In an 18-month randomized trial, people who followed a “green-Mediterranean” diet saw less of a protein signature associated with aging in the brain than those on a standard healthy diet.
The green-Mediterranean diet in this study included green tea and the aquatic plant Mankai, in addition to typical Mediterranean diet components.
The study tracked changes in blood proteins tied to brain aging, suggesting diet-linked biological changes may happen before cognitive symptoms appear.
As we get older, our brains don’t always feel as sharp as they used to, and researchers are exploring ways diet might slow or even reverse aspects of that process.
A new study from Harvard T.H. Chan School of Public Health, Ben-Gurion University, and colleagues suggest that a version of the Mediterranean diet with extra “green” additions — specifically green tea and Mankai (an aquatic plant) — might help slow brain aging.
The study
The study is part of something called the DIRECT-PLUS trial. Roughly 300 participants were followed for 18 months and randomly assigned to one of three diet groups:
A standard healthy diet
A traditional calorie-restricted Mediterranean diet (lots of vegetables, less red meat, more fish and poultry, low in simple carbs)
The “green-Mediterranean” diet, which is like the Mediterranean diet but with added green tea and Mankai.
The researchers collected blood samples and measured levels of certain proteins that are believed to correlate with brain aging — that is, how “old” your brain seems compared to your actual age.
Higher levels of some of these proteins are associated with accelerated brain aging. The idea was to see whether dietary changes could shift those protein levels.
What did they find?
Over the 18 months, people in the green-Mediterranean group showed reductions in certain proteins in their blood that are thought to reflect faster brain aging. In contrast, those reductions were not as pronounced in the other diet groups.
In short, adding green tea and Mankai appeared to help slow down markers of brain aging more than a standard healthy or even traditional Mediterranean diet.
The key point: these changes were biological — they happened in protein markers in the blood — before any obvious cognitive decline. This suggests that the green-Mediterranean diet could influence early, underlying processes of brain aging rather than just reacting to symptoms once they appear.
“Studying the circulating proteins in blood allows us to observe, in a real-life setting, how the brain’s aging processes are influenced by lifestyle and dietary changes,” researcher Anat Meir, said in a news release.
“This approach 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.”
How to try a green-Mediterranean approach
You don’t need to overhaul your life overnight to start adopting elements of this eating pattern. Here are a few approachable ways to begin:
Build a Mediterranean base. Focus on vegetables, fruits, legumes, nuts, whole grains, and lean proteins like fish or chicken. Use olive oil as your main fat.
Go greener. Add a couple of cups of unsweetened green tea each day. It’s calorie-free and rich in plant compounds studied for their antioxidant benefits.
Experiment with greens like Mankai. While Mankai (also known as duckweed) isn’t widely available everywhere, some markets and supplements carry it. If you can’t find it, think about incorporating other nutrient-dense greens like spinach, kale, or watercress as a practical stand-in.
Keep it sustainable. The study participants followed their diets for 18 months — so small, steady changes are more realistic than quick fixes.