Yes, there is a vitamin J, but it's more commonly known as choline. It is a water-soluble nutrient considered essential for human life and is often grouped with B-complex vitamins. While our liver can produce some choline, it's usually not enough to meet our needs.
Researchers have considered choline a vitamin (vitamin J) type, and its deficiency can lead to various health problems. You can find choline in foods like eggs, liver, and soybeans.