In the 1970s, Nobel Prize-winning chemist Linus Pauling began advocating for the use of high-dose vitamin C to prevent various diseases, including the common cold. However, his ideas were based on theoretical musings and extrapolations rather than clinical evidence. Nonetheless, Dr. Pauling’s international fame as a respected scientist allowed his ideas to take traction, and they still reverberate among some individuals today.
Since the 1970s we’ve been able to thoroughly test Dr. Pauling’s vitamin C theories in multiple clinical studies so that we now better understand what vitamin C can and cannot do for us, and we no longer have to rely on theory and conjecture. In this article, we’ll answer the question: “Does vitamin C actually stop you from getting sick?”
What Is Vitamin C?
Vitamins are nutrients that our body needs to survive but cannot synthesize on its own. Therefore, we must get vitamins from our diet. Vitamin C (also known as ascorbic acid) is one such nutrient. We obtain vitamin C mostly from fruits and vegetables, but it is added to some processed foods and is available as a dietary supplement.
Vitamin C fulfills a number of functions in our body. It is a potent antioxidant, protecting our cells and body tissues from the damaging effects of free radicals from pollution, ultraviolet light, and other environmental threats to our health. It is also important for growth and healing, as it helps us to produce the collagen we need to produce and repair body tissues.
Vitamin C plays several important roles in our immune function, which is the basis of the conjecture that vitamin C might stop us from getting sick.
Vitamin C and Health
There’s no doubt about it: we need vitamin C to survive. Severe deficiency can result in the horrible and fatal disease called scurvy. Fortunately, scurvy is very rare in the Western world, because an ordinary diet usually provides more than adequate amounts of this vitamin.
Even a deficiency of vitamin C that is not severe enough to cause scurvy can affect our health. Insufficient intake leads to a greater susceptibility to infection, impaired wound healing, and a higher risk of damage to our body cells from environmental toxins.
An area of current interest to researchers is whether vitamin C may reduce the risk of some types of cancer. This is because many cancers are largely caused by the effects of free radicals on our DNA. It appears that vitamin C is indeed linked to a lower risk of some tumors (such as colon cancer, breast cancer, and kidney cancer), although it is unclear if taking vitamin C supplements increases the protective effect.
Can Vitamin C Prevent or Treat a Cold?
Despite the role of vitamin C in our immune function, studies have shown that regular vitamin C supplementation does not reduce our risk of catching a cold.
However, once we have a cold, the story changes. A recent review of clinical trials found that supplementing with vitamin C in amounts up to 1,000 mg per day reduced the severity of the common cold by about 15%, and reduced the duration of a severe cold (but not a mild cold) by about 10%.
How Much Vitamin C Should We Take?
Average daily recommended intakes of vitamin C have been published by the United States (U.S.) National Institutes of Health (NIH). This can be dietary and from supplementation. It appears that when a healthy young adult consumes more than 400 mg per day of vitamin C, their body becomes saturated, and any more than that is no longer absorbed. Our body cannot store excess vitamin C.
The reason that very high doses of vitamin C appear to help when we have a cold is that our busy immune system quickly depletes our vitamin C levels, so the extra intake keeps us at healthy levels. The same may be true of other illnesses, particularly those that involve significant inflammation.
Some individuals have higher vitamin C requirements. Smokers deplete their body’s vitamin C supply by up to 50% because of the huge burden of free radicals from cigarette smoke. They likely require about 130 mg per day of additional vitamin C intake.
Pregnancy also increases our vitamin C requirements, as the developing fetus draws on the maternal vitamin C stores. Insufficient intake has been associated with an increased risk of some pregnancy complications. Pregnant individuals require about 10 to 35 mg of additional vitamin C per day; this is reflected in the NIH daily intake recommendations.
People with diabetes may benefit from taking vitamin C well above the daily recommended levels. Studies have shown that taking 1,000 mg per day of vitamin C supplements improves blood sugar control and is associated with a reduced risk of the complications of diabetes.
