Due to the constant mental, physical, and thermal stress of firefighting, it is imperative to explore interventions that may mitigate any negative health effects the occupation brings to firefighters. One of those risks is heat related illnesses. Because a high amount of firefighters experience symptoms of heat related illness and heat related illness is associated with an increased risk of mortality, this is a critical component to focus on for firefighter safety. Betaine supplementation has been shown to decrease heat related deaths in animals and mitigate rises in core temperature in endurance athletes. Therefore, the aim of this project was to determine if betaine supplementation would decrease risk factors associated with heat related illnesses as well as mitigate rises in core temperature during a live burn scenario. In this double-blind placebo-controlled trial, structural firefighters (n=13) were stratified based on shift type and sex, then randomized to receive 3g/day of rice flour (PLA) or betaine (BET). Participants ingested the supplement for roughly 1 month (30 ±2 days) and completed pre-post testing for vitals, salivary stress markers, and body composition. During that month, the participants also wore a WHOOP 4.0 device to track sleep and components of recovery. At the end of the month, participants then underwent a live burn scenario in which they completed a stair climb of four stories outdoors then sat in a conex box that had a fire in it to be exposed to extreme passive heat (temp here) for 15 minutes. Baseline salivary biomarkers, core temperature, sweat rates, vitals, and sweat content were measured. Pre to post paired t-tests were used within groups for the 4 weeks of supplementation. Unpaired t-tests were used to analyze differences between groups in response to the live burn. One tail tests were used on relative thermoregulatory outcomes and baseline salivary markers, all other assessments were two tailed tests. There were no differences in the BET group for vital signs pre to post supplementation, however the PLA group had an increase in resting heart rate. The BET group had significantly better sleep quality as observed through restorative sleep increases while the firefighters were working on shift and after they got off of work that were not observed in the PLA group. When comparing the before and after 4 week supplementation, the BET group had decreases in C-Reactive Protein and cortisol which resulted in increases in the testosterone:cortisol ratio in the BET group (p<0.05). Arrival interleukin-8 and alpha-Amylase were significantly lower in the BET group compared to the PLA group. Absolute core temperature differences were not significantly different between groups, however when presented relative to caloric expenditure from the stair climb and burn, body weight, heart rate average from the stair climb and burn, and air usage, the BET group was significantly lower (p < 0.05). Sodium content of sweat in the BET group was significantly higher, while sweat rates were not different from the PLA group. Based on these findings, BET may decrease chronic stress and inflammation and acutely better maintain blood volume and decrease the risk of heat related illnesses and improve on shift safety and health in firefighters.
