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.
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.
[bc_video account_id=”5067014667001″ application_id=”” aspect_ratio=”16:9″ autoplay=”” caption=”NHS launches major new stroke campaign as thousands delay calling 999 by nearly 90 minutes” embed=”in-page” experience_id=”” height=”100%” language_detection=”” max_height=”360px” max_width=”640px” min_width=”0px” mute=”” padding_top=”56%” picture_in_picture=”” player_id=”default” playlist_id=”” playsinline=”” sizing=”responsive” video_id=”6364171946112″ video_ids=”” width=”640px”]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.
The research team are planning to verify their findings in humans.
Prof Cao said: “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: “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.
Prof Naveed Sattar, Professor of Cardiometabolic Medicine/ at the University of Glasgow, said: “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.
The International Sweeteners Association (ISA) issued a statement in response to research, saying that contrary to the mouse study’s findings, “scientific evidence shows that aspartame does not affect heart health”.
“Human clinical studies consistently confirm no adverse impact of aspartame on glucose control, blood lipids, blood pressure, or other risk markers of cardiovascular diseases,” it said.
“Clinical research actually shows that, when used to replace sugars, low/no calorie sweeteners such as aspartame have a neutral or modestly beneficial effect on cardiometabolic risk factors such as body weight, glycaemic control, blood pressure and lipid levels and liver fat.
“Moreover, it is important to stress that the suggested mechanism for increasing the risk of atherosclerosis is not confirmed in humans as aspartame does not cause a spike in insulin release and does not otherwise affect our glucose control.
“Numerous randomised controlled trials, the gold standard in clinical and nutrition research, have investigated and confirmed a neutral effect of low/no calorie sweeteners on glycaemic and insulinemic responses in humans.
“From a methodological perspective, it should be emphasised that the type of mouse model used in these experiments is prone to the development of heart disease, as they display perturbed lipid metabolism and inflammation.
“The authors recognise that “feeding ApoE mice with a high-fat, high-cholesterol diet also diminishes clinical relevance” of these findings.
“Finally, it is important to remember that aspartame has been thoroughly researched and approved for use in food and beverages.”
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.