Nelumbo Nucifera is an Asiatic medicine known as 'Sacred Lotus' that is used in a variety of dishes and recipes. It has a delicate aroma, and apparently has a fair bit of symbolic importance as well.
In regards to the studies on it, it is lacking any human interventions. The herb itself appears to be quite high in polyphenolic compounds such as catechin and procyanidins and possesses very general 'healthy' properties secondary to this. There are not too many studies on unique bioactives in Sacred Lotus, but these studies seem to be centered on Neferine; a constituent which is at the moment unique to Nelumbo Nucifera.
Most of the evidence currently is either using extracts of the plant itself which find benefits that can be achieved with other supplements due to being general end points, or they use isolated Neferine in relatively high doses. Studies using isolated Neferine note anti-depressant and sedative properties which are seemingly potent, and some possible anti-obesogenic (not necessarily fat burning) and anti-diabetic properties. Some fat burning properties have been noted with the whole plant, but these are not overly remarkable.
Not enough information is currently known to suggest an optimal dosage of Nelumbo Nucifera for the purpose of supplementation.