Define Interaction of Vitamin C with other vitamins?

a. Ascorbic acid and other vitamins: Ascorbic acid synthesis is diminished in thiamin and riboflavin deficiency. Vitamin A also plays an important role in the biosynthesis of ascorbic acid.

b. Thiamin and Riboflavin: Thiamin deficiency is accompanied by disturbances in riboflavin metabolism and excretion of riboflavin in urine.

c. Vitamin B₆ and other vitamins: Administration of riboflavin, pantothenic  acid and thiamin provide partial protection against seizures in vitamin B,  deficient experimental animals.

d. Niacin and other vitamins: Livers of rats fed thiamin or riboflavin deficient diets contained smaller amounts of niacin than normal controls. Treatment of pellagra with niacin precipitates symptoms of thiamin mid riboflavin deficiencies indicating that niacin deficiency is accompanied by secondary deficiencies of thiamin and riboflavin.

e. Vitamin B₆ and C: Vitamin BG metabolism increases with higher levels of vitamin C intake. Whole blood ascorbic acid levels fall during vitamin B, depletion and returned to normal levels, during repletion phase.

f. Vitamins B₆ and vitamin B₁₂: Vitamins B₆ BI, deficiency is reported to cause impairment in vitamin B₁₂absorption in rats.

g. Folic acid and vitamin C: Anaemia is observed in vitamin C deficient patients. Normochromic, noimocytic or macrocytic or megaloblastic anaemia has been reported. These conditions responded to ascorbic acid therapy alone or along with folic acid.

h. Vitamin E and C: Both vitamin E and vitamin C are powerful anti oxidants.  They protect biological systems against oxidative damage due to free radicals.  Their functions are synergistic to each other. Vitamin C synthesis is reduced in the livers of vitamin E deficient rats and several vitamin E deficiency symptoms resemble those of scurvy.

i. Riboflavin and pyridoxine: Riboflavin deficiency slows down the uptake  of pyridoxine and decrease the conversion of pyridoxine to its metabolites.

j.Folic acid and vitamin B₁₂: For the conversion of folic acid to folinic acid vitamin B₁₂  is required. Vitamin B ,, deficiency causes a rise in un conjugated  folates and a marked depletion of intracellular conjugated folates.