Study reports a decrease in Mediterranean diet adherence during the COVID-19 pandemic

By Pooja Toshniwal PahariaReviewed by Lily Ramsey, LLMApr 14 2023

In a recent study published in the Nutrients Journal, researchers evaluated changes in individual determinants of adherence to the Mediterranean diet (MedDiet) over time.

Study: Adherence to Mediterranean Diet: A Population-Based Longitudinal Cohort Study. Image Credit: MarianWeyo/Shutterstock.com

Background

The conventional MedDiet comprises a minimal intake of processed foods, increased consumption of plant-based foods (vegetables, fruits, nuts, and legumes), and low-moderate consumption of animal-origin food items, with a preference for poultry and fish over other items.

Further, MedDiet limits the intake of simple sugars and favors olive oil intake to obtain fats from the diet.

MedDiets are advised to prevent degenerative and/or chronic diseases, including cardiovascular diseases, metabolic syndrome (MetS), cancer, and cognitive impairments.

Studies have reported that the diet effectively manages and mitigates risk factors for non-communicable diseases. However, a progressive shift has been observed toward Westernized diets among individuals.

About the study

In the present study, researchers assessed changes in MedDiet abidance, concerning individual constituent intake, among free-living individuals residing in urban regions of Milan, Italy.

The team obtained clinical data and MedDiet adherence scores (MEDAS) for 711 individuals (mean age 68.0 years, 42.0% males) who participated in the Progression of Intimal Atherosclerotic Lesions in Carotid Arteries (PLIC) study during two visits conducted five years apart.

The change in MEDAS score between the two visits (∆MEDAS) was calculated. Variations in the percentage of individuals meeting the MEDAS criteria were also assessed, and the results were stratified by age, sex, and ∆MEDAS.

Among PLIC study participants, only individuals undergoing visit five (between 2017 and 2018, baseline visit for the present study), in which the MEDAS was introduced, and visit six (between 2021 and 2022, follow-up visit for the present study).

The participants completed 14.0-item questionnaires to assess MedDiet abidance, developed in the PREDIMED study that evaluated the protective effects of following MedDiet against myocardial infarction among Spanish individuals. MEDAS scores ≥8.0 were considered optimal abidance.

PLIC participants were enrolled between 1998 and 2000, and follow-up assessments were performed over 20.0 years. At follow-up, participants provided data on clinical characteristics, familial and personal medical history, lifestyle, medications, and serum samples for glycemic and lipid profile assessments.

MetS prevalence was ascertained based on serum triglyceride levels, blood pressure, fasting blood glucose, high-density lipoprotein-cholesterol (HDL-C) levels, and waist circumference.

Results

Among the study participants, 34.0% improved their MEDAS scores (∆MEDAS, +1.9) by increasing the intake of fish, legumes, and olive oil and using sofrito-seasoned dishes.

On the contrary, 48.0% of the participants worsened their scores (∆MEDAS, −2.0) by reducing their intake of legumes, fruits, nuts, and fish. The rates of MEDAS score worsening were greater among females and individuals aged 50.0 to 65.0 years.

Individuals showing improved scores had MetS, greater body mass index (BMI) values, and greater blood glucose values at baseline than those whose scores worsened.

The findings indicated that the increasing abidance to MedDiet might be secondary to identifying a compromised metabolic condition, which lifestyle modifications could improve.

Only three items showed percent elevation: Q14 (sofrito-seasoned dishes ≥2.0 times weekly, +48.0%), Q11 (≤2.0 portions of commercially available pastries or sweets, +19.0%), and Q6 (≤1.0 serving of cream, margarine, or butter, daily, +3.0%).

The variations showed no significant differences by age or sex. Items showing higher percent reductions were Q4 (≥3.0 portions of fruits daily, −86.0%) and Q2 [≥4.0 tablespoons (tbsp) olive oil daily, −82.0%]. For Q4, there were no significant age- or sex-based variations.

For Q2, differences were observed in percent variation by sex (−60.0% and -37.0% among women and men, respectively), and age (−60.0% in individuals aged 65.0 to 80.0 years, −29.0% in those aged 51.0 to 65.0 years, and −20.0% in those aged ≤50.0 or above 80.0 years).

In addition, for Q12 (≥3.0 portions of nuts weekly, differences by sex (−45.0% and -24.0% among women and men, respectively) and age (+17.0% in individuals aged ≤50.0 years versus −40.0% to −44.0% for other ages) were observed.

Additionally, concerning Q13 (preferred intake of rabbit, turkey, or chicken rather than sausage, hamburger, pork, or veal), differences of −8.0% among individuals aged ≤50.0 years versus +3.0% to +10% across other ages were observed.

Foods with the highest variations among individuals with MEDAS score improvements were olive oil (Q2, +66.0%), legumes (Q9, +59.0%), fish (Q10, +55.0%), and the usage of sofrito-seasoned dishes (Q14, +177.0%). Among individuals with elevated MEDAS scores, the intake of all foods improved except fruits (Q4, −41.0%).

Items showing greater variations in those with worsened MEDAS scores were fruits (Q4, −86.0%), olive oil (Q2, −78.0%), legumes (Q9, −77.0%), fish (Q10, -75.0%), and nuts (Q12, -65.0%). In this subgroup, the scores for all foods worsened, except commercially available pastries and sweets (Q11, +21.0%) and sofrito-seasoned dishes (Q14, +44.0%).

Conclusions

Overall, the study findings showed a reduction in MedDiet adherence, largely due to reduced intake of olive oil and fruits, with sex- and age-base variations, evaluated during a period extensively impacted by the social restrictions and lockdowns enforced due to the SARS-CoV-2 pandemic.

The financial crisis in Europe may have also affected dietary intake, with increased prices of MedDiet foods, including fruits, compared to the more economically priced sweets, snacks, and refined grains.  

The findings highlight the need for better and tailored nutritional interventions targeting the consumption of particular food items.

However, further research, including other probable determinants of diet quality, with a more representative sample population is required to increase the generalizability of the study findings.