The middle ages were a time where world exploration and domination took a massive jump. However around the 1700s, about half of the sailors fell victim and died thanks to a certain disease that far surpassed deaths from sea sickness, pirates, or infections. This disease is called scurvy, which is a lack of Vitamin C. Later on, the British navy and more specifically General James Lind would use Vitamin C packed limes and other citrus fruits for his soldiers to treat scurvy, given them a large advantage in their victory against the French naval powerhouse at that time.
Today, Vitamin C supplements are very largely consumed, an inseparable part of multivitamins and other nutritional supplements, and highly marketed as very beneficial as well. But with the modern diet in developed countries, what does the evidence say about the benefits of Vitamin C supplements?
What is Vitamin C anyway?
I was always taught as a child that Vitamin C is there to strengthen my immune system, which is not untrue, though it definitely doesn’t encompass the whole story. First off, it is a vitamin, meaning that by definition our body cannot produce enough of it to meet our needs, and we require an external source from foods or supplements.
It is used as a cofactor in a certain enzyme reactions. Wait, what? Basically, as your body creates certain types of tissue, more specifically collagen, Vitamin C plays an important role in facilitating it’s proper creation. Connective tissue (collagens main role) is everywhere in your body, in simple terms it’s all the tissue that connects things. Vitamin C also plays other roles in your metabolism, helping create an enzyme called carnitine, which is largely responsible for turning fatty acids into energy. Interestingly enough Vitamin C is in fact considered to play a role in your immune system, because we know that it is found in high concentrations in immune cells. Exactly what role does it play? There are a few proposed theories, but it’s not very clear. It’s also important to mention that Vitamin C plays a role as an important antioxidant, as well as in the synthesis of neurotransmitters.
What if I don’t have enough? And what is enough?
After about a month of insufficient Vitamin C, the first signs of scurvy usually begin to develop. These signs can include fatigue (remember that Vitamin C turns fatty acid to energy?), malaise, and inflammation of the gums. If the disease progresses, you will begin to see a rash, gum bleeding, lack of tissue healing, anemia, and if untreated this can be fatal as it was in the middle ages. The good news is that treating scurvy with Vitamin C is very effective, and usually results are seen within a day or two, sometimes completely resolving itself after a week.
Recommended adequate intake of Vitamin C ranges between 80-100mg/day depending on gender, age, and if you smoke or not. Smokers need about 35mg more per day due to the oxidative stress of smoking. Signs and symptoms of scurvy are usually only seen however, after several weeks of less than 10mg/day intake of Vitamin C. Next time you check a daily Vitamin C supplement that you would like to buy, see how much it has in it. Most contain anywhere from 500-1000mg. To put all of this into proportions, a single orange has 51mg of Vitamin C, and a tomato has about 17mg. If you have a few fruits and vegetables per day than there is a good chance you are getting more than adequate amounts.
What have supplements proven?
Aside from scurvy, there are multiple claims which speak to the benefits of Vitamin C, specifically targeting 4 main groups of diseases: cancer, cardiovascular disease, eye disease (acute macular degeneration [AMD] and cataracts), and the common cold.
Cancer – There have been a number of studies showing attempting to show correlation between higher Vitamin C levels and lower incidence of cancer. Evidence is conflicting, with some studies claiming they have proven that correlation. On a collective level, this argument isn’t very strong. Additionally, a very large study in France showed no significant benefit with respect to risk for cancer in a population who took a multivitamin containing 120mg of Vitamin C, to a different group that didn’t take it. Many other studies were conducted, some using larger doses of Vitamin C (500mg/d) that reviewed the effect on many different types of cancer, though there was no proven benefit in cancer prevention. There were theories raised that high dose Vitamin C can help in Cancer treatment, though the evidence did not support these theories either.
Cardiovascular disease – It has been proven with very strong evidence that populations that have higher fruit and vegetable intake are at far lower risk for cardiovascular disease than those who have lower intakes. However, the evidence for supplemental Vitamin C is once again weak. Very large reviews compiling a number of studies have proven that there exists a very strong benefit for a healthy Vitamin C intake through dietary means, with respects to lowering the chances of cardiovascular disease. Supplements however, have not proven themselves as superior to a healthy diet at all.
Eye disease – Although there is no evidence that supports the positive effect of Vitamin C, either dietary or supplements in preventing AMD, there has been evidence to support that individuals diagnosed with AMD may prevent disease progression with Vitamin C supplements. The study that proved this provided the patients with multivitamins containing Vitamin C as well as other antioxidants, such as Vitamin E, Zinc, Copper, and beta-carotene. The evidence for cataracts has been disappointing and does not provide anything to support prevention.
Common cold – Studies attempting to prevent cases of the common cold in the general population by taking Vitamin C supplements have come up empty handed. However a very interesting study examining athletes in extreme physical conditions (marathon runners, skiers etc) who took supplements of between 250-1000mg/day showed a decrease of 50% chance of getting the common cold. After the onset of symptoms however, it showed to have little to no effect.
Lastly it’s important to note that the cells in our body cannot absorb much more than 100mg/day of Vitamin C. People who took 200mg/day showed very minor increase in the Vitamin C levels than people who had a 100mg/day intake, so take this into account when you take 500mg or 1000mg per day supplements.
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Here are a list of some of the studies that we used to get the information, and may be interesting to read. If you would like more information, or have questions please feel free to leave a comment and we’ll be happy to get back to you and provide additional information.
Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2007;(3):CD000980.
Hercberg S, Galan P, Preziosi P, Bertrais S, Mennen L, Malvy D, et al. The SU.VI.MAX Study: a randomized, placebo-controlled trial of the health effects of antioxidant vitamins and minerals. Arch Intern Med 2004;164:2335-42.
Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol 2001;119:1417-36.