What Does Vitamin C Actually Do?

We see vitamin C a lot these days, mostly in the context of cold prevention (or treatment). Vitamin C is a water soluble vitamin found in certain foods and added as fortification to others. Humans don’t synthesize vitamin C, so it’s essential that we include it in our diet.

Roles of Vitamin C

Vitamin C is essential for the synthesis of collagen, L-Carnitine, and some neurotransmitters, and is also involved in some protein metabolism. It is also an antioxidant thought to help regenerate other antioxidants like vitamin E, helps the body absorb non-heme iron (meaning iron from plant based foods), and plays an important role in immune function. Vitamin C deficiency results in scurvy (often linked to pirates and sailors, who went long periods without fresh produce), which causes fatigue and connective tissue weakness.

Collagen synthesis and immune function are the most notable and widely recognized roles for Vitamin C. Collagen is the most abundant protein in the body, found in muscle, bone, and tendons among other important tissues.

When Do You Need Vitamin C?

Vitamin  C has been linked to a few conditions over the years.

Cancer Prevention  – numerous studies show that a diet high in fruits and vegetables lowers the risk of many cancers, although similar to vitamin A, there is no research that demonstrates vitamin C alone is responsible for this reduced risk or that supplementation would offer any benefit. It seems the pattern of eating fruits and vegetables is more important than single nutrients.

Cardiovascular Disease – research suggests that higher consumption of fruits and vegetables reduces the risk of heart disease, potentially due in part to the antioxidant content of these foods. This makes sense because oxidative damage is one of the causes of heart disease. One British study found that those with the top 25% in blood vitamin C levels had a 42% risk of cardiovascular disease, but the Physicians Health Study found no significant decrease after 5 years of supplementation.  Most clinical interventions and several larger prevention studies have showed no benefit from supplements. As with cancer, you are better off eating a diet rich in fruits and vegetables than supplementing one single nutrient.

The Cold – evidence indicates that vitamin C intake greater than 200 mg a day does not prevent a cold. One study showed a small reduction in cold duration – 8% for adults and 14% for kids. Although if you think about the common cold lasting about 2 weeks, that adds up to about a day. Taking vitamin C after symptoms have already started provided no benefit. Research has shown vitamin C intake of 250 mg – 1 g/day to reduce the incidence of a cold by 50% among people exposed to large bouts of physical exercise and extreme cold – including marathoners, soldiers, and skiers. So, it would appear supplementation is mostly effective for people exposed to extreme environments.

How Much Do You Need?

According to recommended daily allowance (RDA) – a level that should be sufficient to meet the needs of 98% of the population –  the average adult male needs 90 mg a day and the average female 75 mg a day. This is super easy to attain, and most people get way more than that. If you eat 1/2 cup of red bell pepper, a cup of broccoli, and a glass of OJ, you’re already well over 200% of your daily recommended intake.

My Recommendation?

Eat your fruits and veggies. If you ski a lot in the winter, consider taking a supplement if you get sick often. Once you are sick though, forget about the vitamin C. Consider taking a zinc lozenge instead. Or just sleep and drink a lot of fluids.

One caveat: I do often recommend – and take myself – EmergenC when sick. I know, I just said vitamin C does not good, why would I recommend a supplement with 1,000 milligrams of it right? Well, for one because it makes me feel better. It has other vitamins besides vitamin C (including B6 and B12), and because it makes me drink more water. I like it because it works for me, even if the Vitamin C isn’t the reason.

Source: http://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/

Image c/o Keith Williamson 

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