These Comfort Foods Can Impede Recovery From Stress, Scientists Warn

When you feel stressed, what's the first thing you reach for? Maybe it's a bag of chips or a comforting meal like pizza or mac and cheese. Maybe you decide to start the day with a sweet pastry or an extra creamy coffee.

Unfortunately, these comforting foods may be impairing our body's ability to recover from the effects of a stressful situation, new research shows.

More than a quarter of U.S. adults report feeling too stressed to function most days, according to a poll conducted by the American Psychological Association in 2022. The chronic high levels of stress can have repercussions for both our mental and physical wellbeing, including anxiety, depression, cardiovascular disease, asthma and diabetes. Stress can also lead to chronic fatigue, obesity, digestive issues and immune system disorders.

"When we get stressed, different things happen in the body," Rosalind Baynham, a PhD researcher at the University of Birmingham in the U.K., said in a statement. "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."

However, the impact of our diet on these symptoms has, so far, been largely understudied. Therefore, in two new studies, published in the journals Frontiers in Nutrition and Nutrients, Baynham and her team set about analyzing whether fatty comfort foods could actually make a difference to these symptoms.

"We took a group of young healthy adults and gave them two butter croissants as breakfast," Baynham said. "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."

During and after this stressful event, the researchers used a non-invasive technique to measure the participants' vascular function. The technique, called flow-mediated dilation, measures how much our arteries widen in response to an increase in blood flow. Baynham said that previous research has found that just a 1 percent reduction in vascular function as measured by this method is associated with a 13 percent increase in cardiovascular disease risk. So how was it affected by stress?

"We found that consuming fatty foods when mentally stressed reduced vascular function by 1.74 percent (as measured by Brachial Flow-mediated dilatation, FMD)," Baynham said. "Importantly we show that this impairment in vascular function persisted for even longer when our participants had eaten the croissants."

When consuming low-fat food and drinks, the participants' recovery from stress was less negatively affected: after eating a low-fat meal, being put through the stressful maths exercise still had a negative effect on the participants' vascular function—a 1.18 percent decrease in Brachial Flow-mediated dilatation—but this decline returned to normal within 90 minutes after the stressful event.

The team also found that fatty foods were associated with reduced oxygen delivery to the pre-frontal cortex of the brain—the region of the brain that regulates our thoughts, actions and emotions. This also had a negative impact on the participants' mood during and after the stressful episode. Consumption of low-fat foods did not yield the same results.

"We looked at healthy 18 to 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," Jet Veldhuijzen van Zanten, a professor of biological psychology at the University of Birmingham and senior author on this study, said in a statement.

"For people who already have an increased risk of cardiovascular disease, the impacts could be even more serious. 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."

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