The pharmacophore of vitamin C is the ascorbate ion. In living organisms, ascorbate is an antioxidant, as it protects the body against oxidative stress, and a cofactor in several vital enzymatic reactions.
As a nutrient, its uses and requirements are matters of on-going debate. The North American Dietary Reference Intake recommends 90 milligrams per day and no more than 2 grams per day (2000 milligrams per day). Other related species sharing the same inability to produce vitamin C and requiring exogenous vitamin C consume 20 to 80 times this reference intake.
There is continuing debate within the scientific community over the best dose schedule (the amount and frequency of intake) of vitamin C for maintaining optimal health in humans. It is generally agreed that a balanced diet without supplementation contains enough vitamin C to prevent acute scurvy in an average healthy adult, while those who are pregnant, smoke tobacco, or are under stress require slightly more.
Vitamin C is recognized to be one of the least toxic substances known to medicine, with the LD50 being 11,900 milligrams per kilogram. High doses (thousands of milligrams) may result in diarrhoea, which is harmless if the dose is reduced immediately. Some researchers claim the onset of diarrhoea to be an indication of where the body’s true vitamin C requirement lies. Both Cathcart and Cameron have demonstrated that very sick patients with cancer or influenza do not display any evidence of diarrhoea at all until ascorbate intake reaches levels as high as 200 grams (half a pound).
Independent recommended intakes
Some independent researchers have calculated the amount needed for an adult human to achieve similar blood serum levels as vitamin C synthesising mammals as follows:
400 milligrams per day — the Linus Pauling Institute and the US National Institutes of Health
500 milligrams per 12 hours — Professor Roc Ordman, from research into biological free radicals
3,000 milligrams per day (or up to 300,000 mg during illness or pregnancy) — the Vitamin C Foundation
6,000–12,000 milligrams per day — Thomas E. Levy, Colorado Integrative Medical Centre
6,000–18,000 milligrams per day — Linus Pauling's personal use
3,000–200,000 milligrams per day — Robert Cathcart's protocol known as a "vitamin C flush" wherein escalating doses of vitamin C are given until diarrhoea develops, then choosing the highest dose that does not cause diarrhoea (the bowel tolerance threshold)
Relatively large doses of vitamin C may cause indigestion, particularly when taken on an empty stomach. This unpleasant but harmless side-effect can be avoided by taking the vitamin along with meals or by offsetting its acidity by taking an antacid such as baking soda or calcium carbonate.
When taken in huge doses, vitamin C causes diarrhea. The minimum dose that brings about this effect varies with the individual. Robert Cathcart has called this limit the "bowel tolerance threshold" and observed that it is higher in people with serious illness than those in good health. It ranges from 5 to 25 grams per day in healthy individuals to 300 grams per day in those that are severely ill. Diarrhea is not harmful, as long as the dose is reduced quickly.
Natural and artificial dietary sources
Rose hips are a particularly rich source of vitamin C
The richest natural sources are fruits and vegetables, and of those, the camu camu fruit and the billygoat plum contain the highest concentration of the vitamin. It is also present in some cuts of meat, especially liver. Vitamin C is the most widely taken nutritional supplement and is available in a variety of forms, including tablets, drink mixes, crystals in capsules or naked crystals.
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Echinacea Vitamin C with Elderberry Extract 100 chew - Chewable Echinacea Vitamin C combines a proprietary Echinacea blend with European Elderberry extract and other select nutrients in a delicious chewable tablet. Studies have shown that both Echinacea and Elderberry are effective in enhancing immune function.*
In contrast to most Echinacea products, Chewable Echinacea Vitamin C contains two species of Echinacea – providing double the support of any single-variety Echinacea supplement. The proprietary Echinacea blend contains extracts of E. purpurea and E. angustifolia. Select nutrients, including zinc and vitamins A, B6 and C, support healthy immune system responses.*
The great tasting chewable tablets make compliance simple for patients
Emergen-C | Alacer Corp - 1000mg of great tasting vitamin C in a flavored effervescent drink.
Liposomal Vitamin C 5 fl oz | Empirical Labs - High Quality Liposomal Vitamin C Containing 1000mg Vitamin C and 400 mg
LipoZome-C 8 oz | Nutrasal - Highly absorbed Vitamin C in a base of L-arginine
Liquid Vitamin C Natural Orange Flavor - 4 fl. oz | ChildLife Essentials is prepared from the purest ingredients in a liquid form with natural orange flavoring. It is definitely the best tasting Vitamin C available and can be mixed with foods or juices to add a healthful sweetness.(hide)
Micro Liposomal C 4 oz | Allergy Research Group - this is a Highly Absorbable Vitamin C in Sunflower Phospholipid Liposomes
Physicians' Elemental Diet 1296 g- Elemental Powder for GI Dysfunction
Physicians' Elemental Diet 432 g (15.238 oz) - Elemental Powder for GI Dysfunction
Pure Vitamin C - Cassava Source 100 vcaps | Allergy Research Group - The unique cassava source makes Vitamin C Cassava root source well-tolerated by individuals unable to tolerate other sources of vitamin C.(hide)
Pure Vitamin C 1000 mg 100 caps | NutriCology - This Pure Vitamin C is ascorbic acid in unbuffered for. It can be preferred by sensitive individuals who tolerate its mild acidity.(hide)
Pure Vitamin C Powder - Cassava 300 gms | Allergy Research - The unique cassava source makes Vitamin C Cassava root source well-tolerated by individuals unable to tolerate other sources of vitamin C.(hide)
PurX Vitamin C Etheric Delivery Liposomes 4 fl oz - Vitamin C is the quintessential exogenous (diet-derived) antioxidant. Vitamin C absorption decreases with increasing dosage, so a liposomal delivery of Vitamin C offsets that loss and enables high-level dosing without intravenous therapy(hide)
SightC+ 14 oz | Biosyntrx - designed to for those who wish to take large amounts of buffered vitamin C.
Stellar C | Designs for Health- This completely natural plant-based vitamin C formula is loaded with plant bioflavonoids known for capillary and immune system support.(hide)
Super C Caps | American Biologics - Vitamin C is long noted as the premier antioxidant and commonly recognized as an infection fighter
Ultra Potent-C 1000 | Metagenics - 1,000 mg of vitamin C per tablet.
Ultra Potent-C 500 90 tabs | Metagenics - 500 mg of buffered vitamin C in a patented form.
Ultra Potent-C Chewable 90 chews | Metagenics - pleasant-tasting, chewable form that provides 250 mg of vitamin C per tablet.
Ultra Potent-C Powder 8 oz | Metagenics - Buffered, Vitamin C Designed for Enhanced Utilization
Neo40 Professional Nitric Oxide Booster
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