Fish Oil, Monounsaturated Fats May Be Helpful in Metabolic Syndrome

Laurie Barclay, MD

August 26, 2010

August 26, 2010 — Postprandial lipoprotein abnormalities associated with metabolic syndrome can be attenuated with a low-fat, high-complex carbohydrate (LFHCC) diet supplemented with intake of long-chain (n-3) fatty acids, according to the results of a multicenter, parallel, randomized controlled trial reported in the September issue of the Journal of Nutrition.

"Dietary fat intake plays a critical role in the development of metabolic syndrome (MetS)," write Yolanda Jiménez-Gómez, from University of Córdoba in Córdoba, Spain, and colleagues. "This study addressed the hypothesis that dietary fat quantity and quality may differentially modulate postprandial lipoprotein metabolism in MetS patients."

As part of the LIPGENE study, patients with metabolic syndrome were randomly assigned to 1 of 4 diets for 12 weeks each: (1) a high-saturated fatty acid diet (38% energy from fat, 16% energy as saturated fatty acid); (2) a high-monounsaturated fatty acid (MUFA) diet (38% energy from fat, 20% energy as MUFA); (3) an LFHCC diet (28% energy from fat) supplemented with 1.24 g/day of long-chain (n-3) polyunsaturated fatty acids (ratio, 1.4 eicosapentaenoic acid:1 docosahexaenoic acid); or (4) an LFHCC diet with a placebo supplement (1.24 g/day of high-oleic sunflower-seed oil).

Before and after the dietary intervention, patients underwent a fat challenge with the same fat composition as the diets, as well as determination of postprandial total cholesterol, triglycerides (TG), apolipoprotein B, apolipoprotein B-48, apolipoprotein A-I, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, retinyl palmitate, and apolipoprotein B in TG-rich lipoproteins (TRL; large and small).

Compared with the high-saturated fatty acid group and the LFHCC group, the high MUFA group had earlier and faster postintervention clearance of postprandial TG (P < .001) and large TRL-TG (P = .009). Compared with the other diet groups, the LFHCC (n-3) group had a lower postprandial TG concentration (P < .001).

Compared with preintervention values, participants following the LFHCC diet had increase in postintervention postprandial area under the curve for TG (P = .04), large TRL-TG (P = .01), TRL cholesterol (P < .001), TRL-retinyl palmitate (P = .001), and TRL-apolipoprotein B (P = .002). In contrast, however, participants following the LFHCC (n-3) diet long term did not have augmented postprandial TG and TRL metabolism.

"[P]ostprandial abnormalities associated with MetS can be attenuated with LFHCC (n-3) and HMUFA diets," the study authors write. "The adverse postprandial TG-raising effects of long-term LFHCC diets may be avoided by concomitant LC (n-3) PUFA [polyunsaturated fatty acid] supplementation to weight-stable MetS patients."

Limitations of this study include difficulty in ensuring complete adherence to dietary instructions, mild adverse effects associated with consumption of long-chain (n-3) polyunsaturated fatty acid capsules in some patients with metabolic syndrome, use of long-chain (n-3) polyunsaturated fatty acid capsules instead of increased fish consumption, and duration limited to 12 weeks.

"Our data suggest that long-term intake of an isocaloric, low-fat, high-carbohydrate diet supplemented with LC [long-chain] (n-3) PUFA and MUFA-rich diets have beneficial effects on postprandial lipoprotein response in patients with MetS," the study authors conclude. "On the other hand, the addition of LC (n-3) PUFA to a LFHCC diet may normalize the adverse postprandial lipoprotein effects produced by this diet. Importantly, both diets were effective exclusive of weight loss, which is highly pertinent given the pandemic of obesity-induced MetS that will occur in Europe and North America over the next 20–30 y due to excessive weight gain."

This study was supported in part by FEDER, Fondo Social Europeo, the EU Sixth Framework Food Safety & Quality Programme, Consejería de Salud, Consejería de Innovación, Proyecto de investigación de excelencia, Junta de Andalucía, the Spanish Ministry of Education and Science, and the Spanish Ministry of Science and Innovation (CIBER Fisiopatología de la Obesidad y Nutrición is an initiative of ISCIII). Intervention Foods were supplied by Unilever Best Foods. The study authors have disclosed no relevant financial relationships.

J Nutrition. 2010;140:1595-1601. Abstract

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