Higher adherence to a high-quality carbohydrate diet is associated with a reduced prevalence of metabolic syndrome among middle-aged men, according to results of a study published in the Journal of Clinical Endocrinology & Metabolism.

Recent study findings suggest an association between high scores in the carbohydrate quality index (CQI) and lower cardiometabolic risk factors. However, the relationship between CQI and metabolic syndrome remains unclear.

To evaluate the association between adherence to the CQI and occurrence of metabolic syndrome, researchers conducted a cross-sectional study using data from the Aragon Workers’ Health Study (AWHS), which was a prospective cohort study that recruited workers from an automobile assembly plant in Spain between 2011 and 2014. Participants were adults aged between 39 and 59 years with no cardiovascular disease at baseline.

The researchers assessed carbohydrate intake using the Food Frequency Questionnaire and carbohydrate quality using the CQI, which considers dietary fiber intake, glycemic index, the ratio of whole grains to total grains, and the ratio of solid carbohydrates to total carbohydrates.

Metabolic syndrome was diagnosed according to elevated waist circumference, elevated fasting blood glucose, elevated blood pressure, elevated serum triglycerides, and reduced serum high-density lipoprotein cholesterol (HDL-C). CQI scores were stratified into 4 groups ranging from lowest quality to highest quality. The researchers used logistic regression to examine the association between these 4 groups and metabolic syndrome.

The study included 2316 men (mean age, 50.9 years; SD, 3.9), of whom 49.4% had dyslipidemia, 38.7% had hypertension, and 5.8% had diabetes. The participants had an average BMI of 27.9 kg/m² (SD, 3.5) and CQI scores of 4 to 6 points (n=334), 7 to 9 points (n=1039), 10 to 12 points (n=745), and 13 to 15 points (n=198).

Compared with participants with lower CQI scores, those with higher CQI scores consumed fewer carbohydrates, trans-saturated fatty acids, liquid carbohydrates, and total grains and consumed more protein, whole grains, dietary fiber, and alcohol.

The overall prevalence of metabolic syndrome was 27.5%, with rates of 27.5% and 23.7% in the lowest and highest CQI cohorts, respectively.

Metabolic syndrome risk was lowest among the highest (adjusted odds ratio [aOR], 0.52; 95% CI, 0.30-0.88; P <.001) and second highest (aOR, 0.64; 95% CI, 0.45-0.94; P <.001) CQI cohorts compared with the lowest CQI cohort.

Risk for hypertriglyceridemia was also lower among participants in the highest (OR, 0.48; 95% CI, 0.32-0.71; P <.001) and second highest (OR, 0.61; 95% CI, 0.46-0.81; P <.001) CQI cohorts compared with the lowest CQI cohort. 

Study limitations include a lack of generalizability, as the sample was restricted to working men at the same car assembly plant.

The research concluded, “Our results suggest that there is a protective association between the consumption of high-quality carbohydrates and the presence of [metabolic syndrome] and hypertriglyceridemia among middle-aged men free of [cardiovascular disease].”