Too little salt may hurt memory just as badly as too much

by Sanjukta Mondal, Medical Xpress

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edited by Sadie Harley, reviewed by Robert Egan

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Salt can make or break a dish. A little too much or too little can throw everything off, leaving even the most luxurious ingredients tasting off. But get the balance right, and salt can bring out the flavor in even the simplest ingredients. The brain relies on a similar balancing act for healthy function and memory. While we are aware of the ill effects of having too much salt, what happens when we consume too little?

A recent study compared how long-term low-salt and high-salt diets affected memory, gut health and brain health in mice whose guts were colonized with human gut bacteria. The researchers focused on the gut–metabolite–brain axis, examining how dietary salt alters gut bacteria and their chemical products, and how those changes signal back to the brain.

Mice on either a low-salt or a high-salt diet struggled with memory. Compared with mice eating a normal amount of salt, they did worse on tests of short-term working memory and long-term recognition memory.

Inside the hippocampus, the brain's memory center, both diets lowered critical synaptic proteins like SYN1, PSD95 and BDNF and suppressed CREB activation. All of these are essential tools neurons use to build memories and adapt, so weakening them reduced the brain's ability to form memories.

The findings are published in Food Research International.

The salt conundrum

Most ultraprocessed foods, and even fast food, are high in sodium, meaning they're quite salty. Studies show ultraprocessed foods make up about 60% of total calories in the U.S. diet, and similar trends appear in other countries. Combined with other dietary habits, this has made excessive salt intake a global public health problem. People end up consuming far more than the recommended limit of 2 grams of sodium per day.

We have a large body of research warning us about high salt intake being linked to high blood pressure and cardiovascular disease, and even direct damage to the central nervous system. While public health guidelines widely promote reducing salt to protect heart health, very little was known about how severe, long-term salt restriction affects brain function.

Most earlier experiments that explored this question relied on standard lab mice, whose natural gut bacteria differ substantially from those in humans. To make the findings relevant to human biology, researchers in this study used a humanized mouse model.

The researchers started with 32 healthy male mice and gave them antibiotics to clear out their natural gut bacteria. Then they introduced transplanted gut microbiomes from fecal samples of 10 healthy human donors into the mice.

With their guts humanized, the mice were randomly split into three groups and given one of three custom diets for 14 weeks: The normal-salt group consumed a standard 0.5% salt diet, the low-salt group received a 0.1% salt diet to model severe sodium restriction, and the high-salt group had an 8.0% salt diet to model extreme sodium consumption.

High or low, where do we go?

The team then tested the mice's short-term spatial memory using a Y-maze test. Next, they swapped a familiar object for a new one in an arena and watched how long the mice inspected the new object, which tests long-term recognition memory. Last, they tracked how much time the mice spent exploring the open center of a square arena, which measures anxiety-like behavior and general movement.

The tests indicated that both eating too little salt and eating too much salt impair memory and brain function, but through two different biological pathways. With a low-salt diet, a drop in essential hippocampal synaptic proteins impaired long-term and short-term memory.

A high-salt diet significantly increased pro-inflammatory signals circulating in the blood and shifted the gut microbiota toward a pro-inflammatory state by lowering fecal levels of propionate and butyrate. This led to increased oxidative stress markers in the intestine, which can often trigger higher anxiety-like behavior.

The results demonstrate the importance of a balanced, normal salt intake for one's overall brain and gut health. Too little salt starves the brain of vital gut-derived chemical signals, while too much salt causes inflammatory damage.

Future studies could examine the lowest safe level of salt intake and test whether restoring specific gut microbe metabolites can reduce memory and thinking problems linked to an imbalance in salt intake.

Written for you by our author Sanjukta Mondal, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

More information

Anji Chen et al, Long-term low-salt and high-salt diets differentially disrupt the gut–metabolite–brain axis and induce cognitive impairment, Food Research International (2026). DOI: 10.1016/j.foodres.2026.119719

Key medical concepts

Flora, Intestinal

Clinical categories

NeurologyGastroenterologyHealthy livingCommon illnesses & Prevention Who's behind this story?

Sanjukta Mondal

Master's in Chemistry. Freelance science journalist and communicator. Published in Chemistry World, BioSpace, and The Hindu. Full profile →

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

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