Yes a study is not just a study. If I own a pet food company. I pay xyz company to do research on the best diet for a puppy. Guess what their study will state that my kibble is the best. It meets and exceeds that standardize guidelines for a puppies health.
I have often stated "follow the money." Studies are often biased towards the ones whom are paying for the study. Therefore, most studies should not be trusted. A study done by a non biased party I more reliable.
Unfortunately, there aren't many unbiased people doing study using scientific methods.