The Mediterranean diet is known for its effects on heart health, weight management, and as a contributor to longevity. The lean-protein, plant-centered, polyphenol-loaded approach is so tried-and-true that the Mayo Clinic even recently spun up their own version. Now researchers at Harvard and other universities have identified a handful more ingredients that could add another worthy benefit: memory staying power.

Their study, coming out in the October 2025 issue of Clinical Nutrition, reports that adding green tea and two specific foods to your menu may help protect your brain against aging. 

An international team of public health and brain researchers, hailing from Harvard T.H. Chan School of Public Health, Ben-Gurion University in Israel, and the University of Leipzig in Germany, analyzed data from around 300 participants in what Harvard calls “one of the longest-running studies on the link between brain and diet” to explore the link between the two. Specifically, they compared the impacts of three diets:

• a standard healthy diet
• a traditional calorie-restricted Mediterranean diet
• the “green-Mediterranean” diet

The team explains their finding that a “green-Mediterranean” diet “is potentially neuroprotective for age-related brain atrophy.” This diet namely folds in green tea, walnuts, and Mankai—a nutrient-dense aquatic plant most commonly consumed in Southeast Asia, according to the Alzheimer’s Drug Discovery Foundation. The team also emphasized lower amounts of red and processed meat.

After measuring protein levels in the participants’ blood and performing MRI-weighted brain scans to calculate brain aging based on participants’ “neural network,” they determined that higher levels of two proteins in the blood—Galectin-9 (Gal-9) and Decorin (DCN)—were associated with faster-aging brains. Green tea, walnuts, and Mankai helped to keep these protein levels low, an effect they attribute to the anti-inflammatory content in these foods—specifically, three to four cups of green tea “daily,” and 28 grams of walnuts, which is equivalent to one ounce and works out to around seven walnuts.

One of the study’s co-authors, Harvard postdoctoral research fellow Anat Meir, PhD, MPH, remarked that the research “gives us a dynamic window into brain health, helping to reveal biological changes long before symptoms may appear. By mapping these protein signatures, we gain powerful new insight into how interventions, such as diet, may help preserve cognitive function as we age.”

According to the National Institutes of Health (NIH), aging can affect the brain in several ways, including possible decreased blood flow, increased inflammation, or the shrinking of certain brain parts that can be important for learning or other tasks. To combat this, experts regularly recommend—along with dietary changes—engaging in brain health habits through exercise, healthy sleep habits, managing stress and underlying health conditions, and staying socially and cognitively active.  

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