April 20, 2017

expert reaction to artificially-sweetened fizzy drinks, stroke and dementia

A new prospective cohort study publishing in Stroke investigates if there is an increased risk of stroke and dementia after sugar and artificially sweetened beverage consumption.

Dr James Pickett, Head of Research at Alzheimer’s Society said: 

“This research does not show that artificially sweetened drinks cause dementia. But it does highlight a worrying association that requires further investigation

“Research into dietary factors is very complex and there are a number of issues that need clarifying, for example why drinks sweetened with sugar were not associated with an increased risk in this study, and teasing out links between all types of sugary drinks, diabetes and dementia.

“What we do know is that the things we eat and drink can have an effect on our brain health. Evidence shows that along with eating a healthy diet, including watching what you drink, the best way to reduce your risk of dementia is to take plenty of exercise and stop smoking.”

Dr Sujoy Mukherjee, Consultant Psychiatrist (Old Age), West London MH NHS Trust, said:

“This is an important study that systematically looked into a big cohort for correlation between consumption of sugary and artificially sweetened drinks and future risk of development of stroke and dementia.

“Focussing on  dementia,  It is important to note that the study sample for dementia had a mean age of 69 years ( SD 6 years) at onset of the study and they were followed up for 10 years. Out of 1484 participants 81 developed dementia ( 5.45%). This is fairly similar to prevalence figure in general population for that age group, so the study sample appears fairly representative.

“This study has not adequately explained why artificially sweetened drinks but not sugar containing drinks should increase the risk of dementia and stroke. Contrary to many other studies, they have also noted that prevalence of cardiovascular disease and diabetes mellitus actually decreased with more frequent consumption of total sugary beverages.  This finding should be treated with caution and may reflect selection bias of healthier people consuming sugary drinks.

“While this study raises interesting questions about health risks of artificially sweetened drinks that merit further research, it should not prompt people to switch to sugar containing drinks but may serve as a caution that both types of drinks should only be consumed in moderation to protect our brain.”

Prof. Naveed Sattar, Professor of Metabolic Medicine at the University of Glasgow, said:

“This is an interesting paper but I would strongly caution against the conclusion that artificially sweetened drinks may increase the risk of stroke and Alzheimer’s.

“It is only one study and relatively small at that – there is little other strong evidence to support a link between artificially sweetened drinks and adverse health outcomes.

“It’s an observational study, so the authors of this study could not be certain that people who are developing ill health switch to artificially sweetened drinks in preference to sugary ones.  This is a phenomenon called reverse causality whereby some apparent health behaviours are the result of ill health rather than the cause.  The same sort of finding is true for alcohol; when folk become sick, they tend to stop or cut alcohol beverages.  The study could also be subject to residual confounding so unmeasured factors and not the different drink types are the true reasons for associations.

“Hence, on a personal note, I remain very happy to drink diet drinks rather than sugar-rich drinks since the latter clearly both harm teeth and are a source of lots of refined sugar.  Those are facts.”

Dr Amitava Banerjee, Senior Clinical Lecturer in Clinical Data Science and Honorary Consultant Cardiologist at UCL, said:

“We already know that sugar-sweetened drinks are associated with increased risk of diabetes, hypertension, stroke and coronary artery disease. However, there is still uncertainty about any link between artificially sweetened drinks, which are often used as an alternative to sugar-sweetened drinks, and cardiovascular disease or dementia. The research claims to show an association between artificially sweetened drinks and stroke and dementia, whereas no similar association was seen for sugar-sweetened drinks.

“This is an observational study, where it is very hard to control for all the possible confounders. Moreover, this population is neither ethnically diverse nor necessarily representative of the USA or other countries. The researchers relied upon self-reported data about drinks and diet which may be biased.

“Crucially, the association with stroke and dementia disappeared after adjusting for diabetes and vascular risk factors, such as high blood pressure and prior heart attack. In other words, individuals who drank a lot of artificially sweetened beverages already had cardiovascular risk factors which explained their risk of dementia or stroke, rather than the drinks per se.

“There is no evidence that artificially sweetened drinks cause stroke or dementia on the basis of this analysis. However, we also cannot assume that they are good for your health as a substitute for sugar-sweetened drinks, and so they should be used in moderation.”

Dr Elizabeth Coulthard, Consultant Senior Lecturer in Dementia Neurology at the University of Bristol, said:

“Although interesting, this paper does not tell us that artificially sweetened drinks cause stroke or dementia. The statistical relationship between artificially sweetened drinks and dementia disappears when the analysis controls for diabetes. This makes it more likely that there is a group of people who both use artificially sweetened drinks and are at higher risk of dementia, presumably because they have a risk factor, such as diabetes, for which a low sugar diet has been recommended.

“While the stroke effect remains even after diabetes has been taken into account, we should bear in mind that this is just one study with relatively small subgroups of participants. There is still strong evidence that high sugar intake is bad for general health. Nevertheless, it is good to question our assumptions about replacing sugar and future research could clarify the relationship between artificially sweetened drinks and neurological disease.”

Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said:

“As people are becoming more aware of the consequences of a high-sugar diet, many are turning to artificially-sweetened diet fizzy drinks as an alternative to those with lots of sugar. This interesting new study has pointed to higher rates of dementia in people who drink more artificially-sweetened drinks, but it doesn’t show that these drinks are the cause of this altered risk. When the researchers accounted for other risk factors for Alzheimer’s, such as risk genes, diabetes, heart disease, cholesterol levels and weight, this significant association was lost suggesting that these drinks are not the whole story.

“Future studies will need to confirm these findings in other groups of people, and explore what might be underlying any link between artificially-sweetened soft drinks and dementia. The best current evidence suggests that when it comes to reducing your risk of dementia, what is good for your heart is also good for your head. Eating a healthy balanced diet, keeping physically and mentally active, not smoking, drinking in moderation, maintaining a healthy weight and keeping cholesterol and blood pressure in check are all good ways to support healthy brain ageing.”

* ‘Sugar- and Artificially Sweetened Beverages and the Risks of Incident Stroke and Dementia – A Prospective Cohort Study’ by Pase et al. will be published in Stroke on Thursday 20^th April.

Declared interests

None declared