AN INGREDIENT found in diet fizzy drinks could increase the risk of stroke and heart attack, scientists claim.
An artificial sweetener used in sugar-free sodas and ice-creams may trigger insulin spikes and a build-up of fatty plaques in the arteries, a study in mice suggests.
A sweetener used in diet drinks was found to increase the risk of heart attacks and strokes in mice[/caption]
Artificially sweetened treats are often touted a way to sidestep the negative effects of sugar-packed fizzy drinks and sweets.
But new research, published in the journal Cell Metabolism, suggests that aspartame – one of the most common sugar substitutes – may impact vascular health.
The findings show that aspartame triggered increased insulin levels in animals, which in turn contributes to atherosclerosis – a build-up of fatty plaques in the arteries, which can up the risk of heart attacks and stroke over time.
Scientists not involved in the study said you don’t need to pour out your diet soda just yet – as we don’t yet know whether the artificial sweetener has the same effect on humans.
It’s not the first study to delve into the possible side effects of sugar substitutes – with previous research linking high consumption of artificially sweetened food and drinks to an increased risk of cardiovascular disease and and type 2 diabetes.
But experts still stress that picking sugar-free substitutes over calorific treats if better for your health.
For the new study, researchers fed mice daily doses of food containing 0.15 per cent aspartame for 12 weeks – the equivalent of consuming about three cans of diet soda each day for humans, they said.
Aspartame-fed mice developed larger and more fatty plaques in their arteries compared to mice who weren’t given sweeteners.
They also showed higher levels of inflammation, both of which are hallmarks of poor cardiovascular health.
When the research team analysed the mice’s blood, they found a “surge” in insulin levels after aspartame entered their system.
The team said it wasn’t a surprising result, given that our mouths, intestines, and other tissues are lined with sweetness-detecting receptors that help guide insulin release.
They said aspartame – which is approximately 200 times sweeter than sugar – seemed to “trick” the receptors into releasing more insulin.
The mice’s elevated insulin levels appeared to fuel the growth of fatty plaques in their arteries, researchers added.
They then investigated how high insulin levels may lead to plaque build-up in the arteries, identifying an immune signal called CX3CL1 that is especially active when insulin is released.
Senior author Yihai Cao, who studies chronic diseases related to blood vessel disorders at Karolinska Institute in Sweden, said: “Because blood flow through the artery is strong and robust, most chemicals would be quickly washed away as the heart pumps.
“Surprisingly, not CX3CL1. It stays glued to the surface of the inner lining of blood vessels. There, it acts like a bait, catching immune cells as they pass by.”
He said many of the trapped immune cells are known to trigger blood vessel inflammation.
But when researchers eliminated CX3CL1 receptors from one of the immune cells in aspartame-fed mice, the harmful plaque build-up didn’t occur.
How to reduce your risk of heart attacks and stroke
You can reduce your risk of heart attack and stroke with many of the same methods.
Heart attacks and strokes, althouh affecting different organs of the body, are both what we call cardiovascular events.
Both arise from similar underlying conditions, such as atherosclerosis —a buildup of fatty deposits in the arteries.
According to the American Heart Association, the risk factors for heart attacks and strokes are largely the same: high blood pressure, high cholesterol, smoking, obesity, physical inactivity, and diabetes.
Therefore, addressing these risk factors can simultaneously reduce the risk of both conditions.
Here are ways you can prevent the two:
Healthy diet
- More fruit and veg: The DASH, which emphasises fruit, vegetables, whole grains, and lean proteins, has been shown to reduce blood pressure and improve heart health.
- Less fats: Too much saturated and trans fats can raise cholesterol levels and increase the risk of atherosclerosis. Go for healthier fats like those found in olive oil, nuts, and avocados.
- Limit salt: High salt intake is linked to high blood pressure, a major risk factor for both heart attack and stroke. The NHS recommends no more than 6g of salt per day for adults.
- Fibre: Foods high in soluble fibre, such as oats and beans, can help lower cholesterol levels.
Exercise
Walking, running, cycling, swimming – whatever you like, do it!
Aerobic exercise can strengthen the heart and improve circulation.
The NHS advises at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity activity each week.
Strength training exercises can help control weight, improve cholesterol levels, and reduce blood pressure. It is recommended twice a week by the NHS.
Manage blood pressure
Healthy diet and exercise can help keep your blood pressure in check.
But it is worth monitoring it yourself after the age of 40, at least, when the NHS invites adults for a check-up every five years.
High blood pressure often has no symptoms but significantly increases the risk of heart attack and stroke.
Quit smoking
One of the best ways to quit smoking is to use resources provided by NHS Smokefree. Support groups, medications, and other tools to help quit smoking such as vapes could be what you need to kick the habit for good – and it’s free.
Limit booze
Excessive alcohol consumption can increase blood pressure and contribute to weight gain, which can snowball and become a heart health risk.
The NHS recommends not regularly drinking more than 14 units of alcohol per week.
The research team are planning to verify their findings in humans.
Prof Cao said CX3CL1 seems to play a key role in how aspartame affects arteries.
He also thinks the immune signal could be used to understand other chronic conditions, given that blood vessel inflammation is involved in stroke, arthritis, and diabetes.
He added: “Artificial sweeteners have penetrated almost all kinds of food, so we have to know the long-term health impact.”
Prof James Leiper, director of research at the British Heart Foundation, urged caution in applying the study’s findings to humans.
He said: “This study has revealed much more about the known potential risks of artificial sweeteners.
“In these mice, a diet that included an artificially high level of aspartame did exacerbate the size and number of fatty plaques in their arteries.
“The effect of these plaques was not measured here, but they are known to greatly increase the risk of a heart attack or stroke.
“While it is important to note that these findings have not yet been seen in humans, the results highlight the importance of further research to determine whether these additions to our food, and their effect on insulin levels, are contributing to an increased risk of cardiovascular events.”
Prof Leiper added that many people might be consuming more artificially sweetened foods that they realise.
“But this research is not a green light to have more sugar instead,” he noted.
“We all need to reduce our intake of the processed foods and beverages that contain high levels of fat, sugars, sweeteners and salt.
“This is the best way of ensuring a healthy diet and a lowered risk of heart and circulatory disease.”
Prof Naveed Sattar, Professor of Cardiometabolic Medicine/ at the University of Glasgow, added: “This seems like worrying findings but of course, before it can taken seriously, the findings have to be replicated in man.
“For now, I remain happy to take sweeteners and related diet beverages instead of sugar filled drinks, as the former limits excess calorie intake.”
Meanwhile Prof Oliver Jones, Professor of Chemistry, RMIT University in Melbourne, said researchers had used “a particular type of lab mouse called an ApoE mouse, which is bred to be prone to heart disease“.
He added that aspartame “is one of the most researched ingredients in the world” and has been “rigorously tested and safety assessed” before being added to foods and drinks.
“Even if aspartame did cause some increase in cardiovascular risk – which this study does not prove – then that risk would likely be very small compared to things like high fat, high sugar diets and lack of exercise,” Prof Jones said.
In 2023, the World Health Organisation designated aspartame as “possibly carcinogenic to humans”.
But health experts ruled that aspartame is safe to consume, if you stick to accepted daily limits.
