Vitamin F is certainly not a vitamin within the traditional understanding of the saying.
Rather, vitamin F is basically a term loads of fats — alpha-linolenic acid (ALA) and linoleic acid (LA). They are necessary regular body functions, including aspects of brain and heart healthy living .
ALA is basically a a part of the omega-3 fat family, while LA is a member of the omega-6 family. Common forms of both include vegetable oils, nuts, and seeds.
They were sourced out of the 1920s when scientists showed that fat-free diets had uncomfortable side effects on rats. Initially, the scientists suspected the rats were deficient in a new vitamin they called vitamin F — later discovered to be ALA and LA .
Author’s reference: https://www.healthline.com/nutrition/vitamin-f