Consuming iron-rich food may increase the risk of Type 2 diabetes in workers who punch in for the graveyard shift, found a research.
The researchers found that dietary iron plays an important role in the circadian clock of the liver.
"Iron is like the dial that sets the timing of the body clock," said study lead author Judith Simcox from the University of Utah in the US.
Discovering a factor such as iron that sets the circadian rhythm of the liver may have broad implications for people who do shift work, Simcox added.
The liver's circadian clock is set by food intake. As people sleep, this clock helps maintain a constant blood glucose level and then causes it to spike just before they wake up.
The researchers wanted to identify external signals that set the circadian clock in the liver.
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They fed iron to mice as part of their natural eating cycle and observed that dietary iron increases the cellular concentration of heme, an oxygen-carrying iron compound found in haemoglobin.
They found that when heme binds to circadian proteins, their activity increases and causes the liver to optimally control blood glucose levels.
Increased activity of a circadian protein is healthy when it occurs in the liver's natural clock cycle.
But if this happens at a time that is out of sync with the circadian clock, such as during a graveyard shift, it could result in abnormal blood glucose levels.
"When a shift worker eats foods high in iron at night it could exacerbate the lack of synchronisation between the clock in the liver and the main one in the brain," concluded senior study author Donald McClain.
The study appeared online in the journal Diabetes.