Recently, a study from the University of Birmingham in the United Kingdom showed that the intake of fatty foods can damage the cerebrovascular system by changing the hemodynamic activity of the brain when people complete mental stress tasks. This is the first study to show that fat burning in young healthy adults in stressful states may impair brain tissue perfusion. The study was published in the journal Nutrients.
Recently, a new study by the same team at the University of Birmingham in the United Kingdom found that eating fatty foods during periods of stress can impair the body's ability to "recover" from the effects of stress. Researchers have found that consuming high-fat foods before experiencing mental stress reduces brain oxygenation and leads to poorer vascular function. The study was published in the journal Frontiers in Nutrition.
Mental stress is known to cause an increase in heart rate and blood pressure, which is driven by the activation of the sympathetic nervous system and the withdrawal of the parasympathetic nervous system. Mental stress also affects the vasculature, and this activation of sympathetic and parasympathetic nerves is associated with increased nitric oxide (NO)-mediated peripheral vasodilation during stress.
Crucially, fat intake can negatively affect the vasculature: in healthy and clinical populations, brachial artery FMD has been reported to be damaged for 8 hours after consuming a high-fat diet. Therefore, an increase in fat intake during stresses may further exacerbate the effects of stress on the vasculature. Given the prevalence of fat burning during stress, it is important to determine the full impact of this interaction on vascular health in humans.
To the investigators' knowledge, only one previous study attempted to address this issue using a repetitive stress model, but probably due to the relatively small number of participants, did not show the effects of stress and fat on FMD or the interaction between stress and fat, respectively. The current study aims to investigate the effects of a high-fat diet on peripheral (FBF) blood flow as well as endothelial function (FMD) in healthy adults in the setting of mental stress challenges. The investigators hypothesize that a high-fat diet impairs peripheral blood flow during periods of stress and exacerbates stress-induced endothelial dysfunction compared to a low-fat diet.
The investigators recruited participants between the ages of 20-30 years, had a healthy body mass index (BMI), and were identified as either Caucasian European or Asian ethnicity. The researchers gave them two butter croissants for breakfast. Then we asked them to do mental arithmetic and speed it up, and the time was set to eight minutes. They can also see themselves on the screen while they are doing Xi exercises. The experiment is designed to simulate the daily stresses that we may have to deal with at work or at home.
Researchers have found that when we feel stressed, there are corresponding changes in the body: heart rate and blood pressure rise, blood vessels dilate, and blood flow to the brain increases. In addition, the elasticity of blood vessels, which is a measure of vascular function, decreases after mental stress. Researchers have found that eating fatty foods during stressful times reduces blood vessel function174% (measured by brachial artery flow-mediated dilation (FMD)).
Previous studies have shown that a 1% decrease in vascular function leads to a 13% increased risk of cardiovascular disease. Importantly, the researchers found that this damage to vascular function lasted even longer when participants consumed a high-fat diet. In addition, the study data suggest that the reduction in endothelial function after stress after fat consumption is only evident at least 90 minutes after stress, while the fat-stress interaction was not detected at an earlier time point (30 minutes).
Consistent with previous studies, the current study suggests that fat consumption has no effect on resting cardiovascular parameters. While fat consumption may affect sympathetic activation, there is evidence that other nutrients and general food consumption play a major role. This is also confirmed by the observed increase in postprandial resting heart rate after consuming high-fat and low-fat meals.
As expected, mental stress causes immediate changes in heart rate, blood pressure, and measurements of sympathetic and parasympathetic activity, which are not affected by fat burning. But this is not surprising, since fat consumption does not affect resting cardiovascular parameters, so it is also unlikely to alter cardiovascular response during stress.
There is little evidence of the effect of fat on cardiovascular response during stress, and there is a huge difference in approach. Therefore, future research is needed to draw definitive conclusions. In addition, while fat consumption does not appear to affect cardiovascular and vasodilation responses during stress, fat intake may affect resting cardiovascular function after stress. Therefore, future studies should similarly assess cardiovascular and vascular changes after stress as well as FMD measurements.
In conclusion, we tend to tend to eat high-fat foods when stressed, either because of limited options or as a way to cope with stress. But in doing so, our physical and mental response to stress becomes worse. Therefore, by choosing low-fat foods, we can cope with stress better.