Vanilla was discovered in regions of (present-day) Mexico back in the 14th century, when Spanish conquistadors came across vanilla-flavored foods and drinks consumed by Meso-American individuals.
After having been brought back to Spain, vanilla began being used to flavor a drink consisting of honey, water, corn, vanilla, and cacao beans.
The drink eventually spread to England and France, and then the rest of Europe by the early 1600s. In 1602, the apothecary of Queen Elizabeth I, Hugh Morgan, suggested that vanilla should be used separately from cocoa.
Later, the French began using vanilla in ice cream, which was a rather popular dessert in 18th century France. It was Thomas Jefferson who discovered vanilla ice cream in France and brought the recipe to the USA.
Vanilla Ice Cream Day is an unofficial holiday observed every year on the 23rd of July. While having a scoop or two of vanilla ice cream might no do any significant harm to you, provided you don’t suffer from any illnesses, try to not overindulge in the celebration, as too much ice cream can be bad for you, regardless of its flavor.
More info here:
https://www.timeanddate.com/holidays/fun/vanilla-ice-cream-day
https://www.awarenessdays.com/awareness-days-calendar/national-vanilla-ice-cream-day-2020/
https://www.wincalendar.com/Vanilla-Ice-Cream-Day