Vitamin C – Facts and research

Pure vitamin C (L-(+)-ascorbic acid) is a colourless, crystalline, acidic, readily water-soluble powder, which human beings and a number of other species (guinea pigs, primates [apes]) cannot produce for themselves and are therefore required to obtain from their food. The main functions of this vitamin are:

  • To strengthen the immune system
  • To provide protection against harmful substances – foreign substances and metabolic breakdown products
  • The formation and strengthening of the subcutaneous tissue
  • To regulate fat metabolism and energy production

Good sources of vitamin C in our food are fresh, if possible raw and unchopped, vegetables and fruit. Vitamin C in the food is very unstable and is rapidly oxidized by oxygen in the air and then becomes worthless. Therefore cut potatoes, for example, lose up to 50% within 1-2 hours. It is agreed that in order to avoid an acute deficiency of vitamin C, called scurvy, 10 mg/day is needed; and in situations where mild deficiency can occur 50-200 mg are needed. 1,2

Moreover a close relative of humans, the gorilla, takes in the quantity of vitamin C daily from its food (mostly fruit), which in a 70-kg person would correspond to around 2 g/day.

It is interesting that the diet of our hunting and fruit-gathering forebears (approx. 40,000 years ago) is estimated as providing 400 mg of vitamin C 48, an indication that the optimum supply is well above the minimum quantity. The benefit of high vitamin C intake with the aim of prophylactic and therapeutic objectives (0.2-10 g/day) is assessed in varying ways in the literature. Is there really still a vitamin C deficiency in our time?


Deficiency situations are in fact widespread and can have various causes:

Inadequate supply:

This is found particularly in the elderly 3. But unbalanced eating habits, slimming diets, and a loss of appetite also pose a risk to an adequate vitamin C supply. Furthermore it is not only important what quantity of this vitamin is eaten, but above all how much is actually absorbed and taken up by the Body.

Reduced absorption and disrupted vitamin C metabolism:

Reduced absorption occurs in diseases such as gastroduodenal ulcers and general absorption difficulties of the intestine. Disrupted vitamin C metabolism is found in chronic liver diseases, cancers, chronic alcoholism, diabetes inflammatory rheumatic diseases, infections, and even in the common cold. In the latter case the vitamin C concentration falls by up to 50% in the first few days of the onset of the cold! 4

Increased requirement:

An increased requirement is seen in women who use oral contraceptives 6, as well as during pregnancy and lactation. Smokers have increased vitamin C metabolism 7 and frequently lower vitamin C values in the blood plasma and in the white blood cells. According to estimates, the vitamin C requirement of smokers rises by approx. 40% and the risk of a vitamin C deficiency situation rises three to four-fold, compared with non-smokers 8.

In patients with infectious diseases it was recognized that in spite of the vitamin C supply remaining the same, the quantity excreted with the urine fell. This indicates an increased requirement of vitamin C in the tissues. When taking certain painkillers (acetylsalicylic acid, e.g. aspirin) or certain antibiotics (tetracyclines), there is an increased requirement for vitamin C. Its concentration in the blood falls and its excretion via the urine increases somewhat. As compensation for this and to support the liver, 100-500 mg vitamin C/day are to be recommended here 2. If a person has one or more risk factors, it is strongly recommended that vitamin C is taken in order to avoid deficiency situations. Increased losses are also seen in dialysis patients. An additional dose of 200 mg/day or more is recommended. 5


Functions of vitamin C in the body

Vitamin C is one of the factors which takes care of correct processes in the cell membranes. With its property as an antioxidant and as a co-factor of enzyme reactions, it enables a large number of the body’s own biological processes. Its anti-oxidant effect is very important. In various tissues, together with the fat-soluble vitamin E, it protects essential molecules from attack by oxygen radicals. It is also able to detoxify environmental oxidants such as ozone, for example. Due to its property as a free radical, vitamin C is associated with the slowing down of ageing processes and the degenerative diseases which accompany these 2,9.

The crosslinking of collagen depends on vitamin C 10. Therefore this vitamin plays a central role in wound healing 11. A series of toxic breakdown products (toxic metabolites) are created during metabolism. In order to be able to be detoxified and excreted, these must be impeded chemically. This happens in the liver with the help of complex biochemical reactions which, in addition to co-factors, also use vitamin C as essential partners. In vitamin C deficiency this specific action by the liver decreases by up to 50% 12.

Carnitine is a substance produced by the body, which, among other things, takes care of energy production in the cardiac muscle cells 13. It also takes part in the maturation of the spermatozoa 14. The formation of carnitine from the amino acids lysine and methionine is dependent on vitamin C. The general symptoms occurring during vitamin C deficiency, such as tiredness and weakness, may be explained by reduced carnitine biosynthesis and the deficiency of carnitine in the muscles caused by it.

Vitamin C is of decisive importance in the absorption of iron from plant foods, e.g. spinach 16. In most cases a vitamin C deficiency is also accompanied by an iron deficiency. As vitamin C and iron display synergistic activity in the metabolism, the deficiency symptoms also mutually increase.

Vitamin C also plays a decisive role in the production of the neurotransmitter serotonin and its precursor tryptophan, as well as noradrenalin and adrenalin through dopamine from tyrosine 17. Vitamin C affects the metabolism of histamine in ways which cannot yet be explained. It could therefore play a role in mitigating allergies and asthma. Another factor which still has to be investigated is the observation that vitamin C would appear to protect the body to a certain degree from deficiencies in vitamins A, E and the B complex.

A few guaranteed effects of additional doses of vitamin C

Wound healing:

Particularly large quantities of vitamin C have been found in wound tissue. Surgeons administered 0.5-1 g of vitamin C daily to their patients before and after surgical procedures for several weeks. Studies confirm accelerated wound and fracture healing and increased scar strength 18.

Immune system:

Taking 1g vitamin C/day increases the number of certain signal substances which are important for the immune response (IgA; IgM; C3 complement) 19. At doses of 1g or 3g vitamin C/day, children and adult patients with recurring bacterial infections displayed clearly improved chemotactic activity, i.e. the group of white blood cells responsible for the destruction of bacteria which penetrated the body was considerably more active than without taking vitamin C 20. Indeed there is a myth about the effectiveness of vitamin C in preventing and treating cold symptoms. In brief, it is thought to be true that 1-3 g/day and, if symptoms start, 4g/day do at least mitigate the symptoms and can possibly also reduce their length and frequency 21.

Fat metabolism

When they were given 1 g vitamin C/day, patients with fat metabolism disorders saw a significant reduction in their otherwise raised cholesterol values 22. Therefore high doses of this vitamin indirectly reduce problems such as high blood pressure and arterial calcification. This is to be particularly emphasized as it is known that almost half of all deaths in Europe are due to cardiovascular diseases. And 95% of these people had raised cholesterol values!

Mental state:

Vitamin C has been shown to have therapeutic effects in neuropsychiatric diseases, which are accompanied by raised dopamine levels in the brain (schizophrenias, chorea), and in manias and depression 2.


Chronic fatigue syndrome (CFS) and other forms of tiredness and lack of energy were investigated among 411 dentists 48, in whom it was established that those dentists who had a higher intake of vitamin C (over 400 mg) were less tired than those with a lower intake of vitamin C.

Cancer screening

Nitrosamines are carcinogenic substances, which have been demonstrated to contribute to the occurrence of oesophageal, gastric, and large intestine tumours. Nitrates and nitrites are required for them to form. We take in nitrate through our food (particularly vegetarians because of their increased consumption of vegetables) and nitrites in small quantities (enriched in smoked meat). Cigarette smoke also contains high levels of nitrite.

In the body nitrites are converted from nitrates, and the dangerous substance nitrosamine is formed from both substances in combination with so-called amides and amines. Studies show that by taking in larger quantities of vitamin C (4g/day) the conversion into nitrosamines and therefore the risk of cancer is reduced 25,26.

Another carcinogenic substance is benzopyrene. Contained in cigarette smoke, it harms both the smoker and the passive smokers around him/her. Animal experiments on rodents revealed that the administration of additional vitamin C greatly reduced the risk of cancer from benzopyrene. The vitamin C intake was monitored in a 10-year large-scale study in over 11,000 people between 25 and 74 years of age. Of those who took more than 0.8 g/vitamin C per day, significantly fewer people died from cancerous diseases (First National Health and Nutrition Examination Survey).


Environmental toxins

Vitamin C can reduce the dangerousness of heavy metals (lead, cadmium), while reducing their absorption into the body 27,28. In the study 40 pregnant women contaminated with heavy metals received 1 g/C combined with calcium phosphate daily. The lead content in their placentas was around 90% lower than in untreated mothers 29. Because of the anti-oxidative properties of vitamin C, it can be assumed that there will be a lung-protecting effect in the face of “irritating” gases, such as ozone for example.


Fertility and pregnancy

Vitamin C displayed astonishing results in infertility cases. 1g per day administered over two months produces a positive effect in men on the number and motility of the spermatozoa 30. Also, it was possible to promote ovulation in non-ovulating women 31. No harm to the developing child in the womb from high doses of vitamin C was found 37. Administration of up to 200mg of vitamin C per day for pregnant women will therefore only have a positive effect. Habituation on the part of the foetus to this dose is not expected.


Cancer therapy

In two studies Cameron and Pauling (1976 and 1978) reported a clear lengthening of the life expectancy of non-operated tumour patients when 10 g of vitamin C/day was given. The main effect of such megadoses of this vitamin was an improvement in the general condition of the patients and partial or even full freedom from bone pain 32,33. This positive effect of vitamin C therapy cannot, however, be guaranteed as yet, as other studies were not able to confirm these results 34.


Interesting facts on the absorption of vitamin C:

The percentage of this vitamin which is actually absorbed by the body after ingestion falls with increasing dosage. Of 180 mg of vitamin C taken, up to 90% was absorbed; of 2000 mg or more, on the other hand, only up to around 20% was absorbed 2. That means that increasing the amount of vitamin C ingested by a factor of ten only increases absorption by a factor of two. It can be deduced from this that taking vitamin C in smaller doses divided over the day or as ‘time-release’ is better than a single dose.

It is also known that due to the natural excipients, the so-called bioflavonoids, vitamin C is absorbed approx. 35% better. 44

A study by Rhead & Schrauzer (1971) describes individual cases in which, after suddenly stopping high doses of vitamin C, typical vitamin C deficiency symptoms were seen 43. This was interpreted to mean that the high doses over a prolonged time could have led to metabolic changes, so that lower quantities could no longer be absorbed as in the way described above. Controlled studies carried out subsequently were not, however, able to confirm the cases referred to above 2. If users of high-doses of vitamin C have doubts, it is enough to reduce the dose step-by-step over a few weeks to the lower value aimed at.


When is care recommended when taking large quantities of vitamin C?

Kidney stones

A dosage of 1-10 g/day, which can be used to treat various types of illnesses, was investigated to see whether it could contribute to the formation of oxalate kidney stones. More recent studies refute earlier studies which reported clearly increased oxalate excretion after doses of vitamin C were given 35,36. The nine authors maintain that even when taking megadoses the excretion of oxalate (the salt of oxalic acid) only increases slightly, and treatment with vitamin C cannot be regarded as a risk factor for the formation of oxalate, kidney, or urinary stones 2, 37.

But it should be noted that people who already have or have had problems with kidney stones, or who because of an enzyme defect constantly display increased excretion of oxalic acid (hyperoxaluria), should avoid any source of additional oxalate. In this case the administration of vitamin C should not exceed 1g/day.


Iron storage diseases

High doses (1g/day) but not low doses (50mg/day) stimulate the absorption of iron from the food. This normally desirable effect can, however, lead to problems in people with iron storage diseases 38,39. In these cases administrations of vitamin C should be expressly introduced and monitored by a doctor.

The results of the on-going laboratory tests for certain blood values (glucose, urea, creatinine, inorganic phosphate), but in particular for sugar in the urine and occult blood in the stools, can be falsified by megadoses of vitamin C 4,6,45. Therefore the patient should tell the doctor if s/he is taking high doses. The informed doctor can perform tests which remain unaffected by vitamin C.

Earlier studies reported that vitamin C destroys vitamin B12 in the components of the food 40. This was refuted by more recent studies which worked with improved methods. An administration of vitamin C of 2g/day was thought to be the reason for this 37. Mutagenic effects of high doses of vitamin C consequently do not appear in the most recent studies 41.


When taking 10 g of pure vitamin C it is possible that diarrhoea can occur in isolated cases. This is caused by its acid property 42. To avoid such unpleasant episodes and for people with a stomach which is sensitive to acid, vitamin C in the non-acid form of calcium ascorbate is recommended. A further advantage of this ‘neutralized’ type of ascorbic acid is that there is no risk of calcium being released from the tooth enamel because of the acid.

People who therefore buy the inexpensive, acidic vitamin C powder should clean their teeth immediately after swallowing the dissolved powder or at least rinse their mouths out thoroughly with water. This brings the acidity (pH value) of the saliva back to normal values.



Vitamin C supplements, administered in a suitable form and way, can definitely support people in avoiding widespread diseases. It is a natural and valuable agent for improving personal well-being and for avoiding various types of diseases.


Dosage recommendations for orthomolecular nutrition by S. Liebermann, MA Clinical Nutrition, NY University:


Optimum supply 500-5,000 mg/day
Allergies & asthma 3,000-7,000 mg/day
Surgical procedures, wound healing 5,000-10,000 mg/day
Cancer screening 5,000 mg/day
Air pollution 1,000-5,000 mg/day
Increased stress 1,000-5,000 mg/day




  1. Barley W. et al. (1953). Vitamin C requirements of human adults. Med Res Council Spec Rep. Ser p 280.
  2. Bayer, W. Schmidt, K.H. (1987) Vitamin C – Aktueller wissenschaftlicher Erkenntnisstand. Grenzach-Wyhlen: Hofmann-LaRoche AG.
  3. Brubacher, G. Schlettwein-Groll. D (1971). Untersuchungen über die Vitaminversorgung alter Menschen. Aktuelle Gerontologie, 1, 461-467.
  4. Hume, R. Weyers, E. (1973). Scot Med J. ,18, 3-7.
  5. Sullivan, JF, Eisensein, AB (190). Ascorbic Acid depletion in patients undergoing chronic hemodialysis. Am J. of Clinical Nutrition, 23, 1339-1341.
  6. Annals of Nutrition and Meabolism, 1984, 28: 186-191.
  7. Kallner, A. et al (1981). On the requirements of ascorbic acid in man: steady state turnover and body pool in smokers. American J. of Clinical Nutrition, 34, 1347-1355.
  8. Hornig, DH, Glatthaar, B.E. (1985). Vitamin C and smoking: increased requirements of smokers. In: Vitamins: Nutrients and therapeutic agents. Bern: Hans Huber Publ. 139-155.
  9. Am. J. of Clin. Nutrition, (1981) 34, 871-876.
  10. Barnes, MJ, Kadicok, E. (1972) Biological hydroxylations and ascorbic acid with special regard to collagen metabolism. Vimains and Hormones, 30, 1-43.
  11. Burr, RG, Rajan, KT (1972) British J. Nutr, 28, 275-281.
  12. Zannuni, YG, e al. Ascorbic acid and drug metabolism. In: Hathcock, JN, Oann, J. et al (178). Nutrition and drug interrelations. New York: Academic Press, 347-370.
  13. Bieber, LL et al. (1982) Possible functions of short-chain and medium -chain carnitine acyltransferase. Fed Proc, 41: 2858-2862.
  14. James MJ, et al. (1981). Kinetics of carnitine uptake by rat epidermal cells. FEBS Letters, 126: 153-156.
  15. Roquirst, HP (1982). Carnitine biosynthesis and function. Fed Proc, 41, 2840-2842.
  16. Hallberg, L. (1981) Bioavailability of dietary iron in man. Ann Rev Nutr. 1, 123-147.
  17. Deana R. et al (1975). Changes relevant to catecholamine metabolism in liver and brain of ascorbic acid deficient guinea pigs. Int J. Vit Nutr Res, 45, 175-182.
  18. Wintermayer U. (1985). Vitamin C. Stuttgart: Deutscher Apotheker Verlag.
  19. Prizn W. et al (1977). The effect of ascorbic acid supplementation on some parameters of the human immunological defense system. Int J. Nutr Res, 47: 248-257.
  20. Anderson, R. Thoma A (1979) Effects of ascorbate on leucocytes: Part II. In vitro and in vivo stimulation of abnormal neutrophil motility by ascorbate. S Ar Med J. 56-429-433.
  21. Anderson W (1974). Large scale trials of vitamin C in the prevention and treatment of common cold. Acta Vitamin Enzymu. 28: 99-100.
  22. Ginter, E. (1976). Vitamin C and plasma lipids. N. Engl J. Med. 10: 559-560.
  23. Sokaloff, B. et al (1966). Aging, artheriosclerosis and ascorbic acid metabolism. J. Am Geriatr Soc. 14, 1239-1260.
  24. Nutritional Review, 1982, 40, 293-295
  25. Ohishima M., Bartsch M. (1981) The influence of Vitamin C on the in vivo formation of nitrosamines. In Consell, JN, Hornig, DH (Eds). Vitamin C. London: Applied Science Publ. 215-224.
  26. Weisburger, JH (1985). Causes of gastric and esophageal cancer. Possible approach to prevention by vitamin C. In Hanck, A, Horng, D (Eds). Nutrients and therapeutic agents. Bern: Hans Huber Publ., 381-402.
  27. Fox MRS (1975). Protective effects of ascorbic acid against toxicity of heavy metal. Ann NY Acad Sci. 258, 144-150.
  28. Fox MRS, et al (180). Effects of vitamin C and iron on cadmium metabolism. Am NY Acad Sci. 355: 249-261.
  29. S Althmann P, et al (181). Über die entbleiende Wirkung einer kombinierten Therapie mit Kalziumphosphat und Vitamin C bei erhöhter Bleibelastung in der Schwangerschaft. Wien Med Wschr 131: 311-314.
  30. Harris, WR et al (1979 Apparent effects of ascorbic acid medication on semen levels. Fertility and Sterility, 132: 455-459.
  31. Cameron, E. Pauling L (1976). Supplemental ascorbate in the supportive treatment of cancer: prolongation of survival times in terminal human cancer. Proc Nal Acd Sci, 73, 3685-3689.
  32. Cameron, E. Pauling L, (1978). Supplemental ascorbate in the supportive treatment of cancer. Re-evaluation of prolongation of survival times in terminal human cancer. Prac Natl Acad, 75, 4538-4542.
  33. Pauling, L. Maertel, C. (1986). A proposition: megadoses of vitamin C are valuable in the treatment of cancer. Nutritional Review 44:28-32.
  34. Briggs, MH. (1973). Side effects of vitamin C. Lancet, 1973: 1439.
  35. Briggs, MH. Lancet (1976), 154.
  36. Orning DH, Marer U. (1981). The safety of high vitamin C intakes in man. In Counsell JN, Hornig DH (Eds,.) Vitamin C. London: Applied Science Publs, 245-248.
  37. Wapnick AA , et al. (1968). Effect of iron overload on ascorbic acid metabolism. Brit Med J, 3:704-707.
  38. Nienhuis AW (1981). Vitamin C and iron. N. Engl J Med, 304: 170-171.
  39. Herbert Y, Jacob E (1974). Destruction of vitamin B12 by ascorbic acid. J Am Med Assoc. 230:241-242.
  40. Shamberger RJ (1984). Genetic toxicology of ascorbic acid. Mutag Res 133:135-159.
  41. Kuorner WF, Weber F (1982). Zur Toleranz hoher Ascorbinsäuredosen. Int J Vit Nutr Res, 42: 528-544.
  42. Rhead WJ, Schrauzer, GN. Nutritional Review, 1971, 29:262.
  43. American Journal of Clinical Nutrition, 1988, 48:601-604.
  44. Siert G. et al. Drug interference in clinical chemistry: Studies on ascorbic acid. J. Clin Chem clin Biochem, 1978, 16:103-110.
  45. Mayron JS, et al (1972) False negative test or urinary glucose in the presence of ascorbic acid. Am J Clin Pathol, 58:297-299.
  46. Scott Med J (1982),27, 240-243.
  47. J. Amer. Geriat. Soc. 1976, 24, 136


All details are for information only and should not replace treatment or be used for self-medication. For treatment always consult a doctor you trust.