[Association between the metabolic syndrome and free fatty acid]

To explore the association of free fatty acid (FFA) with the metabolic syndrome (MS) and its components.

A cross-sectional study on cardiovascular risk factors was carried out in a natural population of Beijing in 1999, recruited by a stratified-random sampling method. The association of FFA with MS and its components was analyzed in a sample of 997 subjects aged 35-64 years.

(1) The prevalence of MS increased with FFA level. (2) After adjustment for age, sex, smoking, alcohol consumption, body mass index (BMI) and insulin resistance index using a multi-variable logistic regression, FFA was significantly associated with MS. The odds ratio (OR) for the second, third, and fourth quartiles of FFA was 3.1, 3.1 and 4.1, respectively (all P < 0.001). (3) FFA correlated significantly with triglycerides (TG), glucose, systolic blood pressure, diastolic blood pressure, and waist circumference in the correlation analysis (all P < 0.001). The strongest correlation was found between FFA and TG, but no significant correlation was found between FFA and high-density lipoprotein cholesterol (HDL-C). (4) After adjustment for other factors in the logistic regression, FFA was significantly associated with central obesity, hypertriglyceridemia, hypertension, and hyperglycemia, but not with low HDL-C. (5) After adjustment for FFA, BMI and other factors, insulin resistance was also associated with central obesity, hypertriglyceridemia, low HDL-C, and hyperglycemia, but not hypertension.

FFA was associated with MS and four of the five components of MS, i.e. central obesity, hypertriglyceridemia, hypertension, and hyperglycemia. It is suggested that FFA be one of the underlying pathogenic factors or risk factors for MS. FFA and insulin resistance may lead to MS through different but synergistic mechanisms.