Are artificial sweeteners safe?

Regularly eating or drinking foods and drinks with artificial sweeteners is linked with a greater risk of heart and circulatory diseases, according to a recent study published in the British Medical Journal.

It’s well known that added sugars have a harmful effect on our health, in particular, because consuming too much of them can lead to excess weight, which can harm our heart and circulatory system. This has led to artificial sweeteners being used as a sugar alternative in many foods and drinks.

However, past studies have been divided over whether artificial sweeteners themselves might have a harmful effect on our cardiovascular health.

This recent study included around 100,000 people in France, aged 42 on average. Every 6 months they were asked to record everything they ate and drank over a 3-day period.

The participants were then followed up for an average of nine years to see whether they had any heart problems or a stroke.

The researchers found that regularly having artificial sweeteners (either already in manufactured foods, or adding them at the table) was linked to a 9 per cent increase in the risk of cardiovascular diseases (heart problems and stroke). The biggest increase was in the risk of a stroke or transient ischaemic attack (sometimes called mini-stroke), where sweeteners were linked to an 18 per cent increase in risk.

The study also reports that one artificial sweetener, aspartame, was more closely linked to an increased risk of stroke, whereas the sweeteners sucralose and acesulfame potassium were more strongly linked to coronary heart disease.

This kind of study can’t tell us why sweeteners could be having this effect. The researchers pointed to other studies which suggest that artificially-sweetened drinks could be linked to metabolic syndrome (a collection of problems such as high blood pressure, raised cholesterol levels, and worse blood sugar control), which can lead to heart and circulatory diseases as well as diabetes. Other studies have suggested that sweeteners could affect the way our body controls blood sugar levels.

The researchers said that artificial sweeteners “should not be considered a healthy and safe alternative to sugar”.

The BHF verdict

Tracy Parker, Senior Dietitian at the British Heart Foundation (BHF), said:

“Observational studies like these can only show a link, and more research is needed to understand the relationship between artificial sweeteners and the risk of developing heart and circulatory diseases.

“Most adults in the UK eat too much sugar, and this is linked to health problems such as obesity and tooth decay. Artificial sweeteners are an attractive way to reduce sugar intake, and before they can be added to food in Europe the European Food Safety Agency (EFSA) has to approve their use. This is a rigorous process, so you can feel confident they are safe to eat.

“While these findings shouldn’t cause undue concern, it’s always a good idea to look at the amount of sugar and sweeteners in your diet. Try to swap fizzy drinks for water and increase your intake of heart healthy foods, like lentils, nuts and seeds, as well as fruit, vegetables and wholegrains.”

• Find out how to spot sugar on the ingredient’s list

How good was the research?

While other past studies only looked at artificial sweeteners in drinks, this study included artificial sweeteners added to foods, such as yogurts, as well as “table top” sweeteners, which people added to their own food and drink, so its findings about the relationship between sweeteners and cardiovascular disease may be more accurate.

One of the major strengths of this study was the large number of people that took part, which means the findings are more reliable.

However, the study was based on a French population, with different dietary and lifestyle habits to those in the UK, four out of five people included were women, and they had on average higher education levels, so we can’t be certain that these findings would apply to the wider UK population.

The study used self-reporting and medical databases to track cardiovascular events. However, they could not rule out that some events could have been missed, which may make the findings less accurate. The study relied on participants self-reporting their food and drink intake which could also make the findings less accurate.

The researchers adjusted the findings to take into account factors including their diet, alcohol and cigarette intake, how much exercise they did, and their family history of cardiovascular disease.

However, this type of study is observational, meaning it can’t prove cause, or rule out that other unknown factors could have affected the results. So, when the researchers said artificial sweeteners “should not be considered a healthy and safe alternative to sugar”, they are perhaps too strongly suggesting that artificial sweeteners are definitely responsible for an increased risk of heart and circulatory diseases.

How good was the media coverage?

This study was widely covered in the media, including in The Guardian and The Daily Mail.

The Guardian article clearly describes the approach and key findings of the study and also explains that this type of research can only show a link and cannot exclude unknown factors which may have influenced the findings.

The Daily Mail gives an accurate description of the study and its key findings. It also helpfully includes comments from an independent expert, helping to give a more balanced overview of the findings. The expert quoted warns that “the researchers suggested 'far too strongly' that artificial sweeteners could be behind poor heart health when its observational evidence is 'weak and potentially flawed'.”

However, the Daily Mail headline (“Diet Coke ‘may be bad for your heart’ as experts say artificial sweeteners ‘should not be considered a safe alternative to sugar’”) may leave readers thinking the health risks linked with artificial sweeteners are limited to diet Coke, when in fact this is just one of many food and drink products which contain artificial sweeteners.

What to read next...