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Vitamin C History

By Dr Liji Thomas, MD

Vitamin C is an essential cofactor for mixed-oxidase enzymes which catalyze the production of many proteins such as those involved in building supporting tissue in the body.

Vitamin C absorption

It is almost completely absorbed at doses of 200-400 mg/day, and plasma concentrations plateau at 60-80 μmol/L. Excess vitamin C in the gut is largely excreted. This absorption barrier may be overcome by administration of a direct intravenous infusion of vitamin C, which leads to high plasma levels.

These will slowly return to normal via urinary excretion. At doses lower than 200 mg/day, absorption is directly proportional to the dosage. Plasma levels of vitamin C are thus controlled largely by intestinal absorption, renal reabsorption and tissue transport mechanisms.

Dietary reference intakes

Dietary reference intakes may be classified as:

  • Recommended daily allowances (RDA), which cover the amount required for normal physiological function in the vast majority of healthy people
  • Adequate intakes, which are sufficient to stave off deficiency symptoms, and which are set when the RDA has not yet been determined
  • Tolerable upper intake levels, which are the greatest doses considered safe for consumption

The following table shows the recommended daily allowance of vitamin C in various groups:

Table 1. RDA of vitamin C

Group

RDA

0-6 months

40 mg

7-12 months

50 mg

1-3 years

15 mg

4-8 years

25 mg

9-13 years

45 mg

14-18 years

65-75 mg (females and males respectively)

>19 years

75-90 mg (females and males respectively)

Pregnancy

80-85 mg (less than or above 18 years respectively)

Lactation

115-120 mg (less than or above 18 years respectively)

Smokers

RDA for respective group + 35 mg/day extra

In practical terms, five servings of fruit and vegetables a day, which comes to about two and one-half cups, are estimated to supply about 200 mg of vitamin C a day.

Low levels of vitamin C are likely in the following situations, though not overt deficiency:

  • Active and passive smokers have lower plasma vitamin C levels, probably because of the oxidative stress induced by tobacco smoke inhalation.
  • Infants fed on boiled cow’s milk or evaporated milk have lower vitamin C levels because the naturally low levels of this vitamin in cow’s milk is further reduced by boiling. Both breast milk and infant formula do, however, supply the required amounts of vitamin C.
  • Malnutrition due to restricted access to a variety of foods may cause low vitamin C levels. The reasons for poor food choices include:
    • poverty,
    • alcohol or drug abuse,
    • eating disorders,
    • food fads,
    • mental illness
    • malabsorption syndromes,
    • malignancies, and
    • end-stage renal disease patients on hemodialysis

Determination of vitamin C status

The following plasma levels have been suggested to define the baseline vitamin C status:

  • Vitamin-C replete: 60-80 μmol/L
  • Sub-optimal levels: <50 μmol/L,
  • Marginally deficient levels: <28 μmol/L
  • Severely deficient levels: <11 μmol/L

References

Further Reading

Last Updated: Feb 25, 2016

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Comments
  1. Vadim Shapoval Vadim Shapoval Ukraine says:

    Scurvy is a disease caused by a diet that lacks vitamin C. Humans cannot synthesize vitamin C, which is necessary for the production of collagen and iron absorption. Scurvy was originally thought to be an infectious disease because sailors on long voyages tended to come down with it en masse. When Dr James Lind, a British naval surgeon, published a book in 1753 establishing that scurvy was in fact brought about by a nutritional deficiency it took 40 years for his discovery to be accepted by the prevailing medical orthodoxy of the day. Plague is a recurring infectious disease. People in ‘plague times’ were very superstitious. So flagellates stood in the streets and whipped themselves and said it was cleaning them of their sins. Some scientists have warned that the Black Death, one of the most devastating pandemics in human history that killed between 75 million and 200 million people, could one day return with the emergence of antibiotic-resistant forms of the bacterium. Cholera is a diarrheal illness caused by the bacteria Vibrio cholerae. Physicians of the 19th century used such characteristic treatments of cholera as bleeding or opium. Today, cholera is treated using oral rehydration therapy, which consists of large volumes of water mixed with a blend of sugar and salts. Antibiotics can shorten illness. Syphilis is caused by bacteria called Treponema pallidum. Mercury (as treatment for syphilis) was used in the form of ointments, oral administration, and vapor baths. Such treatment remained popular for three centuries. Today, primary and secondary syphilis can be successfully treated with penicillin and other antibiotics. In 1928 Alexander Fleming discovered penicillin, made from the Penicillium notatum mold. Fleming published his discovery in 1929, in the British Journal of Experimental Pathology, but little attention was paid to his article. The U.S. Department of Agriculture first grew large quantities of penicillin in 1941. Today, scientists ignore iron-AIDS, iron-ALS and iron-Cancer information. Ferromagnetic Cancer Theory will beat Cancer. Ferromagnetic ALS Theory will beat ALS. Deficiency of iron destabilizes enzyme systems of any virus. HIV/AIDS cannot survive artificial iron-deficiency anemia. HIV/AIDS must disappear. The U.S. Department of Agriculture may help scientists to beat AIDS, ALS and Cancer.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
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