartame), as was the increase of apoB (HFCS-25%: 0.108 g/L 95%CI [0.032 to 0.184], P = 0.001; fructose 25%: 0.072 g/L 95%CI [-0.004 to 0.148], P = 0.074 versus aspartame). The post hoc analyses showed significant interactive effects of fructose*glucose on LDL-C and apoB (both P < 0.01), but not on 24-h triglyceride (P = 0.340).

Conclusion: A significant interaction between fructose and glucose contributed to increases of lipoprotein risk factors when the two monosaccharides were co-ingested as HFCS. Thus, the effects of HFCS on lipoprotein risks factors are not solely mediated by the fructose content and it cannot be assumed that glucose is a benign component of HFCS. Our findings suggest that HFCS may be as harmful as isocaloric amounts of pure fructose and provide further support for the urgency to implement strategies to limit free sugar consumption.

Trial registration: ClinicalTrials.gov NCT01103921.

Keywords: Dietary intervention trial; Fructose; Glucose; Interaction; Lipoproteins.