Experts weigh in on study suggesting high salt may cause dementia

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  Last updated November 15, 2019 at 3:38 pm


In mice a high salt diet might lead to dementia, but experts suggest the results might not translate to humans.

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Why This Matters: We know lots of salt is bad for us, but these findings may need to be taken with a grain of salt.

Eating too much salt might lead to conditions such as dementia, according to a mouse study published in Nature earlier this week.

International researchers fed mice a diet 8-16 times higher in salt than a normal mouse diet and found these mice were less able to recognise new objects and struggled with maze tests.

The mice fed the high salt diet also had damage to their blood vessels and an accumulation of modified tau in the brain – a protein associated with conditions that cause dementia, such as Alzheimer’s disease.

We should take the results with a grain of salt

In an Expert Reaction to the AusSMC, Rosemary Stanton OAM from the University of New South Wales says the study “unveiled some reasonably complicated biochemistry” as researchers were also able to restore the brain function of the mice by giving them the amino acid arginine.

Researchers say this helped them identify a previously unknown pathway linking dietary habits to brain health.

Also: Gut microbiome link to high blood pressure from high salt diets

And while many experts agree the study adds to the evidence suggesting we should limit the amount of salt in our diets, some like Evangeline Mantzioris from UniSA says we should take these results with well, a grain of salt.

“Firstly, the amount of salt that was given to these mice does exceed the highest reported intake in humans, which is 3-5 times the recommended level of salt intake,” she says.

“Secondly, while this mouse model does provide a good biological equivalence to the human brain, we cannot with certainty say the same effect would happen in humans.”

John Funder AC from the Centre for Neuroscience at The University of Melbourne also told the AusSMC that translating these results “to the human situation may be cute, but it is grossly irresponsible in terms of science.”

A high salt diet goes hand-in-hand with poor eating habits

Dietitian and nutritionist Joanna McMillan also pointed out that human diets are much more complex than the mouse diets in this study and often our high salt diets also come hand-in-hand with poor lifestyle and eating habits.

“More than three-quarters of the salt in an average diet comes from processed foods and not salt added in home cooking or at the table,” she says.

“It can be difficult therefore to tease apart the key factors – it is likely that high salt, combined with factors such as unhealthy fats, highly refined grains and not enough whole plant food to provide protective factors, are responsible for the dietary effects on cognitive health.”

Also: An extra burger meal a day eats the brain away

So while this study represented an extreme version of a high salt diet, Stanton says: “The take-home message is that this study gives extra strength to the need to cut back on salt.”

“This is yet another reason for us to return to fresh foods, or to seek out those prepared without salt.”

“Supermarkets stock canned products such as chickpeas, tomatoes and fish without added salt. By choosing rolled oats and turning them into porridge or muesli you can avoid the salt in prepared breakfast cereals.

“With any processed product, check the salt content. Low salt products have sodium levels of no more than 120mg sodium/100g.”

You can read the full AusSMC Expert Reaction here.

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About the Author

Olivia Henry
Olivia Henry is Media Officer at the Australian Science Media Centre. She spends her days nerding out about the latest research in the hopes that journalists will nerd out too. Olivia has Bachelor’s degrees in Biomedical Science and Media (Journalism), and has studied in Japan and Spain. Before joining the AusSMC in 2018, Olivia worked at Fairfax Media, SciWorld, Channel 44 Adelaide and interned at Australia's Science Channel. If you like this super-funky-science-machine, you can catch her talking science on 2CC Canberra or hosting the Night Shift on Radio Adelaide.

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The Australian Science Media Centre (AusSMC) is an independent, not-for-profit service for the news media, giving journalists direct access to evidence-based science and expertise. We aim to better inform public debate on the major issues of the day by improving links between the media and the scientific community. The Centre works with journalists to help them cover science as well as identify the science angles in everyday news stories and works with the scientific community to help them interact more effectively with the media and ensure that their voices are heard on issues of national importance.

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