Vitamin C

What can high-vitamin C foods do for you?
  • Help protect cells from free radical damage.
  • Lower your cancer risk.
  • Regenerate your vitamin E supplies.
  • Improve iron absorption.
What events can indicate a need for more high-vitamin C foods?
  • Poor wound healing
  • Frequent colds or infections
  • Lung-related problems
What is vitamin C?

Because of its widespread use as a dietary supplement, vitamin C may be more familiar to the general public than any other nutrient. Studies indicate that more than 40% of older individuals in the U.S. take vitamin C supplements; and in some regions of the country, almost 25% of all adults, regardless of age, take vitamin C. Outside of a multivitamin, vitamin C is also the most popular supplement among some groups of registered dietitians, and 80% of the dietitians who take vitamin C take more than 250 milligrams. Why is this nutrient so popular? Vitamin C, also called ascorbic acid, is a water-soluble nutrient that is easily excreted from the body when not needed. It’s so critical to living creatures that almost all mammals can use their own cells to make it. Humans, gorillas, chimps, bats, guinea pigs and birds are some of the few animals that cannot make vitamin C inside of their own bodies. Humans vary greatly in their vitamin C requirement. It’s natural for one person to need 10 times as much vitamin C as another person; and a person’s age and health status can dramatically change his or her need for vitamin C. The amount of vitamin C found in food varies as dramatically as our human requirement. In general, an unripe food is much lower in vitamin C than a ripe one, but provided that the food is ripe, the vitamin C content is higher when the food is younger at the time of harvest.

What is the function of vitamin C?

Vitamin C serves a predominantly protective role in the body. As early as the 1700’s, vitamin C was referred to as the “antiscorbutic factor,” since it helped prevent the disease called scurvy. This disease was first discovered in British sailors, whose sea voyages left them far away from natural surroundings for long periods of time. Their body stores of vitamin C fell below 300 milligrams, and their gums and skin lost the protective effects of vitamin C. Recognizing limes as a good shipboard source of vitamin C, the British sailors became known as “limeys” for carrying large stores of limes aboard ship.\r\n\r\nThe protective role of vitamin C goes far beyond our skin and gums. Cardiovascular diseases, cancers, joint diseases and cataracts are all associated with vitamin C deficiency and can be partly prevented by optimal intake of vitamin C. Vitamin C achieves much of its protective effect by functioning as an antioxidant and preventing oxygen-based damage to our cells. Structures that contain fat (like the lipoprotein molecules that carry fat around our body) are particularly dependent on vitamin C for protection.

What are deficiency symptoms for vitamin C?

Full-blown symptoms of the vitamin C deficiency disease called scurvy—including bleeding gums and skin discoloration due to ruptured blood vessels—are rare in the U.S. Poor wound healing, however, is not rare, and can be a symptom of vitamin C deficiency. Weak immune function, including susceptibility to colds and other infections, can also be a telltale sign of vitamin C deficiency. Since the lining of our respiratory tract also depend heavily on vitamin C for protection, respiratory infection and other lung-related conditions can also be symptomatic of vitamin C deficiency.

What factors might contribute to a deficiency of vitamin C?

Poor intake of vitamin C-rich vegetables and fruits is a common contributor to vitamin C deficiency. In the U.S., one third of all adults get less vitamin C from their diet than is recommended by the National Academy of Sciences, and 1 out of every 6 adults gets less than half the amount recommended. Smoking and exposure to second hand smoke also increase the risk of vitamin C deficiency.\r\n\r\nThe body’s immune and detoxification systems make special use of vitamin C, and overload in either of these systems can increase risk of deficiency. The immune system relies on a wide variety of mechanisms to help protect the body from infection, including white blood cells, complement proteins, and interferons; and vitamin C is especially important in the function of these immune components.\r\n\r\nVitamin C is also critical during the first phase of the body’s detoxification process. This process occurs in many types of tissue, but it is especially active in the liver. When the body is exposed to toxins, vitamin C is often required for the body to begin processing the toxins for elimination. Excessive toxic exposure is therefore a risk factor for vitamin C deficiency.

What health conditions require special emphasis on vitamin C?

Most forms of cardiovascular disease, joint disease, cancer, eye disease, thyroid disease, liver disease, and lung disease require special emphasis on vitamin C intake. The process of aging itself requires special attention to vitamin C. In addition to these broader categories, several specific health conditions also require special emphasis on vitamin C. These specific health conditions include:

  • Acne
  • Alcoholism
  • Alzheimer’s disease
  • Asthma
  • Autism
  • Depression
  • Diabetes
  • Irritable bowel disease
  • Parkinson’s disease

What are the current public health recommendations for intake of vitamin C?

In 2000, the National Academy of Sciences established the following Adequate Intake levels for vitamin C:

  • 0-6 months: 40 milligrams
  • 7-12 months: 50 milligrams

In 2000, the National Academy of Sciences established the following Recommended Dietary Allowances for vitamin C:

  • 1-3 years: 15 milligrams
  • 4-8 years: 25 milligrams
  • Males 9-13 years: 45 milligrams
  • Males 14-18 years: 75 milligrams
  • Males 19 years and older: 90 milligrams
  • Females 9-13 years: 45 milligrams
  • Females 14-18 years: 65 milligrams
  • Females 19 years and older: 75 milligrams
  • Pregnant females 18 years: 80 milligrams
  • Pregnant females 19 years and older: 85 milligrams
  • Lactating females 18 years: 115 milligrams
  • Lactating females 19 years and older: 120 milligrams

The National Academy of Sciences set a Tolerable Upper Intake Level (UL) for vitamin C at 2,000 milligrams (2 grams) for adults 19 years or older.

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