Vitamin C (ascorbic acid) Sources

Food sources

As shown in the table below different fruits and vegetables vary in their vitamin C content, but five servings should average out to at least 200 mg of vitamin C.

Food	Serving	Vitamin C (mg)
Orange juice	3/4 cup (6 ounces)	75
Grapefruit juice	3/4 cup (6 ounces)	60
Orange	1 medium	70
Grapefruit	1/2 medium	44
Strawberries	1 cup, whole	82
Tomato	1 medium	23
Sweet red pepper	1/2 cup, raw chopped	141
Broccoli	1/2 cup, cooked	58
Potato	1 medium, baked	26

Supplements

Vitamin C (L-ascorbic acid) is available in many forms, but there is little scientific evidence that any one form is better absorbed or more effective than another.

Natural vs. synthetic vitamin C: Natural and synthetic L-ascorbic acid are chemically identical and there are no known differences in their biological activities or bioavailability.

Mineral ascorbates: Mineral salts of ascorbic acid are buffered and therefore, less acidic than ascorbic acid. Some people find them less irritating to the gastrointestinal tract than ascorbic acid. Sodium ascorbate and calcium ascorbate are the most common forms, although a number of other mineral ascorbates are available. Sodium ascorbate generally provides 131 mg of sodium per 1,000 mg of ascorbic acid, and pure calcium ascorbate provides 114 mg of calcium per 1,000 mg of ascorbic acid.

Vitamin C with bioflavonoids: Bioflavonoids are a class of water-soluble plant pigments that are often found in vitamin C-rich fruits and vegetables, especially citrus fruits. Although many bioflavonoids are thought to function as antioxidants, there is little evidence that the bioflavonoids in most commercial preparations increase the bioavailability or efficacy of vitamin C.

Ascorbate and vitamin C metabolites: One such supplement (Ester-C^®) contains mainly calcium ascorbate, but also contains small amounts of the vitamin C metabolites dehydroascorbate (oxidized ascorbic acid), calcium threonate, and trace levels of xylonate and lyxonate. Although the metabolites are supposed to increase the bioavailability of vitamin C, the only published study in humans found no difference between Ester-C^® and commercially available ascorbic acid tablets with respect to the absorption and urinary excretion of vitamin C. Ester-C^® should not be confused with ascorbyl palmitate, which is also marketed as "vitamin C ester" (see below).

Ascorbyl palmitate: Ascorbyl palmitate is actually a vitamin C ester (vitamin C that has been esterified to a fatty acid). In this case, vitamin C is esterified to the saturated fatty acid, palmitic acid, resulting in a fat-soluble form of vitamin C. Ascorbyl palmitate has been added to a number of skin creams due to interest in its antioxidant properties as well as the important role of vitamin C in collagen synthesis. Although ascorbyl palmitate is also available as an oral supplement, it is likely that most of it is hydrolyzed (broken apart) to ascorbic acid and palmitic acid in the digestive tract before it is absorbed. Ascorbyl palmitate is also marketed as, "vitamin C ester," which should not be confused with Ester-C^® (see above).