Vitamin C
Vitamin C used in supplements and foods is almost entirely L-ascorbic acid made industrially from glucose: the glucose is converted to sorbitol and then, through fermentation and chemical conversion steps, to ascorbic acid, which is purified by crystallization. Mineral salts such as sodium and calcium ascorbate are made by neutralizing ascorbic acid, and ascorbyl palmitate is a fat-soluble ester. China produces most of the world's ascorbic acid, with a smaller number of producers elsewhere.
Suppliers sell different products under the same name. Specify the one you need.
Pure L-ascorbic acid sold in mesh grades, from coarse crystals for blending to fine powder for beverages and premixes; USP, FCC and Ph. Eur. grades are common.
Ascorbic acid granulated with a binder such as starch or HPMC, typically 90-97% active, so it can be pressed into tablets without separate granulation.
Crystals coated with ethylcellulose or a fat to slow reaction with other ingredients and limit browning in mixes; the active percentage is below 100%.
Sodium salt of ascorbic acid; less acidic than the free acid and widely used in tablets and powders, and in foods to slow browning and oxidation.
Calcium (and sometimes magnesium or potassium) salts of ascorbic acid sold as non-acidic or buffered vitamin C; they also contribute the mineral.
Fat-soluble ester of ascorbic acid and palmitic acid, used mainly to slow oxidation in oils and oil-based formulas.
Compare each result with your own specification when the lot arrives.
Ascorbic acid and its salts oxidize when exposed to moisture, heat, light and trace metals, and the powder darkens as it degrades. Store in tightly closed, lined containers in a cool, dry place away from light, and reseal opened bags quickly. Suppliers give a retest date or shelf life per lot; coated grades are used where the vitamin must sit in a blend with reactive minerals.
Assay can drift down over time once a container is opened, so record the assay and retest date for each lot and use the oldest lots first (FEFO). Keep acid, salts, coated and DC grades as separate inventory items because their active percentages differ, and adjust formula input amounts when a grade is not 100% ascorbic acid.
Facts from regulators and standards bodies, each linked to its source.
21 CFR 182.8013 lists ascorbic acid as generally recognized as safe (GRAS) as a nutrient when used under good manufacturing practice.
Source: ecfr.gov (opens in a new tab)21 CFR 182.3731 lists sodium ascorbate as GRAS (chemical preservative listing).
Source: ecfr.gov (opens in a new tab)In the EU, Annex II to Directive 2002/46/EC (as replaced by Regulation (EC) No 1170/2009) lists L-ascorbic acid and its sodium and calcium salts as vitamin C sources for food supplements.
Source: eur-lex.europa.eu (opens in a new tab)This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Manufacturers and distributors whose own websites say they sell it.
Manufacturer · Shijiazhuang, China
Vitamin C production unit of the CSPC group in Hebei, making vitamin C along with sodium, calcium, coated and granulated forms.
Manufacturer · Kaiseraugst, Switzerland
Sells it as Quali-C
Global nutrition and beauty ingredients company that makes Quali-C vitamin C in Dalry, Scotland, and vitamin D3 in Sisseln, Switzerland, and sells cosmetic-grade niacinamide.
Novato, CA
California ingredient company that supplies specialty ingredients, including AlphaWave L-theanine and vitamin C.
Manufacturer · Nanjing, China
Nanjing-based maker and marketer of ingredients for food, nutrition, personal care and feed. Its food and nutrition range includes vitamin C and the main B vitamins in several forms.
Manufacturer · Zibo, China
Shandong-based vitamin C producer offering ascorbic acid in food, pharma and feed grades plus fine powder, granulated and sodium ascorbate forms.
Manufacturer
Sells it as COVITAS
Chinese producer of functional chemicals and nutrition ingredients that sells vitamin C and vitamin D3 under its COVITAS human-nutrition line.
Suppliers are in alphabetical order and none pays to appear. Each claim is checked against the supplier’s own website on the date shown. Ask for the specification sheet and a recent COA before you order, and confirm details with the supplier.
Common forms include ascorbic acid, crystalline or fine powder, granulated / direct-compression ascorbic acid, coated ascorbic acid, sodium ascorbate, calcium ascorbate and other buffered forms and ascorbyl palmitate. Ask each supplier for the specification sheet of the exact grade they quote.
Expect assay, identification, specific rotation and pH, appearance and color of solution, heavy metals, particle size and microbiology, each with its method, specification and result for that lot.
Ascorbic acid and its salts oxidize when exposed to moisture, heat, light and trace metals, and the powder darkens as it degrades. Store in tightly closed, lined containers in a cool, dry place away from light, and reseal opened bags quickly. Suppliers give a retest date or shelf life per lot; coated grades are used where the vitamin must sit in a blend with reactive minerals.
21 CFR 182.8013 lists ascorbic acid as generally recognized as safe (GRAS) as a nutrient when used under good manufacturing practice. 21 CFR 182.3731 lists sodium ascorbate as GRAS (chemical preservative listing). In the EU, Annex II to Directive 2002/46/EC (as replaced by Regulation (EC) No 1170/2009) lists L-ascorbic acid and its sodium and calcium salts as vitamin C sources for food supplements.
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