Eating fatty foods during stressful periods can impair the body’s ‘recovery’ from the effects of stress, according to a new study at the University of Birmingham.

Researchers found that turning to fatty and other unhealthy foods for solace reduced vascular function and raised the risk of heart disease, a report on the university’s website on 5 December said.

As part of the study, a group of young healthy adults were given two butter croissants for breakfast.

“We then asked them to do mental maths, increasing in speed for eight minutes, alerting them when they got an answer wrong. They could also see themselves on a screen while they did the exercise,” Rosalind Baynham, a PhD researcher at the University of Birmingham and first author, said.

The experiment was designed to simulate everyday stress that people had to deal with at work or in the home.

“When we get stressed, different things happen in the body, our heart rate and blood pressure go up, our blood vessels dilate and blood flow to the brain increases. We also know that the elasticity of our blood vessels – which is a measure of vascular function – declines following mental stress,” Baynham said.

The research team found that consuming fatty foods when mentally stressed reduced vascular function by 1.74% (as measured by Brachial Flow-mediated dilatation, FMD). Previous studies had shown that a 1% reduction in vascular function led to a 13% increase in cardiovascular disease risk but the new research showed that this impairment in vascular function persisted for even longer when participants had eaten the croissants.

The scientists were also still able to detect reduced arterial elasticity in participants up to 90 minutes after the stressful event was over.

The team also found that eating high-fat foods reduced blood flow to the brain, with lower oxygen delivery (39% reduction in oxygenated haemoglobin) during stress compared to when participants consumed a low-fat meal.

In addition, it was found that fat consumption had a negative effect on mood both during and after the stress episode.

“We looked at healthy 18–30-year-olds for this study, and to see such a significant difference in how their bodies recover from stress when they eat fatty foods is staggering. For people who already have an increased risk of cardiovascular disease, the impacts could be even more serious,” Jet Veldhuijzen van Zanten, Professor of Biological Psychology at the University of Birmingham said.

“We all deal with stress all the time, but especially for those of us in high-stress jobs and at risk of cardiovascular disease, these findings should be taken seriously. This research can help us make decisions that reduce risks rather than make them worse.”

The research also suggested that by consuming low-fat food and drinks, people’s recovery from stress was less affected. After eating a low-fat meal, stress still had a negative effect on vascular function (a 1.18% decrease in FMD), but this decline returned to normal 90 minutes after the stressful event.

Published in the journal Frontiers in Nutrition and Nutrients, the research also showed that consuming healthier foods, particularly those rich in polyphenols, such as cocoa, berries, grapes, apples and other fruits and vegetables, could prevent the impairment in vascular function.