Metabolic Effects of Monounsaturated Fatty Acid–Enriched Diets Compared With Carbohydrate or Polyunsaturated Fatty Acid–Enriched Diets in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

OBJECTIVEDietary interventions in patients with type 2 diabetes (T2D) are important for preventing long-term complications. Although a healthy diet is crucial, there is still uncertainty about the optimal macronutrient composition. We performed a meta-analysis comparing diets high in cis-monounsaturated fatty acids (MUFA) to diets high in carbohydrates (CHO) or in polyunsaturated fatty acids (PUFA) on metabolic risk factors in patients with T2D.RESEARCH DESIGN AND METHODSWe systematically reviewed PubMed, MEDLINE, and Cochrane databases and prior systematic reviews and meta-analyses to identify interventions assessing HbA1c, fasting plasma glucose and insulin, LDL and HDL cholesterol, triglycerides, body weight, or systolic/diastolic blood pressure. Meta-analyses were conducted using both fixed- and random-effects models to calculate the weighted mean difference (WMD) and 95% CI.RESULTSWe identified 24 studies totaling 1,460 participants comparing high-MUFA to high-CHO diets and 4 studies totaling 44 participants comparing high-MUFA to high-PUFA diets. When comparing high-MUFA to high-CHO diets, there were significant reductions in fasting plasma glucose (WMD −0.57 mmol/L [95% CI −0.76, −0.39]), triglycerides (−0.31 mmol/L [−0.44, −0.18]), body weight (−1.56 kg [−2.89, −0.23]), and systolic blood pressure (−2.31 mmHg [−4.13, −0.49]) along with significant increases in HDL cholesterol (0.06 mmol/L [0.02, 0.10]). When high-MUFA diets were compared with high-PUFA diets, there was a significant reduction in fasting plasma glucose (−0.87 mmol/L [−1.67, −0.07]). All of the outcomes had low to medium levels of heterogeneity, ranging from 0.0 to 69.5% for diastolic blood pressure (Phet = 0.011).CONCLUSIONSOur meta-analysis provides evidence that consuming diets high in MUFA can improve metabolic risk factors among patients with T2D.

Comment on Qian et al. Metabolic Effects of Monounsaturated Fatty Acid–Enriched Diets Compared With Carbohydrate or Polyunsaturated Fatty Acid–Enriched Diets in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Diabetes Care 2016;39:1448–1457

“…In patients with abnormal glucose metabolism and T2D, higher intakes of MUFA were associated with lower triacylglycerol and higher HDL cholesterol levels, as well as improvements in glycemic control parameters such as fasting plasma glucose and glycosylated hemoglobin, quite similar to the findings of Qian et al (1). A very important statement made by the authors is that evidence from observational studies substituting MUFA for carbohydrates and saturated fatty acids yielded inconsistent results, most likely due to the fact that in the Western diet, MUFA intake is largely based on foods from animal origin (such as meat) rather than edible plants.…”

“…We strongly agree with the conclusions made by Qian et al (1): replacement of carbohydrates by MUFA represents a useful dietary tool to improve metabolic risk factors. However, future studies should focus on the topic of whether the origin of MUFA in the diet is crucial for fostering their beneficial effects.…”

“…We read with great interest the metaanalysis by Qian et al (1). The authors showed consistent evidence that replacing carbohydrates with monounsaturated fatty acids (MUFA) has beneficial effects on metabolic risk factors in patients with type 2 diabetes (T2D) and concluded that these findings have broad implications for dietary recommendations for this population.…”

An evidence‐based approach to developing low‐carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods

“…For example, fat in whole eggs and beef rump is 43% and 45% monounsaturated and 36% and 45% saturated, respectively . The cardio‐protective effects of high monounsaturated fat intakes in T2D are well known, yet greater primary research investigating the necessity to reduce saturated fat intake in the context of a low‐CHO diet for T2D is required. The recommendation to include fat mostly from whole‐food sources may sufficiently achieve balanced proportions of unsaturated and saturated fats without concern for rigid prescriptions.…”

Comparison of the effect of Dietary Approaches to Stop Hypertension diet and American Diabetes Association nutrition guidelines on lipid profiles in patients with type 2 diabetes: A comparative clinical trial

“…In general, low consumption of SFA in diet is associated with a decrease in the LDL and HDL levels. Replacing SFA with carbohydrate in the diet may increase the TG level and decrease the HDL and LDL levels . Replacing SFA with monounsaturated fatty acids or PUFA in the diet can have an adverse effect on the HDL level.…”