The Mediterranean Diet, with its focus on fruit, vegetables, whole grains, legumes, and extra virgin olive oil, is famously healthy – but what if it could be even better?
Scientists have studied a “Green” twist on the original and found that it can help keep our brains young.
The Green Mediterranean Diet is similar to the classic version but cuts red and processed meat further and adds daily green tea plus a shake made from the aquatic plant Mankai.
In an 18-month trial, 294 participants consumed one of three diets: a standard healthy diet (HDG), a traditional calorie-restricted Mediterranean diet (MED), or a Green Mediterranean diet (Green-MED).
The MED diet included vegetables, poultry and fish, and little red meat, plus 28g of walnuts daily. The Green-MED diet followed the same calorie and macro guidelines but further reduced red and processed meat and added 3–4 cups of green tea and a daily Mankai (duckweed) shake for dinner.
If you’re wondering what on earth Mankai is, let me explain. It’s one of the world’s tiniest leafy green vegetables and it grows in bodies of freshwater such as ponds and lakes. It has been consumed for centuries in Southeast Asia, particularly in Thailand, Laos, and Myanmar, where it’s traditionally formed into balls and used in soups in place of meat, earning it the nickname “vegetable meatball”.
The reason it’s got scientists so excited is that it really is a good substitute for meat. Unlike most vegetables, which are low in at least one essential amino acid, Mankai provides all nine essential amino acids in sufficient amounts, making it unusually high in protein for a plant.
Moreover, it is highly nutrient dense, delivering iron and vitamin b12 which is normally found in animal products such as meat, eggs and dairy, not vegetables. Mankai also has an advantage over meat – it's packed full of polyphenols: beneficial compounds which help to protect the plant, and – it turns out – us. Polyphenols have an antioxidant and anti-inflammatory effect in the body, as well as acting as food for the good microbes in our gut – and gut health is a key driver of overall health.
During the study, participants following the Green-MED diet showed reductions in blood proteins linked to accelerated brain ageing. The researchers suggest that this protective effect may come from the polyphenols in green tea and Mankai, which help reduce inflammation that can harm the brain.
Dr. Federica Amati, lead nutritionist at ZOE, notes that the benefits of the Green-MED diet go beyond brain health. “The evidence suggests improvements in glucose control, satiety, and potentially liver fat reduction, though longer and larger studies are needed to confirm these effects,” she says.
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A 2020 study also found that the Green-MED diet may enhance the cardiometabolic benefits of the traditional Mediterranean diet, making it even better for heart health. Additionally, there is evidence that it may be more effective than the standard Mediterranean diet at reducing harmful visceral fat.
The polyphenols in green tea and Mankai, which help reduce inflammation that can harm the brain
Dr. Amati highlights that Mankai may be especially valuable for those avoiding animal products. “This diet demonstrates how a plant-based approach can be nutritionally complete when carefully balanced. Mankai’s high-quality protein and micronutrient profile position it as an innovative solution for those seeking more sustainable and ethical food choices. Its ability to provide active vitamin B12 is unusual in plant foods, filling a major nutritional gap for vegans and vegetarians.”
But what to do if you can’t get your hands on the tiny aquatic plant? It’s not as if it’s widely available at Tesco… Dr Amati says: “Good alternatives include legumes and pulses such as lentils and chickpeas, which are excellent sources of protein, iron, and fiber. Quinoa is another strong option, offering complete protein along with a high polyphenol content.
Seeds like hemp, flax, and chia bring omega-3 fatty acids, minerals, and additional protein to the table. While not as protein-dense as Mankai, alfalfa sprouts and watercress provide valuable micronutrients. For those avoiding animal products, fortified vegan cereals and plant-based milks supply vitamin B12, which plants don’t usually offer.
When these foods are combined with a variety of nuts, rich in polyphenols and essential micronutrients, they can form the foundation of healthy, sustainable meals even without access to Mankai.”
