Background Info: Vitamin C is present in all fruits and vegetables. Vitamin C rich foods are also rich in compounds such as flavonoids and carotenes that enhance the effects of vitamin C and exert favorable effects of their own on the body. While most people think that oranges and orange juice are the best food sources of vitamin C, this is not the case, as many vegetables and some fruits contain more vitamin C than oranges –such as red peppers, kale, parsley, and broccoli. Stability: Vitamin C is very reactive and is destroyed by light, oxygen in the air, heat, and water. Absorption: The larger the dose, the less is absorbed -- unless there is great need as in times of illness or stress. For example, almost 100% of a 200 mg dose of vitamin C is absorbed, but only about 50 % of a 2,000 mg dose is absorbed. This is why it is recommended that a person take divided doses of vitamin C throughout the day, rather than one big dose. Structure/Function Statements • During stress, the vitamin C stored in the adrenal glands is used up. Stressful situations increase metabolism. Tissue requirements for vitamin C are increased during increased metabolism.8 • Vitamin C prevents the release of histamine from mast cells, by stabilizing mast cell membranes.1 • Vitamin C is one of the body’s most important antioxidants. Vitamin C is important in regenerating other important antioxidants, among which are vitamin E and glutathione.2 • Vitamin C contributes to optimal health by strengthening capillaries, due to its role in collagen formation.3 • Vitamin C is necessary for the proper functioning of the immune system.3 Forms of Vitamin C Natural vs. synthetic ascorbic acid: Natural and synthetic L-ascorbic acid are chemically identical and there are no known differences in their biological activity.4,5 ascorbates: Mineral salts of ascorbic acid (mineral ascorbates) are buffered, and therefore, less acidic. Thus, mineral ascorbates are often recommended to people who experience gastrointestinal problems (abdominal pain or diarrhea) with plain ascorbic acid. The research is mixed about mineral ascorbates being less irritating to the gastrointestinal tract. When mineral salts of ascorbic acid are taken, both the ascorbic acid and the mineral are absorbed, so it is important to take into consideration the dose of the mineral accompanying the ascorbic acid when taking large doses of mineral ascorbates. It should be noted that 1 gram = 1000 milligrams (mg) and 1 mg = 1000 micrograms (mcg). Mineral ascorbates are available in the following forms: • : Sodium ascorbate generally provides 131 mg of sodium per 1000 mg of ascorbic acid. Individuals following low-sodium diets should avoid consider avoiding this form. • Calcium ascorbate: Pure calcium ascorbate provides 114 mg of calcium per 1000 mg of ascorbic acid. Calcium in this form appears to be reasonably well absorbed. • Potassium ascorbate: The purest form of commercially available potassium ascorbate contains 0.175 grams (175 mg) of potassium per gram of ascorbic acid. • Others that can be found include ascorbate, zinc ascorbate, molybdenum ascorbate, chromium ascorbate, and manganese ascorbate. Vitamin C with bioflavonoids: Bioflavonoids are a class of water-soluble plant pigments. Vitamin C-rich fruits and vegetables, especially citrus fruits, are often rich sources of bioflavonoids as well. Some studies have found that bioflavonoids increase the bioavailability of ascorbic acid. 6 Although not all studies have found the same effect,7 there is no question that bioflavonoids are found in conjunction with vitamin C and work synergistically

CF231 – Updated 3/04 1 with it in the body.8 The idea holds that, like anything else, rarely is a single compound by itself the best way to achieve optimal nutrient status. Ascorbate and vitamin C metabolites (Ester-C®): Ester-C® is a patented vitamin C that contains mainly calcium ascorbate, but also contains small amounts of the vitamin C metabolites dehydroascorbate (oxidized ascorbic acid – or vitamin C that has neutralized a free radical), calcium threonate, and trace levels of xylonate and lyxonate. Metabolites of ascorbic acid are produced in the body in the process of metabolizing ascorbic acid and are produced as vitamin C is oxidized by the environment. In fact, most vitamin C supplements, as well as most food sources of vitamin C, probably contain dehydroascorbate as a result of ascorbic acid’s exposure to air, moisture, heat, and light. Manufacturers of Ester C® claim that the metabolites increase the C’s bioavailability. However, this has not been confirmed and a small published study of 9 people found no difference between Ester-C® and commerical ascorbic acid with respect to the absorption and urinary excretion of vitamin C.7 Ascorbyl palmitate (Vitamin C Ester): Ascorbyl palmitate is a fat-soluble antioxidant used to increase the shelf life of vegetable oils and potato chips.9 It is an amphipathic molecule, meaning one end is water-soluble and the other end is fat-soluble. This dual solubility allows it to be incorporated into cell membranes. When incorporated into the cell membranes of human red blood cells, ascorbyl palmitate has been found to protect them from oxidative damage and to protect alpha-tocopherol (a fat-soluble antioxidant) from oxidation by free radicals.10 However, these protective effects have only been demonstrated in the test tube and may not be result when taken orally. It is thought that this form of vitamin C is hydrolyzed (broken apart into palmitate and ascorbic acid) in the human digestive tract before it is absorbed.11 The role of vitamin C in promoting collagen synthesis and its antioxidant properties have generated interest in its use on the skin. Ascorbyl palmitate is frequently used in topical preparations because it is more stable than some water-soluble forms of vitamin C.12 Supplement Absorption: While the bioavailability of ascorbic acid appears equivalent whether it is in the form of powder, chewable tablets, or non-chewable tablets, the bioavailability of ascorbic acid from slow-release preparations is less certain.13,14 On Our Shelves: Almost all of the vitamin C on the shelf is synthetic made from the glucose obtained from corn. It would be prohibitively expensive to extract enough vitamin C from a natural source to make a supplement over 100 milligrams. The few natural-source vitamin C products on the shelf will be very low potency, probably below 60 mg (children’s and infant formulas). A label may say “Vitamin C from Rose Hips,” however, most often it is a mixture of ascorbic acid and rose hips, and the rose hips probably make up a very small portion of the product. It is good to include a natural source vitamin C in a synthetic product since it contains many the other nutrients that vitamin C works with synergistically. NUTRIENT TYPE NATURAL OR SYNTHETIC Vitamin C - natural Vitamin C (Rose hips, Sago Natural source. Low potency (60 mg or lower) from palm, or Acerola cherry) rose hips, sago palm or acerola cherries. Vitamin C - synthetic Vitamin C (Ascorbic acid) Synthetic (made from corn glucose). High potency. Vitamin C - buffered Vitamin C (Mineral Synthetic (made from corn glucose). High potency. ascorbate, usually calcium, The ascorbic acid will be buffered by the addition of magnesium or sodium) minerals. The minerals are from a natural source. Vitamin C - hypo- Vitamin C (Beet) Synthetic (made from sugar beet glucose for those allergenic who are sensitive to corn.) Ester-C Ester-C (mineral ascorbate Synthetic (made from corn glucose). The plus metabolites) manufacturing process is supposed to imitate what happens in the body as it metabolizes vitamin C, and thus produce natural or body ready metabolites. Vitamin C (fat Vitamin C (Ascorbal Synthetic (made from corn glucose). The ascorbic soluble, ascorbyl Palmitate) acid has been modified to make it fat soluble. palmitate)

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