Monounsaturated Fatty Acids and Risk of Cardiovascular Disease: Synopsis of the Evidence Available from Systematic Reviews and Meta-Analyses

Abstract

No dietary recommendations for monounsaturated fatty acids (MUFA) are given by the National Institute of Medicine, the United States Department of Agriculture, European Food and Safety Authority and the American Diabetes Association. In contrast, the Academy of Nutrition and Dietetics, and the Canadian Dietetic Association both promote <25% MUFA of daily total energy consumption, while the American Heart Association sets a limit of 20% MUFA in their respective guidelines. The present review summarizes systematic reviews and meta-analyses of randomized controlled trials and cohort studies investigating the effects of MUFA on cardiovascular and diabetic risk factors, cardiovascular events and cardiovascular death. Electronic database Medline was searched for systematic reviews and meta-analyses using “monounsaturated fatty acids”, “monounsaturated fat”, and “dietary fat” as search terms with no restriction to calendar date or language. Reference lists and clinical guidelines were searched as well. Sixteen relevant papers were identified. Several studies indicated an increase of HDL-cholesterol and a corresponding decrease in triacylglycerols following a MUFA-rich diet. The effects on total and LDL-cholesterol appeared not consistent, but no detrimental effects on blood lipids were observed. Values for systolic and diastolic blood pressure were found to be reduced both during short- and long-term protocols using high amounts of MUFA as compared to low-MUFA diets. In type 2 diabetic subjects, MUFA exerted a hypoglycemic effect and reduced glycosylated hemoglobin in the long term. Data from meta-analyses exploring evidence from long-term prospective cohort studies provide ambiguous results with respect to the effects of MUFA on risk of coronary heart disease (CHD). One meta-analysis reported an increase in CHD events, however, most meta-analyses observed a lesser number of cases in participants subjected to a high-MUFA protocol. Although no detrimental side effects of MUFA-rich diets were reported in the literature, there still is no unanimous rationale for MUFA recommendations in a therapeutic regimen. Additional long-term intervention studies are required to characterized efficacy and effectiveness of recommending MUFA-rich diet among general and clinical populations.

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

“…Recently, we summarized the evidence from systematic reviews and metaanalyses regarding the effects of MUFA on cardiometabolic risk (2). 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).…”

Avocado and Cardiovascular Health

“…For weight management and prevention of cardiovascular disease, international dietary recommendations regarding MUFA ingestion vary from 12% to 25% of total daily calories [37].…”

Dietary Fatty Acids and Cardiovascular Disease: A review

“…Two additional meta-analyses of randomized clinical trials and cohort studies also reported the beneficial effects of MUFA-rich diets on the reduction of CVD, although these findings were not conclusive 37,38 .…”