**1. Introduction**

Obesity, metabolic syndrome, and cardiovascular disease (CVD) have major impacts on US emergency responders, such as firefighters. These non-communicable, lifestyle-influenced conditions can put firefighters' career and life at risk [1–6]. The hazardous working environment, with risks of burns and physical trauma, air pollutants, physical and emotional stress, and shiftwork, causes additional stress to the cardiovascular system and may put firefighters at a higher cardiovascular disease risk with respect to the general population [7,8]. In fact, among US firefighters, sudden cardiac death is the leading cause of on-duty death, is, in most cases, due to underlying coronary heart disease and cardiomegaly, and is responsible for over 40% of duty-related deaths [9,10].

The number and proportion of CVD fatalities have remained relatively similar over the years, which suggests the need for more aggressive lifestyle-related interventions [11]. A recent study in older firefighters suggested that wellness programs can improve the cardiorespiratory function [12]. The eating and lifestyle patterns of firefighters often lead to obesity and have negative impacts on society by contributing to an increased rate of sick leave and increased healthcare expenses [13,14]. On the other hand, firefighters who follow a healthy lifestyle by exercising and maintaining a healthy weight are more likely to maintain high levels of cardiorespiratory fitness during aging [15].

The Mediterranean diet has been shown to reduce the risk of CVD and promote longevity in a variety of international settings [16–18]. There is also an increasing trend to introduce the Mediterranean diet at work as an intervention to prevent non-communicable diseases [19]. The existing evidence also suggests that adherence to the Mediterranean diet not only improves the physical health and wellbeing of workers but also may reduce work stress and blood pressure [20–22]. In two recent meta-analyses of Randomized Control Trials (RCT), the Mediterranean diet, also in combination with physical activity, was the only eating pattern which showed significant and beneficial e ffects on weight, body mass index (BMI) waist circumference, total cholesterol, high-density lipoprotein (HDL)-cholesterol, glucose, and blood pressure, without any evidence of adverse associations [23,24].

Various Mediterranean diet scores have been developed worldwide to quantify adherence to the Mediterranean diet [25–29]. In the ATTICA intervention in Greece, adherence was measured with the MedDietScore (0–55 items) [30,31], while the European Prospective Investigation into Cancer Nutrition (EPIC) group used the MED score (0–9 scale) [32,33]. Other adaptations include the Italian alternative Mediterranean diet score aMED (0–9 scale) [34] and the I-MEDAS from Israel (17-item questionnaire) [35]. The PREDIMED score, which is based on 14 items from the Prevención con Dieta Mediterránea in Spain, is also widely used [36,37]. However, the use of these scores in di fferent populations, cultures, and ethnicities has been questioned, as they may not be directly adaptable to di fferent ethnic and social groups [38].

In the US, a Mediterranean diet score was constructed specifically to measure adherence to the Mediterranean diet in career firefighters and is known as the modified Mediterranean Diet Score (mMDS) [39].

"Feeding America's Bravest" is a cluster-randomized-controlled trial that aimed to assess the e fficacy of a Mediterranean Diet intervention in 60 fire stations in two Indiana (USA) Fire Departments [40]. To assess Mediterranean diet adherence, the aforementioned mMDS was used. Its validity versus previously validated questionnaires [41,42] was established using a sample of firefighters participating in "Feeding America's Bravest" [43]. The aim of the present study was to further corroborate the validity of the mMDS as a measure of Mediterranean diet adherence by examining its cross-sectional associations with anthropometric indices, blood pressure, and biochemical parameters in participants of the "Feeding America's Bravest" study.

#### **2. Materials and Methods**
