Vitamin B3 - niacin, niacinamide, nicotinic acid -
Niacin also called nicotinic acid, niacinamide or nicotinic acid and referred to as vitamin B 3, which can be manufactured by the body.
Niacin is derived from two compounds - nicotinic acid and niacinamide.
Vitamin B3 is required for cell respiration, helps in the release of energy and metabolism of carbohydrates, fats, and proteins, proper circulation and healthy skin, functioning of the nervous system, and normal secretion of bile and stomach fluids.
It is used in the synthesis of sex hormones, treating schizophrenia and other mental illnesses, and a memory-enhancer.
Nicotinic acid (but not nicotinamide) given in drug dosage improves the blood cholesterol profile, and has been used to clear the body of organic poisons, such as certain insecticides. People report more mental alertness when this vitamin is in sufficient supply.
Deficiency of vitamin B3:
A deficiency may cause pellagra, the classic niacin deficiency disease, and is characterized by bilateral dermatitis, diarrhea, and dementia.
A shortage of niacin may be indicated with symptoms such as canker sores, depression, diarrhea, dizziness, fatigue, halitosis, headaches, indigestion, insomnia, limb pains, loss of appetite, low blood sugar, muscular weakness, skin eruptions, and inflammation.
Dosage:
The dosage underneath is the Recommended Dietary Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Male 18 mg per day and female 13 mg per day although 100 mg is mostly used in supplementation.
Large doses given to lower cholesterol may produce hyperuricemia, and hepatic abnormalities. These effects are reversed if the drug is reduced in amount or discontinued.
Toxicity and symptoms of high intake:
Nicotinic acid, but not nicotinamide in doses larger than 200 mg causes flushing by dilating the blood vessels, which can also cause the blood pressure to drop.
These flushes are normally harmless. Large dosages can also cause itching, elevated blood glucose, peptic ulcers and liver damage.
Best used with:
Niacin is best taken with the B group vitamins and vitamin c.
When more may be required:
Consuming alcohol and not having enough protein in your diet may increase your need for niacin.
People with diabetes, glaucoma, any liver disease or peptic ulcers should be careful of niacin supplementation.
Enemy of vitamin B3:
Niacin is lost readily when food is cooked in water.
Other interesting points:
Nicotinamide is under investigation for helping to prevent and control diabetes.
Food sources of vitamin B3:
Liver, lean meat, poultry, fish, rabbit, nuts, peanut yeast, meats including liver, cereals, legumes, asparagus, seeds, milk, green leafy vegetables, and fish.
Your daily cup of coffee also provides about 3 milligrams of niacin.
Friday, February 23, 2007
FoOdS In ViTaMiN B-12(CoBaLaMiN)
Vitamin B12 (cobalamin) is an important water-soluble vitamin.
In contrast to other water-soluble vitamins it is not excreted quickly in the urine, but rather accumulates and is stored in the liver, kidney and other body tissues. As a result, a vitamin B12 deficiency may not manifest itself until after 5 or 6 years of a diet supplying inadequate amounts.
Vitamin B12 functions as a methyl donor and works with folic acid in the synthesis of DNA and red blood cells and is vitally important in maintaining the health of the insulation sheath (myelin sheath) that surrounds nerve cells.
The classical vitamin B12 deficiency disease is pernicious anaemia, a serious disease characterized by large, immature red blood cells. It is now clear though, that a vitamin B12 deficiency can have serious consequences long before anaemia is evident. The normal blood level of vitamin B12 ranges between 200 and 600 picogram/milliliter (148-443 picomol/liter).
A deficiency often manifests itself first in the development of neurological dysfunction that is almost indistinguishable from senile dementia and Alzheimer's disease.
There is little question that many patients exhibiting symptoms of Alzheimer's actually suffer from a vitamin B12 deficiency.
Their symptoms are totally reversible through effective supplementation. A low level of vitamin B12 has also been associated with asthma, depression, AIDS, multiple sclerosis, tinnitus, diabetic neuropathy and low sperm counts. Clearly, it is very important to maintain adequate body stores of this crucial vitamin.
The amount of vitamin B12 actually needed by the body is very small, probably only about 2 micrograms or 2 millionth of a gram/day. Unfortunately, vitamin B12 is not absorbed very well so much larger amounts need to be supplied through the diet or supplementation.
The richest dietary sources of vitamin B12 are liver, especially lamb's liver, and kidneys. Eggs, cheese and some species of fish also supply small amounts, but vegetables and fruits are very poor sources.
Several surveys have shown that most strict, long-term vegetarians are vitamin B12 deficient.
Many elderly people are also deficient because their production of the intrinsic factor needed to absorb the vitamin from the small intestine decline rapidly with age.
Fortunately, oral supplementation with vitamin B12 is safe, efficient and inexpensive. Most multi-vitamin pills contain 100-200 microgram of the cyanocobalamin form of B-12. This must be converted to methylcobalamin or adenosylcobalamin before it can be used by the body. The actual absorption of B12 is also a problem with supplements. Swallowing 500 micrograms of cyanocobalamin can result in absorption of as little as 1.8 microgram so most multivitamins do not provide an adequate daily intake. The best approach is to dissolve a sublingual tablet of methylcobalamin (1000 micrograms) under the tongue every day. That will be sufficient to maintain adequate body stores. However, if a deficiency is actually present then 2000 microgram/day for one month is recommended followed by 1000 microgram/day. Some physicians still maintain that monthly injections of vitamin B12 is required to maintain adequate levels in the elderly and in patients with a diagnosed deficiency. There is however, no scientific evidence supporting the notion that injections are more effective than sublingual supplementation.
In contrast to other water-soluble vitamins it is not excreted quickly in the urine, but rather accumulates and is stored in the liver, kidney and other body tissues. As a result, a vitamin B12 deficiency may not manifest itself until after 5 or 6 years of a diet supplying inadequate amounts.
Vitamin B12 functions as a methyl donor and works with folic acid in the synthesis of DNA and red blood cells and is vitally important in maintaining the health of the insulation sheath (myelin sheath) that surrounds nerve cells.
The classical vitamin B12 deficiency disease is pernicious anaemia, a serious disease characterized by large, immature red blood cells. It is now clear though, that a vitamin B12 deficiency can have serious consequences long before anaemia is evident. The normal blood level of vitamin B12 ranges between 200 and 600 picogram/milliliter (148-443 picomol/liter).
A deficiency often manifests itself first in the development of neurological dysfunction that is almost indistinguishable from senile dementia and Alzheimer's disease.
There is little question that many patients exhibiting symptoms of Alzheimer's actually suffer from a vitamin B12 deficiency.
Their symptoms are totally reversible through effective supplementation. A low level of vitamin B12 has also been associated with asthma, depression, AIDS, multiple sclerosis, tinnitus, diabetic neuropathy and low sperm counts. Clearly, it is very important to maintain adequate body stores of this crucial vitamin.
The amount of vitamin B12 actually needed by the body is very small, probably only about 2 micrograms or 2 millionth of a gram/day. Unfortunately, vitamin B12 is not absorbed very well so much larger amounts need to be supplied through the diet or supplementation.
The richest dietary sources of vitamin B12 are liver, especially lamb's liver, and kidneys. Eggs, cheese and some species of fish also supply small amounts, but vegetables and fruits are very poor sources.
Several surveys have shown that most strict, long-term vegetarians are vitamin B12 deficient.
Many elderly people are also deficient because their production of the intrinsic factor needed to absorb the vitamin from the small intestine decline rapidly with age.
Fortunately, oral supplementation with vitamin B12 is safe, efficient and inexpensive. Most multi-vitamin pills contain 100-200 microgram of the cyanocobalamin form of B-12. This must be converted to methylcobalamin or adenosylcobalamin before it can be used by the body. The actual absorption of B12 is also a problem with supplements. Swallowing 500 micrograms of cyanocobalamin can result in absorption of as little as 1.8 microgram so most multivitamins do not provide an adequate daily intake. The best approach is to dissolve a sublingual tablet of methylcobalamin (1000 micrograms) under the tongue every day. That will be sufficient to maintain adequate body stores. However, if a deficiency is actually present then 2000 microgram/day for one month is recommended followed by 1000 microgram/day. Some physicians still maintain that monthly injections of vitamin B12 is required to maintain adequate levels in the elderly and in patients with a diagnosed deficiency. There is however, no scientific evidence supporting the notion that injections are more effective than sublingual supplementation.
FoOdS In ViTaMiN B-2(RiBoFlAvIn)
Overview
Essential to energy generation, nerve development...
Benefits: Keeps healthy mucous membranes linings...
Natural Sources: Beef liver, dairy products...
How to Use Liquid: the best form due to its high bioavailability...
Cautions Consult your doctor if you are pregnant...
Deficiency Fatigue, red, swollen, cracked mouth tongue...
Overdose Itching, numbness, a burning sensation...
Side Effects Yellow urine (in large doses),
No needed action...
Interactions Antidepressants (tricyclic) - faReduces B-2 efficacy...
Overview: Vitamin B-2, otherwise known as riboflavin, is readily absorbed from foods, such as meat, dairy products, and fortified grains. This vitamin is essential to energy generation, nerve development, blood cell development, and the regulation of certain hormones.
How This Vitamin Works in Your Body:Releasing food energy ,Normal growth and development.Keeps healthy mucous membranes linings together with vitamin A.Keeps healthy brain and nervous system, skin, hair, and blood cells.Essential for iron, pyridoxine, and niacin functions.Could increase growth of body during development stages.Potential treatment for cheilitis.
The following may benefit from this supplement: People with needed nutritional supplements.Pregnant or breastfeeding women.Substance abusers.People with excess stress or who have undergone recent surgery.Hyperthyroidism sufferers.Participants in vigorous physical activity.
Where This Vitamin is Found: Bananas,Beef ,liver,Dairy products,Eggs,Enriched breads,Fortified cereals,Ham,Mixed vegetables,Pork,Tuna,Wheat germ.
How to Use:Available as:Liquid: the best form due to its high bioavailability and fast absorption.
Always choose liquid as your first choice when supplementing your diet.
Tablets: available
Recommended Daily Intakes.Men: 1.3 mgWomen: 1.1 mgPregnancy: 1.4 mgLactation: 1.6 mg
Cautions:Consult your doctor if you have:Are or planning to be pregnant.
Over 55:Increased need for riboflavin.
Pregnancy:Keep within DRI.
Breastfeeding:Keep within DRI.
Storage:Heat and/or moisture may alter the vitamin. Refrigeration is recommended.
Symptoms of Deficiency:Symptoms include red, swollen, cracked mouth and tongue; fatigue; depression; anemia; and greasy, scaly skin. The formation of cataracts may be a result of this vitamin deficiency.
Overdose:Signs of Overdose:None expected in individuals with normal kidney functioning. However, in rare cases, symptoms may be itching, numbness, a burning sensation, or light sensitivity.
Side Effects:Reaction or effect : What to do Yellow urine (in large doses) : No needed action. Interactions:Interacts with : Combined effect Antidepressants (tricyclic) : Reduces B-2 efficacy. Phenothiazines : Reduces B-2 efficacy.Probenecid : Reduces B-2 efficacy. Alcohol/Tobacco products : Reduces B-2 efficacy.
Essential to energy generation, nerve development...
Benefits: Keeps healthy mucous membranes linings...
Natural Sources: Beef liver, dairy products...
How to Use Liquid: the best form due to its high bioavailability...
Cautions Consult your doctor if you are pregnant...
Deficiency Fatigue, red, swollen, cracked mouth tongue...
Overdose Itching, numbness, a burning sensation...
Side Effects Yellow urine (in large doses),
No needed action...
Interactions Antidepressants (tricyclic) - faReduces B-2 efficacy...
Overview: Vitamin B-2, otherwise known as riboflavin, is readily absorbed from foods, such as meat, dairy products, and fortified grains. This vitamin is essential to energy generation, nerve development, blood cell development, and the regulation of certain hormones.
How This Vitamin Works in Your Body:Releasing food energy ,Normal growth and development.Keeps healthy mucous membranes linings together with vitamin A.Keeps healthy brain and nervous system, skin, hair, and blood cells.Essential for iron, pyridoxine, and niacin functions.Could increase growth of body during development stages.Potential treatment for cheilitis.
The following may benefit from this supplement: People with needed nutritional supplements.Pregnant or breastfeeding women.Substance abusers.People with excess stress or who have undergone recent surgery.Hyperthyroidism sufferers.Participants in vigorous physical activity.
Where This Vitamin is Found: Bananas,Beef ,liver,Dairy products,Eggs,Enriched breads,Fortified cereals,Ham,Mixed vegetables,Pork,Tuna,Wheat germ.
How to Use:Available as:Liquid: the best form due to its high bioavailability and fast absorption.
Always choose liquid as your first choice when supplementing your diet.
Tablets: available
Recommended Daily Intakes.Men: 1.3 mgWomen: 1.1 mgPregnancy: 1.4 mgLactation: 1.6 mg
Cautions:Consult your doctor if you have:Are or planning to be pregnant.
Over 55:Increased need for riboflavin.
Pregnancy:Keep within DRI.
Breastfeeding:Keep within DRI.
Storage:Heat and/or moisture may alter the vitamin. Refrigeration is recommended.
Symptoms of Deficiency:Symptoms include red, swollen, cracked mouth and tongue; fatigue; depression; anemia; and greasy, scaly skin. The formation of cataracts may be a result of this vitamin deficiency.
Overdose:Signs of Overdose:None expected in individuals with normal kidney functioning. However, in rare cases, symptoms may be itching, numbness, a burning sensation, or light sensitivity.
Side Effects:Reaction or effect : What to do Yellow urine (in large doses) : No needed action. Interactions:Interacts with : Combined effect Antidepressants (tricyclic) : Reduces B-2 efficacy. Phenothiazines : Reduces B-2 efficacy.Probenecid : Reduces B-2 efficacy. Alcohol/Tobacco products : Reduces B-2 efficacy.
FoOdS IN ViTaMiN B-1(ThIaMiNe)
COLLOIDAL MINERALS
THIAMIN
Thiamin (vitamin B-1) is a water-soluble substance, consisting of thiazole and pyrimidine rings joined by a methylene bridge, with both moieties needed for full biologic action. Thiamin is found in high concentrations in skeletal muscle, the heart, liver, kidneys and brain. The total amount in an adult is about 30 mg and the biologic half-life in the body is about 15 days. It is not surprising that a state of severe depletion can be seen in patients on a strict thiamin-deficient diet in 18 days.
Thiamin pyrophosphate (TPP) is the coenzyme for pyruvate dehydrogenase, transketolase, and a-ketoglutarate. Decarboxylation in the tricarboxylic cycle is essential for generation of energy and production of the neurotransmitter acetylcholine. The pentose cycle generates NADPH (fatty acid synthesis) and pentoses for nucleic acid formation. TPP has been implicated also in sodium movement and impulse initiation in neuronal membranes.
In animals, thiamin is absorbed from the small intestine by an active (energy-requiring) process at concentrations below 2 µmoles/L and by passive (diffusion) transfer at higher levels. In rodents active transport is inhibited by ethanol, but this has not been documented in man. Malnutrition in man may contribute to decreased thiamin absorption, but this, too, requires more study. In blood, thiamin is present in erythrocytes as well as in plasma where it is bound largely to albumin.
Deficiencies:
1) Neurologic problems. These consist of central nervous manifestations including mystagmus, ophthalmoplegia, ataxia and memory deficit usually termed collectively as Wernicke's syndrome. This may merge into more extensive mental confusion with confabulation, usually called Korsakoff's psychosis. Another manifestation of thiamin deficiency, often in the setting of alcoholism, is peripheral neuropathy.
2) Cardiac problems. Cardiomegaly and congestive heart failure, with a characteristic high cardiac output presumably related to low peripheral resistance, is seen in thiamin deficiency and is termed cardiac (Shoshin) beriberi. The precise pathogenic mechanisms of these clinical syndromes are still uncertain, but are felt to be reflections of deranged carbohydrate metabolism, likely affecting the decarboxylation pathway. Detection of thiamin deficiency depends on a high index of suspicion (i.e. the syndrome may be seen with poor food intake, prolonged vomiting, intake of thiaminases in some types of fish and not just alcoholism) and the use of confirmatory laboratory tests. These include the measurement of erythrocyte transketolase activity and its enhancement on in vitro addition of thiamin pyrophosphate (TPP effect) and blood thiamin levels. The TPP effect may not be seen with chronic thiamin loss.
Clinical uses: Therapy in deficiency consists of parenteral administration of thiamin (intramuscular or intravenous) as 50-100 mg/day for 7-14 days, followed by oral therapy. In clinical disorders related to thiamin deficiency, therapy is urgent and should bypass the intestinal tract.
Diet recommendations: The Recommended Dietary Allowance for children and adults is 0.5 mg (1.9 µmoles) per 1000 Kcalories. A minimal intake of 1.0 mg/day is advised. In pregnancy an additional increment of 0.4 mg is suggested.
Food sources: Thiamin is present in many dietary products, but is found in large amounts in lean pork, legumes and yeast. Thiamin is destroyed by cooking at high temperature and by a pH above 8. As it is water-soluble, significant amounts may be lost in cooking water.
Toxicity: There is no toxicity with oral thiamin. There are only a few reports of toxic reactions to intravenous thiamin.
THIAMIN
Thiamin (vitamin B-1) is a water-soluble substance, consisting of thiazole and pyrimidine rings joined by a methylene bridge, with both moieties needed for full biologic action. Thiamin is found in high concentrations in skeletal muscle, the heart, liver, kidneys and brain. The total amount in an adult is about 30 mg and the biologic half-life in the body is about 15 days. It is not surprising that a state of severe depletion can be seen in patients on a strict thiamin-deficient diet in 18 days.
Thiamin pyrophosphate (TPP) is the coenzyme for pyruvate dehydrogenase, transketolase, and a-ketoglutarate. Decarboxylation in the tricarboxylic cycle is essential for generation of energy and production of the neurotransmitter acetylcholine. The pentose cycle generates NADPH (fatty acid synthesis) and pentoses for nucleic acid formation. TPP has been implicated also in sodium movement and impulse initiation in neuronal membranes.
In animals, thiamin is absorbed from the small intestine by an active (energy-requiring) process at concentrations below 2 µmoles/L and by passive (diffusion) transfer at higher levels. In rodents active transport is inhibited by ethanol, but this has not been documented in man. Malnutrition in man may contribute to decreased thiamin absorption, but this, too, requires more study. In blood, thiamin is present in erythrocytes as well as in plasma where it is bound largely to albumin.
Deficiencies:
1) Neurologic problems. These consist of central nervous manifestations including mystagmus, ophthalmoplegia, ataxia and memory deficit usually termed collectively as Wernicke's syndrome. This may merge into more extensive mental confusion with confabulation, usually called Korsakoff's psychosis. Another manifestation of thiamin deficiency, often in the setting of alcoholism, is peripheral neuropathy.
2) Cardiac problems. Cardiomegaly and congestive heart failure, with a characteristic high cardiac output presumably related to low peripheral resistance, is seen in thiamin deficiency and is termed cardiac (Shoshin) beriberi. The precise pathogenic mechanisms of these clinical syndromes are still uncertain, but are felt to be reflections of deranged carbohydrate metabolism, likely affecting the decarboxylation pathway. Detection of thiamin deficiency depends on a high index of suspicion (i.e. the syndrome may be seen with poor food intake, prolonged vomiting, intake of thiaminases in some types of fish and not just alcoholism) and the use of confirmatory laboratory tests. These include the measurement of erythrocyte transketolase activity and its enhancement on in vitro addition of thiamin pyrophosphate (TPP effect) and blood thiamin levels. The TPP effect may not be seen with chronic thiamin loss.
Clinical uses: Therapy in deficiency consists of parenteral administration of thiamin (intramuscular or intravenous) as 50-100 mg/day for 7-14 days, followed by oral therapy. In clinical disorders related to thiamin deficiency, therapy is urgent and should bypass the intestinal tract.
Diet recommendations: The Recommended Dietary Allowance for children and adults is 0.5 mg (1.9 µmoles) per 1000 Kcalories. A minimal intake of 1.0 mg/day is advised. In pregnancy an additional increment of 0.4 mg is suggested.
Food sources: Thiamin is present in many dietary products, but is found in large amounts in lean pork, legumes and yeast. Thiamin is destroyed by cooking at high temperature and by a pH above 8. As it is water-soluble, significant amounts may be lost in cooking water.
Toxicity: There is no toxicity with oral thiamin. There are only a few reports of toxic reactions to intravenous thiamin.
FoOdS ThAt GiVe ViTaMiN A
Vitamins have been one of the major nutritional discoveries of the 20th century. Health foods and cosmetics started promoting the vitamins. Vitamins cannot synthesise in the body in adequate amounts and therefore it should be supplied in food.
Deficiency of vitamins leads to various illnesses. Few of the vitamins are soluble in water where as some are soluble only in fat.
Vitamin A is a fat-soluble vitamin. MC Collum and Davis discovered this vitamin in 1913 at John Hopkins University in America, when they isolated a growth factor in egg yolk, butter, and cod liver oil. In 1920 Rosenhein and Drummond demonstrated the relationship of vitamin A to the plant pigment carotene. Carotene is a precursor of vitamin A in the body and is therefore known as pro-vitamin A.
Carotene is present in green and yellow vegetables and yellow fruits. Animals do not produce this. Carotene has alpha, beta, and gamma isomers. Among these isomers beta-carotene is the most widely distributed in food and more effectively converted into vitamin A. It does not get destroyed at ordinary levels of heat.
Vitamin A plays an important role in various functions of the body. It plays an important role in maintaining proper vision. This vitamin is required for formation and integrity of the epithelial tissue result in a healthy glowing and soft skin. It is required for proper growth and development of skeletal system of the body. Role of this vitamin in the immunological defence mechanism of the body is very important. Beta-carotene also has an important role as an anti-oxidant. Studies have shown that diets high in carotenoids are often associated with a reduced risk of certain cancers. This protection is however seen only if the source of beta-carotene is a food, and not the supplements.
Vitamin A is absorbed along with fat from the proximal small intestine. The absorption is more rapid in men than women and the absorption is decreased with intestinal roundworm, hookworm, and giardiasis infestations. After absorption this fat-soluble vitamin is stored in the liver. Among the carotene that is absorbed from vegetable foods, beta-carotene accounts for about 33-50%. Only one third of the beta-carotene is absorbed and only one half of what is absorbed is converted to vitamin A. Liver can store large amounts up to about 100000mg of vitamin A these reserves may last for 6-9 months.
Vitamin A is present in animal foods like whole milk, curd, butter, ghee, egg yolk, and liver. The liver oils of certain fish like cod halibut and shark are the richest sources of vitamin A. Spinach, amaranth, coriander leaves, curry leaves, drumstick leaves, ripe mangoes, papaya, fresh apricot, orange, raspberry, carrot, yellow pumpkins, mint, lettuce and tomato are rich in carotene. Among pulses red gram and masoor dhal has most carotene content.
Source
Carotene contentug /100g
Vitamin A equivalent(ug) Per 100g
Red palm oil
25,000-33,000
4167-5500
Green leafy vegetables
Amaranth leaves
1,600-7,000
266-1166
Cabbage
1300
217
Coriander leaves
7,000-8,000
1166-1333
Curry leaves
8,000
1333
Drumstick leaves
7700
1283
Fenugreek leaves
2700
450
Radish leaves
4500
750
Mint
1800
300
Spinach
3600
600
Other vegetables
Carrot
1,300-2,600
217-434
Pumpkin, yellow.
600-720
100-120
Fruits
Jack fruit
320
54
Mango, ripe
3000
500
orange
210
35
Tomato ripe
190
32*Source -Food & Nutrition Dr.M.Swaminathan
Night blindness
Bitot's spot
Xerophthalmia
Xerosis conjunctiva
Xeroasis cornea
Keratomalacia
Follicular hyper keratosis or phrynoderma
Consumption of excess of vitamin A causes headache, fatigue, irritability, nausea, vomiting, and anorexia, which will disappear on withdrawal of vitamin A in take.
Vitamin A and carotene are stable to ordinary cooking methods, though some loss may occur at temperature above 100 degree Celsius as when butter or palm oil is used for frying.
Fruits and other foods that are dried in the sun lose much of their vitamin A. Considerable losses of vitamin A may occur in fish liver oils bottled in colourless glass.
Deficiency of vitamins leads to various illnesses. Few of the vitamins are soluble in water where as some are soluble only in fat.
Vitamin A is a fat-soluble vitamin. MC Collum and Davis discovered this vitamin in 1913 at John Hopkins University in America, when they isolated a growth factor in egg yolk, butter, and cod liver oil. In 1920 Rosenhein and Drummond demonstrated the relationship of vitamin A to the plant pigment carotene. Carotene is a precursor of vitamin A in the body and is therefore known as pro-vitamin A.
Carotene is present in green and yellow vegetables and yellow fruits. Animals do not produce this. Carotene has alpha, beta, and gamma isomers. Among these isomers beta-carotene is the most widely distributed in food and more effectively converted into vitamin A. It does not get destroyed at ordinary levels of heat.
Vitamin A plays an important role in various functions of the body. It plays an important role in maintaining proper vision. This vitamin is required for formation and integrity of the epithelial tissue result in a healthy glowing and soft skin. It is required for proper growth and development of skeletal system of the body. Role of this vitamin in the immunological defence mechanism of the body is very important. Beta-carotene also has an important role as an anti-oxidant. Studies have shown that diets high in carotenoids are often associated with a reduced risk of certain cancers. This protection is however seen only if the source of beta-carotene is a food, and not the supplements.
Vitamin A is absorbed along with fat from the proximal small intestine. The absorption is more rapid in men than women and the absorption is decreased with intestinal roundworm, hookworm, and giardiasis infestations. After absorption this fat-soluble vitamin is stored in the liver. Among the carotene that is absorbed from vegetable foods, beta-carotene accounts for about 33-50%. Only one third of the beta-carotene is absorbed and only one half of what is absorbed is converted to vitamin A. Liver can store large amounts up to about 100000mg of vitamin A these reserves may last for 6-9 months.
Vitamin A is present in animal foods like whole milk, curd, butter, ghee, egg yolk, and liver. The liver oils of certain fish like cod halibut and shark are the richest sources of vitamin A. Spinach, amaranth, coriander leaves, curry leaves, drumstick leaves, ripe mangoes, papaya, fresh apricot, orange, raspberry, carrot, yellow pumpkins, mint, lettuce and tomato are rich in carotene. Among pulses red gram and masoor dhal has most carotene content.
Source
Carotene contentug /100g
Vitamin A equivalent(ug) Per 100g
Red palm oil
25,000-33,000
4167-5500
Green leafy vegetables
Amaranth leaves
1,600-7,000
266-1166
Cabbage
1300
217
Coriander leaves
7,000-8,000
1166-1333
Curry leaves
8,000
1333
Drumstick leaves
7700
1283
Fenugreek leaves
2700
450
Radish leaves
4500
750
Mint
1800
300
Spinach
3600
600
Other vegetables
Carrot
1,300-2,600
217-434
Pumpkin, yellow.
600-720
100-120
Fruits
Jack fruit
320
54
Mango, ripe
3000
500
orange
210
35
Tomato ripe
190
32*Source -Food & Nutrition Dr.M.Swaminathan
Night blindness
Bitot's spot
Xerophthalmia
Xerosis conjunctiva
Xeroasis cornea
Keratomalacia
Follicular hyper keratosis or phrynoderma
Consumption of excess of vitamin A causes headache, fatigue, irritability, nausea, vomiting, and anorexia, which will disappear on withdrawal of vitamin A in take.
Vitamin A and carotene are stable to ordinary cooking methods, though some loss may occur at temperature above 100 degree Celsius as when butter or palm oil is used for frying.
Fruits and other foods that are dried in the sun lose much of their vitamin A. Considerable losses of vitamin A may occur in fish liver oils bottled in colourless glass.
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