Pee C?

We will delve into the water solubles this week.  The water soluble vitamins are the B vitamins (B1, B2, B3, B5, B6, B9, B12), and vitamin C.  These are water soluble and therefore when we have excess amounts we pee them out.  There are two schools of thought on these- 1) excess amounts are ok, because they are natural and therefore better than medicine 2) excess amounts are not ok, it is hypothesized over time that excessive consumption of water soluble vitamins can over-work the kidneys that work so hard to excrete them with excess water.

I’ll be honest with you.  As an RD I’m really uncertain where I fall in this spectrum.  I think in food form large doses are not bad, but in the form of supplements things can get dicey- again these are my person feelings.  Just because you can pee it out doesn’t mean you need to overwork your kidneys. 

So let’s get on with the Vitamin C.  Vitamin C is the last of our Antioxidant vitamins, and it is another vitamin that is overall a big helper out in the body.  Vitamin C is also known as Ascorbic Acid.  It’s main function is that it acts as an antioxidant in our body and helps protect our cells from damage caused by the oxidation of free radicals we encounter- whether we encounter free radicals from food being converted into energy, or ones we are exposed to from air pollution, cigarette smoke, and even UV light from the sun.

We also need Vitamin C to make collegen.  Collegen is really important, it is a protein that helps wounds to heal.  And lastly Vitamin C improves the absorption of iron in our bodies, helps our immune system work properly. 

The tolerable upper intake for Vitamin C is 2000 mg/day for adults- meaning this is the threshold most people can handle before experiencing symptoms of toxicity. 

The actions of Vitamin C

The recommended amount for adult men is 90 mg, and 75 mg/day for adult women.  Pregnant women need about 85 mg/day, and pregnant teens 80 mg/day.  Breastfeeding women need about 120 mg/day, and breastfeeding teens about 115 mg/day.  Notice the considerable gap between what we “need” versus what we can “tolerate”??

-Fun fact though if you smoke you should tack on about an 35 mg to your recommended amount. 

In terms of toxicity most studies indicate that high levels of supplementation were not associated with any adverse responses with the exception of mild diarrhea, and GI upset. 

Some studies show that even 3-10 g of Vitamin C per day will not damage the kidneys, that they efficiently excrete any excess, and some studies of looked at this for up to or over a year.  (1)

In terms of getting Vitamin C intake is usually pretty simple.  You will find Vitamin C in about any fruitFind your Vitamin C or vegetable with a red-orange-yellow-green color, and even some fruits and veggies that are not those colors.  Some examples of very good sources:

-Papaya; 1 medium = 188 mg of Vitamin C

-Strawberries; 1 cup = 84 mg          

-Orange, navel (1) = 75 mg

-Broccoli 1/2 cup = 58 mg

-Mango (1) = 57 mg-Brussels Sprouts 1/2 cup = 48 mg-Sweet pepper, raw, 1/2 cup = 45 mg-Grapefruit (1/2) = 42 mg  

Another fun fact, Scurvy was very common on ships from England/Europe in the 1800’s.  Once it was figured out that sailors were developing deficiencies in Vitamin C, ships were stocked with Limes & Lemons.  And so the term “limey” was born, a (derogatory) nickname for the Royal Navy sailors from the Americans due to them juicing these fruits and adding them to their beverages to avoid getting Scurvy.  Don’t you love fun facts?  You’re welcs.  


Lastly I want to hit what some of the research about C says, and some interactions to be on the lookout for (both good and bad)

 Important interactions:

– C increases iron absoprtion (ferric acid), if you need to take an iron supplement it’s best to take it with OJ

– C may prolong the clearance time of acetaminophen- meaning it hangs out in your body longer….and you may feel effects for a longer time

-C may increase activity of anticogulants (one reason grapefruit and citrus fruits are usually reduced or eliminated when people start taking these meds)

– C can interfere with activity of B-12- excessive amounts of this, in studies 4 g of vitamin C did not causes a B12 deficiency

-Excess C can interfere with Copper and Chromium absorption-When taking with aluminum containing antacids vitamin C may increase the absorption of aluminum

-Aspirin, corticosteroids, and NSAIDs increase urinary losses of Vitamin C 

Understanding the research being done for Vitamin C can help substantiate or unsubstantiate claims behind vitamin C.  For this I am using a combination of the grading system from the Natural Standard, and my Popular Supplement book.  Each resource has their own grading system of existing research. 

 1) The common cold; based on the research I think there is enough good evidence in humans that shows that Vitamin C DOES NOT prevent the common cold, however it seems that people who eat foods high in vitamin C and have adequate intakes of C, tend to have less severe symptoms, and shorter colds 

2) Cardiovascular disease; it is well thought that those who have a diet that is high in fruit and vegetable intake typically have a lower likelyhood of developing cardiovascular disease.  It is now being studied to see if there is an antioxidant “effect” that helps reduce likelihood of heart disease.  There is conflicting evidence on this, nothing solid, but plenty of promise 

In closing Vitamin C has a lot of great benefits, but in many cases folks likely do not require a supplement, and quite frankly it is better to acquire what you need from food versus a supplement in my humble opinion.  Stay tuned for some B vitamin action.  🙂 


1-The Health Professional’s Guide to Popular Dietary Supplements by Allison SarubinFragakis, MS, RD & Cynthia Thompson, PhD, RD

2-The Office of Dietary Supplements Facts Sheets (NIH)

3-The Natural Standard

Leave a Reply