Recent research suggests that the food we eat may influence the biological aging of our brains. A study involving over 20,000 adults indicates that consuming a diet high in pro-inflammatory foods is associated with accelerated brain aging. This effect appears to be most pronounced in older adults. The findings were published in the European Journal of Epidemiology.
Chronic systemic inflammation is increasingly recognized as a contributing factor to various health issues, including neurodegenerative diseases. As people age, levels of inflammatory markers in the blood typically rise. Elevated levels of these markers often correlate with a higher risk of cognitive decline and conditions such as dementia. Scientists have established that diet is a primary way to regulate inflammation in the body.
Certain dietary patterns, such as the Western diet, are known to promote inflammation. These diets usually contain high amounts of red meat, processed foods, and high-fat dairy products. In contrast, diets rich in vegetables, fruits, and whole grains tend to lower inflammation. While previous studies have linked pro-inflammatory diets to memory problems and specific brain changes, the impact on overall brain aging remained less clear.
The researchers behind this new study aimed to fill this gap in knowledge. They sought to determine if a diet that promotes inflammation is linked to a comprehensive measure of brain health known as “brain age.” They also wanted to understand if this relationship varied based on a person’s chronological age or their genetic risk for dementia. Additionally, the team investigated whether systemic inflammation in the body acted as a bridge connecting diet to brain health.
“There is growing evidence to suggest that diet may play an important role in brain and cognitive health, and specifically that inflammation from an unhealthy diet could be one contributing mechanism. However, whether dietary inflammation is associated with a comprehensive measure of brain health has not been previously examined,” explained study author Michelle M. Dunk, a researcher at the Aging Research Center and Division of Neurogeriatrics at the Karolinska Institutet.
“One way to measure someone’s overall brain health is by measuring their ‘brain age’ from MRI scans. We can then calculate the “brain age gap” by comparing a person’s brain age to their chronological age. When someone’s brain looks older than their actual age, it may signal an increased risk for cognitive decline or dementia.”
Data for this analysis came from the UK Biobank, a large-scale biomedical database. The study included 21,473 participants who were between the ages of 40 and 70. None of these individuals had neurological disorders at the beginning of the study. This exclusion helped ensure that the results reflected typical aging rather than the progression of pre-existing brain diseases.
To assess dietary habits, the researchers used a web-based questionnaire called the Oxford WebQ. Participants reported their food and drink consumption from the previous twenty-four hours. This assessment was administered up to five times over a period of several years. The repeated assessments allowed for a more accurate estimation of habitual dietary intake than a single questionnaire would provide.
From this dietary data, the investigators calculated a Dietary Inflammatory Index score for each participant. This index is based on the intake of thirty-one specific nutrients and dietary components. The researchers looked at nutrients that either increase or decrease inflammation levels. For instance, components like fiber, omega-3 fatty acids, and certain vitamins are considered anti-inflammatory. Conversely, saturated fats and carbohydrates are often classified as pro-inflammatory.
Based on these scores, participants were divided into four distinct groups. Group 1 consisted of individuals with the most anti-inflammatory diets. Group 4 included those with the most pro-inflammatory diets. This categorization allowed the researchers to compare brain health outcomes across different levels of dietary quality.
Approximately nine years after the initial dietary assessments, participants underwent magnetic resonance imaging (MRI) scans of their brains. The researchers used these scans to estimate the biological age of each participant’s brain. They employed a machine learning model to analyze 1,079 different structural and functional measures from the MRI data. This advanced technology can detect subtle patterns of aging that might be missed by traditional analysis.
The team then calculated a metric called the “brain age gap.” This was done by subtracting the participant’s chronological age from their estimated brain age. A positive gap indicates that the brain appears older than expected for the person’s actual age. A negative gap suggests the brain appears younger and healthier. This metric serves as a proxy for general brain integrity.
The study also utilized blood samples collected at the beginning of the research period. The investigators measured several biomarkers of systemic inflammation, including C-reactive protein and white blood cell counts. These markers were combined into a composite inflammation score. This score allowed the team to test if inflammation in the body explained the link between diet and brain changes.
The results revealed a significant association between dietary habits and brain aging. Individuals who consumed the most pro-inflammatory diets had a larger brain age gap compared to those who ate anti-inflammatory diets. Specifically, those in the most pro-inflammatory group had brains that appeared about half a year older on average than those in the healthiest diet group. This suggests that poor dietary quality may accelerate the biological clock of the brain.
This association was dependent on the age of the participants. The link between a pro-inflammatory diet and older brain age was much stronger in adults aged 60 and older. In this older demographic, a pro-inflammatory diet was associated with an advanced brain age of nearly a full year. This implies that older adults might be more vulnerable to the negative effects of a poor diet.
The researchers also found that systemic inflammation played a measurable role in this relationship. Statistical analysis showed that the composite inflammation score accounted for about 8 percent of the association between diet and brain age. This finding provides evidence that pro-inflammatory foods may harm the brain in part by increasing overall inflammation in the body. The remaining effect is likely due to other mechanisms not captured by the inflammation score.
Genetic risk factors were also considered in the analysis. The researchers looked at polygenic risk scores for Alzheimer’s disease and the presence of the APOE4 gene. The association between diet and brain age was generally consistent regardless of genetic risk. However, the link appeared somewhat stronger in individuals who were not carriers of the APOE4 gene. This suggests that diet remains a relevant factor for brain health across different genetic profiles.
These findings align with previous research showing that healthy diets support cognitive function. Diets like the Mediterranean or MIND diet emphasize the same anti-inflammatory foods identified in this study. These include plant-based foods rich in polyphenols and healthy fats. The current study adds to the literature by using a global measure of brain structure rather than focusing on specific regions like the hippocampus.
“We found that those eating more pro-inflammatory diets had a significantly larger brain age gap – meaning they had an older, less healthy brain than would be expected based on their chronological age,” Dunk told PsyPost. “Those consuming the most pro-inflammatory diets had an advanced brain age by half a year compared to those with the most anti-inflammatory diets. This association was stronger in adults 60 years of age or older, suggesting that older adults may benefit most from an anti-inflammatory diet.”
“We were also able to confirm that systemic inflammation partially accounted for this association, by using a composite score of several inflammatory markers in the blood. In other words, those consuming more pro-inflammatory diets tended to have higher levels of circulating inflammatory biomarkers, which were in turn associated with older brain age. This finding suggests that an anti-inflammatory diet could potentially support brain health in part by promoting lower levels of inflammation in the body.”
But there are some limitations to this study. The UK Biobank participants are generally healthier and wealthier than the average population. This selection bias might affect how well the results apply to the general public. The study is also observational in nature. It can show a connection between diet and brain age but cannot definitively prove that diet causes the aging.
Another limitation involves the dietary assessment method. Self-reported data is subject to memory errors and may not perfectly reflect actual intake. Additionally, the Dietary Inflammatory Index focuses on nutrients rather than whole foods. People consume complex combinations of foods, not isolated nutrients. However, the index is a validated tool that generally correlates well with healthy eating patterns.
“The Dietary Inflammatory Index is calculated based on a person’s consumption of a variety of macronutrients, micronutrients, whole foods, and spices,” Dunk noted. “Because this index isn’t primarily based on whole foods, it might not be immediately obvious what a pro- or anti-inflammatory diet actually looks like.”
“Some of the anti-inflammatory components include dietary fiber (found in whole plant foods), omega 3 fats, onion, garlic, ginger, turmeric, green and black tea, isoflavones (soy), polyphenols (especially high in berries), and many vitamins and minerals. On the other hand, foods high in saturated fat, trans fat, or cholesterol tend to be pro-inflammatory.”
“This scoring is generally consistent with healthy dietary patterns we often hear about – like the Mediterranean, MIND, or whole food plant-based diets. Each of these dietary patterns are high in healthy plant foods (fruits, vegetables, whole grains, legumes, nuts, seeds) and limit foods like red and processed meat, deep-fried and ultraprocessed foods, and other animal-based foods to varying degrees, which are higher in saturated fat and cholesterol.”
Future research is needed to confirm these findings in more diverse populations. It would be beneficial to investigate whether switching to an anti-inflammatory diet can reverse accelerated brain aging. Clinical trials could provide stronger evidence of a causal relationship. For now, the results suggest that choosing anti-inflammatory foods may be a practical strategy for maintaining brain health as we age.
The study, “The association between a pro-inflammatory diet and brain age in middle-aged and older adults,” was authored by Michelle M. Dunk, Huijie Huang, Jiao Wang, Abigail Dove, Sakura Sakakibara, Jie Guo, Adrián Carballo-Casla, David A. Bennett, and Weili Xu.
