0 one of a group of vitamins (= natural substances important for health) that dissolve in water and are found in food:
B vitamins are water-soluble, so whatever the body doesn't use, it gets rid of.
Hazelnuts also contain plenty of biotin, a B vitamin good for the hair and skin.
The B vitamin niacin may protect people against Alzheimer's disease and other forms of mental decline, new research suggests.
Complex carbohydrates usually carry with them other nutrients, such as B vitamins, which are necessary for muscles to get energy from food.