High-sugar diets increase cardiac dysfunction and mortality in hypertension compared to low-carbohydrate or high-starch diets

Abstract

Objective: Sugar consumption affects insulin release and, in hypertension, may stimulate cardiac signaling mechanisms that accelerate left ventricular hypertrophy and the development of heart failure. We investigated the effects of high-fructose or sucrose diets on ventricular function and mortality in hypertensive Dahl salt-sensitive rats.

Methods: Rats were fed chows that were either high starch (70% starch, 10% fat by energy), high fat (20% carbohydrates, 60% fat), high fructose (61% fructose, 9% starch, 10% fat), or high sucrose (61% sucrose, 9% starch, 10% fat). Hypertension was induced by adding 6% salt to the chow (n = 8-11/group).

Results: After 8 weeks of treatment, systolic blood pressure and left ventricular mass were similarly increased in all rats that were fed high-salt diets. Hypertension caused a switch in mRNA myosin heavy chain isoform from alpha to beta, and this effect was greater in the high-salt sucrose and fructose groups than in starch and fat groups. The cardiac mRNA for atrial natriuretic factor was also increased in all high-salt groups compared to respective controls, with the increase being significantly greater in the hypertensive sucrose fed group. Mortality was greater in the sucrose group (44%) compared to all the other hypertensive groups (12-18%), as was cardiomyocyte apoptosis. Left ventricular ejection fraction was lower in the high-salt sucrose group, which was due to an increase in end-systolic volume, and not increased end-diastolic volume.

Conclusion: Diets high in sugar accelerated cardiac systolic dysfunction and mortality in hypertension compared to either a low-carbohydrate/high-fat or high-starch diet.

Fig. 1

Survival of rats over the 8 weeks duration of the study. *P <0.05 compared to the same dietary group with low salt. ^† P <0.05 compared to all other diets with high salt. Values are means ± SEM.

Fig. 2

mRNA levels for ANF (top) and the ratio of mRNA for MHC-β/MHC-α (bottom). Filled bars represent low-salt diets and open bars represent high-salt diets. *P <0.05 compared to the same dietary group with low salt. ^† P <0.05 compared to FAT + S group. ^‡P <0.05 compared to STC + S and FAT + S groups. Values are means ± SEM.

Fig. 3

Levels of apoptosis as indicated by the presence of nuclear DNA fragmentation (DNAfr). Filled bars represent low-salt diets and open bars represent high-salt diets. *P <0.05 compared to the same dietary group with low salt. ^† P <0.05 compared to STC + S and FAT + S groups. Values are means ± SEM.