this have to do with dr. and presidential candidate ben carson? this. >> let me just briefly delve into how i became associated with the products of this company. >> reporter: ben carson has a relationship with mannatech spanning nearly a deck said since he began taking it beginning in 2004 to 2013, dr. carson made four speeches in front of mannatech sales associates and the most recent speech carson was paid $42,000. for the three previous speeches, the company made donations to the carson scholarship fund but wouldn't say how much. in his speeches and testimonial interviews used in promotional videos, carson discussed how he beat prostate cancer with surgery while taking mannatech's supplements. >> that was as close to nature as i could possibly get and that's really how i settled on it. >> reporter: until he decided to run for president, dr. ben