Biosynthesis of Vitamin C

Posted by Blog Wednesday, March 2, 2011

The vast majority of animals synthesize vitamin C. It is not a vitamin for them as they do not need to obtain it from food. The few animals that cannot synthesize vitamin C in their bodies include apes, humans, guinea pigs, one type of bird, one type of bat, and one type of fish. All other animals synthesize vitamin C in a fourstep proces.

The first step in synthesizing vitamin C starts with glucuronate, which is made from blood sugar (glucose), as seen in Figure 2-1. In the second step, glucuronate is converted to L-gluconate. The third step changes the L-gluconate to L-gulonogamma- lactone. It is interesting to note that humans can perform these three initial steps to synthesize vitamin C. Humans are lacking the enzyme gulonolactone oxidase, in which L-ascorbic acid is made from L-gulono-gamma-lactone.

 We cannot synthesize vitamin C in our bodies, and must ingest it. This fourth step is catalyzed in the liver of most animals. The amount of vitamin C that humans would synthesize, if they had the ability, may be a clue to our needs. The rate of biosynthesis of vitamin C in those species capable of producing the vitamin varies considerably between species.

Figure 2-1 Biosynthesis of vitamin C.

The lowest biosynthesis of vitamin C is 40 mg per kilogram of body weight daily for the dog or cat; this works out to 2800 mg daily for a person of 70 kilograms (154 pounds). The highest biosynthesis of vitamin C is in the mouse, which synthesizes 275 mg of vitamin C per kilogram of body weight daily; this works out to about 20 grams (20,000 mg) daily for a 70-kilogram person. If humans could synthesize their own vitamin C, the amount synthesized daily might be between 2800 mg and 20,000 mg.

If humans could synthesize their own vitamin C, the amount synthesized daily might be between
2800 mg and 20,000 mg.

More about C-Vitamin:

Vitamin C The Citrus Antioxidant

Most Popular Supplement

Biosynthesis of Vitamin C

Collagen and Vitamin C

Vitamin C as an Antioxidant

Vitamin C, Infections, and the Common Cold

Vitamin C and Disease Prevention

Other Roles of Vitamin C

Vitamin C Food Sources

Supplemental Forms of Vitamin C


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