Vitamins

Vitamins are nutrients required for essential metabolic reactions in the body . Vitamins can act both as catalysts and participants in chemical reactions. The body typically assembles vitamin-dependent catalysts from a variety of building blocks including amino acids, sugars, phosphates, and vitamins. Each vitamin is typically used in multiple different catalysts and therefore has multiple functions. The role of a catalyst is to participate in a chemical reaction without being altered itself. Catalysts function like knitting needles, which convert yarn to mittens without undergoing any change themselves.

Until the 1900's, vitamins could only be obtained by eating food. Each food source contains different ratios of vitamins. Therefore if the only source of vitamins is food, a change in diet from season to season, year to year, or day to day changes the doses of vitamins. Ordinary people do not sense any change in health as a consequence. This leads to the conclusion that the nervous system maintains a feeling of normalcy across a wide range of vitamin dosages.