A common artificial sweetener can trigger dangerous insulin spikes, warns a new study. The spikes led to blood vessel inflammation in tests – which raises the risk of a heart attack or stroke, say scientists.
Artificial sweeteners have been promoted as a guilt-free way to indulge our sweet tooth and are in many popular foods, such as zero-sugar ice cream, and “diet” drinks. But new research, published in the journal Cell Metabolism, shows that aspartame – one of the most common sugar substitutes – may impact vascular health.
The findings show that aspartame triggers increased insulin levels in animals, which in turn contributes to atherosclerosis – a build-up of fatty plaque in the arteries, which can lead to higher levels of inflammation and an increased risk of heart attacks and stroke over time. The research was inspired by a can of diet soda during a meeting.
Study senior author Professor Yihai Cao, of the Karolinska Institute in Sweden, said: “One of my students was sipping on this sugar-free drink, and I said, ‘Why don’t you look into that?’” Previous studies have linked sugar substitutes to increased chronic disorders such as cardiovascular disease and diabetes.
But the mechanisms involved were previously unexplored. For the new study, researchers fed mice daily doses of food containing 0.15% aspartame for 12 weeks- an amount that corresponds to consuming about three cans of diet soda each day for humans.
Compared to mice without a sweetener-infused diet, aspartame-fed mice developed larger and more fatty plaques in their arteries. They also showed higher levels of inflammation, both of which are hallmarks of compromised 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.
But they said aspartame, 200 times sweeter than sugar, seemed to “trick” the receptors into releasing more insulin. The research team then showed that the mice’s elevated insulin levels fuelled the growth of fatty plaques in the mice’s arteries, suggesting that insulin may be the key link between aspartame and cardiovascular health.
They then investigated how exactly elevated insulin levels lead to arterial plaque build-up and identified an immune signal called CX3CL1 that is especially active under insulin stimulation.
Prof Cao 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 stoke 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.
Prof Cao says the results point to CX3CL1’s role in aspartame’s effects on the arteries. The research team are planning to verify their findings in humans.
Prof Cao also sees CX3CL1 as a potential target for chronic conditions other than cardiovascular disease, 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.”