Adherence to a Mediterranean Diet (MedDiet) for 6 months improves dietary quality and dietary inflammatory index in a western population: results from the Mediterranean diet for cognition and cardiovascular health in the elderly (MedLey) study
Authors: Murphy Karen J , Dyer Kathryn A , Davis Courtney R , Woodman Richard , Shivappa Nitin , Hebert James , Hodgson Jonathan M 
Published: November 2023

Inflammation is thought to be an underlying pathophysiological cause of a range of chronic diseases including cardiovascular disease (CVD). Diet is a modifiable risk factor for CVD and can influence the inflammatory process depending on the quality of the diet. Western diets, typically characterised by processed foods, red and processed meats, refined carbohydrates and added sugars, have been shown to be positively associated with inflammatory markers, while a Mediterranean diet, rich in plant foods and low in processed foods, has been shown to have a contrasting effect. The dietary inflammatory index (DII) was developed to determine the inflammatory potential of a dietary pattern. Positive DII scores indicate a pro‐inflammatory diet and negative scores indicate an anti‐inflammatory diet. This opportunistic study sought to evaluate the change in dietary quality and dietary inflammatory index following the administration of a traditional MedDiet in older Australian adults.

152 Australian men and women (mean age 71±5yrs) were recruited for the MedLey study. Participants were randomly allocated either a MedDiet (n=80) or continue their habitual diet (HabDiet) (n=72) for 6 months. Volunteers followed a prescribed MedDiet plan under dietetic supervision. All volunteers attended the clinic on a fortnightly basis to have their weight measured, discuss the intervention and receive study foods. Dietary intake was calculated using 3‐day weighed food records. Data was analysed using linear regression.

137 volunteers completed the trial (MedDiet n=70, HabDiet n=67). Our volunteers were able to comply with the MedDiet throughout the intervention (92% compliance rate) according to daily monitoring of food intake. At baseline, 14% of the population were meeting recommended intakes for vegetables and 54.9% for fruits, and 5.1% for dairy foods.. With administration of a traditional MedDiet, the MedDiet group increased their mean daily intake of vegetables (+60g), fruit (+123g), dairy (+98g), fish (+42g), nuts (+33g), legumes (29g,) and decreased their intake of meat (−21g) and discretionary foods (−168g). The HabDiet achieved only minor changes at 4 months, although decreased their intake of discretionary foods 95g but in contrast also decreased their mean daily intake of dairy foods (−19g) and fish (−12g). The baseline DII was −0.10±1.71 (mean±SD) for our Australian population (n=152). For the MedDiet group the DII score was −1.40±0.20 and −1.47±0.20 at 2 and 4 months of the intervention, respectively, whilst the HabDiet DII score did not change significantly (0.47±0.21 at 2 months and 0.54±0.21 at 4 months).

This dietary pattern was sustainable to follow for 6 months as evident by the high compliance rate and facilitated improves in the quality of the diet by increases plant based foods and decreases in discretionary food. This resulted in changes in the DII promoting a low inflammatory diet which could be beneficial for healthy ageing and the avoidance of chronic disease.

Support or Funding Information

This project was supported by a grant from the National Health Medical Research Council of Australia.