Multivitamins and Nutrition

Ascorbic acid, or Vitamin C is a water soluble vitamin, related chemically to glucose, which is only a vitamin for humans, higher primates, guinea pig, some fruit bats and some birds. The vast majority of animals, including farm, they can synthesize it, so do not accumulate in your body (or, possibly, secreted in milk). This has the effect that food animals are generally poor in this vitamin.

Ascorbic acid has a lactone structure. The acidity is not due to a carboxylic group, but the possibility to ionize the hydroxyl located on carbon 3, forming an anion that is stabilized by resonance. Its pKa is 4.04. Eventually, it may even dissociate the hydroxyl located at carbon 2, forming a dianion, although its pK is much higher (11.4), because it is not stabilized by resonance, such as carbon 3.

Ascorbic acid deficiency causes a disease called scurvy, resulting in damages related to the synthesis of collagen, since ascorbic acid is an essential cofactor in this process. The clinical consequences ranging from weak to bleeding gums spread throughout the body.

Although known since long ago (described in various texts of the thirteenth century), from the historical point of view scurvy was very important, especially for its impact on the fleets of the sixteenth and eighteenth centuries, a period which caused more casualties crews themselves naval battles. Among other cases, three quarters of the crew of Magellan’s expedition died because of scurvy, and a similar proportion of the crew of George Anson’s expedition against the Spanish fleet in the Pacific in 1740.

In 1757 James Lind published A Treatise of the Scurvy, a book in which he showed the dramatic beneficial effect of citrus fruits on the sick. Although it took some years to be accepted and implemented in practice, this finding be generalized to a greater or lesser extent all fresh vegetables and finished with the deficiency disease scurvy.

Ascorbic acid is only found in significant concentrations in the plant (which is ignored which could be the possible biological role). Many fruits are found in high concentrations (50 mg/100g in citrus fruits), but for many people the main contribution is obtained from vegetables such as cabbage or cauliflower. The new potato contain about 30 mg/100 g, although they are losing during almecenamiento.

It is a water soluble vitamin and as such can be lost through leaching. This loss greatly influences the contact surface, so more easily lost from foods that have more relative area as foliaceous vegetables or sliced food. Moreover, the maintenance of protective structures during cooking (the skin of potatoes, for example) is protected from oxidation and other alterations

Ascorbic acid is particularly sensitive to oxidation reactions, very easily destroyed during food processing in the presence of oxygen. The oxidation is pH dependent because the ionized form is more ensible that the unionized form. The dianion is even more sensitive, but is formed in significant need an alkaline pH that is not found in food.

Initially passed in the oxidation of ascorbate to dehidroascorbato, in a reaction that is reversible, so the principle remains dehidroascorbato value as vitamin C. However, for the dehidroascorbato lactone is much less stable than that of ascorbate, so very easily hydrolyzed to produce acid 2, 3 diketogulonic, which can then be degraded by decarboxylation. Neither the acid 2, 3 diketogulonic or its breakdown products have already activity as vitamin C.

The oxidation reaction can be catalyzed by the enzyme ascorbate oxidase, abundant in some plants, and also occurs as side reaction in oxidations catalyzed by peroxidases or polyphenoloxidases. Consequently, the breakdown of compartmentalization greatly speeds up the destruction of ascorbic acid, and also provides access to oxygen.

The ascorbate oxidase (EC 1.10.3.3) is a relatively thermostable enzyme, and also very sensitive to changes in pH. It has a molecular weight of about 140,000, with glucidic remains attached to the polypeptide chain. Each molecule contains eight copper atoms, divided into three types, which differ in their spectroscopic behavior. Of these, only one of the “type 1″, another of the “type 2″ and two “Type 3″ are in the active site of the enzyme associated with histidine residues.

It also produces the oxidation of ascorbic acid chemical form, without the intervention of enzymes, especially in the presence of metals such as iron or copper, which act as catalysts. Copper is about 80 times more potent than iron. In total absence of metals, ascorbic acid is relatively stable, even in the presence of oxygen. The chelating agents are relatively effective against copper, but not against the iron.

Ascorbic acid can be changed also in non-oxidative reactions, especially in acidic (between pH 3 and 4), by opening the lactone ring and subsequent decarboxylation. This effect may be important in canned goods. In any case, at equal temperature this reaction is much slower than the oxidation.

Ascorbic acid is a powerful reducing agent capable of reacting with oxygen, and thus usable as an antioxidant. Also used as a flour improver. In this application, the dehydroascorbic acid formed at the expense of ascorbic acid is reduced to ascorbic, while oxidized SH groups of gluten forming disulfide bonds.

Functions:
* Improved vision and has preventive role to cataracts or glaucoma.
* It is antioxidant thus neutralizes free radicals, preventing damage that they generate in the body.
Their antioxidant capacity makes this vitamin the body eliminate toxic substances such as nitrites and nitrates in meat products and prepared meats. Nitrates and nitrites increase the likelihood of developing cancer.
Her virtue as an antioxidant protects us against cigarette smoke, and as boost the immune system is also used in patients undergoing radiotherapy and chemotherapy.
* It is antibacterial, so it inhibits the growth of certain bacteria harmful to the body.
* Reduce complications from diabetes type II
* Decreases blood pressure levels and prevents the development of vascular disease
* Has antihistaminic properties, so it is used in allergy treatment, asthma and sinusitis.
* It helps prevent or improve skin conditions like eczema or psoriasis.
* It is healing of wounds, burns, because vitamin C is essential in collagen formation.
* Increase production of estrogen during menopause, many times this vitamin is used to reduce or relieve symptoms of hot flashes and others.
* Improve constipation laxative properties.
* Repairs and maintains cartilage, bones and teeth.

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Tags: ascorbic acid, vitamin c, water soluble vitamin