How metabolic health and diet are linked to brain health

There are now numerous studies linking lifestyle with brain health, cognitive functioning, and longevity, And more are being published daily. Here are two studies published recently about how metabolic health and diet are two keys to maintaining brain health and cognitive functioning.

Metabolic health is linked to brain volume

"Alterations in brain structure and function can be detected long before the symptoms of cognitive impairment are diagnosed."

This study from the University of South Australia analyzed UK Biobank data from 25,239 individuals between the ages of 37 and 73.

The researchers compared 39 individual biomarkers of metabolic health with brain MRI measures, including total brain volume, grey matter volume, white matter, hippocampal volume, and white matter hyperintensity. Metabolic health is often defined as the absence of metabolic syndrome that includes high blood pressure, high blood fat, low levels of good cholesterol (HDL), high blood sugar, and a large waistline, among others.

Those with high HDL and low BMI, regardless of age, had the most overall preserved total brain volume and the researchers used this group as the reference group.

Metabolic profiles linked to high BMI were associated with greater white matter hyperintensities and lower grey matter volume. "White matter hyperintensities [are a measure of small microbleeds and lesions in white matter which] proliferate as the brain ages and are associated with increased risk for cognitive decline as well as Alzheimer’s disease and related dementias." 

This study shows that poor metabolic health especially when linked to obesity affects brain structure. Age was factored out so these results apply to all age groups. This is important because brain structure and function is affected years before cognitive impairment is diagnosed.

This is not the first study to show that metabolic health is related to brain health. Previous studies have revealed a relationship between obesity and diabetes with lower total brain volume, grey matter volume, and hippocampal volume and with adverse effects on cognition and dementia. 
High carbohydrate consumption is linked to poor cognitive function

The second study is from Harbin Medical University in China, which analyzed the data of 2,485 individuals over the age of 60 from the US National Health and Nutrition Examination Survey. The individuals were interviewed twice, 3 - 10 days apart, about their food intake for the previous 24 hours. They also completed a series of validated cognitive function tests. The individuals were divided into 4 groups based on the percent of calories consumed from carbohydrates. 

The group with the highest carbohydrate consumption was about 2 times more likely to experience poor cognitive function than the group with the lowest carbohydrate consumption. The two middle groups were only somewhat more likely to experience poor cognitive function.

However, for those who fasted for more than 16 hours, there was no relationship between carbohydrate consumption and poor cognitive function. So fasting seems to offer protection from the negative effects of high carbohydrate consumption.

There are previous studies showing that high carbohydrate consumption is related to poor cognitive health. Other studies have found that time-restricted eating can improve cognitive function and even longevity. In time-restricted eating, food is consumed in an eating window of usually 8 - 10 hours. If restricting carbohydrates is difficult, limiting the time of food consumption to a window of 8 hrs or less and fasting for 16 hours or more may protect against cognitive decline.


Changes in brain structure are seen years before cognitive function is impaired. To maintain brain health and cognitive function throughout life:

  • Maintain or achieve a normal weight.
  • Optimize your metabolic health
  • Reduce carbohydrates
  • If you find reducing carbohydrates difficult, try fasting for 16 hrs a day.

Lumsden, A. L., Mulugeta, A., Mäkinen, V., & Hyppönen, E. (2022). Metabolic profile-based subgroups can identify differences in brain volumes and brain iron deposition. Diabetes, Obesity and Metabolism.

Zhao, S., Han, T., Pei, X., Song, Y., Zhang, Y., Liu, L., Wang, X., Hou, W., & Sun, C. (2022). The association of diet carbohydrates consumption with cognitive function among US older adults modification by daily fasting duration. Frontiers in Aging Neuroscience14, 991007.

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