Mediterranean Diet Intervention Associated with Reduced Inflammation in Older Adults

by | Mar 3, 2023 | 2023, Aging, Mediterranean Diet

Written by Taylor Woosley, Staff Writer. 6-month Mediterranean dietary intervention resulted in a lower dietary inflammatory index and improved anti-inflammatory activity compared to the habitual diet group. 

Mediterranean DietSystemic chronic inflammation refers to persistent, low-grade inflammation, and it is involved in the pathogenesis of a wide variety of chronic non-communicable diseases that collectively constitute the leading cause of death globally1.  Inflammation is a normal biological defense against infection and tissue damage, but when it is chronic it may lead to an increased risk of diabetes, metabolic syndrome, cardiovascular disease, and autoimmune diseases2. Low level elevation of proinflammatory cytokines and chemokines, a process also defined as “inflammaging” specifically contributes to age-related decline in function and increases risk of mortality3.

The Mediterranean diet is considered one of the healthiest dietary patterns worldwide thanks to a combination of foods rich mainly in antioxidants and anti-inflammatory nutrients4. The MedDiet is a food pattern which includes high consumption of fruits, vegetables, legumes, olive oil, and moderate intake of fish and meat5. The diet is naturally high in polyphenols, which possess anti-inflammatory properties and reduces oxidative stress6.

Clark et al. conducted a study to determine the effect of a 6-month MedDiet intervention on dietary inflammatory index (DII) and energy-adjusted DII, while also analyzing secondary exploration of the relationship between the DII and cardiovascular risk factors. Data used in the study was from the MedLey study, a dietitian-led, randomized, controlled, parallel dietary intervention trial comparing the effect of the MedDiet with a habitual diet on cognitive and cardiometabolic health outcomes in a healthy elderly population. Subjects (n=152) consisted of healthy Australian men and women aged 65 years and older who were randomly assigned to either a MedDiet or a habitual diet (HabDiet, control) for 6 months. 137 subjects completed the study (MedDiet, n =74, HabDiet, n=63).

Outcome measures included anthropometry (BMI, weight, abdominal adiposity, endothelial function, inflammatory biomarkers, lipids, blood pressure, glucose, insulin, F2-isoprostanes (F2-IsoP), dietary compliance, and cognitive performance. Measurements were collected at baseline, month 3 and month 6 of the intervention. Dietary intake was assessed using a 3-day weighed food record (WFR) and a food frequency questionnaire (FFQ) at baseline and during each intervention phase at 2 months and 4 months. DII and E-DII scores were calculated using the WFR data of participants to estimate the inflammatory potential of an overall food pattern.

Independent t-tests were utilized to compare baseline data from the MedDiet and HabDiet, and the effects of diet over time were assessed with linear mixed effects models, between groups and within groups, with a group x time interaction term to determine overall differences in effects across time and at each time point. Baseline data were analyzed to determine relationships between DII and body composition, cardiometabolic health, and vascular health. DII was divided into tertiles to establish low, medium, and high inflammatory dietary patterns.

On average, participants were 71 ± 5 years, with a BMI of 26.9 ± 3.9 kg/m2. There was no significant difference in the DII score between the MedDiet and HabDiet groups at baseline (p = 0.159). Significant findings of the study are as follows:

  • At 2 and 4 months of dietary intervention, the MedDiet group had significantly changed to a more anti-inflammatory diet with a reduction in DII score from -0.20 ±84 at baseline to -1.49 ± 183 at 4 months. Compared with HabDiet, the MedDiet resulted in a significant reduction in DII score over 4 months (p < 0.001).
  • Compared to the control, the MedDiet resulted in a significant reduction in F2-IsoP, triglycerides, and systolic blood pressure at 3 months and 6 months. Furthermore, the MedDiet improved endothelial function at 6 months, as measured by flow mediated dilatation (FMD), compared with the HabDiet group.
  • A significant difference was noted in average baseline BMI between both the lowest and middle DII tertiles and the highest tertiles (p = 0.001 and p = 0.025, respectively), where subjects with a more pro-inflammatory DII had higher BMI.
  • In the most anti-inflammatory tertile, the average HDL-C was 1.78 ±06 mmol/L, which was significantly higher (p = 0.02, p = 0.04, respectively) than the middle tertile (1.55 ± 0.06 mmol/L) and the most pro-inflammatory tertile (1.57 ± 0.06 mmol/L).

Results of the study show that 6-month dietary intervention using the Mediterranean diet led to improved DII/E-DII scores compared to the HabDiet group. Additionally, higher anti-inflammatory activity was observed in the MedDiet group. Study limitations include the small study sample and short study length, along with measuring only one inflammatory biomarker.

Source: Clark, Jessie S., Kathryn A. Dyer, Courtney R. Davis, Nitin Shivappa, James R. Hébert, Richard Woodman, Jonathan M. Hodgson, and Karen J. Murphy. “Adherence to a Mediterranean Diet for 6 Months Improves the Dietary Inflammatory Index in a Western Population: Results from the MedLey Study.” Nutrients 15, no. 2 (2023): 366.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted March 3, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

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