Firefighters on a Mediterranean diet-based worksite program showed significantly improved — and maintained — dietary habits after 12 months compared with fire stations that remained on usual diets, according to findings of a large randomized controlled trial conducted in Indiana.
Adherence to the diet resulted in statistically significant improvements in the bread/starches consumed at work, increased fish and nut consumption, and fewer alcoholic beverages and fast food. Firefighters on the Mediterranean diet showed a significantly greater decline in body fat percentage by 0.79 absolute percentage points (95% CI, 0.18 - 1.40) and LDL cholesterol by −6.92 mg/dL (95%CI, −13.58 to −0.27) at 6 months compared with controls.
This population, many of whom are middle-aged and have obesity, often eat communally; the study provided an opportunity to explore the potential benefit of a "whole fire station" approach to changing dietary habits, with the ultimate goals of lowering their risks for cardiovascular disease and cancer.
Asked why researchers chose the firefighter population specifically, senior author Stefanos N. Kales, MD, MPH, from Harvard School of Public Health, Boston, said, "Sudden cardiac death on duty is the number one on-duty cause of death for firefighters due to high rates of heart disease," said Kales. "They also have high prevalence of obesity, around 40%, as well as an elevated risk of cancer. Despite action-related aspects to their role, the firefighter population is prone to chronic disease and the Mediterranean diet and lifestyle are associated with lower rates of heart disease, obesity, and chronic disease."
The modified Mediterranean Diet score (mMDS) was 2.01 points higher in fire stations on the Mediterranean diet compared with a usual diet at 6 months (P = .005), and 2.67 points higher (P = .001) at 12 months. Among secondary outcomes, changes in cardiometabolic risk factors were not statistically significant at 1 year.
"The study shows that firefighters on the Mediterranean diet improved their dietary adherence, especially at 12 months, and more so than the control group," Kales told Medscape Medical News. "We also think that if maintained over many years, this increased adherence to a Mediterranean diet will have positive effects on metabolic status, inflammation, and risk of chronic diseases."
Study co-author Mercedes Sotos-Prieto, PhD, added that, "even though the 12-month improvement is small, it can be sustained over time because the diet is not calorie-restricted, nor requires the elimination of certain food types, but [rather] is culturally based such that over time, and based on other evidence, there can be a beneficial impact."
The Feeding America's Bravest cluster RCT was a cluster randomized study — at the fire station level. "It makes sense when firefighters food shop for the group, eat together and so on," said Kales. "Firefighters also have around one third of their weekly meals at the firehouse, so it's a whole-station approach. It's interesting to know if work places, including fire stations, might be an environment suitable for health promotion."
The study findings were published this week in JAMA Network Open | Nutrition, Obesity, and Exercise.
US Career Firefighters — Multicomponent Worksite Diet Approach
This study tested the effectiveness of a multicomponent worksite intervention focused on adherence to the Mediterranean diet in modifying the dietary habits and disease risk factors of US career firefighters, a non-Mediterranean working population at high cardiovascular risk.
Firefighters get checked for physical fitness and health when first hired, often at a very young age, but over the years they regress near to the general population average for weight and some aspects of health, Kales said, adding that larger studies are needed to determine the generalizability of this intervention to other settings, such as more urban and more racially/ethnically diverse fire departments.
The study recruited a total of 485 firefighters from two Indiana fire departments (94.4% male; mean age, 47 years). Of these, 241 firefighters (27 fire stations) were randomly assigned to the Mediterranean nutrition intervention, and 244 (25 fire stations) were randomly assigned to usual diet.
The study is unique in that the intervention strategy was designed for this specific population with advice on shift-related sleep patterns, and hydration as well as nutrition. "There's a communal aspect to fire-service eating, and it has its own unique culture; for example, they might all fancy something rich to eat, or have extra portions for the big guys who might be more hungry and so on," remarked Kales.
Fire stations had access to supermarket discounts for group shopping; free samples of Mediterranean diet foods such as extra virgin olive oil and nuts for consumption at the fire station; online nutrition education platforms; grocery shopping tips; and family and peer education. In contrast, those in the control group received no such materials and were asked to follow their usual diet.
"Intervention design was based on prior qualitative work to ensure it was well matched to the Midwest firefighter's tastes; so chicken, for example, was coated in whole grain but baked not fried," explained Kales.
Adherence Measured by Modified Mediterranean Diet Score
Firefighters had a mean body mass index between 29-30 kg/m2, aged 45-46 years, 92%-95% men, 77%-88% White, 27%-28% body fat, waist circumference 89-101 cm, 64%-67% were heavy exercisers. Just under one third had a chronic condition including self-reported cardiovascular disease, hypertension, arrythmia, diabetes, dyslipidemia, or angina.
The primary endpoint was the 12-month change in adherence to the Mediterranean diet, as measured by a validated 13-domain modified mMDS monitored at baseline, 6-month, and 12-month study visits. Components of mMDS included the consumption of fast food, fruits, vegetables, desserts, fried food, fish, alcohol, wine, legumes, and nuts, as well as primary cooking oil, bread/starches, and beverages at home and work.
The Mediterranean diet was also continued in the home, because prior work found that firefighters said their spouse's opinion/support was important for healthy eating. The mMDS score was weighted according to time spent consuming the diet at each location.
Secondary outcomes, including blood pressure, body composition, and lab values from annual examinations were assessed at study visits.
Firefighters found the dietary pattern acceptable, as supported by other national surveys. "There's greater favorability compared to other diets because there is no calorie counting nor other restrictions or abstention from certain food types. We found Mediterranean diet adherence was maintained out to the 12-month endpoint of the study," said Kales.
JAMA Netw Open. Published online August 17, 2023. Full text
This work was supported by a grant from the US Department of Homeland Security Federal Emergency Management Agency Assistance to Firefighters and the Boston Nutrition Obesity Research Center Small Grants program for Epidemiology and Genetics Core (2016).
Lead author Maria Soledad Hershey, PhD, receives Occupational Safety and Health Education and Research Centers training grant support (grant T42 OH008416). Sotos-Prieto holds a Ramón y Cajal contract (grant RYC-2018-025069-I) from the Ministry of Science, Innovation and Universities and European Regional Development Fund/European Social Fund. Kales reported grants from US Department of Homeland Security as well as nonfinancial support from Barilla America, California Almond Board, Arianna Trading Company, and Innoliva/Molina de Zafra during the conduct of the study as well as personal fees from Mediterranean Diet Roundtable and Medicolegal outside the submitted work.