Hypervitaminosis
Acute hypervitaminosis A results from ingestion of very large amounts of the vitamin during a relatively short period of time.
The symptoms, which resolve after supplementation is stopped, include irritability, headache, vomiting, bone pain, weakness, blurred vision, and peeling of the skin.
Chronic hypervitaminosis A can result from high intakes of vitamin A over long period of time and/or in connection with liver or kidney disease.
Some of the signs of chronic hypervitaminosis A are dry skin, hair loss, weakness, headache, bone thickening, enlarged, liver and spleen, anemia, abnormal menstrual periods, stiffness and joint pain; most of these symptoms are reversible, but bone changes and liver damage may be permanent.
Vitamin A in very large doses is known to be teratogenic in many animals. Excessive intake of vitamin A has also been associated with human congenital abnormalities in some cases reports although a causal relationship has not been established.
High intakes should be avoided by pregnant women.
Levels of vitamin A intake associated with hypervitaminosis A varies according to the health and size of the person.
As little as 12,000 IU/day, given to small children for an extended period, has reportedly led to toxicity symptoms.
Hypervitaminosis A may result from acute ingestion of about 500,000 IU of vitamin A by an adult, or from a chronic daily intake of about 100,000 IU.
Hypervitaminosis
Tuesday, November 17, 2009
Monday, October 26, 2009
Vitamin in Fruit Juice
Vitamin in Fruit Juice
Fruit juice is important in human nutrition for beyond its use as a refreshing source of liquid. Many fruits contain a variety of minor ingredients, particularly vitamins and minerals, as well as carbohydrates which are the predominant solid component.
Although fruit contains small amounts of protein and fat, these are not important ingredients of juices.
Nutrients frequently consumed in sub-optimal concentrations by humans are protein, calcium, iron, vitamin A, thiamin (vitamin B1), riboflavin (vitamin B2) an ascorbic acid (vitamin C).
Some of these nutrients occur in higher concentrations in fruit juices than in other foods.
There is experimental evidence that indicates that ascorbic acid of natural origin is apparently superior to that of synthetic origin.
It has been established that the above phenomenon is caused by the presence of certain flavonoids compounds in fruit juice that influence blood circulation, increasing the permeability and elasticity of capillaries.
This action is known as vitamin P activity, but the flavonoids showing this property are not classified as vitamins, because there several substances with is activity and no serious deficiency diseases occur if they are not consumed.
There are indications that these flavonoids have a useful protective action, in particular against some respiratory diseases, but they are readily decomposed in the body, and it is impossible to maintain an effective concentration.
Apart from the more obvious benefits of fruit juice, such as being a source of potassium, it contains other substances that have or are claimed to have useful pharmacological activity. Sorbitol, which occurs in many fruit juices, has a laxative effect.
Several components with antioxidant activity are found in fruit juices. These are including ascorbic acid, tocopherols (vitamin E), beta carotene and flavonoids.
Beta carotene has antioxidant activity that can quench the singlet oxygen that can induce precancerous cellular changes.
Whatever the nutritional interest, it should be noted that changes occur during storage, particularly to the minor components of juices and particularly under adverse conditions (e.g., light, increasing temperature, time).
Vitamin in Fruit Juice
Fruit juice is important in human nutrition for beyond its use as a refreshing source of liquid. Many fruits contain a variety of minor ingredients, particularly vitamins and minerals, as well as carbohydrates which are the predominant solid component.
Although fruit contains small amounts of protein and fat, these are not important ingredients of juices.
Nutrients frequently consumed in sub-optimal concentrations by humans are protein, calcium, iron, vitamin A, thiamin (vitamin B1), riboflavin (vitamin B2) an ascorbic acid (vitamin C).
Some of these nutrients occur in higher concentrations in fruit juices than in other foods.
There is experimental evidence that indicates that ascorbic acid of natural origin is apparently superior to that of synthetic origin.
It has been established that the above phenomenon is caused by the presence of certain flavonoids compounds in fruit juice that influence blood circulation, increasing the permeability and elasticity of capillaries.
This action is known as vitamin P activity, but the flavonoids showing this property are not classified as vitamins, because there several substances with is activity and no serious deficiency diseases occur if they are not consumed.
There are indications that these flavonoids have a useful protective action, in particular against some respiratory diseases, but they are readily decomposed in the body, and it is impossible to maintain an effective concentration.
Apart from the more obvious benefits of fruit juice, such as being a source of potassium, it contains other substances that have or are claimed to have useful pharmacological activity. Sorbitol, which occurs in many fruit juices, has a laxative effect.
Several components with antioxidant activity are found in fruit juices. These are including ascorbic acid, tocopherols (vitamin E), beta carotene and flavonoids.
Beta carotene has antioxidant activity that can quench the singlet oxygen that can induce precancerous cellular changes.
Whatever the nutritional interest, it should be noted that changes occur during storage, particularly to the minor components of juices and particularly under adverse conditions (e.g., light, increasing temperature, time).
Vitamin in Fruit Juice
Tuesday, October 13, 2009
Isolation of Vitamin A
Isolation of Vitamin A
In nature vitamin A is largely found as an ester and consequently, is highly soluble in organic solvents but not in aqueous solutions.
The major pro vitamin carotenoid, B-carotene, has similar solvent properties. One of the richest sources of vitamin A is liver tissue, in particular the liver oils of marine fish and mammals.
The ester can be directly isolated from these oils by molecular distillation at very low pressure, a procedure that has been used extensively for the commercial preparation of vitamins A - rich oils.
Alternatively, vitamin A might be directly extracted with chloroform or with some other solvent combination, such as hexane together with ethanol, followed by purification of vitamin A by chromatographic means.
To hydrolyze esters not only of vitamin A and carotenoids but also of triglycerides and other lipids saponification with KOH is commonly used, followed by extraction with organic solvents.
Retinol or its esters can be readily crystallized at low temperature from a variety of organic solvents, including ethyl format, propylene oxide, and methanol.
Isolation of Vitamin A
In nature vitamin A is largely found as an ester and consequently, is highly soluble in organic solvents but not in aqueous solutions.
The major pro vitamin carotenoid, B-carotene, has similar solvent properties. One of the richest sources of vitamin A is liver tissue, in particular the liver oils of marine fish and mammals.
The ester can be directly isolated from these oils by molecular distillation at very low pressure, a procedure that has been used extensively for the commercial preparation of vitamins A - rich oils.
Alternatively, vitamin A might be directly extracted with chloroform or with some other solvent combination, such as hexane together with ethanol, followed by purification of vitamin A by chromatographic means.
To hydrolyze esters not only of vitamin A and carotenoids but also of triglycerides and other lipids saponification with KOH is commonly used, followed by extraction with organic solvents.
Retinol or its esters can be readily crystallized at low temperature from a variety of organic solvents, including ethyl format, propylene oxide, and methanol.
Isolation of Vitamin A
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