> Participants completed an interview that included a 66-item semi-quantitative food frequency questionnaire (FFQ), modified from a 61-item FFQ designed and validated by Willett and colleagues,16 at Visit 1 (1987–89) and Visit 3 (1993–95).

Retrospective self reported questionaire.

Pah.

Around about the weakest evidence you can get as to what their actual diet was.

I would rate this study as "Junk Science".