I remember listening to an NPR story 2 or 3 decades ago which I can't find about how White people in the United States (probably referring to health food eating yuppies in NYC and Northern California) adopted a staple diet very close to an African American diet in the 40's and 50's while the modern African American diet more often included what White people were eating in the 40's and 50's.

If anyone has any links to stories about how diets have change by demographics over time in the United States, please share.