Stress and Snacks: How Fatty Foods Hinder Recovery

Summary: Consuming fatty foods during stressful times can hinder the body’s recovery from stress effects.

Researchers found that high-fat meals, like butter croissants, consumed before a stressful event, reduced vascular function and brain oxygenation, and negatively affected mood.

The study demonstrated a 1.74% decrease in vascular function and a 39% reduction in oxygenated haemoglobin in the brain’s pre-frontal cortex following high-fat consumption during stress. Conversely, low-fat meals showed less impact on stress recovery, and foods rich in polyphenols like fruits and vegetables could prevent vascular function impairment altogether.

Key Facts:

  1. High-Fat Diet Impairs Stress Recovery: Eating fatty foods before a stressful event can lead to prolonged impairment in vascular function and reduced brain oxygenation.
  2. Impact on Mood and Cognitive Function: Fat consumption not only affects physical health but also mood and cognitive abilities during and after stress.
  3. Healthy Alternatives for Stress Management: Consuming low-fat or polyphenol-rich foods can mitigate or even prevent these adverse effects, offering a healthier way to cope with stress.

Source: University of Birmingham

Eating fatty foods during stressful periods can impair the body’s ‘recovery’ from the effects of stress, new research suggests. 

Different findings from a study, published recently in Frontiers in Nutrition and Nutrients, have shown that consuming foods high in fat before a mentally stressful episode can reduce brain oxygenation and cause poorer vascular function in adults.  

This shows a stressed looking woman eating chips.
The research also suggested that by consuming low-fat food and drinks people’s recovery from stress is less affected. Credit: Neuroscience News

Rosalind Baynham, a PhD researcher at the University of Birmingham and first author explained: “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. 

“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.

“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.

“Importantly we show that this impairment in vascular function persisted for even longer when our 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 attenuated cerebral oxygenation in the pre-frontal cortex, with lower oxygen delivery (39% reduction in oxygenated haemoglobin) during stress compared to when participants consumed a low-fat meal.  Furthermore, fat consumption had a negative effect on mood both during and after the stress episode.  

Jet Veldhuijzen van Zanten, Professor of Biological Psychology at the University of Birmingham said: “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. 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 is less affected. After eating a low-fat meal, stress still had a negative effect on vascular function (1.18% decrease in FMD), but this decline returned to normal 90 minutes after the stressful event. 

Further research from the University of Birmingham team has shown that by consuming ‘healthier’ foods, particularly those rich in polyphenols, such as cocoa, berries, grapes, apples and other fruits and vegetables, this impairment in vascular function can be completely prevented.  

Dr Catarina Rendeiro, Assistant Professor in Nutritional Sciences at the University of Birmingham, said: “The impact of these foods during stressful periods cannot be understated. For example, reduced oxygenation to the brain could potentially impact mood and mental health, making people even more stressed.

“On the other hand, it could affect cognitive function and people’s ability to perform the very task they are stressing about, such as an interview, an exam or work meeting. This is something we would like to do more research into in the future. 

“Our studies show that food choices around stressful episodes can exacerbate or protect from the effects of stress on our cardiovascular system. The good news is that this means we can do something about this.

“We know that when people are stressed, they tend to gravitate towards higher-fat foods, either because it is the more convenient option if time is in short supply, or as a treat to deal with the stress.

“But by doing this, they are making their physical and psychological response to stress worse. By picking low-fat foods, they could be positioning themselves to cope with the stress more effectively.”  

Rosalind Baynham concluded: “The world is an incredibly stressful place right now, and even without outside factors such as war or a cost-of-living crisis, stress is something we all need to deal with. So, next time you are in a big meeting, or taking part in a job interview maybe try and resist the free biscuits and go for some berries instead. You might find you feel more relaxed and can cope with the stress just a little bit better.” 

About this stress and diet research news

Author: Eleanor Hail
Source: University of Birmingham
Contact: Eleanor Hail – University of Birmingham
Image: The image is credited to Neuroscience News

Original Research: Open access.
Fat intake impairs the recovery of endothelial function following mental stress in young healthy adults” by Rosalind Baynham et al. Frontiers in Nutrition

Open access.
Fat Consumption Attenuates Cortical Oxygenation during Mental Stress in Young Healthy Adults” by Rosalind Baynham et al. Nutrients


Fat intake impairs the recovery of endothelial function following mental stress in young healthy adults

Introduction: Mental stress has been identified as a trigger of cardiovascular events. A single episode of stress can induce acute impairments in endothelial function in healthy adults. Importantly, during stressful periods, individuals often resort to unhealthy behaviors, such as increased consumption of high-fat foods, which is also known to negatively impact endothelial function. Therefore, this study examined whether consumption of a high-fat meal would further exacerbate the negative effect of mental stress on vascular function.

Methods: In a randomized, counterbalanced, cross- over, postprandial intervention study, 21 healthy males and females ingested a high-fat (56.5 g fat) or a low-fat (11.4 g fat) meal 1.5 h before an 8-min mental stress task (Paced-Auditory-Serial-Addition-Task, PASAT). Plasma triglyceride (TAG) concentration was assessed pre-and post-meal. Forearm blood flow (FBF), blood pressure (BP), and cardiovascular activity were assessed pre-meal at rest and post-meal at rest and during stress. Endothelial function, measured by brachial flow-mediated dilatation (FMD) was assessed pre-meal and 30 and 90 min following mental stress.

Results: Plasma TAG concentration was significantly increased following the high-fat meal compared to the low-fat condition. Mental stress induced similar increases in peripheral vasodilation, BP, and cardiovascular activity, and impaired FMD 30 min post-stress, in both conditions. FMD remained significantly impaired 90 min following stress in the high-fat condition only, suggesting that consumption of fat attenuates the recovery of endothelial function following mental stress.

Discussion: Given the prevalence of fat consumption during stressful periods among young adults, these findings have important implications for dietary choices to protect the vasculature during periods of stress.


Fat Consumption Attenuates Cortical Oxygenation during Mental Stress in Young Healthy Adults

Mental stress has been associated with cardiovascular events and stroke, and has also been linked with poorer brain function, likely due to its impact on cerebral vasculature. During periods of stress, individuals often increase their consumption of unhealthy foods, especially high-fat foods.

Both high-fat intake and mental stress are known to impair endothelial function, yet few studies have investigated the effects of fat consumption on cerebrovascular outcomes during periods of mental stress. Therefore, this study examined whether a high-fat breakfast prior to a mental stress task would alter cortical oxygenation and carotid blood flow in young healthy adults.

In a randomised, counterbalanced, cross-over, postprandial intervention study, 21 healthy males and females ingested a high-fat (56.5 g fat) or a low-fat (11.4 g fat) breakfast 1.5 h before an 8-min mental stress task. Common carotid artery (CCA) diameter and blood flow were assessed at pre-meal baseline, 1 h 15 min post-meal at rest, and 10, 30, and 90 min following stress.

Pre-frontal cortex (PFC) tissue oxygenation (near-infrared spectroscopy, NIRS) and cardiovascular activity were assessed post-meal at rest and during stress. Mental stress increased heart rate, systolic and diastolic blood pressure, and PFC tissue oxygenation. Importantly, the high-fat breakfast reduced the stress-induced increase in PFC tissue oxygenation, despite no differences in cardiovascular responses between high- and low-fat meals.

Fat and stress had no effect on resting CCA blood flow, whilst CCA diameter increased following consumption of both meals. This is the first study to show that fat consumption may impair PFC perfusion during episodes of stress in young healthy adults.

Given the prevalence of consuming high-fat foods during stressful periods, these findings have important implications for future research to explore the relationship between food choices and cerebral haemodynamics during mental stress.

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