Brain age and nutrition – how eating habits affect mental health in the long term

As life expectancy increases, so does the concern about declining cognitive function in old age. But our brain is not predetermined – it reacts sensitively to what we put on our plates every day. Current research shows that certain diets can literally keep the brain younger. From the MIND diet and the gut-brain axis to the harmful effects of highly processed foods, science is increasingly deciphering how eating habits shape mental health in the long term.

The scale of the problem: Dementia as a global challenge

The World Health Organization (WHO) predicts that the number of people with cognitive impairments could rise to over 150 million by 2050. Given the lack of cures for neurodegenerative diseases like Alzheimer's, preventive strategies are coming into focus – above all, nutrition as a modifiable lifestyle factor. .

The MIND diet: Targeted nutrition for the brain

The most promising development of recent years is the MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay). It combines elements of the Mediterranean diet with the blood pressure-lowering DASH diet and was specifically designed to prevent cognitive decline. .

What's on the plate

The MIND diet emphasizes ten particularly brain-healthy food groups. :

• Green leafy vegetables (e.g. spinach, kale)

• Berries (especially blueberries and strawberries)

• nuts

• Legumes

• whole grains

• Fish

• poultry

• Olive oil as the main source of fat

• Moderate wine consumption

At the same time, five unhealthy food groups are restricted: red meat, butter and margarine, cheese, sweets and pastries, as well as fried and fast food dishes. .

The scientific evidence

A systematic review from October 2025, which evaluated 11 studies with a total of 17,201 participants aged 57–91 years, comes to a clear conclusion: Six cohort studies and two cross-sectional studies showed a significant association between high MIND adherence and better cognitive outcomes. .

The results of the Multiethnic Cohort Study, involving nearly 93,000 US adults, are particularly impressive. Participants who improved their MIND diet over ten years had a 25% lower risk of dementia compared to those whose diet quality declined. Study leader Song-Yi Park emphasizes: "This suggests that it is never too late to adopt a healthy diet for dementia prevention." .

The REGARDS study, published in September 2024 in the journal Neurology , examined over 14,000 adults and found that people who closely followed the MIND diet had a 4% lower risk of memory and thinking problems. . In women, the effect was even more pronounced, with a 6% risk reduction .

Why the MIND diet works

The combination of lean protein, heart- and brain-healthy omega-3 fatty acids, antioxidants and fiber, with a low amount of added sugar, saturated and trans fats, has been proven to reduce inflammation in the body. Studies suggest that inflammatory processes may accelerate the development of Alzheimer's disease. .

The downside: How Western diets harm the brain

While the MIND diet offers protection, the opposite is not the case. A recent review article from July 2025 details how Western dietary patterns—characterized by high consumption of saturated fats, refined sugars, highly processed foods, and linoleic acid—are associated with cognitive decline. .

The mechanisms are diverse:

• Elevated levels of 4-hydroxynonenal (4-HNE) , a lipid peroxidation product associated with neuronal damage

• Systemic inflammation and oxidative stress

• Endothelial dysfunction (impairment of vascular function)

• Reduced neurotrophic support (fewer growth factors for nerve cells)

Particularly alarming is an animal study from November 2024, which shows that a high-fat diet directly ages microglia – the brain's immune cells – and causes cognitive decline. .

The gut-brain axis: How nutrition controls the brain via the gut

One of the most fascinating areas of research in recent years is the so-called gut-brain axis . A comprehensive review article from September 2025 in the journal Nutrients describes in detail how diet influences brain health via the microbiome. .

The vagus nerve as an information highway

The vagus nerve (nervus vagus) is the tenth cranial nerve and the longest nerve of the parasympathetic nervous system. It connects the brain to almost all internal organs – especially the intestines. Through its afferent fibers, it constantly transmits information about the condition of the intestines to the brain. .

The messenger substances of the intestinal bacteria

The gut microbiota produces a variety of bioactive substances that reach the brain via this axis. :

• Short-chain fatty acids (SCFAs) : These are produced during the fermentation of dietary fiber and have anti-inflammatory properties.

• Neurotransmitters : Approximately 90–95% of the body's own serotonin is produced in the gut.

• Polyphenols : These secondary plant compounds are converted into bioactive metabolites by intestinal bacteria.

• Vitamins and other micronutrients

Dysbiosis as a risk factor

According to current knowledge, an imbalanced gut flora (dysbiosis) contributes to the pathogenesis of neurodegenerative diseases. The mechanisms include:

• Impaired intestinal barrier function ("Leaky Gut")

• Triggering and maintenance of neuroinflammatory reactions

• Promotion of pathological protein aggregation

Food components with neuroprotective potential

A comprehensive review article from December 2025 in Biochemical Pharmacology identifies several dietary components that may have neuroprotective effects via the gut-brain axis. :

Polyphenols

These secondary plant compounds – abundant in berries, green tea, extra virgin olive oil and red wine – have been shown to modulate the microbiota composition and reduce oxidative stress and neuroinflammation. .

Omega-3 fatty acids

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), particularly those found in fatty fish (salmon, mackerel, herring), are essential for neuronal structure and function. They have anti-inflammatory properties and can positively influence the gut microbiota. .

Dietary fiber

As food for healthy gut bacteria, they promote the production of short-chain fatty acids and thus the anti-inflammatory processes in the body. .

Probiotics and prebiotics

While probiotics provide live microorganisms, prebiotics serve as food for the existing beneficial bacteria. Both can positively modulate the gut-brain axis .

The challenges of research

Despite the impressive evidence from observational studies, the research is not without its contradictions. A randomized controlled trial published in the New England Journal of Medicine in 2023 with 604 participants found no significant difference between the MIND diet and the control diet regarding cognitive changes after three years. .

A review article in Nature Reviews Neurology from January 2025 discusses possible reasons for this discrepancy. :

• Intervention duration too short : The effects observed in cohort studies are based on 10+ years – clinical trials often only run for 2–3 years.

• Problems with participant selection : The right risk groups may not have been included.

• Inadequate detection of cognitive changes : The tests used may be insufficiently sensitive.

The authors advocate a two-pronged approach: intensive personalized interventions with precise biomarker measurements on the one hand, and large-scale pragmatic public health interventions on the other. .

Ethnic differences and personalized approaches

Research increasingly shows that the effects of diet are not the same for all population groups. In the Multiethnic Cohort Study, the protective association between the MIND diet and dementia was pronounced in African American, Hispanic, and white participants , while it was less pronounced in Asian American and Hawaiian participants. .

The REGARDS study also found that the MIND diet was a better predictor of cognitive development in Black participants than in white participants. These results underscore the need for personalized, culturally adapted nutritional recommendations.

Conclusion

The link between diet and brain aging is complex, but scientifically well-established. The MIND diet offers a promising approach to reducing the risk of dementia – especially when consistently followed over many years. At the same time, research on the gut-brain axis is opening up entirely new perspectives for preventative strategies.

The good news: It's never too late to change your diet. Starting today to eat more berries, leafy green vegetables, and whole grains, while reducing red meat, sweets, and highly processed foods, is a long-term investment in brain health. In an aging society, this is one of the most effective strategies with the fewest side effects for staying mentally fit.

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Official sources & studies:

• Kim S et al.: Effects of the MIND Diet on Cognitive Function of Older Adults (Clinical Nutrition Research, October 2025) - PubMed

• ICAA: It's Not Too Late To Start Eating Better For Your Brain (July 2025) – Multiethnic Cohort Study

• Tuigunov D et al.: Precision Nutrition and Gut–Brain Axis Modulation (Nutrients, September 2025) – PMC

• Yeh TS et al.: Dietary Factors and Cognitive Function (Current Nutrition Reports, April 2025) - PubMed

• Park SY et al.: Multiethnic Cohort Study – MIND diet and dementia risk (NUTRITION 2025, presented May/June 2025)

• Scarmeas N et al.: Diets to promote healthy brain aging (Nature Reviews Neurology, January 2025)

• Lehoczki A et al.: Western Diet and Cognitive Decline (Nutrients, July 2025) - PubMed

• Sawyer R et al.: MIND diet and cognitive impairment (Neurology, September 2024) – MedicalBrief

• Ghosh N et al.: Nutraceutical interventions for neuroprotection (Biochemical Pharmacology, December 2025) - PubMed

• Chithanathan K et al.: Elocalcitol mitigates high-fat diet-induced microglial senescence (Immunity & Aging, November 2024) - PubMed