The impact of meal timing on cardiometabolic syndrome indicators in shift workers

Shift workers exhibit a greater risk for several cardiovascular and metabolic diseases including heart disease, obesity, hypertension, and type II diabetes (Boivin, Tremblay, & James, 2007; Chen, Lin, & Hsiao, 2010; Knutsson, Jonsson, Akerstedt, & Orth-Gomer, 1986; Kroenke et al., 2007). Shift workers have been reported to consume more pro-inflammatory diets than day workers (Wirth, Burch, Shivappa, Steck, et al., 2014) and to redistribute their food intake to the night during work (Lennernas, Hambraeus, & Akerstedt, 1995; Pasqua & Moreno, 2004). Numerous studies in animal models and humans have shown that eating during the sleep or inactive period is associated with cardiometabolic impairment and obesity (Arble, Bass, Laposky, Vitaterna, & Turek, 2009; Baron, Reid, Kern, & Zee, 2011; Bray et al., 2013; Gamble, Berry, Frank, & Young, 2014). However, whether this model holds true for shift workers, whose sleep schedules are highly variable, remains to be determined. Thus, the primary goal of this descriptive study was to examine not only what hospital shift workers eat, but also when they eat and how meal timing may contribute to cardiometabolic disease. As such, we characterized the timing of energy/macronutrient intake as well as dietary factors associated with inflammation (via the Dietary Inflammatory Index, DII) in hospital shift work nurses, and we found that greater total gram consumption during work nights significantly predicted increased triglyceride and cholesterol levels for night-shift nurses above and beyond that predicted by body weight alone. In addition, higher work day caloric and macronutrient intake by night-shift nurses was associated with higher HDL cholesterol levels. Our novel approach of combining time-of-day specific and work-day specific analyses of dietary inflammatory factors and macronutrient composition with measurement of metabolic syndrome risk factors establishes a link between meal timing and cardiometabolic health for shift workers. Collectively, our findings point to potential dietary timing interventions to improve cardiometabolic health in shift workers.