Facts and Stats on Vitamin C

We received this question from one of our readers: “I have taken 1,000 mg time-released vitamin C every morning for many years. I used to be plagued with colds about twice a year and they always turned to bronchitis. A friend told me to take vitamin C, not as I'm starting to feel a cold coming on, but every single morning. I finally got into the habit. I have not had a cold for 3-4 years!! Because I have not had a cold, I also haven't come down with bronchitis and other respiratory ailments. Seriously - I feel the time-released vitamin C has kept me from getting sick! While others in my office are always sick - coughing, wheezing and snuffling, many times with colds and sinus infections, their germs never seem to infiltrate my system. “

“I was at the drugstore the other day picking up timed-released vitamin C and the pharmacist said there is some controversy on taking too much - that it can cause kidney damage. I have cut down to 500 mg but I would like to know what you think about this.”

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin. Although our body is unable to manufacture vitamin C on its own, the vitamin helps our body form collagen in bones, cartilage, muscle, and blood vessels. Vitamin C also helps our body absorb iron, which is why dietitians often suggest spinach salad with orange slices or strawberries on top.

Our body doesn’t make vitamin C, so we get vitamin C from food (mostly fresh fruits and vegetables) and supplements. The orange juice folks would like to have a monopoly on vitamin C, but grapefruit (fruit and juice), strawberries, cantaloupe, red bell peppers, broccoli, Brussel sprouts, turnip and collard greens, cauliflower, and the increasingly popular leafy kale all contain great levels of vitamin C.

The research on common cold prevention is interesting. More than 30 clinical trials including more than 10,000 participants examined the effects of taking daily vitamin C, and overall, a significant reduction in the risk of developing colds wasn’t seen. However, a subset of the studies looked at people living in extreme circumstances – including skiers and marathon runners, and found almost a 50 percent reduction in the risk of developing a cold! As the subset of elite athletes was small, more studies are needed, but it looks like vitamin C for cold prevention in this population may make great sense.

Many people grab their vitamin C supplements the second they start to feel a cold coming on in hopes that they can ward off the inevitable. Numerous studies have examined the effects of starting vitamin C after the onset of cold symptoms, and unfortunately supplementation doesn’t seem to lesson the symptoms, or the duration, of the cold. On the other hand, the science does show that people who take 1,000 mg of vitamin C daily throughout the cold season can modestly reduce the symptoms and duration of colds. Cooper Complete adult formulations contain vitamin C. Cooper Complete Elite Athlete, for marathoners and anyone exercising at 80 percent of predicted maximum heart rate for a minimum of five hours per week contains 2,000 mg vitamin C, while Cooper Complete original formulations (Iron Free and With Iron) contain 500 mg, and Basic One contains 150 mg.

The US recommendation for daily intake of vitamin C is 75 mg for adult women and 90 mg for adult men. As a water soluble vitamin, whatever our body doesn’t need immediately is eliminated. In an article published in the American Journal of Clinical Nutrition, researchers reported that when the daily dose of vitamin C was increased from 200 to 2,500 mg, the plasma concentration increased by only 12- to 15 mg/L, and renal clearance of vitamin C rose sharply. In addition, the digestive tract also stops absorbing vitamin C as well as these higher levels. So, the net effect is that after a certain level it doesn’t really matter our much vitamin C we take as our blood level concentration of vitamin C isn’t going to increase much more.

The upper intake level (UL) for vitamin C is 2,000 mg per day for men and women. Taking high levels of vitamin C can cause severe diarrhea, as well as kidney stones. And if the vitamin C of your choice is the chewable kind, too many of these tablets can wreck havoc on tooth enamel. Because vitamin C may increase adverse affects of acetaminophen and antacids, the supplement (or a multivitamin including vitamin C) shouldn’t be taken at the same time as these over-the-counter medications.

To purchase Cooper Complete supplements, visit the Cooper Store.

Reference
Blanchard J, Tozer TN, Rowland M. Pharmacokinetic perspective on megadoses of ascorbic acid. Am J Clin Nutr. 1997;66:1165-1171.
http://www.ajcn.org/content/66/5/1165.short

Micronutrient Information Center – Linus Pauling Institute
http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/

The World’s Healthiest Foods
http://www.whfoods.com/genpage.php?tname=nutrient&dbid=109

Jill Turner is VP Operations for Cooper Concepts, the company that markets Cooper Complete nutritional supplements. Email (jsturner@cooperwellness.com) or call 972-560-3262 with your questions and comments regarding supplements.