In 1941, President Franklin Delano Roosevelt summoned hundreds of scientists, doctors, and food manufacturers to Washington, D.C. to discuss a weapon that would help the U.S. win World War II: vitamins.

“There was this idea of optimization: ‘What do we need to do to optimize Americans’ health, to make sure we have enough pep and vigor to get us through this war?’” said Catherine Price, the author of Vitamania: Our Obsessive Quest for Nutritional Perfection. “There were all these rumors that the Nazis were restricting vitamins in their conquered people’s foods and giving their young men vitamin supplements and basically race-building through vitamins.”

Three ideas emerged from the National Nutrition Conference for Defense that still exist today. One was the creation of the Recommended Daily Allowances, the first set of guidelines for how much of each nutrient a person ought to consume. The other was the practice of enriching the country’s flour supply with vitamins and minerals—particularly, Price said, with thiamin, or vitamin B1: “There was a huge trend with thiamin, the idea that all of America was deficient in thiamin, and, ‘Oh my god, if we don’t put thiamin in flour, then we’re not going to be able to fight the Nazis.’”

The third idea wasn’t new, and wasn’t born from the conference so much as strengthened by it: the notion that vitamins were the key not only to health, but to a state of health-plus, with the ability to boost bodies past sick, past normal, and into something even better. In recent years, researchers have debunked, over and over, the idea that vitamin supplements confer any measureable benefit at all—but still, around half of Americans take them regularly. Together with other dietary supplements, they enjoy a reputation for nutritional power that stretches far beyond their true capabilities.

“In the case of religion, we put our faith in gods. And in nutrition, we have vitamins,” Price wrote in her book. “Despite the fact that nearly half of us take vitamins as pills, nearly none of us stop to wonder why—out of all of the thousands of chemicals in food—we revere these particular 13.” Below is a lightly edited transcript of our conversation about the history, the myth, and the staying power of vitamins.

Cari Romm: What is a vitamin, and how is that different from a dietary supplement?

Catherine Price: There’s actually only 13 human vitamins: A, D, E, K, C, and the eight B vitamins. But when we use the word vitamin in our everyday speech, we tend to lump in all the other dietary supplements that you could take—things like fish oil or all the herbals and botanicals that you can find if you go into the drugstore or GNC.

In terms of the chemical definition of a vitamin, there actually isn’t one. [Most of those 13] were discovered around the same time, and the word was coined before any of them had been isolated, and it just ended up being such a great word that it stuck around, even after scientists found out that the vitamins actually weren’t all chemically in the same family. But in general, it’s a substance you need in an extremely small amount, usually from your diet, that prevents a specific deficiency.

Romm: If they aren’t all chemically united, what is it that groups vitamins together?

Price: A lot of it is the history. They were discovered because of deficiency diseases—things like scurvy, which is a deficiency of vitamin C, or rickets with D. Or beriberi, which none of us know about now, which was horrible—that’s vitamin B1. And pellagra, which is niacin [B3]. So they were discovered through this process of recognizing the idea of a deficiency disease. And that was really revolutionary, because there was this idea that you could get sick from something you didn’t have, as opposed to a germ. So scientists started hypothesizing in the early 1900s that there was a group of chemical compounds in food that prevented these diseases. In 1911, this Polish biochemist, Casimir Funk, suggested that they be called vitamins. So that’s kind of how the concept became established and the word was created, and why they started to get lumped together. It was only after that point that they actually discovered what the substances were.

Romm: So how did vitamins get from the realm of science to something that consumers were concerned about?

Price: The first vitamin to actually be chemically isolated didn’t happen until 1926, with thiamin, B1. People suspected [there were] vitamins before then, but they had never separated one entirely from food. But what’s really fascinating is that starting as early as the late 1910s, and early 20s, food marketers started to latch on to this term vitamin as just a really great word. It was inspired by combining the Latin word for life, vita, and amine, which is the chemical structure that the scientists thought all the vitamins would be proven to be, which they’re not. And so it originally was vitamine, and then the e got chopped off when it became clear that they actually weren’t all amines.

So food marketers recognized that this was a brilliant term, and they started to use it to sell their products. What was particularly appealing about it was that you had these invisible compounds that scientists were increasingly discovering that we need in order to stay alive. But no one knew how to measure them in food, and you couldn’t see them, so you could kind of go crazy with your marketing claims and no one could disprove you. They became this incredibly useful marketing idea.

Romm: Were vitamins marketed more for their health benefits, or in terms of what would happen if people didn’t get enough of them?

Price: Both, actually. On the one hand, you had advertisers warning you of what would happen if you were deficient. Some of the early researchers were writing for the popular press, and they would write these terrifying columns saying how your teeth would fall out if you didn’t have enough vitamin C—which is true, but most Americans don’t have scurvy. That’s extreme deficiency. So a lot of it was this fear-mongering, and I thought that was fascinating because we still see it today all the time. And then there was this flipside, where the idea of optimization started to take hold—if vitamins were necessary to prevent a deficiency in a small amount, then if you had more of them, you’d be like a superhero. So yeah, they were doing both. Vitamins, more than any other dietary chemical, really established that two-sided relationship, where we’re driven both by fear and by the hope that we’ll become superhuman, that we can optimize ourselves if we just eat the right things.

Romm: So how did “vitamin” become shorthand for “healthy”?

Price: I think that that started early. The word itself has this aura—it means “life,” but health and life often go together. So I think that’s the reason it appealed so much to food marketers, is that the word itself had that connotation to begin with. Even Casimir Funk, the guy who came up with that word, thought it was brilliant. He was very into his own creation. And what I found really funny was, if you consider some of the other suggestions of the time—people were saying, “Oh, we shouldn’t call it a vitamin, we should call it a food hormone, or a food accessory factor.” It’s just funny to think about how our attitude towards these 13 unrelated dietary chemicals would be different if we called them “food accessory factors.” You’d never have ad campaigns or parents insisting that their children have their food accessory factors. It’s just not as catchy.

Romm: When did companies shift from advertising their foods’ natural vitamin content to advertising how they had fortified their food?

Price: Well, you couldn’t fortify until you had the ability to make synthetic vitamins that you could add to food. Fortification means adding vitamins in excess of what was already in the food, or adding micronutrients that weren’t there originally. So for example, the vitamin D that you find in milk these days is a synthetic addition, most of the time. You couldn’t do that until you could actually make these synthetic vitamins, and that started happening in the 1920s and 30s. That was when it started to become possible to add vitamins to products and use that as an additional selling point.

Romm: Did the ability to add vitamins change the way Americans thought about their food?

Price: I think it did. It made it possible to pass off otherwise really unhealthy products as nutritionally complete or beneficial. And around the same time that all the stuff with vitamins was happening, you had the expansion of the modern-day processed-food industry and the development of the modern supermarket, which required having products that can be shelf-stable for a really long time and be transported around the country. The difficult thing is that shelf-stability requires a lot of refinement and processing, and that destroys a lot of a food’s natural vitamins and micronutrients. So unless you have a way of adding those back in, you’re not going to be able to have those foods as the cornerstone of the population’s diet. It’s kind of crazy to think that if we didn’t have these synthetic vitamins, Americans would be at risk for things like scurvy or rickets, but it’s actually true. There was a 2011 study in the Journal of Nutrition that found a significant percentage of Americans’ vitamins were coming from synthetic sources.

Romm: When did vitamins make the leap from something you could get through food to something you could take as a pill?

Price: That was also in the 30s. Once it was possible to make the synthetic versions of vitamins and measure them, then you started seeing this idea of supplements become more popular, vitamins as pills as opposed to foods that contain them.

Romm: So is the popularity of dietary supplements tied to the rise in popularity of vitamins?

Price: I think they’re profoundly connected. When the dietary-supplement industry really started taking hold in the 1960s and 70s, they started using the word “vitamin” with the public to describe their products. And that word, the way they used it, represented far more than just vitamins. It eventually came to represent any substance that you use as a pill to supplement your diet. The supplement industry managed to launch an enormously successful campaign in the 90s when the FDA was trying to come up with new rules for regulation, and the theme was “Don’t let the government take your vitamins away.” They weren’t talking about vitamins—they were talking about all these herbals and botanicals and amino acids and all these other things. But I think that being associated with this halo of vitamins really affected how supplements are regulated. It gave this aura of health and safety to non-vitamin substances, and made us take their safety as a given without asking any more serious questions.

Romm: Why are vitamins and dietary supplements regulated differently than food or pharmaceuticals?

Price: That’s a long story, but in part because of this big industry push to portray them as totally safe. A law was passed in 1994, called the Dietary Health and Education Act, that separated the way supplements were regulated from the way food or pharmaceuticals or over-the-counter drugs were regulated. For over-the-counter and pharmaceutical drugs, you need to prove safety and efficacy before you sell anything. For supplements, there’s no requirement like that. And the argument was partially that since vitamins are in food, vitamins should be regulated more like food, which has lower standards of proof before you sell it. But that’s different from ginkgo biloba or St. John’s wort or bodybuilding powder or whatever else. Those are not vitamins, and so it does seem strange, at least to me, that those non-vitamin products should be regulated like food, or almost more loosely than food, which is what our current system is.

Romm: How much of this reverence of vitamins is legitimate? How much can they actually do to keep us healthy, or make us healthy-plus?

Price: At the base of it, we do need those 13 vitamins. If you don’t have enough of them, you’ll die in often quite gruesome ways. Scurvy is a horrible disease. It prevents your body from making collagen, which is the connective tissue that holds your body together, so you sort of fall apart from within—your teeth fall out, your connections all loosen, and you hemorrhage and die. So I think it’s important not to lose sight of the fact that we do need vitamins. And there are a lot of people in the world who don’t have access to them—the latest estimate I read was 2 billion people [who are vitamin-deficient]. If you give someone vitamin A and they’re suffering from nutritional blindness, which is a stage of vitamin A deficiency, they will regain their sight, often within days. And that’s crazy. It’s like a miracle drug. But it doesn’t translate into the idea that we seem to want to have, which is that if you can cure nutritional blindness with vitamin A, then if you take 17 times that amount in a pill, you’ll be able to see in the dark. The idea that more is better, and more gives you superpowers, is not true.

Romm: How did that idea emerge, then?

Price: I think it has a lot to do with the fact that they really are so amazing when you need them—the idea that you can reverse these diseases with these invisible compounds does give them a legitimately miraculous aura. But those facts were used by food marketers to promote a product and then those claims started to go beyond what vitamins could actually do. An interesting example I found was thiamin [vitamin B1], which was enormously trendy in the 20s through the 40s. It started off with legitimate things that B1 is important for or can help with, and then by the 1940s you had ads saying that thiamin could do everything from improving your complexion to improving your energy, which they called “pep,” to giving the country better morale for World War II. There was a claim for these thiamin-rich yeast cakes that said they restored this woman’s ability to walk. So it quickly started to spin out of control, and I think that happens a lot today, too.

Romm: Why are people so willing to accept these sometimes outrageous claims of what vitamins can do?

Price: That’s where things can get pretty philosophical, because it doesn’t really make sense on the surface. What I came away with is the idea that we really don’t like uncertainty, especially in terms of our health. And there are so many things about health and life that are terrifying—not just getting sick, but inevitable mortality. So we’re really eager to have some kind of salve against that uncertainty, and vitamins really help play that role. I think part of that is probably because for the most part, with the exception of vitamin A, too much of a vitamin is not going to kill you. So you’re able to take these pills and feel like you’re doing something, and just feel like you have more of a sense of control over your life and your health than you did before. That sense of control is enormously appealing, and the desire for than control leaves us very susceptible to anyone who promises to provide it to us, in their pill or in their product.