Frederick Hopkins suggested that trace ingredients in food other than carbohydrates, proteins, and fat are essential to the diet of humans, leading to the concept of vitamins.
Sir Frederick Hopkins’s pioneering work in the field of diet and nutrition led to the discovery of vitamins. Vitamins are organic molecules that the body needs in minute quantities; they are thus called micronutrients. Vitamins play a vital role in the biochemical reactions that take place in the cells of the body by aiding enzymes, which catalyze (speed up) biochemical reactions. They are essential to the diet of humans.
The existence of the substances we now call vitamins has been known since the time of the ancient Greeks. Aristotle knew that raw liver contained an ingredient that could cure night blindness, which is caused by a deficiency of vitamin A. An early account of the cure of scurvy, which stems from a vitamin C deficiency, was recorded in 1535 during the voyages of Jacques Cartier to Newfoundland. Captain Cook was also aware of the antiscurvy properties of lime juice in the 1700’s.
Thirteen vitamins are now known to be required in the diet of human beings for normal growth and development. Vitamins are divided into two classes: water-soluble and fat-soluble. The water-soluble vitamins include the vitamin B complex (thiamine, riboflavin, pantothenic acid) and vitamin C (ascorbic acid). The fat-soluble vitamins are vitamins A, D, E, and K, which are not soluble in water.
Hopkins was an English biochemist working at the forefront of biochemical thought and the combining of chemistry with the metabolism of the body. His research brought together these two diverse areas. Hopkins was trained early as an analytic chemist; he entered biochemistry relatively late in his career but in the infancy of the biochemistry field. Using his analytic chemistry skills, he had an enormous impact on the field of experimental biochemistry.
Frederick Hopkins.
After Hopkins had published several more papers on proteins, he began studying diet and metabolic function. In his 1906 address to the Society of Public Analysts titled “The Analyst and the Medical Man,” Hopkins alluded to some trace substance that might be required in the diet in addition to proteins, fats, and carbohydrates. He stated: “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.” Hopkins believed that rickets and scurvy may be caused by this missing dietary factor.
Christiaan Eijkman had done pioneering work on beriberi
In 1912, Hopkins published a paper in the Journal of Physiology titled “Feeding Experiments Illustrating the Importance of Accessory Factors in Normal Dietaries.” These experiments showed that animals cannot grow when fed a synthetic diet of pure proteins, fats, carbohydrates, and salts. When Hopkins added milk in minute quantities to the diet of the animals in his sample, they were able to utilize the synthetic food mixture for growth. Hopkins concluded that some substance is present in normal foodstuffs in trace quantities, and only small quantities are required for growth. Looking back at his research in a 1922 Chandler Medal Address at Columbia University, Hopkins talked about his pioneering work on what are now called vitamins. He at first expressed disbelief that in a synthetic diet of pure proteins, fats, carbohydrates, and salts, there was some other substance required for growth of the animal. “So much careful scientific work upon nutrition had been carried on for half a century and more—how could fundamentals have been missed?” Hopkins realized that the pure foodstuffs might not be as pure as scientists had thought.
Even after Hopkins published his results, the significance of vitamins was not universally accepted. Other researchers experimented with feeding rats purified substances and found that the rats could grow quite well on this diet. The synthetic diets they employed, however, may not have been quite as pure as that used by Hopkins.
After Hopkins’s address in 1906 about the existence of vitamins, many researchers worked to isolate these trace substances. In 1912, Casimir Funk, a Polish biochemist, purified a substance that he thought cured beriberi. He coined the term “vitamine” (from “vital amine”) for the substance. It turned out that he had actually isolated nicotinic acid (niacin), a cure for pellagra, that was contaminated with thiamine.
Hopkins’s pioneering research laid the groundwork for other researchers to study the vitamin hypothesis. Research in the United States during World War I by Thomas Osborne and Lafayette Benedict Mendel, as well as that by E. V. McCollum and his colleagues, led to the distinction of water-soluble and fat-soluble vitamins. In 1920 skepticism still existed about the vitamin hypothesis, but by 1923 even the staunchest disbelievers had finally come around to accept it. Eventually, in 1929, Hopkins and Eijkman were awarded the Nobel Prize in Physiology or Medicine for their work on vitamins and the vitamin hypothesis.
A large amount of Hopkins’s work on diet and metabolic function was initiated because of the outbreak of World War I. During the war years, Hopkins served on the Royal Society Food Committee. Food rationing’s effects on nutrition were his primary concern. Butter was a scarce and expensive food commodity, whereas margarine was cheap and readily available. Considerable discussion arose about the nutritional quality of margarine in comparison with butter. This discussion evolved because of Hopkins’s work on accessory food factors (or vitamins). In 1917, Hopkins initiated research on behalf of the margarine industry to determine the nutritional quality of margarine. His results showed clearly that margarine was nutritionally inferior to butter because it lacked vitamin A (later, it became clear that margarine also lacked vitamin D).
After the war, Hopkins acted as a consultant to the margarine industry. His research continued with investigation of the possibility of introducing vitamins into margarine. J. C. Drummond surveyed natural sources for vitamins A and D, and by 1926-1927, vitamins A and D were introduced into margarine as a commercial product. In 1928, vitamin-enriched margarine received certified approval from the Pharmaceutical Society. Now standard in supermarkets, such margarine is most likely not at all inferior to butter in caloric value or vitamin quality.
Hopkins then turned to other areas of research. By the 1920’s, biochemistry had begun to be taught at the entry level in colleges throughout the English university system. In 1925, Hopkins was knighted, and he was awarded the Copley Medal of the Royal Society in 1926. His most impressive distinction, however, came in 1929 when he shared the Nobel Prize with Eijkman.
In addition to his work on vitamins, Hopkins actively conducted research in many other fields of biochemistry and physiology. His research with Walter Fletcher showed that muscle activity and lactic acid production are correlated. In his later studies Hopkins examined sulfur-containing vitamins. He discovered a tripeptide (three amino acids linked together) and published a series of papers on the structure and function of the molecule. Hopkins’s work has had a far-reaching impact on the field of biochemistry.
After years of dietary research, scientists are now quite certain that they have identified all of the vitamins required by the human body. Much of the research after Hopkins was concerned with identifying the structures of various vitamins and their functions within the cell. In the twenty-first century, research continues regarding the amounts of different vitamins that humans require, and official recommendations for daily dosages of vitamins for adequate growth and maintenance of health are the subjects of ongoing debate.
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Asimov, Isaac. “Sir Frederick Gowland Hopkins.” In Asimov’s Biographical Encyclopedia of Science and Technology. 2d ed. Garden City, N.Y.: Doubleday, 1982. Useful contribution to a volume containing brief, easy-to-read biographies of more than fifteen hundred scientists from ancient times to the early 1980’s. Some of the biographies are cross-referenced to major advances in the subjects’ fields. -
Baldwin, Ernest. “Frederick Gowland Hopkins.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 6. New York: Charles Scribner’s Sons, 1972. Well-written, detailed biography of Hopkins for nontechnical readers. Includes references. -
Carpenter, Kenneth J. “A Short History of Nutritional Science: Part 2 (1885-1912).” Journal of Nutrition 133 (April, 2003): 975-984. This second part of a four-part series examines the period in the history of nutritional science when Hopkins was conducting his groundbreaking research. Places Hopkins’s work in the context of nutritional science in general. -
Lehninger, Albert L. “Human Nutrition.” In Principles of Biochemistry. New York: Worth, 1982. Well-written chapter in an elementary biochemistry college textbook. Written for the beginner who has little understanding of biochemistry. Includes references. -
Needham, Joseph, and Ernest Baldwin, eds. Hopkins and Biochemistry. Cambridge, England: W. Heffer & Sons, 1949. Presents Hopkins’s uncompleted autobiography and other works by Hopkins, including excerpts from a paper with commentaries and selected addresses. An interesting collection for the nontechnical reader. -
Williams, Trevor I., ed. “Sir Frederick Gowland Hopkins.” In A Biographical Dictionary of Scientists. 3d ed. New York: John Wiley & Sons, 1982. Brief, easy-to-read biography for the nontechnical reader. Includes references.
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