The role of vitamin C and daily requirements

It is high in lemon juice, greenery and tomatoes. Ascorbic acid is monoclinic lamellae or needle crystals that are easily oxidized to form dehydroascorbic acid, which still has the effect of vitamin C. In alkaline solutions, the lactone ring in the dehydroascorbic acid molecule is easily hydrolyzed to diketogulac acid. This compound cannot become lactone-type in animals. Oxalic acid or sulfate ester combined with sulfuric acid is finally formed in the human body and is excreted in the urine. Therefore, diketogulac acid no longer has physiological activity.

In 1907, Norway chemist Holst discovered it in lemon juice. The pure product was obtained in 1934 and can now be synthesized artificially. Vitamin C is the most unstable vitamin. Because it is easily oxidized, it can be destroyed during food storage or cooking, and even when chopping fresh vegetables. Trace amounts of copper and iron ions can speed up the damage. Therefore, only fresh vegetables, fruits or mixed vegetables are a rich source of vitamin C. It is a colorless crystal with a melting point of 190 - 192 ° C. It is easily soluble in water. The aqueous solution is acidic and has relatively active chemical properties. It is easy to decompose when exposed to heat, alkali and heavy metal ions. Therefore, it is not possible to use copper pots and heat them for too long.

Plants and most animals can synthesize vitamin C in their own bodies. However, humans, primates and guinea pigs lack the enzymes that convert L-gulac acid into vitamin C and cannot synthesize vitamin C. Therefore, they must consume it from food. If vitamin C is lacking in food, scurvy will occur. At this time, symptoms such as bleeding, loose teeth, difficult wounds to heal, and easy fractures occur due to the disorder of interstitial formation. Since the half-life of vitamin C in the human body is longer about 16 days, scurvy will not appear until 3 to 4 months after eating foods that do not contain vitamin C. Because vitamin C is easily oxidized and reduced, it is generally believed that its natural effect should be related to this property. Vitamin C is directly related to the normal synthesis of collagen, tyrosine metabolism in the body and iron absorption. The main