Daily Value

From Scurvy to Success: How Vitamins Revolutionized Modern Nutrition Science (The Vitamins Part 1)

• Dr. William Wallace • Episode 19

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In today’s episode of Daily Value, we begin a special series called “The Vitamins,” where we’ll dive deep into the discovery, functions, and importance of vitamins in human health. This first episode lays the groundwork by exploring the history of vitamin discovery, from the 19th-century realization that certain diseases were tied to diet, to the revolutionary concept of vitamins and their role in preventing specific deficiency diseases. We’ll also cover key definitions, the defined physiological functions of vitamins, thereby allowing us to better understand how they impact our daily health.

Episode Talking Points:

  • The historical context of vitamin discovery and how it changed the course of nutrition science.
  • Defining vitamins: their essential role, how they differ from macronutrients, and the five-part definition of what makes a vitamin.
  • The functions of vitamins in the body, from acting as coenzymes and antioxidants to influencing gene transcription.

Tune in to gain a deeper understanding of vitamins and their critical role in supporting overall health.

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Speaker 0:

Hello everyone, welcome back to Daily Value. I'm William Wallace, and today will be the start of a series of episodes that I will simply call the Vitamins. This series will include four or five parts, but I will not do four or five episodes in a row dedicated to this series. Rather, I'll likely use one day a week dedicated to this series for the next few weeks, so that I'm still touching on different topics outside of vitamins at least twice a week. This series will consist of an introductory look into micronutrients, specifically vitamins. What they are, that is, how do we define them, how it was the process of vitamin discovery that catapulted nutrition science from more of an observational science to an experimental one, and their relationship with health and disease. I'll lay the groundwork for understanding the importance of vitamins, important definitions that you may not have heard elaborated upon before, and so on. I'll also be going through some of the literature describing the prevalence of micronutrient deficiencies and inadequacy status in the United States. This particular episode will be dedicated to elaborating on the definitions and functions of vitamins, along with some historical context. I think that this is great information to provide a more in-depth understanding of vitamins as you revisit them in any context of life outside of this podcast. So let's get into it.

Speaker 0:

Nutrients are factors essential to normal physiological function in microorganisms, animals and humans, some nutrients we do not synthesize in necessary amounts to support normal physiological functioning. Therefore, we need to take in these nutrients from the external chemical environment, and we refer to these factors as essential nutrients. Among these essential nutrients are vitamins and minerals. However, this episode will place more of an emphasis on vitamins. Unlike proteins, carbohydrates and fats, vitamins do not serve structural functions, and breaking them down or metabolizing them does not provide any meaningful amount of energy. Rather, they have functions that are very specific and, as such, we only require them in small amounts. Hence the term micronutrients.

Speaker 0:

Now, prior to the discovery and defining of vitamins, this would be during the 19th century, that would be the 1800s. The consensus among physiologists was that food was a source of only four types of nutrients protein, fat, carbohydrate and ash which collectively account for nearly 100% of the mass of food. By the beginning of the 20th century, four major diseases had been linked to different types of diet or eating styles. Those would be scurvy, berry, berry, rickets and pellagra. By 1900, it became apparent to some that two or three of these could be cured by dietary changes. However, germ theory, which suggested that all diseases were caused by microorganisms like bacteria, fungi and viruses, was the popularly held belief in the medical field. Thus, people in the very early 1900s believed that all disease was due to the presence of something harmful or undesirable, as opposed to the absence of something beneficial.

Speaker 0:

There were two key realizations toward the end of the 19th century that led to the concept of a vitamin and that triggered a revolution in nutrition science. One, food is a source of many nutrients. And two, insufficient intake of these nutrients can cause disease, even very predictable disease states at times. These realizations led to three major forces that led to the emergence of nutrition science as we know it today. Those three things were one, which is a bit redundant here, but the recognition that disease or disease is, were or could be tied to diet. Two, the use of defined diets for experimentation. What I mean by that is, by using diets of defined composition, where the chemical composition could be tested and quantified, researchers could prepare the same diets over and over again to yield comparable results, and thus repeatability in nutritional experimentation became possible. It was defined diets that propelled nutrition science into more of an experimental science. The third of these major forces was the development of appropriate animal models. The use of animal models that were appropriate to diseases or physiological processes of interest in human medicine made possible studies that otherwise would not be able to be conducted in humans. It was the use of animal models that led to the discovery of every vitamin, as well as the metabolic functions of all the vitamins. So, to recap, the three major forces that are responsible for the emergence and development of nutrition as a scientific discipline were realizing diet was tied to certain diseases, the use of defined diets for experimental research and the development of appropriate animal models.

Speaker 0:

There was a period of two decades, between 1890 and 1910, where very crucial animal studies were conducted, revealing two key insights that led to the actual discovery of vitamins. One, there were substances in diet that were not protein, fats or carbohydrates that prevent disease. Two, food contained what were called at the time accessory factors. These were compounds animals seemingly needed for growth, repair and maintenance functions. At the time, it wasn't known if it was the same compound or groups of compounds that were needed to prevent disease and promote normal growth and maintenance functions, but it was those two insights that led to the concept of a vitamin proposed in 1906 by a Dutch physician and professor, christian Eichmann, and the vitamin theory, that's vitamin spelled with an E at the end. This was proposed by Polish chemist, casimir Funk, in 1912, when he also proposed four different vitamins.

Speaker 0:

While developing the vitamin theory, kazimir Funk had determined that a vitamin later came to be known as thiamine that's vitamin B1, had an organic nitrogenous base and therefore an amine group attached to it which is a derivative of ammonia. He decided to create a term generalizing from this finding and decided on vitamin, again with an E at the end. That's a combination of vital meaning pertaining to life and amine gives vital amine Condensed, that became vitamin. This happened during a time before any of the vitamins had officially been isolated and given names as we know them today. Actually, the first four vitamins proposed by Funk were the anti-berryberry vitamin, which we now call thiamine, that's vitamin B1, the anti-rickets vitamin, which we now call vitamin D. Vitamin D prevents the development of rickets in children. There was the anti-scurvy vitamin, which we now call vitamin D. Vitamin D prevents the development of rickets in children. There was the anti-scurvy vitamin, which we now call vitamin C Ascorbate. This is vitamin C is short for anti-scorbutic, reflecting vitamin C's ability to prevent scurvy. The last of Fung's vitamins was the anti-polygora vitamin, which we now know as vitamin B3, that's niacin.

Speaker 0:

Funk's vitamin theory paper allowed etiologies of diseases to be looked at through a different lens, without being constrained by the popularly held germ theory. At the time, like I'd mentioned, germ theory assumed that something like the presence of microorganisms were driving most disease states and tended to look past the absence of something like a nutrient being causal to disease progression. It was 1920 when the E was dropped off vitamin to give us vitamin After it became clear that not all of these compounds being explored had an amine group. The term vitamin has been defined several different ways, but for the purpose of this episode we will be using the operating definition of a vitamin that has five parts to it.

Speaker 0:

One, a vitamin is a compound distinct from proteins, fats and carbohydrates. Two, it's a natural component of food, usually found in small amounts. Three, it's essential, usually in small amounts, for normal physiological function. This includes maintenance, growth and development processes. Four, it's not synthesized by the host, that's us, in amounts needed to meet those physiological needs. And five, it prevents a specific deficiency syndrome or disease when it's absent or not being utilized.

Speaker 0:

That definition is absolutely not without its limitations. It's important to keep in mind two major caveats to the vitamin definition. One, some compounds are vitamins for some species but not for others. For instance, vitamin C can be synthesized by most animals besides humans, non-human primates, guinea pigs and some avian species. For those of us and the species that cannot synthesize vitamin C, it is a vitamin. For animals that can make enough vitamin C, it's not considered a vitamin under the definition I just gave. The second caveat to the vitamin definition we'll use is that some compounds are only vitamins under specific dietary or environmental conditions. Take, for example, vitamin D. Only individuals without sufficient ultraviolet light exposure require dietary sources of vitamin D.

Speaker 0:

When it comes to the actual naming of vitamins or vitamin terminology, they were mostly given their naming convention and familial designation based on the history of their discovery. In other words, the conditions in which they were found, and the researchers who discovered them played large roles in their naming, and also the chronology of their discovery played a role as well. That is, the order in which they were discovered. That's a combination of the compound being isolated and having its structure determined. For example, by the time vitamin D was isolated and its structure determined, vitamin C had already been classified. Then you have the concept of the B-complex, which was interesting, and it came along because several compounds that we now know of as B vitamins had been mistaken for the same compound in yeast. As time went on, it became apparent that there were several separate compounds and were just lumped together as part of the same water-soluble complex, the B complex. That's a very short and oversimplified explanation of how vitamins got their individual names.

Speaker 0:

As of now, there are 13 families of compounds that we call vitamins. You know these as vitamins A, c, d, e, k, all the B vitamins and so on In some cases, but not all. The name you're most familiar with is actually a generic descriptor for a family of compounds that are chemically related and share similar metabolic activity. For example, vitamin E is a family of compounds also known as tochochrominols, and consists of eight different vitamin E parent compounds, four different tochopherols that's alpha, beta, gamma, delta tochopherol and four different tocotrienols same thing alpha, beta, gamma and delta tocotrienol. The term vitamins is an important one. It's used to describe compounds that fall in the same vitamin family, like is the case for the vitamin E family of vitamins. The 13 vitamin families collectively comprise two to three times that number of relevant vitamins. In other words, take all the obvious vitamins you've heard of A, c, d and so on, add in the vitamins as part of each of those families and what you end up with is somewhere around three times more vitamins than you may have been initially aware of.

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Another term that is important to address and describe is a provitamin A. Provitamin is a compound that is not a vitamin until ingested, but once metabolized can be converted into a metabolically active vitamin. The best example of this is the carotenoid beta-carotene, which is an orangish-red pigment that converts into vitamin A at a certain rate when ingested. Just a bit ago, I gave a working definition for vitamins that consisted of five parts. Now I will give the five physiological functions that the vitamin families and their respective vitamins serve, in no particular order. One vitamins act as coenzymes, meaning some enzymes need a specific vitamin, usually a vitamin metabolite, to bind to it so that it can catalyze a reaction, in other words, work properly. Most vitamins act as coenzymes, but not all coenzymes or vitamins.

Speaker 0:

The second function of several vitamins is that they act as electron donors and acceptors. For instance, vitamin E can donate an electron to neutralize free radicals, at which point vitamin E becomes oxidized Vitamin C can then donate an electron to vitamin E to convert it into its reduced state, meaning vitamin E acts as an electron acceptor in this case, and vitamin C then becomes oxidized in the process because it donated or lost an electron acceptor in this case and vitamin C then becomes oxidized in the process because it donated or lost an electron. The third function of most vitamins is that they act as antioxidants. Now, this has a bit to do with the last point of vitamins being able to donate or accept electrons, as that could be considered a function of what we call a direct antioxidant. However, the most basic definition of an antioxidant is a compound that prevents, delays or reverses the oxidation of another compound. This can be accomplished directly and indirectly. A fourth function of a vitamin is the ability of some of them to function similar to hormones, meaning a vitamin can be taken up or made, as is the case with vitamin D, by one type of cell in the body, where it's broken down into metabolites, and those metabolites are then released to affect tissues or cell function in another part of the body. The primary difference is that most vitamins are taken in from the external environment, where a true hormone is manufactured inside the body, although vitamin D does function in this way, as I just described. Lastly, vitamins are effectors of gene transcription. Gene transcription is the first step in the process of gene expression, where a DNA sequence is used to make mRNA.

Speaker 0:

The first half of the 1900s was an exciting period in nutrition science, because all major vitamin families had been discovered before 1950. Does this mean that all vitamins in the world have been discovered? Maybe it does and maybe it doesn't. There are several compounds that fulfill vitamin-like roles. Choline would be one example. L-carnitine is another example. Whether or not these things are called vitamins at some point in time may come down to whether the definition of a vitamin is reinterpreted, which we won't really get into further here. That concludes part one of this series, the vitamins. If you found today's episode informative or just interesting, be sure to subscribe and share with others who might benefit. As always, stay healthy.

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Dr. William Wallace

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