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The vitamin C controversy

Last Modified: 1/21/2020

vitman c controversy

This post was written by Meriana Nadrous, PharmD candidate, and reviewed by Josh Winebaugh, PharmD, Parkview Health.

It’s the middle of winter and everyone’s thinking the same thing, “I don’t have time to be sick!” According to the Centers for Disease Control and Prevention (CDC), common colds are the main reason that adults miss work and children miss school during these long winter months. Over the years, there has been some debate over the use of vitamin C as a means to prevent and treat this condition. But does it have a scientifically proven benefit, or does it simply act as a placebo, only making you think you feel better after taking it. Here, we explore the facts to see if vitamin C is the best option for preventing or treating the common cold.

What is vitamin c and how does it work?

Vitamin C is a vitamin that our body needs but can’t create on its own. We depend on food sources such as fruits and vegetables to obtain adequate amounts of vitamin C, which is required for over 300 metabolic functions in the body and has been shown to impact immune function. Studies have shown that it may:

  • Increase neutrophil function (white blood cells that fight infections)
  • Boost T-cell proliferation (the expansion of a type of white blood cell that plays a central role in the immune response)
  • Increase interferon production (signaling proteins that heighten antiviral defenses)
  • Protects against oxidant damage during infection
  • Halt virus replication

Unfortunately, the bulk of this research was observed in animal studies, and it’s been hard to tell if there’s much of an impact in human trials. While the research on vitamin C and whether it could cure the common cold continues to be a controversial topic. The general consensus is that vitamin C could shorten the length or severity of a cold. However, it remains unclear whether or not it could prevent a cold altogether.

Does vitamin C really work?

In clinical trials, researchers started by assessing the effect of vitamin C at doses of 1g per day. A large body review done in 2013 illustrated that in normal populations, clinically, there was no significant effect on the incidence, duration or severity of the common cold from preventative and therapeutic doses of vitamin C. The authors believed it wasn’t worthwhile to continue researching a daily supplementation for prevention, but that isn’t the case for all therapeutic doses.

On the other hand, there have been a small number of studies that have shown proportional benefit. Meaning the higher the dose studied, the larger effect seen, indicating a potential opportunity for researchers to reveal a possible benefit to vitamin C consumption. As a result, researchers have investigated doses as high as 8g per day. This effort has received a decent amount of pushback with some calling anything above 3g per day a “waste of money”.

In addition, professionals are also advising against a high daily dose of vitamin C due to the risk of rebounding scurvy symptoms. This could occur as a result of an abrupt halt to the supplementation instead of a slow, gradual decrease in doses. This would materialize with hallmark symptoms such as loose teeth and bulging eyes (proptosis).

With that said, due to the overall safety and low cost of vitamin C, it may be beneficial to consider the pros and cons. Looking at the cost vs. benefit and whether it would be better to have the duration of your cold shortened by one day. It may be worthwhile for those who are common cold victims to test, on an individual basis, whether therapeutic vitamin C, dosed as soon as symptoms are noticed, is effective for them.

Is vitamin C right for everyone?

For the rare population of marathon runners, skiers and soldiers in subarctic temperatures with abnormal and extreme physical or environmental stress, studies have shown a reduction in the occurrence of a cold by as much as 50%.

However, the opposite is true for patients with chronic liver or kidney conditions. Anyone with these conditions should be cautious with their self-medication of vitamin C, considering the risk of gout or calcium-oxalate kidney stones that could occur, outweighing any benefits of the vitamin C. Patients with these conditions should cap their intake to 1g per day.

What are some other ways to prevent sickness this time of year?
  • Rest and relaxation. While easier said than done, stress and lack of sleep have been shown to increase the risk of the common cold in adults. Children have increased risk from attending daycare and school where there are other germ-carrying children. 
  • Wash your hands. Regular handwashing with soap and water can help protect you from the viruses that cause colds and maybe living on your hands. The proper technique is to wash for at least 20 seconds, which as a reminder, is the “happy birthday song” from beginning to end, twice.  
  • Get your flu shot. Everyone, who is medically able, should get their flu shot annually. Most of the time, it will be covered with insurance at a local pharmacy or your doctor’s office.
  • Homeopathic medicines and remedies. Over-the-counter products containing zinc have been a hot topic regarding the shortening of cold symptoms and may have more of a scientific backing with better results when tested. However, keep in mind that the National Center for Complementary and Integrative Health doesn’t strongly support natural products due to the lack of strong evidence. They also revert to recommending vaccination as the best means of prevention.
So, what’s the verdict on vitamin C?

To sum it all up:

  • Vitamin C may be useful if you start taking it on the first day you feel a cold coming on.
  • Vitamin C should not be used in high amounts if you have chronic liver or kidney disease.
  • Vitamin C is not a replacement for things like washing your hands or getting the flu shot yearly.

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