Right, "said to" is doing an awful lot of work here. I had a look for studies but all I could find was this: https://www.isrctn.com/ISRCTN85247318 https://www.

Right, "said to" is doing an awful lot of work here. I had a look for studies but all I could find was this: https://www.isrctn.com/ISRCTN85247318 https://www.isrctn.com/ISRCTN85247318 So, looks like a study was done, but the results not published.