Dietary Intake of Linoleic Acid, Its Concentrations, and the Risk of Type 2 Diabetes: A Systematic Review and Dose-Response Meta-analysis of Prospective Cohort Studies.

Background: Earlier evidence on the association between dietary polyunsaturated fatty acids and risk of diabetes has been conflicting.

Purpose: To quantitatively summarize previous studies on the association between dietary LA intake, its biomarkers, and the risk of type 2 diabetes mellitus (T2DM) in the general population.

Data Sources: Our data sources included PubMed/MEDLINE, Scopus, and ISI Web of Science until 24 October 2020; reference lists of all related articles; and key journals.

Study Selection: We included prospective cohort studies that examined the associations of linoleic acid (LA) with the risk of T2DM in adults.

Data Synthesis: The inverse variance method was applied to calculate summary relative risk (RR) of LA intake and its biomarkers, and dose-response associations were modeled using restricted cubic splines. Twenty-three publications, covering a total of 31 prospective cohorts, were included; these studies included 297,685 participants (22,639 incident diabetes cases) with dietary intake assessment and 84,171 participants (18,458 incident diabetes cases) with biomarker measurements. High intake of LA was associated with a 6% lower risk of T2DM (summary relative risk [RR] 0.94, 95% CI 0.90, 0.99; = 48.5%). In the dose-response analysis, each 5% increment in energy from LA intake was associated with a 10% lower risk of T2DM. There was also evidence of a linear association between LA intake and diabetes, with the lowest risk at highest intakes. The summary RR for diabetes per SD increment in LA concentrations in adipose tissue/blood compartments was 0.85 (95% CI 0.80, 0.90; = 66.2%). The certainty of the evidence was assessed as moderate.

Limitations: A limitation of our work was the observational design of studies included in the analyses.

Conclusions: We found that a high intake of dietary LA and elevated concentrations of LA in the body were both significantly associated with a lower risk of T2DM. These findings support dietary recommendations to consume dietary LA.