Assessment of Mediterranean diet adherence and comparison with Italian dietary guidelines: a study of over 10,000 adults from 2019 to 2022

Abstract Despite the many well-documented benefits of the Mediterranean diet (MD), many Mediterranean countries seem to be moving away from it. The aim of this study was to investigate the MD adherence in 10,916 adults who completed the validated Medi-Lite questionnaire from January 2019 to December 2022 in Italy, and to assess the consumption of its food groups by comparing them with current national dietary guidelines. The sample showed a good level of MD adherence (12 ± 2.5). However, from 2019 to 2022, a significant (p < 0.001) decline in the adherence level emerged. An overconsumption of fresh red meat, cheese and poultry compared to dietary guidelines was observed. In contrast, an under-consumption of vegetables, bread, legumes, fish and milk and dairy products emerged. In recent years, a decline in MD adherence was observed in Italy, probably determined by an excessive consumption of animal products.


Introduction
Among the various nutritional approaches aimed at promoting and maintaining good health, the Mediterranean diet (MD) has become increasingly important over the decades.Numerous evidences have associated MD with a lower risk of cardiovascular, metabolic, neoplastic, and neurodegenerative diseases due to its characteristics, such as the controlled amount of fat mainly represented by olive oil, the consumption of low-glycemic index whole grains and the high content of dietary fibre and antioxidant compounds (Schwingshackl et al. 2017;Dinu et al. 2018;Moore et al. 2018).
Despite the many well-documented benefits of this diet, more and more countries in the Mediterranean basin seem to be moving away from their traditional eating habits, including Italy.Recently, a significant decline in MD adherence was reported in Italy between the years 1985-1986 and 2005-2006, more evident among younger than older participants, and caused mainly by a reduction in olive oil consumption (Veronese et al. 2020).This decline continued in subsequent years, as other data from central and southern Italy, obtained on the large cohort of the Moli-sani study, also showed a significant reduction in adherence to the Mediterranean regimen from 2005 to 2010 (Bonaccio et al. 2014).
This phenomenon appears to vary according to certain socio-demographic variables (Bonaccio et al. 2012).Gender and age differences in MD adherence have been extensively studied.Several studies have associated the female gender with better adherence to MD than the male gender, mainly due to higher fruit and vegetable intake and lower meat consumption (Arvaniti et al. 2006;Lotti et al. 2022).Similarly, the elderly appears to have greater adherence to MD than the young, who are increasingly moving towards eating habits typical of the Western diet (Patino-Alonso et al. 2014).However, the results are still inconclusive: a recent systematic review, including a total of 50 studies observed no gender or age differences in MD adherence (Obeid et al. 2022).
The aim of this study is to define adherence to MD and consumption of its food groups in a large sample of adults from 2019 to 2022 in Italy, also considering differences in gender, age, and educational level.To specifically assess the adequacy of the food group intake, their consumption was compared with the actual Italian dietary guidelines.

Data collection
A retrospective evaluation of the data obtained from the accesses to the http://www.medi-lite.comwebsite by subjects who completed the web-based Medi-Lite questionnaire with the aim of evaluating the adherence to the MD from January 1 st , 2019, to 31 st December 2022, was conducted.The website was developed by NUME PLUS Srl (Florence, Italy), is freely available, and also include a section with brief questions on gender, age groups (18-30 years, 31-45 years, 46-60 years, 61-75 years, 76-90 years, 90 years or more), marital status (never married, married, widowed, domestic partner, divorced), and education level (elementary school, middle school, high school, university).For the analysis, only those who answered all questions and completed the entire questionnaire were considered.To identify potential duplicate submissions from the same user, the IP address of the client computer was used.In case of duplicates, the most recent submission was considered for analysis.Since all responses were provided anonymously and on a voluntary basis, ethics committee approval was not required.Results were reported according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES) statement (Eysenbach 2004).

The web-based Medi-Lite adherence score
The web-based version of the Medi-Lite score was developed in 2018 by NUME PLUS srl (Florence, Italy) and published online as a free version at http:// www.medi-lite.comafter applying the copyright of the University of Florence, Italy.Compared to the paper version, published in its original version in 2014 (Sofi et al. 2014), and validated in 2017 (Sofi et al. 2017), the web-based version has undergone some changes, as previously described (Dinu et al. 2021).In particular, the 9 items of the original score have been divided into 20 different questions assessing the consumption, in terms of daily and/or weekly amounts, of 9 food groups: fruits, vegetables, legumes, cereals, meat and meat products, fish, dairy products, alcohol, and olive oil.For typical products of the Mediterranean diet (fruit, vegetables, cereals, legumes, and fish), 2 points are assigned to the highest category of consumption, 1 point to the intermediate category, and 0 to the lowest category.On the other hand, foods that are not typical of the Mediterranean diet (meat and meat products, dairy products) are assigned 2 points for the lowest category of consumption, 1 point for the intermediate category, and 0 for the highest category.Finally, 2 points are awarded for regular use of olive oil, 1 for frequent use, and 0 for occasional use.Furthermore, respondents are asked to indicate their portion size by selecting one of three options.The options usually represent a small, a medium or a large portion (i.e. for legumes the portion options are 70 g, 140 g or 210 g).In order to improve the understanding of the questionnaire for the general population, a photographic database accompanies each food group.Once completed, the web-based questionnaire calculates the sum of the score assigned to each question and provides personalised guidance on how to improve the diet and increase adherence to the MD.The final score ranges from 0 (low adherence) to 18 (high adherence to the MD).

Statistical analysis
Statistical analysis was performed using the statistical package PASW 27.0 for Macintosh (SPSS Inc., Chicago, IL, USA).Continuous variables were presented as means ± standard deviations (SD), while categorical variables were reported as frequencies and percentages (%).The Mann-Whitney or Kruskal-Wallis was used for testing differences between groups for continuous variables, while the Chi-square test was used for categorical variables.For all tests, a p-value < 0.05 was considered statistically significant.Due to low participation of some age groups in the sample, participants' age was recategorized as 18-30 years, 31-60 years, and older than 61 years.Marital status was recategorized as unmarried/single and married/partner, and education level was recategorized as non-graduates (elementary/middle/high school) and graduates.The dietary intake of each food group component in the Medi-Lite questionnaire was estimated by multiplying the frequency of servings (daily or weekly, respectively) by the portion size and then compared with current Italian dietary recommendations (CREA.Centro di Ricerca Alimenti e la Nutrizione 2018).

Adherence to the Mediterranean diet
The sample reported a mean Medi-Lite score of 12 ± 2.5 suggesting a good level of MD adherence.Analysing the Medi-Lite score from the year 2019 to the year 2022 a significant (p < 0.001) decline in MD adherence was observed, reaching its highest value in the year 2020 (12.2 ± 2.5) and lowest in the year 2022 (11.9 ± 2.4) (Figure 1).
Analysis of the optimal responses (i.e. the choice that gave 2 points) to the individual food groups composing the Medi-Lite score showed that only about half of the study population reported optimal consumption of fruit (n = 5,377; 49.3%), vegetables (n = 5,794; 53.1%), and legumes (n = 5,612; 51.4%).On the other hand, a substantial percentage of subjects responded that they consume meat and meat products (n = 7,073; 64.8%), as well as milk and dairy products (n = 5,859; 53.7%) with high frequency.Interestingly, 27% of the sample (n = 2,895) declared that they did not regularly consume olive oil as main source of fats.

Food group consumption and comparison with dietary guidelines
To estimate the dietary intake of food groups of the Medi-Lite questionnaire, the frequency (daily or weekly, respectively) was multiplied by the portion size.Then, the calculated consumption of each food group was compared with the Italian dietary guidelines (CREA.Centro di Ricerca Alimenti e la Nutrizione 2018).As shown in Figure 2, the study population reported an overconsumption of fresh red meat (209.1 ± 194.9 g/week), cheese (276.6 ± 243.2 g/ week), and poultry (302.5 ± 221.3 g/week), as compared to the national dietary guidelines.On the other hand, a low consumption of vegetables (270.1 ± 209.1 g/day), bread (84.8 ± 87.8 g/day), legumes (233.3 ± 202.3 g/ week), fish (295.6 ± 227.1 g/week) and milk and dairy products (187.1 ± 187.8 g/day) was observed.Consumption in line with national dietary guidelines was found only for fruit (341.6 ± 201.8 g/day) and pasta (96.2 ± 66.1 g/day).
A comparison of the consumption of the individual food groups composing the Medi-Lite score with the national dietary guidelines for each individual year was also carried out (Supplementary Figure 1).The analysis revealed that, between 2019 and 2022, the intake of vegetables, bread, legumes, and milk and dairy products fell below the recommended guidelines.Conversely, the consumption of fresh red meat, poultry and cheese consistently exceeded the guidelines, except for the year 2019 when meat consumption aligned with the recommendations.While fish consumption adhered to the guidelines until 2021, it subsequently declined, remaining below the recommended levels.

Adherence to the Mediterranean diet according to socio-demographic variables
Analysis of MD adherence by socio-demographic variables showed that gender (women: 12.2 ± 2.41 vs. men: 11.7 ± 2.54), age (>61 years: 12.2 ± 2.44 vs. 31-60 years: 12.1 ± 2.49 vs. 18-30 years: 11.9 ± 2.45) and education (graduates: 12.5 ± 2.36 vs. non-graduates: 11.5 ± 2.49) were variables that significantly (p < 0.001) contributed to a higher MD adherence.When the analyses of the consumption of individual food groups were conducted according to gender, age and level of education, women and university graduates reported significantly (p < 0.001) higher consumption of fruit, vegetables, and lower consumption of meat, pasta, and bread, than men and non-graduates (Table 1).Interestingly, graduates also showed significantly (p < 0.001) higher consumption of legumes and fish than non-graduates.Regarding age, older subjects reported significantly lower (p < 0.001) consumption of vegetables and meat, as well as higher consumption of fruit and bread compared to younger subjects.
Finally, by comparing the consumption of the individual food groups with the national dietary guidelines according to the socio-demographic variables, an excessive consumption of cheese was observed in all the study population, while an excessive consumption of fresh red meat and poultry was observed only in men, younger subjects, and non-graduates.On the other hand, consumption in line with dietary guidelines was generally reported only for fruit and pasta (Figure 3).

Discussion
This paper reports data on adherence to MD, calculated through the validated Medi-Lite tool, in a total population of more than 10,000 adult subjects in Italy, with analysis on the consumption of the individual food groups that make up the score compared to the national dietary guidelines.In the entire study group, we could detect, despite an overall good level of adherence to MD calculated through the Medi-Lite score, a significant decline over the 4 years of analysis.From 2019 to 2022, the level of MD adherence decreased significantly and steadily over the years, apart from the year 2020 when there was a slight increase.These results agree with other studies conducted by us and other groups in Italy.In 2020, probably due to the lockdown periods caused by the COVID-19 pandemic, an improvement in the population's dietary habits was observed, resulting in a significant increase in MD adherence (Franco et al. 2021;Pfeifer et al. 2021;Ruggiero et al. 2021;Lotti et al. 2022), but before and after the lockdown periods that occurred in 2020, a significant and steady decline in traditional MD habits was recorded.Actually, this decline is in line with the reduction in MD adherence that has now been reported consistently over the past 50 years worldwide, with the subgroup of Mediterranean countries, in which Italy was included, reporting the greatest decline (Vilarnau et al. 2019).The general abandonment of traditional MD characteristics of Mediterranean countries has several explanations and seems to affect younger generations and lower educated individuals more significantly.In this large sample of the adult population, when we analysed socio-demographic variables in association with MD adherence score, we found that women, older subjects, and university graduates had significantly higher MD adherence in Italy.These data agree with previous studies conducted in several other countries (Arvaniti et al. 2006;Patino-Alonso et al. 2014;Leone et al. 2017).On the one hand, the fact that women show a higher level of adherence to a beneficial diet such as MD was highly expected, as women usually show  greater confidence in healthy eating and greater commitment to body weight control, leading them to have better eating behaviour (Grzymisławska et al. 2020).However, on the other hand, the result that an older age and higher level of education could be key variables influencing adherence to MD was not so obvious.Paradoxically, what in the past has always been traditionally recognised as a "popular" diet, consumed by all age groups including the younger ones, and determined by the consumption of local and homemade products, such as MD, has now turned into a diet followed mainly by the higher age groups of the population, with a higher level of education and those who can afford to spend more to buy food typical of the Mediterranean dietary profile.In this study, we confirm the results obtained from other previous studies by reporting that older, university-graduated individuals demonstrate higher levels of adherence to MD (Pelucchi et al. 2010;Leone et al. 2017;Lotti et al. 2022).Indeed, older subjects seem to have maintained traditional eating habits acquired in childhood, thus remaining less influenced by the Westernisation process of diet and foods from other cultures (Leone et al. 2017), while those with higher levels of education seem to be more aware of the role of nutrition on health status and thus make better food choices (Leone et al. 2017).
Another interesting aspect of the present study involves comparing the actual consumption of food groups with the nutritional recommendations provided to the general population for a healthy diet in Italy.Our results show that this large sample of adults consumes excessive amounts of foods of animal origin, as fresh red meat, poultry and cheese, and a low amount of some foods of plant origin typical of MD like vegetables, legumes and bread.These observations are consistent with recent research conducted in Italy that revels a deviation from the recommendations of the national dietary guidelines (Biasini et al. 2021;Scalvedi et al. 2021;Aureli and Rossi 2022).Notably, Biasini and colleagues reported findings in line with our study, indicating that 55% of their representative Italian sample consumed bread less than once a day, an intake well below the recommended 2.5 portions per day (Biasini et al. 2021).Likewise, other Italian studies have affirmed the underconsumption of fruit, vegetables, and legumes, mirroring our present observations (Scalvedi et al. 2021;Aureli and Rossi 2022).To date, it is known how a low consumption of plant-based products and an excessive consumption of animal products are detrimental to health, being associated with an increased risk of several forms of cancer, as well as ischaemic heart disease, pneumonia, diverticulosis, colon polyps and diabetes (GBD 2017Diet Collaborators 2019;Papier et al. 2021).In our study population, however, we were able to report consumption below the recommended amount for milk and yogurt, in agreement with results reported in a recent study of a representative sample of the Italian population, in which the authors observed that 90% of respondents consumed milk and yogurt below national dietary recommendations (Grant and Rossi 2022).Consumption of this food group seems to have decreased over the years, even though numerous studies show that adequate intake of these products can reduce the risk of osteoporosis, cardiometabolic diseases, and improve weight loss (Rodríguez-Rodríguez et al. 2010;Rodríguez-Rodríguez et al. 2017).
This work has several strengths in that it includes a large sample of Italian adults, uses a validated questionnaire to measure MD adherence at the individual level, and is the first study to assess MD adherence and consumption of its food groups in relation to Italian dietary guidelines.However, the results must be interpreted with some limitations.First, the information collected was self-reported and this may have led to recall bias and misreporting due to the nature of the study.Second, the study population is not representative of the Italian adult population because it consists of a group of unselected individuals who completed the questionnaire on their own initiative.Third, the assessment of the dietary habits of the sample population was carried out by multiplying the portion frequency (daily or weekly, respectively) by the portion sizes of the questions comprising the Medi-Lite questionnaire, thus using data outside of the scope of the questionnaire.
In conclusion, the results of this study, obtained from a large sample of more than 10,000 adults in Italy, showed a good level of adherence to the MD but a significant decline occurring from 2019 to 2022, especially in men, younger subjects, and those with lower education levels.A high consumption of cheese, meat and animal products emerged, while insufficient intake of some typical MD food groups, especially plant-based, was observed.These findings indicate the urgent need for public health interventions aimed at promoting proper dietary behaviour to increase adherence to MD and Italian dietary guidelines, ensuring better health for current and future generations.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Figure 2 .
Figure 2. Intake of each food group making up the Medi-lite score and comparison with the recommendations of the Italian dietary guidelines in the entire study population.

Figure 3 .
Figure 3. comparison of the consumption of the individual food groups making up the Medi-lite score with the dietary recommendations of the Italian guidelines according to socio-demographic variables.

Table 1 .
dietary intake of each food group composing the Medi-lite score according to socio-demographic variables.