Aging isn’t just about birthdays. It’s also about how our organs age on the inside—brains included. Scientists can now estimate a person’s “brain age” from MRI scans and compare it to their actual age. When brain age is older than expected, risk for cognitive problems tends to run higher; when it’s younger, that’s a good sign. 

Diet is one way you can support a healthier brain, and Mediterranean-style patterns keep coming up as brain-friendly. Now, a new analysis points to a specific tweak that could potentially nudge brain aging in the right direction. It’s drinking green tea as part of a higher-polyphenol, plant-forward “green-Mediterranean” plan.

In this study, researchers tracked brain age along with a panel of blood proteins that can reflect inflammation and other brain-relevant biology. They found that people assigned to the green-Med diet (a Mediterranean diet with extra polyphenols from green tea and other sources) showed the most favorable protein shifts and overall signs of a “younger” brain profile.

How Was This Study Conducted?

This was a secondary analysis of the 18-month DIRECT PLUS randomized controlled trial conducted in a large Israeli workplace. About 300 adults (mostly men) with abdominal obesity and/or dyslipidemia were randomized to three diet groups: 

• Healthy dietary guidelines
• A calorie-restricted traditional Mediterranean diet
• A green-Mediterranean diet that emphasized more polyphenols.

The green-Mediterranean group specifically got 3 to 4 cups of green tea, walnuts and a Mankai (duckweed) shake daily. All groups received physical activity guidance. Brain MRI scans were used to estimate brain age with a validated deep-learning model. The brain-age gap (brain age minus chronological age) was the primary aging metric here. Researchers also measured more than 80 circulating proteins and looked for patterns tied to brain-age changes over time.

What Did the Study Find?

Two proteins—galectin-9 and decorin—stood out: higher levels were associated with an older-than-expected brain at baseline. Over 18 months, galectin-9 levels fell significantly in the green-Med group compared with the healthy-guidelines group. The overall pattern also shifted more favorably in the green-Med group. 

In exploratory analyses, drinking about 4 cups of green tea per day and eating about seven walnut servings a week were each associated with greater reductions in galectin-9. (The Mankai trends were similar but not statistically significant in this dataset.)

These molecular shifts align with previous DIRECT PLUS reports showing that both Mediterranean and green-Mediterranean diets may decrease brain shrinkage over 18 months, with green-Med showing the most benefits. Together, the findings suggest that a higher-polyphenol Mediterranean pattern—with green tea as a daily habit—may help create conditions for slower brain aging.

Like all studies, there were limitations. Most participants were male and had metabolic risk, so the findings may not apply to everyone. The study also didn’t detect clear differences between groups on standard cognitive tests over 18 months, so the protein and MRI changes should be viewed as biological signals, not proof of clinical cognition changes. There may also be other biomarkers of brain health that were not measured in this study. More diverse, longer trials are needed.

How Does This Apply to Real Life?

You don’t need a lab to act on this. The core takeaway is practical: build a Mediterranean base and layer in polyphenol-rich “green-Med” upgrades—with green tea as an easy daily upgrade.

• Make green tea your default. Aim for 2 to 4 cups per day (hot or iced). If you’re caffeine-sensitive, try an earlier cutoff or consider decaf green tea.
• Go big on plants and polyphenols. Try eating a small handful of walnuts most days. Fill your plate with vegetables, legumes, whole grains, herbs and leafy greens.
• Swap meats strategically. Tilt away from red/processed meats toward fish and poultry; that was part of both Mediterranean diet-inspired eating plans in this study and integral to the green-Med approach.
• Don’t forget fundamentals. The study suggests that better glucose control and regular physical activity are also associated with brain benefits, so aim for steady meals built from fiber-rich carbs, protein and healthy fats, and keep moving.

Our Expert Take

In a randomized trial, a green-Mediterranean eating pattern featuring daily green tea, walnuts, more plants and less red/processed meat was linked to younger-looking brains on MRI and favorable shifts in blood proteins tied to brain aging. It’s not a magic bullet, and more research is needed to confirm long-term cognitive effects, but as everyday habits go, sipping green tea and eating more plant-forward Mediterranean meals look like smart moves for brain health.