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Vitamin C: Facts, Figures, and Fallacies 
 
by LEXA W LEE July 26, 2005

Vitamin C is among the most popular nutritional supplements, and for good reason. The human body cannot make or store it, and it is involved in numerous vital functions such as detoxification and immunity. How much do we need to take, and when do we need more?

Some Facts

How much do you really know about vitamin C? Like every other vitamin, it has multiple effects and plays many roles in maintaining our health. More than 40% of older Americans take vitamin C supplements, and as many as 25% of all Americans take them.

Humans Don't Make Vitamin C

You may know that our bodies are unable to manufacture this vitamin, and so we must get it in the food we eat. We don’t store vitamin C, either. Excess amounts are lost in the urine. But did you know that most animals make their own vitamin C?

As a result of what some believe was an unfortunate mutation in our evolutionary history, a few mammalian species lost the ability to manufacture vitamin C. Humans, guinea pigs, primates, guinea pigs, birds, and some bats are examples of this unlucky little group. On the other hand, cats make up to 2800 mg a day, goats up to 13,300 mg, rabbits up to 15,820 mg. While humans vary widely in their daily requirements, age and health can dramatically affect an individual’s needs. The average adult dietary RDA is 60 mg, believe it or not. Keep in mind that this is the level thought to prevent scurvy in an adult human (scurvy, rare in the US, is characterized by bleeding gums and poor wound healing). Keep in mind this does not necessarily mean you are in good health; it just means you escape getting scurvy. Congratulations.

Lesser Known Facts

Vitamin C, or ascorbic acid, was first isolated and identified in 1928. These days we can get it in pills, lozenges, powder, effervescent tablets, syrups, injections, IV solutions. It’s added to drinks and even cosmetics like anti-aging creams. It has long been added to food in the form of citric acid to prevent spoilage – you see, some food additives are actually natural substances.

Vitamin C is very sensitive to air, water, and temperature. Boiling and steaming, as well as freezing and unthawing will result in a loss of about one-fourth of total vitamin C levels. The longer food is cooked, the more vitamin C is lost. The highest levels are found in fresh, raw vegetables and fruits, especially broccoli, parsley, bell peppers, strawberries, oranges, lemons, papaya, cauliflower, kale, mustard greens, brussel sprouts.

It has been postulated that human beings lost an enzyme that is involved in the manufacture of vitamin C. Mammals who can generate their own stores do not get scurvy, tuberculosis of the lung, or viral leukemia, to name a few diseases. Although vitamin C was first identified as an anti-scorbutic agent, we have come to think of it as a good treatment for colds and infections. But as mentioned above, it has many lesser known but just as important effects and functions:

  1. Vitamin C is essential to the manufacture and maintenance of collagen, the major protein of the connective tissue that shapes our bodies and strengthens our skin and blood vessels.
  2. It may play a role in preventing atherosclerosis and hypertension.
  3. It is an antioxidant, so it helps reduce the activity of free radicals, by-products of normal metabolism which nonetheless can damage cells and set the stage for aging, degeneration, and cancer. It shouldn’t come as any surprise that vitamin C is being used as a cancer treatment, albeit in much larger doses, sometimes administered intravenously.
  4. It is involved in the activity of many cells of the immune system, like white blood cells, various proteins, and interferons.
  5. It is involved in the process of detoxification, which takes place in various tissues and organs, such as the liver.
  6. Taking vitamin C supplements increases the absorption of iron from the gut, which may or may not be desirable, depending on the person.

Linus Pauling, who won the Nobel Prize in Chemistry as well as the Nobel Peace Prize a few decades ago, was for many years, the lightning rod in the controversy surrounding vitamin C – namely, how much should we take? Scientists, mostly a highly conformist and conventional bunch, are not known for their generosity towards pioneers or theorists. For decades they laughed at Pauling for recommending that we take large doses of vitamin C, far above the recommended 60 mg a day. Pauling himself was known to take 18 grams, or 18,000 mg a day. He thought that humans should take at least as much as rabbits manufacture for themselves – up to 15 or more grams daily.

Here are some things to keep in mind when taking vitamin C:

  • The cheapest and most popular form of vitamin C is ascorbic acid, which is synthesized in laboratories. Manufacturers make it, then supply it to various companies, who often combine it with natural products like rose hips and acerola cherries, mostly for marketing reasons. Research has shown that natural and synthetic ascorbic acid are chemically identical. There are no known differences in their biological availability or activity, as shown in human studies.
  • Since ascorbic acid can damage tooth enamel and cause GI upset, buffered C’s such as calcium and sodium ascorbate were developed as gentler forms. Ester-C is a popular brand name of buffered C, and therefore less acidic. Mineral ascorbates,such as potassium ascorbate, are often recommended to people who experience abdominal pain or diarrhea with plain ascorbic acid. Sodium ascorbate is probably not the best choice for those who suffer from hypertension.
  • While it is true that excess vitamin C is excreted in the urine, its very presence in the urinary tract exerts a protective effect on the system. Still, if you are taking larger doses, it’s advisable to take divided doses. Taking them with food can help avoid GI discomfort.
  • While the bioavailability of ascorbic acid appears equivalent whether it is in the form of powder, chewable tablets, or non-chewable tablets, the bioavailability of ascorbic acid from slow-release preparations is less certain.

Risk Factors for Vitamin C Deficiency

  • Poor intake of vitamin C-containing vegetables and fruits. One-third of all Americans get less vitamin C from their diet than is recommended, and 1 out of every 6 adults gets less than half the amount recommended.
  • Smoking
  • Pregnancy
  • Illness
  • The use of oral contraceptives/birth control pills, NSAIDs (non-steroidal anti-inflammatory drugs including aspirin and acetaminophen), corticosteroids (like cortisone), sulfa drugs (often used as antibiotics or in cancer treatment), and barbiturates.


 




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