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If you work nights, choose the chicken dinner over steak.
People who head to work in the dark may have a better shot at avoiding type 2 diabetes, obesity and cancer if they forgo red meat or other high-iron meals at night.
That's the takeaway in new research from the University of Utah published online Tuesday in the journal Diabetes.
Working at a time when most people are sleeping throws off the rhythmic functions of the liver, which regulates glucose. Researchers believe that's the main reason shift workers are more likely to develop chronic diseases.
At the same time, university researchers found, too much iron also can cause the liver's natural wake-sleep cycle to flatline. That means it falls out of sync with the brain's clock, raising the risk of metabolic diseases, said researcher Donald McClain, a U. medical school professor.
The brain sets the body's main circadian clock. But the liver also helps regulate blood sugar levels, which can determine when a person sleeps and wakes.
Researchers monitored iron intake in mice and found it affected blood glucose levels.
"The bottom line was that dietary iron had a big effect, and it tended to flatten out that normal circadian rhythm," McClain said.
More study is needed, he added, to determine whether eating an iron-rich diet and working nights compounds the likelihood of chronic diseases.
To that end, lead author Judith Simcox, a U. biochemistry researcher, has joined with Harvard University professors, who have tracked nurses extensively to observe the effects of nighttime workdays.
"One is bad, the other is bad, but is the collusion of both even worse?" said McClain. "We still have to do more studies."