Ascorbic acid is a sugar-based substance and the purest form of vitamin C. The name means "no scurvy" in Latin, which refers to the condition caused by vitamin C deficiency. Because human beings are one of the few mammals that cannot synthesize ascorbic acid, it must be continually consumed from dietary sources. Citrus fruits are excellent sources of ascorbic acid, as are many other fruits and vegetables.
Ascorbic Acid Roles
Ascorbic acid plays important roles in connective tissue growth and repair, immunity, wound healing and cardiovascular health. Ascorbic acid is an especially strong antioxidant and eliminates free-radicals that are produced from oxidation reactions. Free-radicals damage blood vessels and other tissues, accelerating the aging process and increasing the risk of some cancers. Ascorbic acid enhances immunity by stimulating white blood cells, especially neutrophils, lymphocytes and phagocytes, according to "Biochemical, Physiological and Molecular Aspects of Human Nutrition." Ascorbic acid also increases the levels of antibodies in blood serum and aids in the production of interferon, a protein-based substance that fights viruses.
Ascorbic Acid in Food
Ascorbic acid is the type of vitamin C found naturally in foods, especially fruits and vegetables. According to the "American Dietetic Association Complete Food and Nutrition Guide," rich sources of natural ascorbic acid include lemons, limes, grapefruits, kiwis, strawberries, papayas, guavas, oranges, sweet potatoes, rose hips, bell peppers, Brussels sprouts, parsley, cauliflower, kale and broccoli. Contrary to popular belief, oranges are not the best source of vitamin C. One orange contains about 70 mg of ascorbic acid, whereas one cup of broccoli contains 125 mg and one papaya has 190 mg. The most concentrated source of ascorbic acid is rose hips.
Ascorbic Acid as Supplements
Pure ascorbic acid is available as a powdered supplement, but it has a sour, sharp taste and can cause stomach upset and diarrhea in large doses. Calcium ascorbate supplements contain ascorbic acid bound to calcium, which is a buffered, non-acidic form of vitamin C that is gentler on the stomach. Magnesium ascorbate supplements are also non-acidic and is the most absorbable form, according to "The Vitamins." Because ascorbic acid is better absorbed in the presence of flavonoids, many supplement makers also add it to their formulas.
Recommended Amounts of Ascorbic Acid
The National Institutes of Health state that the recommended dietary amounts of ascorbic acid for adults range from 75 mg to 125 mg daily. However, many health professionals believe that higher amounts are required for strong immunity and recommend upwards of 1,000 mg daily. Dr. Linus Pauling, the Nobel Laureate who spent many years studying ascorbic acid, recommended daily amounts of 3,000 mg for all adults. However, the majority of the medical community considers high levels of ascorbic acid unnecessary and a potential cause of kidney stones.
Cooking Foods with Ascorbic Acid
Natural ascorbic acid is highly sensitive to air, water, and temperature. According to "Nutritional Sciences," about 25 percent of ascorbic acid in vegetables can be lost simply by boiling or steaming them for a few minutes. The same degree of loss occurs in the freezing and unthawing of fruits and vegetables. Consumption of fresh, raw fruits and vegetables is the best way to maximize vitamin C intake.
References
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006
- "Nutritional Sciences"; Michelle McGuire; 2007
- "The Vitamins, Third Edition"; Gerald F. Combs; 2007
- National Institutes of Health: Office of Dietary Supplements: Vitamin C Fact Sheet
- "Contemporary Nutrition"; Gordon M. Wardlaw; 2010
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