Vitamins are organic compounds that are crucial for normal growth and nutrition, typically required in small quantities in the diet because they cannot be synthesized by the body. There are 13 essential vitamins that humans need to maintain health, including vitamins A, C, D, E, and K, along with the B vitamins such as thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6, vitamin B12, and folate. Each vitamin serves unique roles in the body; for example, vitamin D is essential for calcium absorption and bone health, while vitamin C is important for the repair of tissue and the enzymatic production of certain neurotransmitters.
Vitamins are categorized into two groups based on their solubility: water-soluble and fat-soluble. Water-soluble vitamins, which include all the B vitamins and vitamin C, must be regularly supplied in the diet as they are not stored in the body to any significant extent and are excreted through urine. On the other hand, fat-soluble vitamins such as vitamins A, D, E, and K can be stored in the body's fatty tissue and liver, and are released as needed, which means a daily intake is not absolutely necessary if there are adequate stores.
Deficiencies in certain vitamins can lead to severe health issues. For instance, insufficient vitamin C can cause scurvy, a disease marked by weakened connective tissue, bleeding gums, severe pain, and eventual death if untreated. Likewise, lack of vitamin D can lead to rickets in children, characterized by impaired bone growth and skeletal deformities. This highlights the importance of a balanced diet that includes a variety of vitamins to prevent deficiencies and promote overall health.
The discovery of vitamins began in the early 20th century, a significant advancement in the field of nutrition science. Initially, vitamins were identified as factors necessary to prevent certain ailments such as beriberi and pellagra. This discovery led to the understanding that malnutrition was not only caused by deficiencies in calories or protein but also due to the lack of specific micro-nutrients in one's diet. Today, vitamins are a key focus in the study of nutrition, and ongoing research continues to uncover their complex roles in human health, disease prevention, and the potential therapeutic uses of higher-dose vitamins in treatments like mega-vitamin therapy.