Comparison of blood lipid responses to high polyunsaturated fatty acid compared with high monounsaturated fatty acid dietary interventions: a systematic review and meta-analysis.

BACKGROUND

Blood lipid concentrations are standard clinical biomarkers of cardiovascular disease risk. Replacing dietary saturated fat with unsaturated fat is expected to lower blood lipids. However, meta-analyses are lacking regarding quantifiable differences in blood lipid response between comparable diets rich in mono-(MUFA) and polyunsaturated fat (PUFA), considering food sources and dose-response.

OBJECTIVES

The objective was to compare the effects of "high PUFA" compared with "high MUFA" diets on fasting blood lipids.

METHODS

PubMed and Web of Science were searched through February 2025 for randomized clinical trials comparing "high PUFA" (≥10% of energy intake from PUFAs) and "high MUFA" (≥15% of energy intake from MUFAs) diets in adults. Reviewers extracted fasting total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (TG). Eligible studies were pooled using random-effects models and expressed as mean differences with 95% confidence interval.

RESULTS

Fifty-three records were included, representing 1690 adult participants. "High PUFA" diets reduced TC [-5.71 (-8.02, -3.40) mg/dL], LDL cholesterol [-3.31 (-5.39, -1.24) mg/dL], HDL cholesterol [-0.77 (-1.27, -0.26) mg/dL], and TG [-6.59 (-8.77, -4.42) mg/dL] compared with "high MUFA" diets. Subgroup analyses showed that the effects of LDL cholesterol (P = 0.03), and TG (P = 0.03) were stronger with oil compared with nut or diet interventions. Metaregressions revealed that the benefit of consuming a "high PUFA" compared with a "high MUFA" diet increases with total fat intake, with a ∼0.5 mg/dL greater reduction in TC (P = 0.01) and LDL cholesterol (P = 0.01) for every 1% increase in energy intake from fat. Cochrane Risk of Bias tool identified some concerns in most of the included records.

CONCLUSIONS

High PUFA diets have a small, but significant, advantage for lowering blood lipids compared with high MUFA diets and may be a valuable strategy for improving blood lipids in some populations. This trial was registered at PROSPERO as CRD42023474301 (https://www.crd.york.ac.uk/PROSPERO/view/CRD42023474301).