A Pilot Randomized, Controlled Trial of Nighttime Peanut Butter Supplementation in Firefighters: Blood Pressure and Body Composition Outcomes

Background/Objectives: Dietary approaches to combating risk factors for cardiovascular disease are valuable, especially for individuals in high-stress occupations like first responders. The purpose of this pilot randomized control trial was to determine the effect of regular peanut butter (PB) supplementation on blood pressure and primary measures of body composition (body fat %, fat mass, and lean mass) in firefighters. Methods: Full-time firefighters (N = 40; 1 woman) were randomly assigned to a control group or a peanut butter group for 7 weeks. Participants in the peanut butter group consumed one serving of peanut butter before bed at least 5 days per week for the intervention period. Participants in the control group continued with their usual diet. Indices of body composition and blood pressure were collected before and after the intervention period and compared using mixed-factorial ANOVAs (α = 0.05). Results: No interaction effects between group and time were observed for blood pressure variables (p = 0.619–0.650). Similarly, the changes among the PB group over time in percent body fat (Δ = −0.53 ± 1.74%), fat mass (Δ = −0.73 ± 2.21 kg), and lean body mass (Δ = 0.04 ± 1.65 kg) were not significantly different than the changes over time in the control group (p ≥ 0.067 for all). Conclusions: Seven-week PB supplementation did not affect male firefighter body composition or blood pressure; however, future studies should investigate longer durations with sophisticated dietary recall methods. ClinicalTrials.gov Identifier: NCT06364202.