Cold Prevention: Do Vitamin C Supplements Actually Work?

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Credit: Flickr Creative Commons, Jeepersmedia


With the onset of winter, we may reach for cold remedies and vitamin C supplements to boost the immune system and avoid catching a virus. But, do they work?

One of the most popular is Emergen-C, an effervescent vitamin C drink mix. Research funded by Alacer, the owner of the Emergen-C brand, claimed that this vitamin-rich mix strengthens the immune system enough to reduce the impact of the common cold.

However, recent reports challenged the notion that vitamin C mega dosing is an effective preventative measure against colds. With its health claims in question, Alacer Corp. paid $6.45 million dollars to reach a settlement of a lawsuit filed due to the deceptive advertising. Since then, Emergen-C is marketed only to “boost immune function.”

In the midst of cold and flu-fighting claims made by over-the-counter supplements like Emergen-C, who is right?

Challenging The Cold Prevention Claim

In order for supplements like Emergen-C to live up to its aforementioned claim of cold and flu prevention, the following premises must be true.

Let’s examine the evidence for each premise and evaluate the validity of the attacks on supplement companies for false advertising.

1. Certain high doses of vitamin C prevents colds or alleviates cold symptoms.

The USDA’s dietary reference intake for vitamin C is 60mg per day, assuming a 2000 calorie diet. Meanwhile, some research suggests 200mg/day is a better requirement than the USDA’s guidelines.

Regardless of specific dosages, research has not been found to support intake of 1000mg a day of vitamin C for a significant positive effect in immunity. For instance, one study did not find vitamin C supplementation to be helpful for the majority of the Western population.

Another study concludes that, although vitamin C supplementation may be helpful for significantly increasing immune function in individuals exposed to extremely cold environments or strenuous physical exercise, mega-doses of vitamin C do not appear to reduce the frequency of colds in normal test subjects.

2. The dose of sugar and other non-active ingredients has little to no effect on immune function.

Since the availability of Emergen-C products have reached the consumer market, the negative effect of sugar on the immune system has been found and established in several studies.
Sugar is known to significantly decrease immune function. More specifically, consuming 75-100 grams of sugar solution (two 12-ounce cans of sodas) was found to suppress the body’s immune responses.

Furthermore, simple sugars such as glucose, table sugar, fructose, and honey cause a 50% decrease in the ability for white blood cells to engulf bacteria, with the effect lasting up to 5 hours in the body.

This raises questions about the efficacy of vitamin C supplementation in the presence of immunosuppressive ingredients, given the 5 grams of sugar present in most flavors of Emergen-C packets.

3. The dose of vitamin C is actually present in each packet of cold remedy.

It was found that an Emergen-C packet listed to contain 1000 mg of vitamin C actually contained only 332 mg of vitamin C, according to an independent testing company Labdoor.
It’s not a surprise, as vitamin C is one of the most difficult compounds to keep shelf-stable.

332 mg of vitamin C is equivalent to a large yellow bell pepper or 5 kiwifruits, neither of which are unreasonable to attain through the diet alone.

Final Verdict

Over-the-counter vitamin C supplements like Emergen-C don’t appear to have lived up to the claim of boosting immune function or preventing colds, as each premise upon which the claims are based is refutable using rudimentary research on food science.

Why is Vitamin C Believed to Prevent Colds?

Linus Pauling, a Nobel Prize winning chemist whose work was recognized in an unrelated area,  popularized vitamin C in the early 60s. He suggested that the vitamin, known to prevent scurvy at the time, was even more beneficial in mega doses.

On Pauling’s claims, Dr. Marvin Lipman, an endocrinologist in New York and Chief Medical Advisor for Consumer Reports magazine is skeptical.

“[It’s]…one of the greatest hoaxes ever played on the American public. There have been at least twenty well controlled studies on the use of mega doses of vitamin C….in none of those instances has there been any, really good evidence that vitamin C in mega doses does anything.”

It appears that the evidence is stacked in the favor of the argument “Too little is bad, a little helps reverse damage, but more is not better.” Such products have also received criticism from various other skeptics, here, here, here, and here.

Although the creators of vitamin C supplements may have intended to provide cold prevention for customers, the claims don’t hold up under the scrutiny of a deeper investigation into the research behind vitamin C.

How WellnessFX Can Help

Before winter chill picks up, measure your body’s immune function using biomarkers such as:

  • White blood cell count. White blood cells are a crucial part of the body’s immune response, as they help fight infections. An unusually high white blood cell count may indicate an infection, while a low score may indicate a compromised immune system with decreased ability to handle infections.
  • C-reactive protein. CRP is an indicator of inflammation in the body. This biomarker is important because increased in inflammation may be due to infections as part of the immune response.

All of the above tests are included in the e-Checkup and Baseline, among other WellnessFX packages.

Order a blood test

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The posts on this blog are for information only, and are not intended to substitute for a doctor-patient or other healthcare professional-patient relationship nor do they constitute medical or healthcare advice of any kind. Any information in these posts should not be acted upon without consideration of primary source material and professional input from one's own healthcare professionals.