Wolffia globosa, also known as mankai, is an aquatic plant that is consumed as a vegetable or additive to food in parts of Asia. It is rich in protein, omega-3 fatty acids, polyphenols, vitamins, and minerals. In obese or dyslipidemic people, eating a green Mediterranean diet including Wolffia globosa shakes slowed brain volume loss but did not affect cognitive function. No clinical trials have tested whether Wolffia globosa alone has benefits for cognitive functions. Wolffia globosa contains high levels of manganese, so excessive intake could be unsafe.
One clinical trial tested the effects of a green Mediteranean diet that included Wolffia globosa shakes as part of the diet, but no clinical trials have tested whether Wolffia globosa alone has benefits for cognitive functions. Our search identified:
No studies have tested Wolffia globosa by itself as an intervention for preventing dementia or cognitive decline.
In a randomized controlled clinical trial, 224 participants with obesity/dyslipidemia were assigned to one of three groups: 1) a control group that received nutritional counseling, 2) a low-calorie Mediterranean diet group with high amounts of vegetables, poultry/fish replacing beef/lamb, and 28 grams of walnuts/day, and 3) a low-calorie polyphenol-rich green Mediterranean diet group that followed the Mediterranean diet instructions, but in addition, consumed green tea and a Wolffia globosa shake (100 grams, frozen plant cubes) as a dinner substitute, while avoiding processed and red meat [1]. All groups received free gym membership and were encouraged to exercise. After 18 months of intervention, there was less decline in the volume of the hippocampus, a brain region important for learning and memory, in people eating the Mediterranean diet compared to those in the control group, with the best outcomes seen in the green Mediterranean diet group. Greater intake of Wolffia globosa, green tea, and walnuts, and reduced intake of red and processed meat were associated with slower decline in hippocampus size. People consuming the green Mediterranean diet had improved maintenance of blood glucose levels (i.e., improved glycemic control), which was also associated with the slowing of hippocampus volume loss with aging [2]. Neither the Mediterranean diet nor the green Mediterranean diet were associated with benefits in cognitive functions in this study, which could be explained by good baseline cognitive health of the study participants and the short intervention time.
No human research has examined whether Wolffia globosa can improve cognitive functions or slow decline in people with dementia. No laboratory studies have tested Wolffia globosa in models of dementia.
No clinical trials have tested the long-term safety of Wolffia globosa treatment on its own. A small clinical trial in type 2 diabetes patients reported that a 2-week intervention with Wolffia globosa did not result in any side effects related to the intervention [3]. The clinical trials that included Wolffia globosa as part of a dietary intervention were not designed to investigate safety [1; 4]. In a safety assessment by the European Food Safety Authority Panel (EFSA Panel) on Nutrition, Novel Foods and Food Allergens, Wolffia globosa powder was deemed a safety concern due to a potential increase in manganese intake [5]. Also, Wolffia globosa contains a compound called phylloquinone, which could antagonize the effects of blood thinners such as coumarins.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Wolffia globosa is usually in powder form or frozen cubes for smoothies. A randomized controlled trial testing the green Mediterranean diet including mankai shakes used 100 grams of frozen cubes per day [1]. In Thailand and other Asian countries, it is added to food (e.g., curry, salad, omelet).
Full scientific report (PDF) on Cognitive Vitality Reports