The green Mediterranean diet is a higher-polyphenol version of the traditional Mediterranean diet that adds three specific components: a daily Mankai (duckweed) shake, three to four cups of green tea, and about an ounce of walnuts. At the same time, it cuts red and processed meat almost entirely, shifting protein sources toward plants. The result is a diet that, in clinical trials, outperformed the already-impressive standard Mediterranean diet on several key health markers.
How It Differs From the Traditional Mediterranean Diet
The traditional Mediterranean diet is already built around vegetables, fruits, whole grains, olive oil, legumes, fish, and moderate poultry. The green version keeps that foundation but makes two important changes. First, it adds roughly 800 milligrams of extra polyphenols per day through green tea and the Mankai shake. Second, it virtually eliminates red meat, relying instead on plant-based proteins, fish, and poultry.
Both versions include daily walnuts and favor poultry and fish over beef and lamb. The distinction is really about what gets layered on top: the green tea, the duckweed shake, and a stricter approach to animal protein.
What Mankai Actually Is
Mankai is a strain of duckweed, a tiny aquatic plant that floats on freshwater. It looks unassuming, but its nutritional profile is unusually dense. Roughly 45% of its dry weight is protein, and that protein contains all nine essential amino acids in a ratio comparable to egg protein. A single cup of the Mankai shake (made from about 20 grams of dried plant) provides around 75% of the recommended daily intake for bioavailable iron and 21% of the daily requirement for vitamin B12, a nutrient that’s notoriously difficult to get from plant sources.
That B12 content is significant. Most plant foods contain either no B12 or only inactive analogs that the body can’t use. Mankai contains the bioactive form, at concentrations that remain stable across growing seasons. For people reducing their meat intake, this makes the shake a practical way to cover a common nutritional gap.
The Three Daily Additions
The green Mediterranean diet asks you to incorporate three things each day on top of the standard Mediterranean framework:
- Mankai shake: A 500-milliliter (roughly 2-cup) shake made from the duckweed plant, rich in protein, iron, polyphenols, and B12.
- Green tea: Three to four cups daily, providing a concentrated source of polyphenols, particularly the type found in tea leaves that support cardiovascular and metabolic health.
- Walnuts: About 1 ounce (28 grams) per day, contributing omega-3 fatty acids and additional polyphenols.
These aren’t arbitrary choices. Each was selected for its polyphenol density, and together they roughly double the polyphenol intake of a standard Mediterranean diet.
Liver Fat Reduction
One of the most striking findings from the DIRECT PLUS trial, the 18-month clinical study that put this diet on the map, involves liver fat. Non-alcoholic fatty liver disease affects roughly a quarter of the global population, and even moderate improvements in liver fat levels can meaningfully lower the risk of liver damage and metabolic disease.
Participants on the green Mediterranean diet lost about 39% of their liver fat over the trial period. Those on the traditional Mediterranean diet lost about 20%, and those following standard healthy dietary guidelines lost about 12%. The green Mediterranean group achieved nearly double the liver fat reduction of the traditional group, even though both groups lost similar amounts of body weight. That gap suggests the extra polyphenols are doing something beyond what calorie restriction alone explains.
Effects on Brain Aging
A separate analysis of the same trial, involving around 300 participants, looked at how diet influenced the brain over 18 months. Researchers measured blood proteins associated with accelerated brain aging, the kind that correlate with cognitive decline and structural changes in the brain. Participants following the green Mediterranean diet showed decreased levels of those proteins compared to the other groups.
The implication is that the polyphenol-rich additions may help slow brain aging at a biological level, though the researchers focused on blood-based markers rather than direct brain imaging for this particular analysis. The finding is consistent with broader evidence linking polyphenol intake to neuroprotective effects.
Changes in the Gut Microbiome
The extra polyphenols also reshape the gut. Participants on the green Mediterranean diet showed increases in bacterial groups like Prevotella, Bacteroides, and Lachnospira, while bacteria associated with inflammation (such as Collinsella) decreased. These shifts matter because gut bacteria play a direct role in metabolizing polyphenols into active compounds the body can use.
One of those compounds, urolithin A, was found at higher circulating levels in the green Mediterranean group and was linked to greater reductions in visceral fat, the deep abdominal fat that wraps around organs and drives metabolic disease. Another compound, hippuric acid, also increased and is considered a marker of beneficial polyphenol metabolism. Beyond fat loss, both diet groups saw improvements in blood pressure and fasting leptin levels (a hormone tied to appetite regulation), but the green version consistently showed an edge. Researchers even observed a roughly nine-month favorable difference in biological age based on DNA methylation patterns, suggesting the diet may slow cellular aging.
What You Actually Eat in a Day
If you strip away the clinical language, a day on the green Mediterranean diet looks something like this: your meals are built around vegetables, whole grains, legumes, nuts, olive oil, fish, and some poultry. You avoid red meat and processed meat. You drink three to four cups of green tea throughout the day and have a Mankai shake, which can work as a snack or part of a meal.
For protein, the emphasis is on plant sources: beans, lentils, chickpeas, tofu, tempeh, edamame, quinoa, and nuts. Fish and poultry fill in the gaps, but the overall protein profile leans heavily plant-based. This is a meaningful shift from the traditional Mediterranean diet, which is more flexible about red meat in moderation.
The biggest practical hurdle is Mankai availability. In the clinical trials, it was provided to participants in a convenient form. Outside of a research setting, finding Mankai can be difficult depending on where you live, though it’s increasingly available as a dried powder or frozen product. If you can’t source it, the remaining components of the diet, particularly the green tea, walnuts, and plant-forward protein approach, still deliver a substantial polyphenol boost over a standard dietary pattern.
Who Benefits Most
The DIRECT PLUS trial participants were adults with abdominal obesity, which means the strongest evidence applies to people carrying excess weight, particularly around the midsection, and those with elevated liver fat or early metabolic risk factors. The diet is calorie-restricted in the trial setting, so the results reflect a combination of reduced calories and increased polyphenol intake.
That said, the underlying logic applies broadly. Replacing red meat with plant protein, increasing polyphenol-rich foods, and adding healthy fats from walnuts are changes that benefit cardiovascular health, liver function, and metabolic markers regardless of starting weight. The green Mediterranean diet isn’t a radical departure from established nutrition science. It’s a more targeted, polyphenol-concentrated version of a dietary pattern that already has decades of evidence behind it.