Vitamins are micronutrients that are essential for proper body function. They are required in small amounts but play crucial roles in various metabolic processes such as metabolism, immune system function, and cell growth and division. There are 13 vitamins, classified as either fat-soluble (A, D, E, and K) or water-soluble (B-complex vitamins and vitamin C). Some common sources of vitamins include fruits, vegetables, dairy, meat, and fortified foods.
The theory was first published in 2008 a press released under the name of Cliff Arnall, who at the time was a tutor at the Centre for Lifelong Learning – a Further Education centre associated with Cardiff University.