High incidence of heart disease in shift workers linked to jet lag

The high incidence of heart disease seen in shift workers may be due to the tiredness resulting from the disruption to the body's biological clock as jet lag had a severe effect on red blood cells, IANS reports.

These could be counterbalanced by fresh young red blood cells, which could make blood donations a potential therapy for shift workers, according to the findings.

According to Margit Egg from University of Innsbruck in Austria, blood donations in humans could also stimulate the generation of fresh erythrocytes.

He added, blood donations on a regular basis might be a very simple measure to help reduce the cardiovascular risk in human shift workers.

Zebrafish (Danio rerio), a model oraganism, which like humans was active during the day was the subject of the researcher's study. The fish were subjected to alternate short (seven hour) and long (21 hour) days, resembling shift patterns common in industry.

The "jet-lagged" animals were found to have higher numbers of aged red blood cells, which accumulated in the blood vessels, The Financial Express reported.

According to Egg, normally there was a balance between newly produced red blood cells and old ones which are removed from the blood.

Due to their lower flexibility, old cells became stuck in the spleen and liver, where they were engulfed by white blood cells.

Large aggregates of old red blood cells in the vessels posed a risk, which increased the chance of a clot that could lead to a heart attack.

Also the decreased functionality of the aged cells reduced the oxygen carrying capacity of the blood.

The research also revealed that zebrafish were less badly affected by jetlag when they were simultaneously exposed to conditions where oxygen was limiting (known as hypoxia).

This was because hypoxia stimulated the production of fresh red blood cells.

The cell signalling pathways regulating daily rhythms and the hypoxic response were intrinsically linked.

This was based on the observation that genes activated by hypoxia, such as erythropoietin, regulating red blood cell production, normally showed a daily rhythm of activity which hypoxic conditions disturbed.