High Fat Foods May Impair the Body's Recovery From Stress

New research suggests that eating a high-fat meal before a mentally stressful event can reduce vascular function and oxygen delivery to the brain.

Emotional stress can wreak havoc on a person's health and well-being. Being under excessive and ongoing stress hampers the immune and gastrointestinal systems and can have a negative impact on the heart. Moreover, stress can impair the functioning of the endothelium — a layer of cells that separates the vascular wall from circulating blood. This impairment can lead to adverse cardiovascular events.

Now, in a study recently published in Frontiers in Nutrition, scientists from the University of Birmingham, United Kingdom, found evidence that eating foods high in fat may impact how well the vascular system recovers from stressful events by impairing endothelial function.

The research team recruited 21 male and female participants and divided them into two groups. One group consumed a high-fat meal containing 56.5 grams of fat, and the other ate a low-fat meal with 11.4 grams of fat. They consumed the meals 90 minutes before completing an 8-minute stress task.

"We took a group of young, healthy adults and gave them two butter croissants as 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 whilst they did the exercise. The experiment was designed to simulate everyday stress that we might have to deal with at work or at home," explained first author Rosalind Baynham, Ph.D., a researcher at the University of Birmingham, in a press release.

The team also measured specific cardiovascular markers before and after the stress task, including blood pressure and brachial flow-mediated dilatation (FMD), which assesses endothelial function.

They found that both meal types increased blood vessel dilation, blood pressure, and cardiovascular activity and impaired FMD for 30 minutes after the stress task. However, FMD in participants who consumed the high-fat meal remained significantly impaired 90 minutes after the stressful event ended.

"We found that consuming fatty foods when mentally stressed reduced vascular function by 1.74% (as measured by Brachial Flow-mediated dilatation, FMD). Previous studies have shown that a 1% reduction in vascular function leads to a 13% increase in cardiovascular disease risk," Baynham said.

The team also found that participants who ate a high-fat meal had lower oxygenation of the brain's prefrontal cortex. In addition, those in the high-fat meal group reported more negative moods during and after the stress task.

Participants who consumed the low-fat meal still showed stress-related vascular dysfunction, but this returned to normal 90 minutes after the stressful episode.

Study author Jet Veldhuijzen van Zanten, a professor 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 authors say more research is needed using a more significant number of participants to understand how diet, fitness levels, and other factors play into these findings and how long these fat and stress-induced endothelial function impairments last.