It’s that time of year in the Northern Hemisphere when a certain capless crusader dominates drugstore shelves and the bloodstreams of countless people.
We’re talking about vitamin C supplements, a tiny substance with purported powerful powers against the common cold and respiratory ailments. Furthermore, the scientific evidence is shaky and has been hotly debated for decades.
For almost 50 years this a naturally occurring vitamin has earned a stellar reputation as a first-line supplement for boosting the immune system. (This is largely thanks to one brilliant scientist, Linus Pauling) Yet decades of clinical trials on the benefits of high-dose vitamin C (aka ascorbic acid in its natural form) have shown mixed and rather limited results in actual effectiveness. especially for the general population.
The latest research indicates that the so-called recharging your immune system oral vitamin C is of minimal benefit to the average person battling cold and flu season. Although some populations may benefit from an increase in this vitamin.
The promise and allure of vitamin C
During the second half of Pauling’s life, “the greatest chemist of [the 20th] century” developed something of an obsession with vitamin C. His main book in 1970, Vitamin C and the common coldexplores his many theoretical ideas about the healing potential of vitamin C.
After all, he believed that mega doses of vitamin C could help prevent most types of cancers, the onset of cardiovascular disease and countless other health problems. Shortly before he died (aged 93), he said he was taking up to 18 grams of vitamin C per day. That’s roughly 200 times more than the National Institutes of Health recommended daily amount of 90 milligrams for a typical adult male.
Fast forward to the modern day and we now have popular products like Ener-C delivering 1,000 milligrams of vitamin C per single-use packet. The product touts a “health and energy boost” and “immune support,” along with a disclaimer that the claims are not FDA approved (like all vitamins and nutritional supplements sold in the US.).
Inspired by Pauling, the founder of Ener-C (which is manufactured by a company called Pauling Labs) said that he consumes the equivalent of six to eight packets of Ener-C each day, or six-plus grams of vitamin C.
However, studies show that the body reaches maximum absorption of vitamin C in most people at approximately 400 milligrams per day. An excess of vitamin C at this point is typical excreted in the urine.
Basic need for vitamin C
To be clear, vitamin C plays a crucial role in the normal functioning of the immune system.
The nutrient is it is required for collagen biosynthesis, acts as an antioxidant and supports protein metabolism in the human body, among other functions. Severe vitamin C deficiency can also cause scurvyalthough the disease is rare in most of the world today, as it usually occurs only when vitamin C intake falls below 10 milligrams per day for many weeks.
Since humans do not produce vitamin C naturally, we must consume it. And luckily, it’s widely available in many foods, including citrus fruits, red and green peppers, kiwis, white potatoes, and cruciferous vegetables.
In fact, one serving of several of these foods can exceed the commonly recommended daily allowance of between 75 and 100 milligrams of vitamin C — or closer to 200 milligrams in some circumstances.
Who benefits from extra vitamin C?
Although vitamin C levels between 50 and 200 milligrams per day help protect against illness, dozens of peer-reviewed clinical trials over the past decades have failed to show that higher doses prevent the average person from catching the common cold.
A great review published in Cochrane Database of Systematic Reviews in 2013 concluded that regular vitamin C supplementation (over 200 milligrams per day) did not reduce the incidence of colds in the general population. This is based on 29 placebo-controlled trials involving 11,306 participants.
Interestingly, at least five studies in this review showed that higher doses appeared to benefit people under significant physical stress, such as marathon runners, skiers and soldiers. Based on the five studies with nearly 600 participants, vitamin C supplementation reduced the incidence of colds in this population by approximately 50 percent.
Read more: What stress does to the immune system
The higher doses did reduce the duration of colds by an average of 8 percent in adults. In practice, this means that a person who has been fighting a cold for seven days can recover 12 hours sooner if they take megadoses of vitamin C.
For children, it was slightly more effective, reducing the duration of colds by 14 percent. (That is, perhaps reducing a seven-day cold to six days.) But some of these benefits may depend on whether higher doses of vitamin C are taken before or after symptoms appear.
Recently, a comprehensive review published in 2021 by researchers at Harvard University showed that vitamin C had a modest effect on reducing acute respiratory infections in middle-income countries and men, but made little difference in higher-income countries and women. One interpretation of these findings is that men and less affluent populations may be more prone to vitamin C deficiency based on daily diet and lifestyle.
Research on vitamin C is ongoing
For starters, factors such as daily diet, dosage of vitamin C supplements, frequency of use, and routes of administration (oral or intravenous) are a set of variables that play a role in the complex the human immune system.
With that said, there is a lot tried and tested methods to support your immune system during stuffy nose and sore throat season. These include avoiding smoking, a diet high in fruit and vegetables, regular exercise and getting adequate sleep.