Vitamin C: Fact, Fiction & Function

Vitamin C factsAuthor: Lily Mazzarella
News from the health food craze percolated even through suburban New Jersey in the late 70s and early 80s:  I, like most people, grew up thinking that vitamin C was good for me, and that oranges were the only way to get it.  When I was home sick with a cold, I would tip an icy canister of orange juice concentrate into a pitcher, pausing to eat it by the spoonful, getting perilously high on sugar.  As I felt my energy levels rise, I knew for certain I was curing myself.  Years later, after many years of study, I have concluded that while oranges are not without nutritional value, they are not the be-all-end-all of vitamin C sources, and that “orange juice as a health food” is hoax perpetrated upon the American people by the citrus lobby.

So, let’s learn a little about this incredibly important nutrient—what it does for us, what it doesn’t, and where to get it.

Vitamin C is an essential nutrient, meaning that unlike most other animals, we humans cannot synthesize Vitamin C endogenously.  That means we must obtain it from our diets.  If we don’t, we’re at risk for scurvy, or vitamin C deficiency, in which we literally start to come apart:  C is required for the formation and maintenance of all of our collagen.  And collagen is the foundation of our connective tissues, including blood vessels, cartilage, and bone.  It’s an important antioxidant in the immune system and central nervous system; highest C concentration in the human body occur in white blood cells, the brain, and the eyes, as well as the adrenal glands.

Should I supplement?

Vitamin C, a.k.a. ascorbic acid, can be taken in supplement form, although studies suggest that not more than 200-300 mg can be absorbed at a time (for more info, see this NIH factsheet).  C is water-soluble and we excrete much of it unchanged in the urine when we take doses above 2000 mg/day.  Higher dose supplementation can also cause loose stools and gastrointestinal upset, as unabsorbed C exerts an osmotic pull of water into the large bowel.

I do recommend vitamin C supplementation to my clients—but I suggest they use lower dose (250-500 mg) pills, or a food-based powder.  If higher doses are desired, the amount should be divided throughout the day.  I’m not a huge fan of Ester-C; one study did show that this (expensive) form raised leukocyte levels faster than plain old ascorbic acid, but the researchers concluded that the benefit was not worth the cost.  Of course, I’m AM a huge fan of getting it from the best possible source:  our food.

Where do we get it?

foods with vitamin c

Wondering how to eat those herbs?

  • Make a delicious pesto with your parsley and eat by the spoonful! Here’s our recipe.
  • At 540 mg of vitamin C per cup, rose hips are a potent ally. I recommend making a rose hip jelly!
  • Ever try hibiscus flower tea? Cultures world-round have been brewing up these romantic vitamin C rich petals for ages. In Latin American culture it’s known as Jugo de Jamaica and in Egypt and Sudan you can ask for Jus de Bissap.

Though boiling and cooking does destroy some vitamin C content (see below), I believe that in most cases, lower amounts from a food or tea are preferable to mega-doses of synthetic nutrient.

Let’s be fair:  oranges are delightful.  Oranges contain carotenes, flavonoids, fiber, and a host of complex, beneficial constituents like limonoids.  Kids love them, and they are hydrating. But if you’re going to do juice, do it yourself: buy organic and juice the WHOLE orange—peel and pith included (or at least a few of the peels).  This will give provide abundant bittersweet aromatic components, as well as flavonoids like rutin, which help to strengthen your blood vessels and stabilize inflammatory mast cells.  Many store-bought juices are spiked with high-fructose corn syrup, and many contain as much sugar as soda.

Does cooking destroy vitamin C?

The short answer is:  yes.  But it doesn’t destroy all of it, and the amount of loss varies dramatically depending upon the cooking method and food in question.  According to a study at UC Davis, home cooking methods destroy 15-55% of vitamin C in commonly consumed foods.  Freezing preserves C better than canning for most fruits and veggies, though it can be lost over long storage time (think of all those ice-crystal filled bags in your freezer.  Might be time to compost!).  Boiling and frying destroy more C than other methods, while pressure cooking and microwaving preserve the most C.  Overall, they concluded that fresh is best for vitamin C content, with a couple of interesting exceptions:  “cooked frozen peas and frozen leaf spinach (versus frozen chopped) contained amounts of ascorbic acid greater than or equal to those in the cooked fresh products.”

Vitamin C and your immune system

According to the Linus Pauling Institute, a nutritional research center at Oregon State University, vitamin C influences several components of the human immune system.  It has been shown to stimulate both the production and function of white blood cells, including neutrophils, lymphocytes, and phagocytes, all of which are involved in fighting infection.  Vitamin C accumulates in these cells and protects them from the oxidative stress that occurs when they engage in their explosive battles against invading microorganisms.  In vitro studies have shown that vitamin C increases interferon production in white blood cells, a chemical that is specific to our body’s fight against viruses.  Vitamin C is one of our most important antioxidants, aiding in the recycling of other antioxidants, like vitamin E.

Linus who?

Linus Pauling was the double Nobel Laureate (Chemistry and Peace) who posited that large doses of vitamin C (more than 1000 mg/day) could be used to prevent the common cold.  He published 2 books:  Vitamin C and the Common Cold, and Vitamin C and Cancer, which sparked public interest in high-dose C therapy.  This kind of supplementation is still used by functional nutrition practitioners and alternative physicians to support people with a variety of chronic health conditions, including cancer, heavy metal toxicity, and Lyme disease.

Does Vitamin C protect us from the common cold?  Or speed our recovery once we contract it?

While most meta-analyses on regular vitamin C supplementation (greater than 200 mg) have failed to demonstrate prevention of the common cold, except in certain cases of extreme physical activity (eg, endurance athletes), research does suggest that it can shorten the duration of the common cold, especially in children.  Once a cold is underway, no significant effect vitamin C supplementation has been observed in therapeutic trials.  However, when 1000 mg of vitamin C was combined with 10 mg of Zinc, rhinorrhea (runny nose) was significantly reduced over 5 days of treatment.

Special evidence

Vitamin C supplementation (greater than 200 mg) appears to have specific benefits in these groups:

  • Children
  • People doing extreme physical exercise and/or exposed to very cold temperatures: vitamin C supplementation can halve the incidence of colds in these groups!
  • Common cold-induced asthma

Fun Vitamin C facts

In Arctic cultures, whale skin is prized as the best source of vitamin C in the diet

Vitamin C aids absorption of non-heme (plant-based) iron

In addition to vitamin C, pineapple contains mucus-thinning bromelain, a proteolytic enzyme, making it a double-win for cold season!

In addition to collagen, vitamin C is required for the biosynthesis of L-carnitine, and catecholamines—neurotransmitters like norepinephrine and dopamine, as well as serotonin and acetylcholine.  It is also necessary for proper synaptic transmission of these important neurotransmitters.

Flavonoids—ubiquitous plant kingdom compounds found in green tea, chocolate, citrus, blueberries, cherries—may increase intra-cellular utilization of vitamin C, and with C, aid in collagen formation.  Vitamin C and the flavonoid quercetin appear to have a synergistic anti-allergic effect.

Vitamin C (or lemon juice) taken with green tea can increase the absorption of green tea catechins, well-researched antioxidant compounds, by up to 13 times!

Your C requirements are higher if…

  • You smoke
  • You are healing from a wound, burn, or surgery
  • You have gastrointestinal inflammation (Crohn’s, Colitis, or parasites)
  • You are pregnant, or breastfeeding
  • You have adrenal fatigue
  • You exercise heavily
Back to blog