It appears that scientists conducted some type of survey research, but from the newsletter I do not know if this was on line, in person, through the mail or by telephone. I only have this statement:
"21,000 adults aged 45 and older completed a questionnaire containing 110 food items"
In the article, the reporter suggests that there is strong evidence that links gender, race, age and region to certain dietary styles. The research itself is not available - it has not been published, so it is hard to know what they consider strong evidence and whether or not I would also consider it strong.
We really need to know about the design of the study and who those 21,000 people were before judging or applying the evidence. So that stated - get your grain of salt and read about the 5 most common dietary styles here.