Stress may raise cholesterol blood levels, potentially increasing the risk of heart disease, research suggests.
Stress can have a damaging impact
Previous studies had established that stress is linked to increased heart rate and weakened immune systems.
Now a team from University College London has found stress also appears to raise cholesterol levels over the long-term in some people.
The team gave people 199 people stress tests and cholesterol tests three years apart, Health Psychology reports.
Lead researcher Professor Andrew Steptoe said: "Some of the participants show large increases even in the short-term, while others show very little response.
"The cholesterol responses that we measured in the lab probably reflect the way people react to challenges in everyday life as well.
"So the larger responders to stress tasks will be large responders to emotional situations in their lives and will have a greater chance of raised cholesterol - a major risk factor for heart and circulatory disease."
The participants were followed up three years later.
Cholesterol levels in all had gone up, as might be expected with the passage of time.
However, those people whose cholesterol had risen the most following the initial tests showed substantially greater rises.
Levels of LDL, or "bad" cholesterol were three times as likely to be at potentially harmful levels in this group compared with those who registered the smallest cholesterol rise after the initial tests.
This was after factors such as baseline cholesterol levels, age, gender, smoking and alcohol consumption were taken into consideration.
The researchers said it might be possible that stress encourages the body to produce more energy in the form of fatty acids and glucose.
These substances require the liver to produce and secrete more LDL cholesterol so that they can be transported to the other tissues of the body.
Another possibility is that stress interferes with the body's ability to rid itself of excess cholesterol.
Thirdly, it could be that stress triggers a number of inflammatory processes which also increase cholesterol production.
Professor Steptoe said the rises in cholesterol recorded in the study were not large, but were something to be concerned about.
"It does give us an opportunity to know whose cholesterol may rise in response to stress and give us warning for those who may be more at risk for coronary heart disease."
Dr Charmaine Griffiths, of the British Heart Foundation said: "We know that stress has a link to heart disease.
"The research suggests that this may be due to stress causing long-term increases in cholesterol in some people.
"We can't yet single out those whose bodies respond strongly to stress, but everyone can cut their chances of developing high cholesterol through a healthy diet and regular exercise.
"If worried about the risk, people can get their cholesterol levels checked at their local surgery."