One of the most common artificial sweeteners, aspartame, causes a spike in insulin levels in mice, leading fatty plaques to build up in their arteries and increasing their risk of heart attacks and stroke, according to international scientists.
However, don't switch back to full-fat sugar just yet, because Australian experts contacted by the AusSMC were not convinced the sweetener is affecting us in the same way.
The team fed mice daily doses of food containing aspartame for 12 weeks - equivalent to about three cans of diet soda each day in humans - and found the aspartame-fed animals developed more fatty plaques in their arteries and showed higher levels of inflammation, compared with mice fed a normal diet.
"The research... found [aspartame] caused direct damage to the inner lining of blood vessels," Dr Yutang Wang from Federation University told the AusSMC.
"This damage made the blood vessel walls 'stickier', leading to an increase in inflammatory cells, which in turn contributed to the build-up of plaque in the arteries. This condition, called atherosclerosis, is a key factor in cardiovascular disease, including heart attacks and strokes," he added.
The team says that because aspartame is around 200 times sweeter than sugar, it may trick receptors in the intestines to release more insulin, causing heart issues.
However, Dr Ian Musgrave from the University of Adelaide said that while the study is "elegant", the findings may not be relevant for humans because the mice in the study had been genetically modified.
"Genetically engineered mice on a diet specifically designed to accelerate plaque formation is unlikely to replicate the biology and dietary situation of most humans," he said.
And Professor Oliver Jones from RMIT University told the AusSMC he has several concerns about the study.
"The authors used a particular type of lab mouse... which is bred to be prone to heart disease. They also fed it a high-fat, high-cholesterol diet, which itself increases the risk of heart disease," he said.
Prof Jones added that the research team doesn’t appear to have measured how much aspartame the mice consumed, or the aspartame levels in their blood, "so it is unknown what the mice actually received".
Another concern raised by Prof Jones was that "the authors would appear to think little work has been done on safety testing in aspartame". However, "it is quite well-established that aspartame doesn't stimulate glucose or insulin levels in humans... aspartame is one of the most researched ingredients in the world", he said.
Dr Musgrave concluded that the study "does not suggest people should give up their artificially sweetened drinks."
And Prof Jones agreed: "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, etc.," he said.
Contact: Dr Joe Milton
Phone: +61 8 7120 8666
Email: info@smc.org.au