Abstract
ABSTRACT
Introduction
Shift work is an increasingly prevalent feature of the modern workforce, with first responders constituting a critical occupational group required to sustain 24‐h operations. Modifiable health behaviour interventions, such as improving diet quality, may be effective in preventing or mitigating the non‐communicable disease onset linked to shift work. This review evaluated evidence supporting nutritional interventions in shift workers with first responder populations considered as a pre‐specified subgroup of interest.
Methods
A systematic review (PROSPERO CRD42023421400) evaluated intervention and observational studies informing dietary guidance for shift workers. Four databases (Embase, Cochrane Library, Web of Science, PubMed) were searched from inception to August 2023, with no date restrictions, and searches were updated in July 2025. Searches were supplemented by grey literature searches specifically targeting first responder populations. Studies were screened by two researchers. Studies of a randomised controlled trial (RCT), crossover‐RCT or observational study design, conducted in free‐living shiftwork populations or a laboratory‐controlled shiftwork setting, the intervention included a dietary component, and health‐related outcomes were reported. A narrative synthesis of results grouped by intervention type was conducted, with a pre‐specified subgroup analysis of studies in first responder populations. Quality assessment was measured using the Cochrane Risk of Bias Tools. Observational studies were evaluated using the Newcastle–Ottawa Scale.
Results
From the 6909 articles retrieved, 43 met the inclusion criteria. Most articles reported using a crossover (49%) or observational (33%) study design. Where specified, most studies involved free‐living participants (67%) in nursing and healthcare professionals (40%), with a few studies (9%) involving first responder subgroups (e.g., firefighters and police officers). Frequently reported intervention components included macronutrient adjustments (23%), time‐restricted eating (TRE) (21%), and meal timing and quantity (19%). Frequently reported outcomes were cardiometabolic health (40%), cognitive performance (30%), and sleep quality (12%). Methodological heterogeneity and prevalent risk of bias limited the evidence strength for determining shift worker nutritional guidelines.
Conclusion
The current evidence‐base is insufficient to formulate evidence‐based dietary guidelines for shift workers. The current evidence base is limited by substantial methodological heterogeneity, small sample sizes, and a moderate‐to‐high risk of bias across studies, which restricts the ability to formulate definitive evidence‐based dietary guidelines for shift workers. While findings may have relevance for high‐risk occupational groups, first responders remain underrepresented in the literature. Future research should prioritise well‐controlled, adequately powered, and ecologically valid intervention studies in diverse shift‐working populations, including first responders, to better inform practical and effective nutritional guidance.