Impact of the Mediterranean Dietary pattern on n-3 fatty acid tissue levels-A systematic review

Introduction: The Mediterranean Diet (MedDiet) is described as a plant-based dietary pattern with adherence associated with reductions in chronic disease risk and longevity. Although the nutrient profile is diverse and complex, the MedDiet is often described as a rich source of n-3 polyunsaturated fatty acids (PUFA) derived from fish, seafood and nuts. However, whether MedDiet adherence results in appreciable increases in tissue levels of n3 PUFAs is yet to be systematically investigated. This systematic review synthesized the literature to determine the impact of the MedDiet on n-3 PUFA tissue levels. Materials and methods: Medline, Embase, Amed, and CINAHL databases were searched for studies reporting on adherence to a MedDiet and tissue levels of n-3 PUFAs. PROSPERO registration number is CRD 42020162114. Results: Twenty-two studies were included. Seven were observational studies and 15 were randomised controlled trials (RCTs). All observational studies reported a positive relationship between adherence and higher tissue n-3 PUFA levels. Two-thirds (10/15) of RCTs reported significant increases in n-3 PUFA concentrations. Discussion: MedDiet adherence is associated with higher tissue levels of n-3 PUFA. However, we report heterogeneity in the description across all MedDiet interventions.