People who do shift work are more likely to have a diet that promotes chronic inflammation — which may partly explain the health risks associated with shift work, according to a study by the American College of Occupational and Environmental Medicine (ACOEM).
Michael Wirth of the University of South Carolina, Columbia, and colleagues analyzed the relationship between shift work and pro-inflammatory diet using data from a nationwide sample of employed adults. Based on diet questionnaires, the researchers calculated a "dietary inflammatory index" (DII) for each individual. The greater the DII score, the more pro-inflammatory the diet.
With adjustment for other factors, shift workers had an elevated DII, compared to day workers. The difference was significant for rotating shift workers (those who worked varying shifts): average DII 1.07, compared to 0.86 for day workers.
Women had higher DII values than men. Among women, the DII was higher for evening or night shift workers compared to day workers: 1.48 versus 1.17.
Shift work has been linked to increased risks of disease, including high blood pressure, obesity, cardiovascular disease and diabetes. Poor eating habits may contribute to some of these risks. Western-style diets with higher levels of calories and fats have been linked to increased inflammation, compared to Mediterranean diets high in fruits and vegetables.
The DII provides a way of measuring how "pro-inflammatory" a person's diet is. A recent study of police officers found a higher DII in officers doing shift work. The new study suggests a similar elevation in DII among shift workers in the general population.
It's still unclear how much of an impact the elevated DII would have on health, but a pro-inflammatory diet might be one factor contributing to shift work-related health risks.
"Inflammatory diets represent a target for behavioural interventions to reduce the health impacts of shift work," Wirth and co-authors write. They add that interventions should address other important lifestyle factors as well, including physical activity, proper sleep, and light exposure.