When to Supplement with Vitamin C

As long ago as the 1700s, sailors realized that consuming foods with vitamin C could prevent scurvy, or vitamin C deficiency. Although scurvy is rarely seen in developed countries, certain people are at greater risk, including those who consume few fruits and vegetables or abuse alcohol or drugs. In the United States, low vitamin C levels in the blood are more common in men -especially the elderly - than in women and are more prevalent in lower socioeconomic groups.

Symptoms of scurvy include swollen, bleeding gums: loosening of the teeth; hemorrhaging, including bleeding into the joints; tender and painful extremities; poor wound healing; weakness and fatigue; and psychological disturbances.

For many years experts thought the only use for vitamin C was to prevent scurvy. However, although as little as 10 milligrams of vitamin C per day will prevent deficiency, much higher levels are needed for stress situations such as trauma, wound healing, and infection. Over the years more and more research has shown hat vitamin C may be necessary for the prevention of disease - not just deficiency.

As a result, the RDA for vitamin C was recently increased to 90 milligrams for adult men and 75 milligrams for adult women. The higher levels were set to achieve maximum saturation of vitamin C in the body without excess loss in the urine. It was also recommended that smokers take in an additional 35 milligrams per day to offset some of the oxidative damage from cigarettes. However, some experts argue that these new levels are not high enough. In a report published in 1999, researchers at the National Institutes of Health suggested raising the recommended intake of vitamin C from 100 to 200 milligrams per day.

The USDA Continuing Survey of Food Intakes by Individuals in 1994-96 showed an average daily intake of 109 milligrams of vitamin C for males aged 20 and older, and 91 milligrams for females aged 20 and older.

Although vitamin C toxicity is not a problem for most people, there are certain groups that are at risk of getting too much of this nutrient. Individuals with kidney disease, for instance, should avoid getting more than the RDA.

Additionally, intake above 250 milligrams per day can cause false-negative results in tests for stool and gastric blood. Therefore, high-dose supplementation with vitamin C should be stopped at least two weeks before physical exams because they may interfere with blood and urine tests.