Vitamin C is a potent immune booster that has been researched perhaps more thoroughly than any other nutrient, according to Dr. William and Martha Sears of the Ask Dr. Sears website. This vitamin is capable of boosting your white blood-cell levels and helping you fend off major health problems such as cardiovascular disease. Because you can't synthesize vitamin C, you must obtain it from foods or supplements. Although too much vitamin C isn't likely to harm you, megadoses can have uncomfortable side effects. Stick to the recommended daily allowance. If you have questions about dosage, talk with your physician.
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RDA for Vitamin C
Before puberty, boys and girls should get the same amount of vitamin C. Infants from birth to 6 months need 40 mg daily. From 7 months to 1 year, babies need 50 mg. The RDA for children ages 1 to 3 falls to 15 mg. Children ages 4 to 8 need 25 mg, while those ages 9 to 13 need 45 mg. Male teens ages 14 to 18 require 75 mg daily, while female teens need 65 mg. Men ages 19 and older need 90 mg, and women 19 and older need 75 mg. A glass of orange juice, a red pepper, one or two oranges or kiwi fruits or a cup of strawberries covers the RDA for most people.
While vitamin C enthusiasts once claimed that megadoses of more than 2,000 mg daily could cure a variety of ailments, from the common cold to cancer, double-blind studies have not substantiated this theory. The recommended daily upper limit for vitamin C is 2,000 mg. Because vitamin C is water soluble, occasionally exceeding this is unlikely to be harmful. The excess will simply be excreted. Sustained megadoses, however, have potential adverse effects, including mild diarrhea, nausea, vomiting, heartburn, headache, insomnia, abdominal cramps and kidney stones.
Pregnancy and Lactation
Pregnant and lactating teens and adults require slightly more vitamin C. The recommended daily amount for pregnant teens is 80 mg. For pregnant adults, the RDA is 85 mg. Lactating teens should get 115 mg daily. Lactating adults need 120 mg.
Other Special Conditions
Smokers and those exposed to cigarette smoke also need more vitamin C. The recommendation is an additional 35 mg for anyone who smokes or is around a smoker. Those who have cancer, cachexia or renal disease should consult their health-care providers concerning adequate vitamin C intake. Alcohol and drug abusers are also at risk of vitamin C deficiency and should consult their doctors, as well. Extremely restrictive and fad diets can cause deficiencies. If you are on one of these diets, consult a registered dietitian, who can help you develop a balanced weight-loss plan that includes all the nutrients you need.