Updated: Oct 11, 2019
This is a very common question that gets asked of us so we decided to dive deep and find the answer to this question. We will go over the basics and delve into all the claims about what this Vitamin can and can’t do.
What is Vitamin C?
Vitamin C is the well known vital amine L-ascorbic acid. Everyone has heard of it and the claims of all the good it can do. This water-soluble vitamin (which means the body does not store it) is present in some foods and fruits. Humans cannot synthesize it in our bodies, so we have to get it from our diet. It’s the only way to get it.
Have you heard the story about the sailors who developed scurvy? (More on this below).
A Nobel Laureate by the name of Linus Pauling advocated for high doses of Vitamin C in the 70s. At the time this claim was rejected by the medical community. But is there something to this his theory? All we hear about are the positive, but can too much of it cause harm?
What does Vitamin C do in the body?
Many claims have been about Vitamin C over the years. Here we will go over what Vitamin C actually does in the body.
Its an antioxidant, which means it removes potentially damaging oxidizing agents from the body.
It also makes collagen. Collagen is the main structural protein found in skin and other connective tissues. Also, without Vitamin C you can get scurvy.
Scurvy is exceedingly rare in the Western world. However, since you can’t make it, you need to have Vitamin C in your diet and deficiency leads to vague symptoms such as fatigue and can progress to delayed wound healing, personality changes, and eventually death.
Treatment? Start taking Vitamin C. It doesn’t have to be in pill form, fruits high in Vitamin C will work too. So if you set out on a sea voyage, make sure you take citrus fruits with you so that whole scurvy ordeal won’t be an issue for you. See below.
If you are taking a Vitamin C supplement it is important to understand how it is absorbed in the body. At doses of less than 100 mg, it is completely absorbed by the body.
At doses of 1gm or higher less than 50% is absorbed. If you take higher doses, you just end up having more of it excreted in your urine and feces.
That whole scurvy thing…(Vitamin C deficiency)
Centuries ago, sailors who ventured out to sea with no Vitamin C intake contracted or died from scurvy or Vitamin C deficiency. In the 1700s, a British Navy surgeon conducted experiments and determined that eating citrus fruits or juices was the cure.
This solved the scurvy issue. However, scientists did not prove that L-ascorbic acid was the active component until the 1930s.
Can Vitamin C supplements help?
Because it is an antioxidant and plays a role in immune function, Vitamin C has been promoted as a means to help prevent and/or treat numerous health conditions.
But which of these claims are supported by data? Well, we know that it can prevent and cure scurvy. But what else can it do?
Our mean intake of Vitamin C is 105mg/day for men and 83mg/day for women according to the National Health and Nutrition Examination Survey (NHANES).
This is adequate according to currently established RDA guidelines. Different story if you smoke. More on that below.
The prevalence of Vitamin C containing supplements are ubiquitous and this adds to our total Vitamin C intake. According to NHANES data nearly 35% of adults take multivitamin supplements and 12% take a separate vitamin C supplement on top of that.
If you smoke
Studies have shown that if you smoke, you have lower levels of vitamin C in your blood. The reason? Smoking leads to an increase in oxidative stress. So if you smoke, you need more vitamin C in your diet to have the same blood levels as a non smoker. As opposed to taking more Vitamin C, it might be better to just stop smoking.
Is there any benefit to taking Vitamin C?
Because vitamin C is an antioxidant and plays a role in immune function, it has been promoted as a panacea for numerous health conditions. Here are some of the claims of the health benefits of Vitamin C.
It can prevent cancer
Studies do suggest that higher consumption of fruits and vegetables is associated with lower risk of most types of cancer. Somehow this got translated into Vitamin C can prevent cancer. However, there is no definitive evidence to support this. Most randomized clinical trials suggests that Vitamin C supplementation does not affect cancer risk. There is no consistent evidence that Vitamin C supplements play any role in the prevention of cancer.
Epidemiologic studies suggest that high intakes of fruits and vegetables are associated with a reduced risk of cardiovascular disease, we all know this. Again, Vitamin C gets the credit. Prospective studies looking to make this associations between Vitamin C intake and heart disease risk are conflicting.
Further, results from most clinical trials have failed to show a beneficial effect of Vitamin C supplementation on the primary or secondary prevention of heart disease.
The common cold
This is the big one. You have a cold, take vitamin C so you get better faster. You were exposed to someone sick, take vitamin C to prevent getting whatever they had. How did this get planted in our psyche?
This is because Linus Pauling suggested that vitamin C could successfully treat and/or prevent the common cold. This was in the 1970s. But it has been well studied.
The prophylactic use of vitamin C has not been shown to reduce the risk of developing a cold in the general population.
Overall, the evidence to date suggests that regular intakes of vitamin C at doses of at least 200 mg/day do not reduce the incidence of the common cold in the general population, but such intakes might be helpful in people exposed to extreme physical exercise or cold environments and those with marginal Vitamin C status, such as the elderly and chronic smokers.
The use of Vitamin C supplements might shorten the duration of the common cold and ameliorate symptom severity in the general population possibly due to the anti-histamine effect of high-dose Vitamin C.
However, taking Vitamin C after the onset of cold symptoms does not appear to be beneficial.
Can you take too much Vitamin C?
With proper motivation I guess anything is possible!
Taking more than 2 grams of Vitamin C for a prolonged period can increase the risk of kidney stones, although the data on this is not definitive.
Another issue with taking high doses of Vitamin C is iron toxicity. It can also trigger hemolysis in those with gulcose-6-phospate dehydrogenase deficiency.
And like any supplement, Vitamin C has the potential to interfere with some prescription medications.
The federal government’s 2015-2020 Dietary Guidelines for Americans notes that:
“Nutritional needs should be met primarily from foods…Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts.”
The Dietary Guidelines for Americans describes a healthy eating pattern as one that:
"Includes a variety of vegetables, fruits, whole grains, fat-free or low-fat milk and milk products, and oils. Citrus fruits, fruit juices, and many vegetables are excellent sources of vitamin C."
So a well balanced diet seems to alleviate the need for any supplemental Vitamin C. Taking high levels of Vitamin C does nothing more than get excreted in urine and feces.
Please remember that medical information provided by us must be considered an educational service only. This blog should not be relied upon as medical advice and does not replace your physician’s independent judgement. Please seek the advice of your physician or healthcare provider regarding any issues related to your health.