I have this plant at home, which has amused many of my friends. Initially, no one believed in its ability to change anything that is sour in taste, into total sweetness. Until the person concerned have sampled it .. they will repeatedly asked ---> Why & How come !
However, do not be fooled by the fruit. It only changes the taste of your taste buds, at the time of consumption. The original taste of the said item, that reaches your stomach, will never change. Claimed to be good and safe for those, with diabetic problem. Never heard of any side effect to date.
According to Wikipedia, this fruit is also known as Synsepalum Dulcificum. It is a plant with a berry that, when eaten, causes sour foods (such as lemons and limes) subsequently consumed to taste sweet. This effect is due to miraculin, which is used commercially as a sugar substitute. Common names for this species and its berry include miracle fruit, miracle berry, miraculous berry, sweet berry.
The berry itself has a low sugar content and a mildly sweet tang. It contains a glycoprotein molecule, with some trailing carbohydrate chains, called miraculin. When the fleshy part of the fruit is eaten, this molecule binds to the tongue's taste buds, causing sour foods to taste sweet. At neutral pH, miraculin binds and blocks the receptors, but at low pH (resulting from ingestion of sour foods) miraculin binds protons and becomes able to activate the sweet receptors, resulting in the perception of sweet taste. This effect lasts until the protein is washed away by saliva (up to about 60 minutes).