The story of vitamins is one of humanity's most fascinating scientific journeys spanning centuries of mystery, disease, discovery, and triumph. For thousands of years, sailors died of scurvy without anyone understanding why limes could save their lives. Children in Asia developed beriberi from polished rice. Mothers and children perished from pellagra in the American South during the early 20th century. Then, in a remarkable burst of scientific discovery between the 1910s and 1950s, researchers around the world isolated, named, and characterised the thirteen essential vitamins recognised today and many more bioactive compounds that earned letter designations along the way. Some letters were reassigned; others were abandoned as the compounds they described turned out to be already-known substances. This book takes you on an alphabetical journey through the entire spectrum of vitamin science from the universally recognised (Vitamins A through K) to the historical curiosities (Vitamins G, H, J, M), the semi-nutrients (inositol, CoQ10, bioflavonoids), and the cutting-edge research frontiers (NAD+ precursors, D-ribose). For each entry, you will find: • A clear overview of the nutrient's history and chemistry • Key health benefits supported by peer-reviewed evidence • Primary dietary sources • Recommended Daily Allowances (RDA) or Adequate Intakes (AI) • Deficiency symptoms and toxicity thresholds • Referenced scientific literature