Inflammatory Diets Raise Risk of Brain Disorders

Pro-inflammatory diets are associated with higher risks of brain disorders, including stroke, dementia, anxiety, depression, and sleep disorders, according to a study published in Translational Psychiatry.¹

As the global population continues to age, brain disorders are increasingly recognized as leading causes of disabilities and death, accounting for one-third of all diseases in developed countries.² Inflammation contributes to aging and brain disorders, with diet playing a key role in regulating it.¹

The dietary inflammatory index (DII) is a tool used to evaluate the inflammatory potential of an individual’s diet. It is associated with select inflammatory markers, including IL-4 and IL-6, and is based on the intake of various dietary components. To account for differences in energy intake, the energy-adjusted DII (EDII) modifies DII scores by adjusting for energy expenditure per 1000 kcal.

While numerous studies have explored the impact of DII on myocardial infarction, mortality, and diabetes mellitus, fewer have investigated its relationship with brain disorders. To address this gap, the researchers used dietary data to calculate DII and EDII scores and examine their associations with the risk of developing brain disorders and the potential underlying mechanisms involved.

Vegetables, fish oil, fruit, and high-fiber foods have anti-inflammatory effects, while low-fiber bread and animal fats are associated with pro-inflammatory effects. | Image Credit: Siarhei - stock.adobe.com

They used dietary data from the UK Biobank, a national prospective cohort of participants aged 40 to 69 from 22 regional assessment centers, collected between 2006 and 2010. The researchers assessed the DII and EDII scores using plausible dietary recall from eligible participants.

Each participant’s score was adjusted for energy intake and standardized to the global mean value. Higher scores indicated a pro-inflammatory diet, while lower scores indicated an anti-inflammatory diet. The study’s outcomes of interest included brain MRI measures and brain disorders, specifically all-cause dementia, Alzheimer disease, Parkinson disease, sleep disorders, stroke, anxiety, and depression.

To estimate associations between brain disorders and the DII and EDII scores, the researchers used Cox proportional-hazard models, a restricted cubic spline model, ordinary least squares regressions, and structural equation models.

The study population consisted of 164,863 UK Biobank participants. Most participants (53.2%) were female, and the mean (SD) age was 58.97 (8.05) years. In terms of brain disorders, the study included 2154 participants with incident all-cause dementia, 963 with Alzheimer disease, 1110 with Parkinson disease, 2922 with sleep disorders, 4804 with stroke, 6959 with anxiety, and 5298 with depression.

The researchers noted that DII and EDII scores were normally distributed across the study population. DII scores ranged from –6.5 to 5.5 points, while EDII scores ranged from –4.5 to 7. Their findings suggested that vegetables, fish oil, fruit, and high-fiber foods have anti-inflammatory effects. In contrast, low-fiber bread and animal fats are associated with pro-inflammatory effects.

Compared with participants with the lowest DII or EDII scores, those with the highest scores were more likely to be younger and female, with lower education and income levels. They were also less likely to be White or engage in physical activity and tended to have a high body mass index.

The restricted cubic spline analyses discovered nonlinear associations between DII and EDII scores and the risk of all-cause dementia, Alzheimer disease, sleep disorders, stroke, anxiety, and depression. In the multivariable-adjusted models, each unit increase in DII score was positively associated with the risks of all-cause dementia (HR, 1.039; 95% CI, 1.011-1.068; P = .009), sleep disorders (HR, 1.036; 95% CI, 1.013-1.060; P = .004), stroke (HR, 1.020; 95% CI, 1.002-1.038; P = .044), anxiety (HR, 1.039; 95% CI, 1.024-1.054; P < .001), and depression (HR, 1.036; 95% CI, 1.019-1.054; P < .001).

Similarly, each unit increase in EDII score was positively associated with increased risks of all-cause dementia (HR, 1.090; 95% CI, 1.031-1.154; P = .002), sleep disorders (HR, 1.079; 95% CI, 1.036-1.123; P < .001), anxiety (HR, 1.042; 95% CI, 1.024-1.061; P < .001), and depression (HR, 1.036; 95% CI, 1.014-1.058; P < .001).

Participants with the highest DII scores vs those with the lowest DII scores had a higher risk of all-cause dementia by 16.5% (95% CI, 1.038-1.307), sleep disorders by 17.2% (95% CI, 1.064-1.291), stroke by 11.0% (95% CI, 1.029-1.197), anxiety by 18.4% (95% CI, 1.111-1.261), and depression by 13.6% (95% CI, 1.057-1.221). The researchers noted that similar trends were observed with the EDII scores.

Lastly, the results from the sensitivity and multivariable analyses reinforced the main findings, determining that pro-inflammatory diets were associated with a higher risk of brain disorders.

The researchers acknowledged their study’s limitations, including the dietary intake information being self-reported, which may introduce measurement errors. Also, the calculation of DII and EDII scores is limited by the lack of complete information on several dietary nutrients. Despite these limitations, they expressed confidence in their findings and suggested areas for further research.

“Our study indicated a shift toward food intake that emphasizes [an] anti-inflammatory diet to improve health,” the authors concluded. “However, further studies are needed to clarify the risk of brain disorders in relation to a pro-inflammatory diet among a more racially diverse population.”

References

1. Fu Y, Chen SJ, Wang ZB, et al. Dietary inflammatory index and brain disorders: a large prospective cohort study. Transl Psychiatry. 2025;15(1):99. doi:10.1038/s41398-025-03297-4
2. Olesen J, Leonardi M. The burden of brain diseases in Europe. Eur J Neurol. 2003;10(5):471-477. doi:10.1046/j.1468-1331.2003.00682.x