Vitamin C has long been regarded as one of the best vitamins to take to maintain a healthy body. Many of us remember times during our childhood where we'd feel a little under the weather and be tasked with drinking a tall cup of orange juice or chewing a tangy tablet or two. Did we feel better, faster? Well, maybe, but it's always difficult to tell.
All About Vitamin C
Vitamin C is one of the essential vitamins. For those of you who aren't well versed in biology, "essential" has a very specific meaning. It means two things: your body does not produce it, and your body needs it. In other words, you can only get it through your diet. Many other nutrients can be produced out of component parts in your body. Collagen, for example, can be obtained in your diet but can also be synthesized using amino acids. Vitamin C cannot be synthesized by natural bodily processes.
In your body, vitamin C is used in a number of different ways.
- It's part of wound healing and tissue repair.
- It's used, along with amino acids, to form collagen.
- It's part of the chemical reactions that form certain neurotransmitters.
- It's required for the successful function of the immune system.
- It's an antioxidant, counteracting free radicals throughout the body.
Interestingly, vitamin C can be synthesized by many animals, but some do not. Humans are the one we're most concerned about, of course, but apes, monkeys, bats, and some rodents need to get it from their diet just like we do.
Why Vitamin C is So Prevalent
Vitamin C is just one of dozens of vitamins, so why has it received so much attention? The answer lies in one man: Linus Pauling.
Linus Pauling was a biochemist and activist born in 1901. Throughout his career, he won both the Nobel Prize in Chemistry and the Nobel Peace Prize. This puts him in illustrious company: only three other people have won more than one Nobel Prize; Marie Curie, John Bardeen, and Frederick Sanger. As you might expect, he was a very influential individual in chemistry.
Pauling was, among many other things, hugely influential in the very idea that vitamins are biochemically important. Before his work, the idea that vitamins were important – or even that they existed, in some cases – was novel. We take it for granted today, but without Pauling, you probably wouldn't even know much about vitamins at all.
Of course, Pauling wasn't necessarily right about everything. His theory observed a few factors, such as the fact that vitamin C had a positive influence on the immune system, and ran with it. His advice was to take high doses of vitamin C to ensure that your body is completely saturated with it, and that more than enough is always available when a process or system needs it.
As we now know today, too much of a good thing isn't always still a good thing. Luckily, unlike some vitamins and minerals, vitamin C is relatively fine when taken in too-high doses.
How Much Vitamin C Do You Need?
There are a lot of different recommendations online and elsewhere as to how much vitamin C you need. Some of them are old, and some are new. Let's look at some of them.
Linus Pauling: 2,000 milligrams per day.
Dr. Linus Pauling, a preeminent scholar in vitamin C from the 70s, strongly recommended as much as 2,000 milligrams of vitamin C every day. However, he understood that more was not always better and that there were diminishing returns. In a radio interview, he said this:
"The first 250 mg is more important than any later 250 mg. The first 250 mg leads you up to the level where the blood is saturated. You can achieve a higher volume [concentration] in the blood by a larger intake, but you get much better improvement for the first 250 mg than for additional grams." – Linus Pauling Institute
His megadoses were generally meant to counteract deficiencies in people who didn't necessarily get enough vitamin C in their diet, until such time as they were brought back up to a normal level and restored the function of their body.
The Linus Pauling Institute: 400 milligrams per day.
Linus Pauling founded the Linus Pauling Institute in 1973 in Menlo Park, California. Today, it has moved to Oregon State University, where it continues to conduct research into biomechanics and other advanced science. Vitamin C is part of the legacy of Linus Pauling, so of course, they have continued to study it. Here's what they have to say about their recommendation:
"In this context, it is important to note that data from the National Institutes of Health (NIH) have indicated that vitamin C levels in plasma and circulating cells become fully saturated at intakes of about 400 mg/day in young, healthy nonsmokers. These observations are consistent with other data that intakes of about 400 mg/day are associated with reduced risk of heart disease. While these NIH studies are the best we currently have regarding the pharmacokinetics of vitamin C in the human body, they have numerous limitations, including the fact that they are based on a small number of young, healthy men and women. We currently do not know how much vitamin C is required to achieve saturation of cells and tissues in children, older adults, and diseased or stressed individuals. A meta-analysis of 36 studies on the relationship between vitamin C intake and plasma concentrations found that the elderly require a substantially higher daily intake of vitamin C to attain plasma concentrations that younger adults achieve at a lower intake. Additionally, work by Linus Pauling Institute investigators has shown that cellular uptake of vitamin C declines with age, supporting the notion that vitamin C requirements are increased in the elderly.
Therefore, the Linus Pauling Institute's intake recommendation of 400 mg/day of vitamin C for generally healthy adults takes into account the currently available epidemiological, biochemical, and clinical evidence, while acknowledging the extremely low toxicity of vitamin C and the incomplete information regarding optimum intake." – LPI.
They also make note of the fact that some diseases may require higher doses of vitamin C to treat, so this recommendation is only for people who are otherwise healthy.
Various National and International Health Organizations: Between 40 and 110 milligrams per day.
Many countries around the world have their own health organizations, which make their own judgments and decisions based on what information they have available. Recommendations include:
- 40 milligrams per day, from the India National Institute of Nutrition
- 45 milligrams per day, from the World Health Organization
- 90 milligrams per day, from the United States National Academy of Sciences
- 110 milligrams per day, from the European Food Safety Authority
These are all significantly lower than the Linus Pauling Institute's recommendations. Indeed, they can generally be considered a baseline or "bare minimum" amount of vitamin to consume to stay healthy and avoid a deficiency.
Does a Vitamin C Overdose Do Anything?
While too little vitamin C is definitely bad for you – it can cause scurvy, among other things – what about too much?
Given that, in the 70s, many parents were giving their children as much as 2,000 milligrams per day (especially while they were sick), and no one died from it, we find it safe to say that a vitamin C megadose isn't going to be terribly harmful. However, "not deadly" and "safe" are two very different things.
The fact is, megadoses of vitamin C can be harmful in small ways, but it's very rare to have extreme side effects. It's also important to know what a megadose is.
If a recommended bare-minimum dose of vitamin C is 90 milligrams per day, and a high saturation dose is 400 milligrams per day, a megadose can be considered to be that upper level from Linus Pauling, around 2,000 milligrams per day.
Quite a bit of study has been performed on vitamin C, particularly with the kinds of megadoses people were taking decades ago. Generally, somewhere around 2,000 milligrams is considered to be the "tolerable upper limit" of the vitamin. This is because negative side effects start to be observed around 3,000 milligrams per day or per dose.
What are the negative side effects?
- Gastrointestinal discomfort.
- Stomach cramping.
All of these, as you might imagine, come back to something very potent hitting the stomach in a large dose. Many medications, vitamins, and even foods can do the same things to you.
There are, however, a few potentially much more severe side effects of large doses, particularly if you take large doses for an extended period. Some people never experience these, while others will. Obviously, if you experience any of these, dial back on the amount of vitamin C you're taking.
- Kidney stones. Excess vitamin C is processed by the kidneys and excreted in the urine. Some people are prone to forming hard, sharp stones in their kidneys or bladder, which can be extremely painful and require hospitalization and even surgery in rare cases.
- Nutritional imbalances. Vitamin C is used in several different processes throughout the body. It regulates the amounts of copper and vitamin B12 you take in, and it enhances the amount of iron you absorb. Thus, too-high doses of vitamin C can lead to too-high levels of iron and deficiencies in B12 and copper. This can have far-reaching consequences.
- Bone problems. Too little vitamin C causes a deficiency in collagen, which can cause or exacerbate arthritis. On the other hand, too much vitamin C was found (in one study) to cause bone spurs, which can be very painful.
- Interference with other medications. Some medications, such as niacin-simvastatin (a cholesterol medication), are impaired by vitamin C.
These tend to be in extreme circumstances. For example, kidney stones were only observed in people who took more than 4,000 milligrams per day for several months.
For most people who are normally healthy and not on any long-term medications, exceptionally high doses of vitamin C are unlikely to cause any serious problems, but may have long-term effects that haven't been fully studied.
How Much Vitamin C Should You Take?
When it all comes down to it, pretty much everything we've written above can be summed up in just a few short sentences.
- Getting too little vitamin C in your diet can lead to life-threatening issues, including scurvy.
- Getting too much vitamin C in your diet can be very dangerous, but only at extreme intake levels.
Consider this. A single serving of spinach contains around 34 milligrams of vitamin C. A single orange contains around 50 milligrams of vitamin C.
The generally-recommended safe minimum for vitamin C is around 1-2 oranges per day, then.
A megadose of vitamin C, the 2,000-milligram doses recommended decades ago to combat sickness, would require eating 40 oranges. One cup of orange juice has 125 milligrams of vitamin C, so you would have to drink 16 cups (a full gallon) of orange juice every day.
Negative side effects start to kick in for most people around 3,000 milligrams, and significant side effects around 4,000. That means you would have to drink two gallons of orange juice every day, for weeks or months, before significant problems started occurring. Frankly, the sugar and acid in the orange juice would cause much more significant issues much more quickly.
Our vitamin C booster – meant to be a supplement that helps boost your immune system – contains 250 milligrams of vitamin C. You would have to take 12-16 times the recommended dose to experience negative side effects. Obviously, we don't recommend doing that.
Vitamin C is one of the safest supplements you can take. It, perhaps, isn't all it's cracked up to be in terms of a super antioxidant or cancer-fighting mega-nutrient, but it's beneficial to ensure that your body has at least as much as it needs to function. You can rest assured that you would have to go very, very far out of your way to take too much vitamin C.