Eating a Mediterranean diet full of fruits and vegetables, olive oil, whole grains, and seafood is well known for benefiting heart health. But a new study suggests that one particular version of the diet could help boost brain health—especially if it includes green tea. More specifically, the research, published in the journal Clinical Nutrition, found that following a green-Mediterranean diet—which includes green tea and the aquatic plant Mankai—is associated with slower brain aging. This sounds promising, but what exactly is a green-Mediterranean diet? And how does green tea help your brain? Here’s what you need to know.

What’s a Green-Mediterranean Diet?

The green-Mediterranean diet builds upon a traditional Mediterranean diet. Both are centered around emphasizing vegetables, fruits, whole grains, legumes, nuts, seeds, olive oil, and moderate amounts of fish and poultry, while limiting red meat and processed foods. “The green version places an even bigger emphasis on plant-based foods,” says Matthew Landry, PhD, RDN, an assistant professor of population health and disease prevention at the UC Irvine Joe C. Wen School of Population and Public Health. “The green-Mediterranean diet has been associated with improvements in brain health, cardiovascular and diabetes risk factors, and improvements in the gut microbiome.”

The green-Mediterranean diet consists of an abundance of vegetables, fruits, beans/lentils, legumes, whole grains, olive oil, and nuts/seeds with small amounts of fish and poultry, says Lon Ben-Asher, RDN, LD/N, a registered dietitian, nutrition specialist, and educator with Pritikin Longevity Center. “It focuses on consuming most protein intake from plants and the addition of polyphenols, which are bioactive compounds that reduce oxidative stress and inflammation—found in green tea, walnuts, and dark green leafy vegetables,” she explains.

How Does Green Tea Benefit Brain Health?

For the study, researchers analyzed data from around 300 participants for 18 months while they consumed one of three diets: a standard healthy diet, a traditional calorie-restricted Mediterranean diet, and the green-Mediterranean diet, which included green tea and Mankai. They found that higher levels of certain proteins were associated with faster brain aging, and that those protein levels decreased in those following the green-Mediterranean diet. The researchers attributed this protective effect to the anti-inflammatory molecules contained in green tea and Mankai.

But there are plenty of other brain-boosting benefits of green tea. For starters, green tea consumption is associated with reduced risk of cognitive impairment, improved memory, and potential prevention of neurodegenerative diseases, Landry says, whose current research focuses on identifying the optimal diets for chronic disease prevention. “The protective benefits found in green tea can be attributed to polyphenols,” he explains. “These are plant compounds that have antioxidant and anti-inflammatory benefits. [They] work by scavenging free radicals in the body and also by enhancing antioxidant enzyme activity.”

Additionally, L-theanine, also found in green tea, is an amino acid that increases dopamine and GABA in the brain, which can improve mood and sleep quality, while also having a relaxation effect, says Stacie Stephenson, DC, a practitioner of functional and integrative medicine and board member of The American Nutrition Association. “Generally, many research studies have correlated green tea consumption with better brain aging,” she says. “One meta-analysis from 2025 of 18 studies covering nearly 59,000 participants between the ages of 50 to 69 over the past 10 years showed that the more green tea participants consumed, the less cognitive impairment they had.” 

In addition, green tea’s catechins help calm brain inflammation by lowering inflammatory markers like TNF-α and IL-1β, says Michelle Routhenstein, RD, a cardiology dietitian at EntirelyNourished.com. “This anti-inflammatory effect further supports long-term brain protection and healthy aging,” she notes. Green tea also benefits how we think and feel day-to-day, says Alexander LeRitz, RDN, a registered dietitian at JM Nutrition. “Its unique mix of caffeine and L-theanine works together to improve alertness, focus, and working memory by increasing alpha brain-wave activity,” he says. “This creates a calm but attentive state which many people describe as feeling ‘clear and steady,’ rather than the sharp rise and crash that can come with coffee.”

Additional Health Benefits of Green Tea

Green tea doesn’t just benefit your brain. “The polyphenols that reduce oxidative stress and inflammation likely contribute to better heart health, lower cancer risk, better blood sugar regulation, less joint pain, and may even contribute to longer life,” Stephenson says. More specifically, the green tea catechins help to lower both systolic and diastolic blood pressure by boosting nitric oxide, which relaxes vessel walls and enhances blood flow, Routhenstein says. Additionally, regular consumption of green tea can also help prevent LDL or “bad” cholesterol from becoming oxidized, which is a key step that can lead to plaque formation in the arteries, she notes. “We also see some improvements with insulin sensitivity and reduced risk for diabetes,” Landry says. And according to Ben-Asher, green tea also supports the immune system, reducing the risk of infections and viruses thanks to the polyphenol content.

“All in all, green tea is one of those simple daily habits that can support your health on several fronts,“ LeRitz says. “The blend of polyphenols, caffeine, and L-theanine doesn’t just lift your energy—it also protects the body at a cellular level. As a registered dietitian, I often describe green tea as one of the simplest, evidence-backed habits to support both mental and physical longevity.”