Salt is an essential nutrient, but new research suggests that both excessive and very low salt intake may affect brain function and memory.
A study published in Food Research International examined the effects of long-term low- and high-salt diets in mice. Researchers divided the animals into three groups and fed them diets containing normal, very low or very high levels of salt for 14 weeks.
The mice on both the low- and high-salt diets showed impairments in tests of spatial and recognition memory compared with those receiving a normal-salt diet. The researchers also observed changes involving the gut–metabolite–brain axis and reductions in certain hippocampal proteins associated with memory formation
The findings suggest that extreme sodium intake in either direction may negatively affect cognitive function. However, the experiment was conducted in mice, so the results cannot be taken as proof that the same effects occur in humans.
A separate six-year human study, published in Neurobiology of Aging, examined 1,208 cognitively healthy older adults participating in Australia’s Australian Imaging, Biomarkers and Lifestyle (AIBL) study. Participants had an average age of about 71 and underwent repeated cognitive assessments over 72 months.
Researchers found that higher sodium intake was associated with a faster decline in episodic recall among older men. No significant association was found in women or in the overall study population
The researchers cautioned that more research is needed to understand the reasons behind the sex-specific finding and how sodium intake may relate to long-term cognitive health. The human study also relied on self-reported dietary information, which is an important limitation.
Overall, the available evidence does not establish that salt directly causes memory loss in humans. It does, however, add to research examining how sodium intake, blood pressure, vascular health and other biological pathways may interact with brain health.