Discovery of vitamins

September 10, 2019, 10:38 347

        The discovery of the vitamins was a major scientific achievement in our understanding of health and disease. In 1912, Casimir Funk originally coined the term “vitamin”. The major period of discovery began in the early nineteenth century and ended in the mid-twentieth century. The puzzle of each vitamin was solved through the work and contributions of epidemiologists, physicians, physiologists, and chemists. Rather than a mythical story of crowning scientific breakthroughs, the reality was slow, stepwise progress that included setbacks, contradictions, refutations, and some chicanery. Research on the vitamins that are related to major deficiency syndromes began when the germ theory of disease was dominant and dogma held that only four nutritional factors were essential: proteins, carbohydrates, fats, and minerals. Clinicians soon recognized scurvy, beriberi, rickets, pellagra, and xerophthalmia as specific vitamin deficiencies, rather than diseases due to infections or toxins. Experimental physiology with animal models played a fundamental role in nutrition research and greatly shortened the period of human suffering from vitamin deficiencies. Ultimately it was the chemists who isolated the various vitamins, deduced their chemical structure, and developed methods for synthesis of vitamins. Our understanding of the vitamins continues to evolve from the initial period of discovery.

        In 1906, Frederick Gowland Hopkins (1861 – 1947) articulated what is now known as the “vitamin theory” during a speech given in London. Hopkins hinted at some dietary studies he had conducted that suggested: “…no animal can live upon a mixture of pure protein, fat, and carbohydrate, and even when the necessary inorganic material is carefully supplied the animal still cannot flourish.” He continued: “Scurvy and rickets are conditions so severe that they force themselves upon our attention, but many other nutritive errors affect the health of individuals to a degree most important to themselves, and some of them depend upon unsuspected dietetic factors. There were previous expressions of the “vitamin theory” prior to Hopkins. Nicolai Lunin (1853 – 1937) conducted studies with mice and concluded: “Mice can live quite well under these conditions when receiving suitable foods (e. g., milk), however, as the above experiments demonstrate that they are unable to live on proteins, fats, carbohydrates, salts, and water, it follows that other substances indispensable for nutrition must be present in milk…”. His mentor, Gustav von Bunge (1844 – 1920) reiterated in 1887: “Does milk contain, in addition to [protein], fat, and carbohydrates, other organic substances, which are also indispensable to the maintenance of life?. A study by another von Bunge student, Carl A. Socin, demonstrated that there was an unknown substance in egg yolk that was essential to life, and he raised the question of whether this substance was fat-like in nature. Perhaps the earliest articulation of the “vitamin theory” came from the French chemist, Jean Baptiste Dumas (1800 – 1884). During the Siege of Paris (1870 – 1871), many infants and toddlers died when the city was cut off from the milk supply of the countryside. Some opportunists tried to manufacture an artificial substitute for cows’ milk, but this artificial milk failed to sustain the infants. Many children died. Dumas pointed out: conscientious chemist can assert that the analysis of milk has made known all the products necessary for life… we must renounce, for the present, the pretension to make milk… it is therefore always prudent to abstain from pronouncing upon the identity of these indefinite substances employed in the sustenance of life, in which the smallest and most insignificant traces of matter may prove to be not only efficacious but even indispensable. The siege of Paris will have proved that we… must still leave to nurses the mission of producing milk”.

         A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the dietVitamin C can be synthesized by some species but not by others; it is not a vitamin in the first instance but is in the second. The term vitamin does not include the three other groups of essential nutrientsmineralsessential fatty acids, and essential amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. The thirteen vitamins required by human metabolism are: vitamin A (as all-trans-retinol, all-trans-retinyl-esters, as well as all-trans-beta-carotene and other provitamin A carotenoids), vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B12 (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones). 

 

 

References: 

1. Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 978-0-13-981176-0OCLC 32308337

2. Semba RD, The discovery of the vitamins.  Int. J. Vitam. Nutr. Res., 82 (5), 2012, 310 – 315 

3. https://en.wikipedia.org/wiki/Vitamin

 

By Garibli A.