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.
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*
Vital Mixed Ascorbates 250 grams | Pharmax - Vital Mixed Ascorbates (with natural fruit antioxidants) provides a buffered form of vitamin C together with magnesium, calcium, potassium, manganese and zinc in a highly bio-available form as ascorbates.*(hide)
Vitality C 200 gms | American Nutriceuticals - a unique form of L-Ascorbate C crystals, has been further enhanced with 2000 mg of GMS-Ribose for increased bio-availablility.*(hide)
Vitality C Powder 6.5 g 20 pkts | American Nutriceuticals - Our favorite Vitamin C, a unique form of L-Ascorbate C crystals, has been further enhanced with 2000 mg of GMS-Ribose for increased bio-availablility.*(hide)
Vitamin C & Non-Citrus Bioflavonoids 90 vcaps | Pharmax - Easily absorbable,rich in magnesium,bioflavanoids protect against premature oxidation of vitamin C,vegetarian.*(hide)
Vitamin C Buffered 1000 mg 100 tabs | Vinco - Vinco’s Buffered Vitamin C contains 1,000 mg of Buffered C Ascorbate per tablet(hide)
Buffered Vitamin C Powder | Designs for Health - This form of vitamin C is non-acidic, which means it is much better absorbed and provides the additional benefits of calcium, magnesium, and potassium supplementation.*(hide)
Vitamin C Buffered Powder 445 g | Vinco - Vitamin C Buffered Powder 4,000 mg per teaspoon.
Vitamin C Powder 250 grams | Pharmax - The high potency, pure magnesium ascorbate is fully reacted and totally soluble.*
VITAMIN C Ultra-fine ascorbic acid Powder | Klaire Labs - Vitamn C supports the immune system and wound healing, acts as a powerful antioxidant protecting cells from free radical damage, and is an important nutrient in the production of collagen and other connective tissues.*(hide)
Vitamin C w/ Quercetin and Bioflavonoids 180 vcaps | Integrative Therapeutics - This synergistic formula combines the antioxidant support of vitamin C and quercetin with the proteolytic-enzyme support of bromelain*(hide)
Vitamin-C with R-Lipoic 1.7oz | Quicksilver - the most absorbable form of professional-grade VitaminC.*
Vitamin C-250 - 180 tablets | Innate Response Formulas - contains a high potency of 100% whole food vitamin C from True Active™ FoodState*(hide)
Vitamin C-400 180 tabs | Innate Response Formulas - incomparable formulation providing 250 mg of 100% whole food vitamin C from True Active™ FoodState*(hide)
Vitamin Code Raw Vitamin C | Garden of Life - comprehensive, whole-food, vitamin C formula made with RAW Food-Created Nutrients*(hide)
- Physicians' Elemental Diet 1296 g
- Vitamin C with R-Lipoic Acid Liposomal 1.7 oz
- Buffered Lemon C Powder 300 g
- Physicians' Elemental Diet 432 g (15.238 oz)
- Consultation With Dr. Forrest, DC
- Vitality C Powder 6.5 g 20 pkts
- Liposomal Vitamin C 5 fl oz
- Micro Liposomal C
- VITAMIN C Ultra-fine ascorbic acid powder
Neo40 Professional Nitric Oxide Booster
- • Neo 40 helps improve circulation and the cardiovascular system
- • NEO 40 raises Nitric Oxide
- • ED is caused by low Nitric Oxide
- • Now available in 30 or 60 lozenges
- • NEW Proessional Strength version available
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