Average daily intake of fructose has increased and converting this monosaccharide into fat is much easier than other carbohydrates in the body. However, findings regarding fructose's health effects are conflicting. The difference in the source of dietary fructose and the different metabolism of this nutrient in the two sexes may explain some of these differences. So this study investigated the effect of gender on the association between dietary fructose intake (from natural and industrial sources) and metabolic syndrome in northern Iran, Amol.

This population-based cross-sectional study was conducted in the second phase of the Amol cohort study. In the present study, adults between 18 and 65 years old who had informed consent and required information (including demographic, biochemical, anthropometric, medical, physical activity and dietary information) were included in the study according to the exclusion criteria. Food intake was evaluated using a semi-quantitative food frequency questionnaire (168 items) and the Rapid Assessment of Physical Activity (RAPA) form was used to evaluate physical activity level. Adult Treatment Panel III standard (ATP III) was used to diagnose metabolic syndrome. In each of the two genders, the amount of dietary fructose intakes (total amount and intake from natural and industrial sources) were divided into three groups based on the 33rd and 66th percentile values. Multivariate logistic tests (with adjustment of relationships based on confounding factors) were used for data analysis.

This study included 2308 participants between 18 and 64 years old (49.17% male) with an average age of 43.17±12.30 years. The prevalence of metabolic syndrome in the studied population was 25.64% (significantly more in women than men, p<0.001). In men, those who were in the highest tertile of total fructose intake were 73% (p=0.02) more exposed to the risk of diastolic blood pressure increase and those in the highest tertile of fructose intake from natural sources were 77% (p=0.02) more at risk of systolic blood pressure increase and 60% (p=0.02) more at risk of metabolic syndrome. There was no significant difference in the risk of metabolic syndrome and its components among tertiles of dietary fructose intake from industrial sources in men. In women, the risk of high systolic and diastolic blood pressure and high blood pressure increased by 58% (p=0.02), 71% (p=0.04) and 77% (p<0.01), respectively, in the third tertile of dietary fructose from industrial sources. However, this association was not observed for fructose intake from natural sources.

Increasing dietary fructose intake, whether from natural or industrial sources, could be related to high blood pressure. Apparently, this association could be related to gender, and in men, high consumption of dietary fructose, even from natural sources, could be associated with high blood pressure and metabolic syndrome.