Why is there no scientific clincial research on alternative methods to treat psoriasis?

I've just seen my 4th or 5th derm today. Have had Psoriasis for 15 years. Not one of them supports alternative treatment for ps because they say there is no clincial research backing it up. They want to see peer-reviewed, double-blind research that includes placebo before they will even give it a 2nd look. Yet we read 1000's and 1000's of people's individual testimonies that their alternative method worked. But because it is all anecdotal, no western medicine doctor buys it. As a result I get prescribed cream after cream after cream and told to go do light therapy. I'm tired of both of those options and don't want the long term effects of them on/in my body.

Anyone have any information about why there isn't any research? Is it because it is just plain hard to do - monitor/control people's diets well enough to consider it "research"? Or do you think there may be something evil out there - like drug companies not wanting the "uneducated" public to know that alternative therapies really do work?

BTW, I'm currently trying to treat my ps with a Naturopath who currently has me on a no yeast diet and Yeast Away product. No results yet (2 weeks) except weight loss!

I welcome any discussion about this. Thank you!