We all grew up with our parents telling us to wash our hands, stay home from school, drink plenty of water and get a good night’s rest to fight off the common cold, but it seems that now-a-days in our fast-paced world that people have adopted to the practice of slamming orange juice and Vitamin C supplements in the hopes of preventing the nasty downward symptomatic spiral of contracting the common cold.
Is this Vitamin C megadose method truly an effective and reliable strategy for avoiding the ever-so-dreaded soar throat, sneezing, cough and fatigue that close to 1 billion people experience as the common cold in the United States every year? Yes, and no.
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Vitamin C Facts
Vitamin C (also referred to ascorbic acid) is a water-soluble vitamin that serves many biological roles in the human body. Not only is it required for the synthesis of collagen and for the facilitation of protein metabolism, but it also serves as an antioxidant by reducing the damaging effects of free radicals in the body.
More relevant to our case of assessing the efficacy of megadoses is the fact that Vitamin C assists in the facilitation of a healthy immune system. Specific immune cells (phagocytes and t-cells) require the accumulation of Vitamin C to function properly. Studies have found that Vitamin C deficiencies are associated with a decreased ability to fight off pathogens while adequate Vitamin C levels are associated with an enhanced immune response.
The question that we are interested in today is not whether or not Vitamin C has any influence upon the immune system, but rather if its interaction with the immune system proves to be effective in reducing the frequency, severity and duration of the common cold.
A Review of the Evidence
A series of investigations regarding whether or not Vitamin C has a significant impact upon fighting off the common cold began in 1970 with the book, Vitamin C and the Common Cold, by Linus Pauling. Pauling promoted the idea that large megadoses of Vitamin C could reduce both the duration and severity of the common cold. Since then, the topic has undergone a lot of experimentation, which leads us to this discussion today…
Does Vitamin C Reduce the Duration and Severity of the Common Cold?
Yes, with an initial megadose of 6000mg.
A 1999 study published in the Journal of Manipulative and Physiological Therapeutics assessed the impact of Vitamin C megadoses upon the incidence, duration and severity of the common cold amongst 252 students at a technical training facility in Santiago, Chile. Each student that presented with cold symptoms was administered a 1000mg dose of Vitamin C every hour for the first six hours (6000mg total), followed by three daily doses of 1000mg of Vitamin C thereafter. The researchers compared the duration and severity of the cold symptoms in the students that received the megadose to students that did not, and found that there was a 85% decrease in cold symptom severity and duration following the megadose.
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Yes, but dosage matters.
A literature review of 21 placebo-controlled studies examined the effects of a daily Vitamin C intake of 1000mg/day upon the incidence, duration and severity of the common cold. Amongst the 21 studies they concluded that there was no effect of Vitamin C supplementation upon the incidence of the common cold, but that there was a significant dose dependent impact upon the severity and duration of the cold. They found a 29% decrease in severity of common cold symptoms for groups that increased their intake from 1000mg to 2000-4000mg throughout the duration of their cold. Similarly they found a 17% decrease in the duration of the common cold amongst participants that consumed 6000mg/day. This study demonstrated that doses of Vitamin C greater than 1000mg confer a beneficial response in battling the duration and severity of the common cold.
Does Vitamin C Reduce the Frequency of the Common Cold?
Yes, when supplements are taken on a consistent daily basis for consecutive years.
A 2006 study published in the European Journal of Clinical Nutrition split up patients with atrophic gastritis into a low-dose Vitamin C group (receiving 50mg/day) and a high-dose Vitamin C group (receiving 500mg/day) and followed their self-reported incidences of the common cold over a 5-year period. They found that the incidence of the common cold for the low-dose group (9.2%) was higher than that for the high-dose group (3.2%), suggesting that a higher daily dose of Vitamin C influences a lower incidence of the common cold (as we would expect by now). While the results of this study should be interpreted with caution considering that the data was based upon self-reported cases of the cold, it nonetheless demonstrates the protective effect of Vitamin C upon the frequency of catching the common cold.
Not All Supplementation is Equal
After reviewing this evidence it appears that there are possible health benefits from slamming Vitamin C supplements if you are concerned about becoming plagued by the common cold, but it is important to take note that the effects of supplementation are not the same for everyone!
This is where the “no” comes into play.
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Studies suggest that certain subpopulations could benefit more than others from Vitamin C supplementation, including:
- People who have below average baseline Vitamin C levels (typically older men)
- Children
- Chronic cigarette smokers
- People who endure intense physical stress (such as intense exercise or exposure to extreme cold conditions)
Surely it makes sense that these sub populations who are either building up their immune systems (children), stressing their immune systems (marathon runners), or struggling with low levels of Vitamin C could benefit from the restorative effects of Vitamin C supplementation. So if you are not part of one of these populations, the effect of Vitamin C supplementation may have less of an effect upon your immune system than you hope.
What does this mean for me? Should I alter my diet when I feel a cold coming on?
If you take a minute to think through your diet, do you frequently consume fruits and vegetables that are high in Vitamin C? What are those you might ask? Presented below is a table that lists foods with some of the highest Vitamin C content. If you haven’t seen a red pepper in your diet since Thanksgiving, it may be time for you to make a trip to the grocery store to stock up on these Vitamin C rich foods so that you can wield them out to battle once you feel the signs of a cold coming on. And let’s face it, incorporating more fruits and vegetables into our diet is never a bad idea.
Table adapted from USA.gov http://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
According to guidelines established by the Food and Nutrition Board, the Recommended Dietary Allowance (RDA) of Vitamin C for adults 19 years of age and older is 90mg/day for men and 75mg/day for women. As exemplified in the table, this RDA can be met rather easily by someone who consumes 2-3 servings of fruits and vegetables on a daily basis. But what if that isn’t you, you ask? This is where Vitamin C supplementation can serve as a benefit to your health.
You may notice that these single serving quantities of Vitamin C are hardly comparable to the 2000mg-6000mg megadoses that were previously discussed to be effective in reducing the severity of cold symptoms. So although it may take some mixing and matching to reach an effective Vitamin C dose of 1000mg or greater, if you are looking to avoid getting the cold this year, stock up on your fruits and vegetables or take a Vitamin C supplement – not as a cure, but as an effective immunity booster.
Final Thoughts
Although it makes me cringe to leave you with the advice that no one wants to hear, according to the reviewed literature it is up to you whether or not you stock up on orange juice, make the effort to slam down Vitamin C supplements, and go that extra mile to reduce the severity of your common cold this winter because depending on your current health status, it may or may not prove effective. That being said, it is important to note that the upper limit of Vitamin C intake (the maximum level of intake at which no adverse health effects are observed) is set at 2,000mg/day and that adverse health effects have been seen at 3,000mg/day. Therefore, if you fully intend to slam down the Vitamin C this winter in hopes of avoiding the common cold, consider an alternative attempt to obtain a healthy amount of Vitamin C through natural food sources, or be sure to consult your doctor before engaging in the megadose routine!
[Updated 02/12/13]
{ 10 comments… read them below or add one }
Beth, nice post. This is a very relevant topic since we all battle colds during these winter months. My one concern about this post is that you neglected to mention that the Upper Limit (UL) for healthy adults is 2000mg/day. While Vitamin C may have low toxicity and is easily excreted, there have been adverse effects observed with 3000mg/day or more and the IOM report recommends caution when exceeding the UL, especially for individuals with certain health conditions. I am always wary of recommending megadoses of anything and fear that citing studies that used such extreme megadoses may encourage readers to try it themselves.
http://books.nap.edu/openbook.php?record_id=9810&page=155
Thank you for your comment, Lola. You are correct that the established upper limit of Vitamin C is 2000mg/day, while the potential adverse effects are gastrointestinal disturbances and kidney stones. I neglected to mention these adverse effects due to the fact that Vitamin C is water soluble, and that excess Vitamin C is likely to be excreted in urine, but since we would not recommend “megadosing” as growing nutrition experts, I should have touched upon this concept in the post. Maybe in the future I will write another post that delves deeper into the risks and benefits of water soluble vitamins to clarify this topic!
Very clear explanation of the attributes of Vitamin C. It seems as though information and moderation are the key aspects to considering whether or not a megadose may be personally beneficial. The aisles at the pharmacy are filled with so called quick relief products that claim to shorten, alleviate, or stave off the symptoms of the common cold. So, trying a natural method that may elicit some of the same benefits may be something to consider.
I definitely agree with that statement. If someone is convinced that Vitamin C will shorten the duration of their cold, they might as well consume their Vitamin C through food sources and acquire other benefits as a result of incorporating more fruits and vegetables into their diet.
I feel that Vitamin C is a very important component of one’s overall health. It is especially important during the cold and flu season. The concept of getting a larger dose of Vitamin C is an interesting thought. I’m a firm believer in natural first, everything else second. With a little planning, one can incorporate Vitamin C rich foods into one’s daily diet.
Thank you for your comment – who knew that between strawberries, oranges, green peppers, broccoli, etc. that a meal full of Vitamin C rich foods could be so delicious!
Beth,
This is a good article. I don’t take supplements for allergy reasons, so I am always trying to get as many vitamins in my food as possible. I love the chart for that reason. I am surprised that you need so much vitamin C to stave off a cold. Almost all of these studies were about high dose vs. low dose, or about really shocking the system with a lot of vitamin C. I am wondering if there are any long term studies on overall health if a population just always had the recommended amount of Vitamin C?
Thanks for the post,
Margaret
Thank you for reading the post, and that is a great question!
I did only focus upon whether or not large doses of Vitamin C are effective in fighting off the common cold, but when consumed in the recommended amounts (90mg/day for men and 75mg/day for women) Vitamin C, in fact, does have some significant (yet, unseen) health benefits. Aside from acting to boost our immune systems, recommended levels of Vitamin C may be involved with decreasing stress, reducing the risk of cardiovascular disease, protecting against skin aging and reducing the incidence of prenatal health problems.
The problem though, is that since we do not make Vitamin C ourselves we need to take it in through our diet. By looking at the list of foods that contain significant levels of Vitamin C, the majority of those sources are fruits and vegetables. People who do not eat 2-3 servings of both fruits and vegetables each day may have a greater chance of Vitamin C deficiency. So, while there are health benefits provided by Vitamin C, it is likely that a large chunk of the population is not getting those benefits! It seems like the greatest health benefits come from eating a healthy amount of fruits and vegetables (which it sounds like you do yourself!).
http://www.medicinenet.com/script/main/art.asp?articlekey=88519
Hi Beth! Thank you for the timely post! I actually wondered about the same thing as Lola – about healthy upper limits – but also about the possibility of vitamin C being absorbed differently by the body, depending on the form in which it is ingested (fruit, pills etc). As you mention both orange juice and supplements in connection with ‘megadoses’, it might be a useful piece of information with which to support your story.
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