Slim larks and overweight owls? A two years dietary intervention in shift workers.

Previous studies have shown that shift workers are more prone to non-communicable diseases. The aim of the present crossover study is to investigate whether it is possible to improve the health status of shift workers. Nineteen male shift workers (38.5 years ± 7.4) received every other month a dietary counseling for one year. All subjects kept a seven-day diet diary during a night shift, received bioelectrical impedance analysis, and a laboratory examination was performed at the beginning of the study, after one year and at the end of the study. The laboratory blood test included the main metabolic parameters, melatonin and serotonin. Beside subjects were also motivated to incorporate more physical training into their daily routine. After the intervention period, participants reduced energy intake, mean portion size, table salt, consumption of sugar and saturated fat. C-reactive protein (CRP), mean corpuscular volume (MCV), liver enzymes, triglycerides, and uric acid decreased, while melatonin level increased. Participants lost body weight and reduced waist circumference after the intervention. Lifestyle modification and dietary information could contribute to the health of shift workers. However, further studies are needed to investigate whether this can prevent disease and whether melatonin production can be influenced by diet.