I saw an advertisement for a weight-loss product. When I called the manufacturer to find out what's in it, I was told they couldn't tell me because it's a "proprietary blend." What does that mean?  [electronic resource] 

 -  Mayo Clinic health letter (English ed.)  Nov 2005 
 - 8 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0741-6245 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Chemistry, Pharmaceutical--legislation & jurisprudence<br/>Dietary Supplements--analysis<br/>Drug Labeling--legislation & jurisprudence<br/>Humans<br/>Patents as Topic<br/>Weight Loss