People differ in their ability to make choline, and rats do it better than humans. Most of our need for choline is met with foods. Some people, depending on their genetic makeup, can make some choline on their own. Men and children have less capacity than pre-menopausal women. Women at that time in their life are better at making choline due to high estrogen levels. This is possibly because pregnancy and lactation require lots of extra choline. Looks like the human body needs choline and is not fooled by rat experiments!
In 1989 choline was elevated to an essential nutrient by the Institute of Medicine. It’s grouped with the B vitamins. People’s need for choline during their life span is not yet well understood; for that reason choline isn’t called a vitamin. Essential nutrients are as important as vitamins but we only have guesstimates for the amounts needed by people, what we call Adequate Intake (AI) instead of Recommended Daily Allowance (RDA).