That greasy Friday night takeout might seem like a harmless treat, but new research reveals a hidden danger.

Consuming just one meal high in fats can limit blood flow to the brain, possibly increasing the likelihood of serious conditions such as stroke and dementia.

It’s well-known that eating indulgent, fatty meals like cheeseburgers or fried chicken negatively impacts the heart and blood vessels by increasing ‘bad’ LDL cholesterol. This cholesterol can lead to plaque buildup in arteries, obstructing blood flow to both the heart and brain.

The brain, which doesn’t store much energy, needs a continuous blood supply to receive the nutrients it requires. To ensure a regular flow despite daily changes in blood pressure, it relies on biological mechanisms that stabilize it under pressure.

However, even a single high-fat meal can disturb this fragile system, reducing its ability to manage these changes. This causes potentially harmful fluctuations in brain blood flow, which over time, could substantially elevate the risk of severe neurological disorders.

To explore this connection, researchers at the University of South Wales in the UK conducted a study with groups of younger and older men. 

Researchers assessed crucial signs of vascular health in both the body and brain before and after participants ate a high-fat meal, featuring a milkshake known as the ‘brain bomb.’

This drink, created to replicate a fast-food meal, contained 1,362 calories and 130g of fat, which is double the advised total fat and four to six times the suggested saturated fat intake for a whole day, all in a single drink.

New science reveals that eating just one fatty meal can swiftly slow blood flow to the brain, potentially upping the risk for devastating conditions like stroke and dementia (stock)

The findings confirmed that a high-calorie, high-fat meal can impair the healthy function of blood vessels. 

They not only observed impairments in vessels related to heart health but also a reduced natural ability of the brain to protect itself from changes in blood pressure. 

The study also found that this effect is dramatically worse in older adults, whose brains are already more susceptible to strokes, which affect about 795,000 Americans each year, and dementia, which affects about 7.2 million people in the US.

Researchers recruited 41 healthy men for the study. Twenty of them had an average age of 24, while 21 had an average age of 67. All were non-smokers and free of major health issues.

Notably, the older men started with higher baseline glucose and insulin, suggesting a pre-existing vulnerability that the high-fat meal later exacerbated. 

The study took place over two visits. During the first visit, participants underwent a heart check and then performed an intense cycling test to exhaustion on a stationary bike to assess their peak fitness level.

A week later, participants were given a high-fat, high-calorie milkshake designed to mimic the effect of a heavy fast-food meal. Before drinking it and again four hours afterward, researchers took a series of precise measurements.

They took blood samples to measure fats, sugars, and hormones. Then, using an ultrasound on the arm, they measured how well a major artery could expand, which is a key indicator of overall heart and blood vessel health.

The CDC reported last year that stroke has increased in people ages 18-64 by around 15 percent when comparing stroke cases from 2011-2013 to stroke cases from 2020-2022

They also used a special ultrasound on the head to measure the speed at which blood was flowing through the arteries inside their brains. 

To test the brain’s ability to regulate its blood flow during changes in blood pressure, participants repeatedly stood up and squatted down while these measurements were taken.

Researchers then compared measurements from before and after the meal, finding it created a state of ‘post-prandial hyperlipidemia’, a flood of fats in the blood, which impaired normal function. 

Levels of triglycerides, or fats in the blood, glucose (blood sugar), and insulin surged significantly in all participants just four hours after consuming the shake.

After the meal, the ability of blood vessels to dilate was significantly impaired in both young and older men. Their blood vessels had become less flexible and responsive.

The effects weren’t confined to the arm; they also reached the brain. The meal increased the ‘pulsatility’ of blood flow in the brain, a sign of stiffer arteries and a more forceful, jarring pulse wave traveling through the brain circulation.

The harmful effects were directly caused by a sharp rise in triglycerides in the blood, but only for the older participants. For them, the amount of fat in the meal directly predicted the amount of damage. The more fat they consumed, the more their brain’s blood flow system was impaired.   

Most alarmingly to researchers, the meal disrupted the brain’s ability to regulate its own blood supply, which protects the brain from sudden changes in pressure. 

The surge of triglycerides from a single high-fat meal directly impairs the brain’s ability to regulate its own blood flow, creating a vulnerable state that elevates the immediate risk for stroke and dementia

Without this ability, the brain becomes vulnerable to pressure swings that can potentially lead to brief moments of oxygen deprivation or stressful surges that, over time, can contribute to the damage that underpins stroke and vascular dementia.

This impairment was also more pronounced in the older participants and was directly correlated with their triglyceride levels. 

The researchers confirmed that everything was malfunctioning at the four-hour peak. However, they did not continue measuring beyond that point and it is unclear how long the impairment lasted. 

The researchers’ findings demonstrated a direct mechanism: the surge of triglycerides from the meal triggers inflammation that destroys Nitric Oxide (NO). 

This crucial molecule tells blood vessels to relax and expand. Without it, blood flow is impaired and stroke becomes more likely. 

The study was published in the Journal of Nutritional Physiology.  

The researchers wrote in The Conversation: ‘This has important clinical implications. While an occasional takeaway is unlikely to cause harm on its own, our results suggest that even one fatty meal has an immediate effect on the body.

‘Our study highlights the importance of consuming a diet that is low in saturated fat to protect not only our heart health, but also our brain health. This is particularly important for older adults whose brains appear to be more vulnerable to the effects of such a meal and are already at increased risk of stroke and neurodegenerative diseases.’