Poly is more effective than monounsaturated fat for dietary management in the metabolic syndrome: The muffin study

Abstract

Background The Metabolic Syndrome (MetS) is highly prevalent and associated with an increased risk for Type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Lifestyle recommendations to treat MetS often include the replacement of saturated fats (SFA) and monosacharides with unsaturated fat. However, it is unclear whether metabolic parameters will improve more when the saturated fat in American Heart Association (AHA) diets is replaced with higher concentrations of mono or poly-unsaturated fatty acids (MUFA, PUFA). Objective To test the hypothesis that an AHA diet enriched in MUFA improves lipoprotein lipids, insulin resistance, inflammation and endothelial function to a greater extent than a diet enriched in PUFA in middle-aged men and women with MetS. Methods A prospective, open-label, parallel group design with randomization to a hypocaloric MUFA or PUFA enriched diet following weight stabilization on an AHA Step I diet. Participants consumed 3 MUFA or PUFA enriched muffins daily with additional supplementation as required to ensure 25-50% increases in dietary fat intake from these sources at the expense of SFA and the opposing unsaturated fat. Changes in MetS components were measured at baseline and after 6 months of dietary intervention. Results Thirty-nine participants (mean age 60.8 years, 79% African-American, 60% women) with MetS completed the 6-month study. Compared to baseline, assignment to either MUFA (n=23) or PUFA (n=16) both were associated with weight loss (WL) (MUFA: −2.3±1 kg, P=0.06; PUFA: −4.6±2 kg; P=0.002), but PUFA was also associated with reductions in triglycerides (TG) (−30±18 mg/dL, P=0.02), systolic blood pressure (BP) (−7±3 mmHg, P=0.01), diastolic BP (DBP) (−4±2 mmHg, P=0.01) and improved flow mediated dilation (FMD) (7.1±1.8% vs. 13.6±2%, absolute increase; P=0.0001). When compared to MUFA treatment, PUFA intervention was associated with reduced TG (P=0.04) and DBP (P=0.07) as well as increased FMD (P=0.04) even after adjustment for changes in weight. There was no effect on total cholesterol, low-density lipoprotein cholesterol (LDL-C), glucose, high-sensitivity C-reactive protein (hs-CRP) or other inflammatory proteins. Overall, 25% (4 of 16) assigned to PUFA and 13% (3 of 23) to MUFA converted to non-MetS status. Conclusion Substitution of SFA with PUFA in patients with MetS is associated with greater reductions in TG and improvement in endothelial function than MUFA that is independent of WL. These preliminary findings raise the possibility that PUFA may be the unsaturated fat of choice to reduce cardiometabolic risk in patients with MetS.

Comparison of the Effects of Brazil Nut Oil and Soybean Oil on the Cardiometabolic Parameters of Patients with Metabolic Syndrome: A Randomized Trial

“…Supplementation of the two types of oils (SO and BNO) did not significantly change the glucose levels, which is consistent with previous studies [42,58,59].…”

“…Similar results were found in other studies with approximate intervention periods [37,38]. Longer intervention periods are needed in order to determine whether this supplementation could have a more significant impact on these parameters [39][40][41][42].…”

“…Although recommendations for the treatment of MS usually include the replacement of saturated fat and monosaccharide by unsaturated fats, it is not yet clear which metabolic parameters are improved when saturated fat is replaced by higher concentrations of MUFAs or PUFAs [42]. Some studies that replaced SFAs by UFAs also obtained inconsistent results in cardiometabolic risk factors [55,56].…”

Specific Macronutrients Exert Unique Influences on the Adipose-Liver Axis to Promote Hepatic Steatosis in Mice

“…These data add to the existing literature as many epidemiologic and interventional studies investigating the health effects of dietary fats have tended to focus on comparisons between CHOs and fats, or alternatively between saturated and polyunsaturated, rather than monounsaturated fats 26, 27. Studies that have concentrated specifically on monounsaturated fats have yielded mixed results 28, 29, 30. Our work directly evaluated the health outcomes induced by defined diets differing only in their permutation of CHOs and fats.…”

Fish oil diet may reduce inflammatory levels in the liver of middle-aged rats

“…However, substitution of SFAs with MUFAs would reduce inflammatory responses 6 , and a MUFA–enriched Mediterranean diet can reduce the incidence of metabolic syndromes 13 .…”