The herb contains L-DOPA, a precursor to the neurotransmitter dopamine. L-DOPA converts into dopamine, an important brain chemical involved in mood, sexuality, and movement. http://en.wikipedia.org/wiki/Mucuna_pruriens
Dopamine works as one of the best natural hgh (human growth hormone) releasers by stimulating the pituitary gland to increase its production. High levels throughout life of the body's own natural growth hormone, not from synthetic hormones injections, is known as a major key for human longevity. Dopamine also increases other youth hormones such as testosterone. It must be mentioned that these increases are never throwing the endocrine system out of balance, merely improving levels which tend to decrease over time in the average person.
The great thing with this herb is that it gets your body to make growth hormone itself and thus control the amount it makes and avoid the problems associated with elevated levels of hgh. This is much safer to use than synthetic human growth hormone which is quickly gaining a reputation as a carcinogenic "steroid-like" performance enhancer. http://www.secrets-of-longevity-in-humans.com/mucuna-pruriens.html
Informative Video: http://www.youtube.com/watch?v=mqdlxzzNQUY
Photo Source: http://www.rain-tree.com/Plant-Images/velvetbean-pic.htm