VITAMIN C

Vitamin C is a water- soluble vitamin, very unstable in water solution, chemically a modified sugar,

Which is stored to a small extent in body

synonyms:

Vitamin C , Sodium Ascorbate ,cevitamic acid , hexuronic acid, Ascorbic Acid.

Active substance:

L-ascorbic acid

Antagonists:

 

        d-Glucoascorbic acid, dieoxycorticostrenrone , Cu 2+, estrogens

Synergists:

       Vitamins A,E,B12,B6,K pantothenic acid, testerone, STH, folic acid, Zn 2+, Fe 3+, Ca2+, MG2+, Mn2+, SeO3 2-

Occurrence:

Plants;

·        Fruit (Strawberry, citrus, pineapple, tomatoes, broccoli, kale, horseradish, parsley, corn).

·        Nuts (English walnuts(green))

·        Miscellaneous (Rose hips, molds).

Animals;

·        kidney ,liver,brain, spleen ,WBC,RBC,retina & lenses.

  ‌ You may know that our bodies are unable to manufacture this vitamin, and so we must get it in the food we eat. We don’t store vitamin C, either. Excess amounts are lost in the urine. But most animals make their own vitamin C except guinea pig .

Cats make up to 2800 mg a day, goats up to 13,300 mg, rabbits up to 15,820 mg. While humans vary widely in their daily requirements, age and health can dramatically affect an individual’s needs. The average adult dietary RDA is 60 mg. this is the level thought to prevent scurvy in an adult human (scurvy).

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Good Sources of Vitamin C
Food	Serving Size	Milligrams Vitamin C	% AI for men	% AI for women
Guava	1 medium	165	183	235
Red Bell Pepper	1/2 cup	95	94.7	135
Papaya	1 medium	95	94.7	135
Orange juice, from frozen concentrate	3/4 cup	75	83.3	107
Orange	1 medium	60	66.6	85.7
Broccoli, boiled	1/2 cup	60	66.6	85.7

Physiological Functions :

1. Absorpation of iron

2.      Cold tolerance,

3.       maintenance of adrenal cortex

4.      Antioxidant (Ascorbic acid is a great antioxidant and helps protect the body against pollutants).

5.      Metabolism of tryptophan, phenylalanine, tyrosine

6.      Growth

7.      Wound healing

8.      Synthesis of polysaccharides and collagen

9.      Formation of cartilage, bone& teeth

10.  Maintenance of capillaries

Commercial Production:

1.Microbiological- Acetobacter suboxidans oxidative fermentation of calcium d-gluconate

2.Chemical- Oidation of /-sorbose

Determination:

·         Bioassay-Guinea pig growth or tooth structure, serum alkaline phosphates.

·         Physicochmical- Titration against standard oxidizing dye solution, colorimetry of excess dye; polarography

Deficiency Diseases and Disorders :

• Scurvy;

        Severe vitamin C deficiency has been known for many centuries as the potentially fatal disease , scurvy. By the late 1700's the British navy was aware that scurvy could be cured by eating oranges or lemons, even though vitamin C would not be isolated until the early 1930's. Symptoms of scurvy include bleeding and bruising easily, hair and tooth loss, joint pain and swelling. Such symptoms appear to be related to the weakening of blood vessels, connective tissue, and bone, which contain collagen. Early symptoms of scurvy such as fatigue may result from diminished levels of carnitine needed to derive energy from fat, or decreased synthesis of the neurotransmitter norepinephrine. Scurvy is rare in developed countries because it can be prevented by as little as 10 mg of vitamin C daily .However, recent cases have occurred in children and the elderly on very restricted diets

·         Edema (water retention) also happens with a shortage of vitamin C, and weakness, a lack of energy, poor digestion, painful joints and bronchial infection and colds are also indicative of an under-supply. .                                                                               

• megaloblastic anemia of infancy.
• Delay healing of wounds

Disease Prevention:

The amount of vitamin C required to prevent chronic diseases appears to be more than that required for prevention of scurvy. Much of the information regarding vitamin C and the prevention of chronic disease is based on prospective studies , in which vitamin C intake is assessed in large numbers of people who are follow.

1.Cardiovascular Disease;

low or deficient intakes of vitamin C were associated with an increased risk of cardiovascular diseases and the modest dietary intakes of about 100 mg/day were sufficient for maximum reduction of cardiovascular disease risk among nonsmoking men and women. In addition, several studies had failed to find significant reductions in the risk of coronary heart disease (CHD) among vitamin C supplement users in well-nourished populations. A study founds that the risk of death from cardiovascular diseases was 42% lower in men and 25% lower in women who consumed more than 50 mg/day of dietary vitamin C and who regularly took vitamin C supplements, corresponding to a total vitamin C intake of about 300 mg/day who were free of CHD at baseline and followed for an average of 10 years, found that those who took more than 700 mg/day of supplemental vitamin C had a 25% lower risk of CHD than those who did not take vitamin C supplements

2.Cancer;

vitamin C and stomach cancer;

The latest results from the most comprehensive study of diet's role in cancer risk ever undertaken suggest that getting plenty of vitamin C may lower risk for stomach cancer. The study also indicated that vitamin C may play an important role in protecting against the specific cancer risks associated with diets high in meat.

3.Cataracts;

Decreased vitamin C levels in the lens of the eye have been associated with increased severity of cataracts in humans. Some, but not all, studies have observed increased dietary vitamin C intake and increased blood levels of vitamin C to be associated with decreased risk of cataracts. Those studies that have found a relationship suggest that vitamin C intake may have to be higher than 300 mg/day for a number of years before a protective effect can be detected .

4.Lead toxicity;

lead toxicity continues to be a significant health problem, especially in children living in urban areas. Abnormal growth and development has been observed in infants of women exposed to lead during pregnancy, while children who are chronically exposed to lead are more likely to develop learning disabilities, behavioral problems. In adults, lead toxicity may result in kidney damage and high blood pressure. In a study of 747 older men, blood lead levels were significantly higher in those who reported total dietary vitamin C intakes averaging less than 109 mg/day compared to men who reported higher vitamin C intakes. A much larger study of 19,578 people, including 4,214 children from 6 to 16 years of age, found higher serum vitamin C levels to be associated with significantly lower blood lead level .

Recommended Dietary Allowance (RDA) for Vitamin C
Life Stage	Age	Males (mg/day)	Females (mg/day)
Infants	0-6 months	40 (AI)	40 (AI)
Infants	7-12 months	50 (AI)	50 (AI)
Children	1-3 years	15	15
Children	4-8 years	25	25
Children	9-13 years	45	45
Adolescents	14-18 years	75	65
Adults	19 years and older	90	75
Smokers	19 years and older	125	110
Pregnancy	18 years and younger	-	80
Pregnancy	19-years and older	-	85
Breastfeeding	18 years and younger	-	115
Breastfeeding	19 years and older	-	120

Pharmacokinetics:

• ABSORPTION;

            Ascorbic acid is absorbed primarily in the upper segments of the small intestine by means of active transport involving sodium pump .at high concentrations; absorption is by passive diffusion .following an oral dose up to approximately 180 mg, 70-90%of the dose is absorbed. When the dose is increased to1-12 g , however , the rate of absorption falls from 50 to approximately 15%, although the absolute quantity of the substance absorbed continuous to increase.

• DISTRIBUTION;

           Binding of ascorbic acid to plasma protein is approximately 24%. Serum concentration are normally 10 mg |(60mmol|l). Concentrations bellow 6mg |l(35mmol|l ) indicate that the supplementary intake is still insufficient while concentration bellow 4mg |l indicate a clear deficiency in intake .clinically overt scurvy is seen at serum concentration bellow 2 mg|l

• METABOLISM;

           Ascorbic acid is partly metabolized to dehydroascorbic acid     , and then to oxalic acid, where high concentrations is ingested, ascorbic acid is eliminated mainly in the un changed form in urine and faeces. A farther metabolite ascoorbate-2-sulphate has also been identified in urine.

• ELIMINATION:

           The body’s physiological stores are approximately 1500mg. the half life time of ascorbic acid depends upon the mode of administration, the quantity ingested and the rate of absorption.  Following oral administration of approximately 50 mg vitamin C the half life is about 14 days; following ignition of 1 mg it is only 13 hours. The half life of absorption of sodium ascorbate following IV administration of 500 mg is approximately 6 hours

           Ingestion of a dose bellow 1 to 3 gof vitamin C per day results primarily in renal elimination in unchanged form in faeces

Indications;

         Prevention and treatment of conditions involving vitamin C deficiency, such as prescorbutic state, scurvy, temporary fatigue, poor general condition, gingivitis, spring tiredness

Pregnancy, lactation.

                                                                   

Dosage;

Prophylaxis: 500 mg per day

Oral therapy: 1gm per day

Intensive therapy: in sever cases (frank scurvy, vitamin C deficiency in acute infections, e.g. influenza, pneumonia, wounds, burns, fractures and deep corneal ulcer):1 to2gm per day

Contraindications:

Should not administrated in cases of renal Lithiasis involving hyperoxaluria with acidic or physiological pH, in case of hyper sensitivity, or in case of uremia and haemochromatosis.

Precautions:

Since vitamin C can lead to increased iron absorption, care is called for in patient with haemochromatosis or diseases such as b-thalassemia.

Pregnancy & breast feeding:

There is no information to suggest any risk to the foetus. Vitamin C may thus be taken during pregnancy and breast-feeding.

Adverse effects:

 Over dose are rapidly tolerated with out symptoms. Mild diarrhea and/or diuresis is occasionally seen following ingestionof very high doses the most recent studies have shown that there is no reason to expect the formation of oxalate calculi following prolonged administration of high doses of vitamin C.

Interactions:

All oral contraceptives result in compromised vitamin C equilibrium due to increased oxidation, probably as a result of high level of ceruloplasmin. Oxidation of vitamin C is enhanced by corticosteroids. Calcitonin results in more pronounced use. Salicylates inhibit active transport across the intestinal wall.

Intracellular metabolism and tubular resorption are inhibited by tetracycline.

Acetyl sacylic acid, barbiturates and tetracycline increase the rate of elimination of vitamin C in urine.

Over dose& Toxicity:

Since ascorbic acid is a water-soluble vitamin, toxic levels are not built up or stored in the body, and any excess is lost mostly through urine. If extremely large amounts are taken gastrointestinal problems may appear, but will normalize when the intake is cut or reduced. To determine a level where a person might experience discomfort is difficult, since some people can easily stomach up to 25,000 mg per day, while others start having a problem at 600 or 1,000 mg.

Some people using mega dose therapy of vitamin C may have side effects such as gastrointestinal complaints including diarrhea, nausea and abdominal cramps. These side effects normally stop as soon as high potency intake is reduced or stopped.

When more may be required:

Mega doses of vitamin C should be avoided in individuals with a history of renal stones due to oxalate formation or hemochromatosis or other diseases related to excessive iron accumulation.

Extremely high dosage of vitamin C may predispose premature infants to hemolytic anemia due to the fragility of their red blood cells.

The need for vitamin C will dramatically increase in times when the body is subjected to trauma, infections, and strenuous exercise, elevated environmental temperatures or if the person is a smoker. Smokers should supplement with another 100 mg per day.

Best used with:

Vitamin C will be more effective if taken with bioflavonoids, calcium and magnesium. To enhance the antioxidant properties, it will be best to take it with the other anti-oxidants, as there is strong evidence of synergy between all of them.

-Vitamin E and vitamin C supplements in combination were associate reduced prevalence and incidence of Alzheimer's disease.

Enemy of vitamin C:

Antagonists that destroy this vitamin are air, heat, water as well as prolonged storage, overcooking and processing.
Antacids, alcohol, antidepressants, birth control pills and steroids will also deplete this vitamin.

Special remarks:

• Effects on diagnostic procedure
• In diabetic subjects, vitamin C may hinder demonstration of glucose in urine with out affecting blood glucose concentration. So vitamin C should be discontinued for several days before attempting to determine the glucose content of urine.

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