You wake up with a stuffy nose and your first reaction might be to down a glass of orange juice. Don't bother: everything we know about research shows that mega-doses of vitamin C are absolutely, positively useless at fighting colds. All that extra orange juice will do nothing to shorten your sniffles.

This all leads to the question: how did America get sold on a massive vitamin C myth? Is it vitamin manufacturers, trying to get us to purchase more pills? Has the orange industry tried to dupe us?

Part of it has to do with the fact that vitamin C is rarely harmful, so there's been little impetus to intervene.

"There’s a lot of misinformation out there on vitamin C because it’s safe," says Heather Mangieri, a nutritionist working with the Academy of Nutrition and Dietetics.

And part of it traces back to one famous scientist, Linus Pauling, who came to believe that vitamin C could be a cure-all for numerous ailments — and, while he's no longer alive, he's still duping millions of people.

Half of all Americans take vitamin supplements on a regular basis. They don't tend to hurt, but many nutritionists say they really don't help, either. Neither do mega-levels of vitamin C, even though supplements like Emergen-C are many people's go-to's when cold and flu season hits. Here's how scientists discovered vitamin C, where the misconceptions about it came from, and what it's actually good for.

Discovering vitamin C

For a long time, people didn't know about vitamin C. They did know about scurvy, which we now know as an extreme vitamin C deficiency. Sailors on long voyages were short on fruits and veggies, which left them with scurvy. They suffered from swollen extremities and painfully inflamed gums.

Today, scurvy is rare in developed countries. To get scurvy, a person's vitamin C intake would have to be under 10 mg a day —well below the recommended daily amount — for many weeks. But back then, it was a huge problem that's estimated to have killed two million sailors between 1500 and 1800.

Scientist James Lind conducted a trial in 1747 treating sailors with scurvy in different ways. He found that the only effective treatment of those he'd tested was oranges and lemons.

It wasn't until the 20th century that scientists would figure out what it was in those fruits that was doing the trick. In 1928, Albert Szent-Gyorgi, a scientist working at the University of Szeged in Hungary, isolated a substance found in the adrenal glands and named it hexuronic acid. In 1931, two American biochemists, J.L. Svirbely and Charles Glen King, found that the crystalline vitamin C in lemon juice matched the properties of hexuronic acid.

Linus Pauling and the vitamin C craze

Their discoveries led one scientist, Linus Pauling, to dig deeper. Pauling is the only person to ever win two unshared Nobel prizes. In 1949, Pauling and his team studying sickle cell anemia established it as a genetic disease. And he was also, arguably, the person most responsible for the great vitamin C myth.

During a talk in 1960, Pauling mentioned he hoped he could live another 25 years to keep following the exciting discoveries in science. A man in the audience, Irwin Stone, would change the course of Pauling’s career. In a letter to Pauling, Stone recommended he take 3,000 mg of vitamin C each day to live longer. Pauling said he began to feel "livelier and healthier" after taking Stone's advice. "In particular, the severe colds I had suffered several times a year all my life no longer occurred."

Over the next few years, Pauling upped his intake of vitamin C, eventually taking 18,000 mg per day. Vitamin C became his scientific obsession.

In 1970, Pauling came out with his book Vitamin C and the Common Cold, where he encouraged Americans to consume 3,000 mg of vitamin C daily.

"Unfortunately, many laymen are going to believe the ideas that the author is selling," Franklin Bing wrote in a scathing review of the "irritating" book in the Journal of the American Medical Association. Bing was right.

For example, a January 1971 article from Oregon newspaper The Bulletin reported that local sales of the nutrient were soaring. "Area stores report vitamin C sales up 10 times that of last year since the first publicity over Dr. Linus Pauling's book "Vitamin C and the Common Cold" came out in September."

It continues, "Pharmacist Bob Gabriel reported that people are not only buying more vitamin C, but are asking for it in higher dosages because of Dr. Pauling's assertions. Before 100 mg. tablets were the common purchase. Now 250 and 500 mg. sizes are the first to go."

Pauling became a vitamin C acolyte. He said it would make the common cold disappear completely off the face of the earth. He said vitamins and nutritional supplements could cure everything from retinal detachment to snakebites to the virus that causes AIDS.

And his methods weren't exactly conventional. One time, he tested megadoses of vitamin C on schoolchildren at a skiing camp in the Swiss Alps and said they saw a big decrease in colds and the lengths of colds. But other scientists said that those results might not translate to the general population.

Pauling fought critics for the rest of his life. In a 1990 interview — four years before his death — Pauling said that people who take vitamin C and other supplements in the "optimum amounts" would live 25 to 35 years longer. "More than that," he said, "they will be free of diseases."

The high doses don't work

Vitamin C, meanwhile, began to say the exact opposite: scientists were repeatedly finding that colds progress much the same way regardless of whether you down a giant jug of Tropicana or not.

A Cochrane review of nearly 30 studies looking at people with colds taking the normal daily dose of vitamin C found that it reduced colds’ length by 8 percent. This means if your cold lasts five days, it might be shortened by about 10 hours.

The idea that it'll do much of anything for our colds is a stubbornly persistent myth

Researchers have also poured a lot of effort into examining whether vitamin C supplements lower the risk of cancer. But evidence from clinical trials, by and large, shows that vitamin C supplements (usually taken with other nutrients like vitamin E and zinc) have no such effect. The same problem cropped up when researchers tried to establish a connection between vitamin C and pneumonia.

"Lots of people have tried to feed high levels of a single nutrient like vitamin C and look at anything from cardiovascular disease to cancer to cataracts, and most of those trials have been very disappointing," says Dr. John Erdman, a nutrition researcher who sat on the panel that decides daily recommended intakes of vitamins.

But people take them anyway

Mega-doses even come with some risks. The National Institutes of Health says people shouldn't take more than 2,000 mg (the equivalent of two Emergen-C packets) per day. Anything higher than that, and you're looking at possible stomach cramps, nausea, and diarrhea.

And that might not be all. In one study, Swedish researchers found that men taking vitamin C were twice as likely to develop kidney stones as their peers who happened to not be taking the vitamins.

So why, if we can usually get all the vitamin C we need from their food, do we buy all these extra vitamin C supplements? The idea that it'll do much of anything for our colds is a stubbornly persistent myth, and one that's perpetuated by supplement companies themselves.

"When the vitamin industry has an opportunity to broadcast news, distribute literature, anything else, it takes that opportunity," says Dr. Stephen Barrett, a retired psychiatrist of the accountability site Quackwatch.org.

So somehow we've ended up with 20-plus flavors of Emergen-C, which its site assures will boost the immune system and enhance energy, a statement their site notes has not been regulated by the FDA.

There's still a massive market for products like Emergen-C. In 2012, Euromonitor International reported the vitamin and supplement industry topped $23 billion in consumer spending.