Key Findings:
The metabolic syndrome (MetS) includes glucose intolerance, abdominal obesity, dyslipidemia, and hypertension and is associated with an increased risk of cardiovascular disease and diabetes. In this research, n6 and n3 PUFAs (ALA, EPA, DHA) intakes were studied regarding effects on MetS and its components in 19 to 84 year old subjects. EPA and DHA were associated with a lower risk of high serum triacylglycerol concentrations, regardless of the background intake of n6 PUFAs. ALA intake with high or low n6 PUFA intake decreased the risk of an enlarged waist circumference and the MetS. An intake of ALA of 1.2 g/d (median 1084 mg/d) was related to declines in coronary heart disease risk when the intake of n3 PUFA intake is low. An inhibitory effect of ALA on the conversion of linoleic acid to arachidonic acid leading to a suppression of the atherogenic activation of several families of compounds was hypothesized. The results showed that the ALA intake was inversely associated with the risk of MetS independent of the PUFA intake.
ABSTRACT:
Objective: To investigate the association of the intakes of n3 (including alpha linolenic acid [ALA], eicosapentaenoic acid [EPA] plus docosahexaenoic acid [DHA]) and n6 polyunsaturated fatty acids (PUFAs), the interaction, and the ratio of these PUFAs with the metabolic syndrome (MetS) in adults. Methods: This cross-sectional study was conducted in a random sample of participants (n of 2451 and 19 to 84 y old) in the Tehran Lipid Glucose Study. Dietary intake was assessed using a validated semi-quantitative food-frequency questionnaire. Anthropometric characteristics, blood pressure, and fasting plasma concentrations of glucose and lipids were measured. The MetS was defined according to the Adult Treatment Panel III guidelines. Results: Among the PUFAs, the ALA and n6 PUFA intakes were inversely associated with the MetS. Subjects in the highest quartile of ALA and n6 fatty acid intakes had a 38% (odds ratio 0.62, 95% confidence interval 0.41–0.95) and a 0.47% (odds ratio 0.53, 95% confidence interval 0.31–0.89) lower prevalence of MetS, respectively, compared with those in the lowest quartile. The dietary ratio of n6 to n3 fatty acids was not associated with the MetS. When the interaction between ALA and n6 fatty acid was assessed, the ALA intake was associated with a lower prevalence of the MetS, without modification by the n6 PUFA intake. Subjects with at least the median ALA intake (1084 mg/d) had a lower prevalence of the MetS, irrespective of an n6 PUFA intake lower or higher than the median compared with subjects with intakes below the median for both. Conclusion: The ALA intake was inversely associated with the MetS, irrespective of the background intake of n6 PUFAs, in adults. (Authors abstract)
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