StarPower is a result of simple trial and error. 
StarPower was invented and developed by a Neuroscientist. Bill Supple received his Ph. D. in Neuroscience from Dartmouth in 1986. His area of study was learning and memory, broadly defined, and brainstem-cerebellar mechanisms of plasticity, in particular. He authored a large number of research papers, authored chapters on Learning and Memory, and received the National Institute of Mental Health's Presidential FIRST Investigator Award. His research program was supported with grants from the American Heart Association, National Institute of Mental Health, National Institute of Health, National Science Foundation and the National Heart, Lung and Blood Institute.
Like many other people in the modern world, Bill suffered from a chronic condition: psoriasis. Initially diagnosed in his early 20s, it would come and go with the seasons and got progressively worse over time.
The answer to his psoriasis condition was not found in traditional remedies or by visiting dermatologists. If anything, prescribed treatments like topical tar and steroids made the psoriasis worse. Using nothing more than informed common sense, and a little luck, he reasoned that the seasonal variation represented by the lack of sunlight and its Vitamin D was probably a factor in his psoriasis (since he lived in Vermont). Supplementing with VitD, at higher doses coupled with folic acid 'cured' the psoriasis. The experimentation phase entailed finding the correct UV light recipe to optimize the synergistic effects of the VitD and folic acid. The resulting product was called StarPower.
Unfortunately, his wife Toni suffered with ulcerative colitis and, again, nothing the doctors did really helped. Since psoriasis is an autoimmune disease it was reasonable to expect StarPower to possibly help other autoimmune-based conditions like ulcerative colitis. She started taking StarPower on a Sunday, by Wednesday the bleeding had stopped and has remained in remission since (11 years and counting). After two years or so into taking StarPower she had a routine colonoscopy. Her gastroenterologist reported that she had an unremarkable result, meaning the colon was healthy...normal. Is no bleeding and a normal colonoscopy evidence of a 'cure'? It really doesn't matter. What matters is that a major risk factor for the development of colon cancer is gone, that's what matters.
An individual may express the chronic lack of VitD in their own way. The disease that you may eventually develop from chronic VitD deficiency is probably already encoded as some sort of weak link in your genes. Bill expressed his chronic VitD deficiency in the form of psoriasis - he was lucky, he could see it on his skin. Toni expressed it as ulcerative colitis. How you may express it will become apparent in the future in the form of your autoimmune disease.
Various cancers of epithelial origin (breast, prostate, lung, colon) and autoimmune diseases of many types share chronic inflammation as a root cause. The chronic inflammation caused by vitamin D deficiency disrupts immune system function which is a precursor to many terrible conditions and diseases. Despite decades of research and billions spent on research, the incidence of all of these diseases are at the highest levels in history. Vitamin D is the string that ties all these seemingly unrelated conditions together. It's just common sense to try to prevent an underlying cause of these diseases if it can be done safely if possible. (A new report finds that all cancers are up 8% in the past 5 years) story here
Why is the incidence of all these autoimmune diseases growing? Because people are irrationally fearful of the sun, producing chronic VitD deficiency, which is the major risk factor for immune system dysfunction causing chronic inflammation which then leads to your increased disease risk.
Read more about the Discovery of StarPower 
