“Don’t waste clean thinking on dirty data.”

For decades we have been trying to understand the effects of vitamin C on the immune system. Linus Pauling wrote Vitamin C and the Common Cold in 1970, and sometimes it feels like we haven’t made any progress. The best and most comprehensive analysis of the data at hand, collected from decades of research studies, shows that vitamin C has effects on the common cold – but they are very limited in the general population.

This has led many to conclude that taking vitamin C to ward off a cold just isn’t worth it.

So is this the final word on the subject?

Hundreds of thousands of people, if not millions, take vitamin C to support their immune function. Anecdotal reports from around the globe have attested to the impact of vitamin C supplementation on health. Are people just fooling themselves? Why can’t the scientific evidence give us a definitive answer?

To put in bluntly: vitamin C studies have been a large mess of dirty data. Despite many decades trying to get it right, scientists still are doing a terrible job.

Vitamin C research has evolved very slowly over the 80 years since the vitamin was discovered. Scientists have yet to develop successful ways of studying many micronutrients, and vitamin C presents a special challenge due. Unfortunately, as the scientists at the LPI recently discussed, many studies on vitamin C are not well designed and hard to interpret. Trying to tie all those studies together is often impossible… and even when you do find a way to do it, the conclusions are weak.

So instead of relying on the past, is it time to rethink vitamin C from the ground up, especially with studies on the common cold? Maybe vitamin C deserves a restart, so to speak.

Common Cold Vitamin C miniWhere does this begin? Just like every new beginning, researchers need to learn from their mistakes.

If you look for it, it is not difficult to see where vitamin C studies fall short. It sounds like a simple task, but astoundingly few studies actually look for changes in blood levels of the vitamin when giving someone a supplement. It not only goes against best practices to assume that vitamin C levels will change, the evidence shows that many factors can influence the response to supplements – people are not all the same.

For example, a recent study by Carol Johnston PhD and her colleagues recruited 28 healthy, non-smoking, young men and measured the vitamin C levels in their blood. At the beginning of the study, half of the subjects were randomized to a group that received 1,000 mg of vitamin C each day, while the other half received a placebo pill.
At the onset of the study, plasma levels of vitamin C were measured each week in each subject. After the first week of supplementation there was no difference in vitamin C levels between the two groups. If the study had terminated after one week, in fact, the conclusion would have been that supplements do nothing to change vitamin C levels in the body.

But the study continues, and although it increased slowly, within four weeks vitamin C levels increased in all men taking the supplements (but not in those who took the placebo).

Orange Juice Vitamin CNow here comes the really interesting part. This study was actually a study on vitamin C and the common cold. By the end of the eight-week study, the men taking vitamin C had fewer colds versus those taking the placebo, suggesting that raising vitamin C levels in the body was very important in preventing a cold from developing. The men taking vitamin C who did get a cold tended to have fewer days with symptoms and shortening their colds by about three days, but unfortunately those results did not reach statistical significance compared to those getting the placebo.

Those taking  vitamin C supplements were also more physically active, but that is possibly because they were feeling better (less cold symptoms), but other possibilities exist: vitamin C has been shown to affect mood and energy metabolism.

This was a remarkable finding and perhaps signals a new beginning for research on vitamin C and colds. However, it is just a start – this study had a small number of subjects, so many more equally well-designed studies will be needed to signal a change in consensus on C.

Overall, vitamin C research needs to be elevated to a higher quality to succeed on these important questions. A recent analysis of vitamin D supplementation in the treatment of respiratory tract infections showed that very specific criteria representing the best of nutritional science and our knowledge about the way vitamin D works in the body can produce some fascinating results. If we can do the same for vitamin C, perhaps one day its effects on the common cold may finally be revealed.

Print Friendly, PDF & Email

11 thoughts on “Vitamin C and Colds: New Beginning

  1. Why all medical trials are made the same way? You do not try all variations. 1 gr. Vit C is not good test. Me and my family and friends that i give vit. C powder use it other way. Like Lunis Pauling says, 3-4 gr powder per day and in first symptoms we rise the grams to 1gr per hour or 1gr per 30 min. Other way of use if you have pain in the throat take 1gr powder directly put on the tongue and take it near to the throat without water. You will feel less pain after that. Make more clinical trials with more scenario. And learn how our bodies work please.

    • Unfortunately, study design is usually limited because of cost. Route of administration and dose often is influenced by the endpoints being measured, but rarely is it determined what route or dose may be optimal for a particular symptom or malady.

  2. Amigos,
    You have to remembers vitamins work in combination with other vitamins and micro-nutrients, including spices and a strong body and healthful habits like exercise and healthful foods.
    The latest research seems to point out the need for higher doses of certain vitamins that does not include in-organic iron and some type of vitamin A. The plant form of vitamin A (carotene) is relatively safe. I recommend you add vitamin E and magnesium to your supplements. The standard multivitamins are helpful, but you probably need more then in the multi-vitamin pills.
    If you suffer from a disease, including mental diseases, or wish to prevent a disease I recommend you do an approach found in the of following books along with your Doctor’s care and recommendations that are an helpful approach using a higher amount of some vitamins, minerals, phyto-nutrients,spices and essential healthful oils.
    You can find more information in vitamin and mineral and mineral books and spice books.
    I recommend you study the following books:

    1) The Real Vitamin and Mineral Book by Pauling
    2) Healing Spices by Aggarwal/Yost
    3) Orthomolecular Medicine for Everyone by Hoffer/ Saul. Studies backed up by science papers and studies.
    4) Dr. Atkins’ Vita-nutrient Solution by Dr. Atkins, MD. Somewhat dated at Copyright 1998, but still worthwhile. Dr. Linus Pauling are Dr. Atkins are the heroes of Vita-nutrient history.

  3. In the study, did the researchers divide the 1000 mg daily dose? Previous studies have shown the body can only absorb 250 mg at one time.

    • They did not divide the dose. It is possible they could have had reached higher vitamin C levels in the blood if they had done so.

      I should also mention that the bioavailability of vitamin C should not be considered absolute. Although pharmacokinetic studies have shown that maximal absorption (100% bioavailability) of vitamin C is seen at doses up to 200 mg, 73% of a 500mg dose (about 365 mg) and 49% of a 1250 mg dose (about 625 mg) was absorbed in the same subjects. This suggests vitamin C transport is less efficient as you increase dose, but certainly does not support a complete lack of absorption at higher doses.


  4. Would you please get off the vitamin C and common cold platform and just imagine yourself as a goat or like most other mammals on the planet. When a goat gets a ‘cold’ it starts taking ten times more C than its daily dose of 6,000 mg.
    We use C for repairing collagen etc. etc. apart from our immune and cell management systems.
    Just use your common sense and start wondering why primates have developed such a complicated social structure around eating foods with C in and behaving in a manner that limits catching strange bugs.
    Just look at our western diseases and compare it with which systems pump vitamin C. Get it yet?
    So no more cold issues please. Check for bruising, my horses don’t bruise when they tap their legs on a twig.
    I hope we all get with it before we hit the wall on healthcare costs. I choose not to get sick.

  5. Very interesting article.

    In my study of one subject, I have noticed taking 2-3 G of Vit. C causes a drying of my mucous membranes when I have a cold. Has anyone else noticed this?

    Are the main symptoms of a cold congestion from mucous membrane overreaction? Is this why I feel better after Vit. C?


    • I have never heard this before, but there have been links between vitamin C and chloride transport, which can drive the tranport of water. If this occurs in mucous membranes it could explain the apparent dryness.

  6. Pingback: What Happens When Your Mucous Membranes are Sick? - Return2Health

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.