Vitamin A forms

Vitamin A exists in several relative forms:

• retinol (alcohol, Vitamin A1)
• degidroretinol (Vitamin A2)
• retinal (retinen, vitamin A-trichloroacetaldehyde)
• retinol acid (vitamin A acid)
• ethers of these substances and their isomers

Vitamin K deficiency

Vitamin K deficiency is uncommon in healthy adults. Vitamin K deficiency can be caused by taking anticoagulant drugs, liver damage or disease.

Vitamin K deficiency symptoms are:

• impaired blood clotting
• bruising
• bleeding (nosebleeds)
• blood in the urine
• blood in the stool
• heavy menstrual bleeding

Vitamin K deficiency can eventually lead to intracranial hemorrhage (life-threatening bleeding in the skull)

Vitamin K dosage (AI)

Recommended daily allowance isn't defined for Vitamin K.

The adequate Intake (AI) for Vitamin K:

• 0-6 months male and female 2 mcg per day
• 7-12 months male and female 2.5 mcg per day
• 1-3 years male and female 30 mcg per day
• 4-8 years male and female 55 mcg per day
• 9-13 years male and female 60 mcg per day
• 14-18 years male and female 75 mcg per day
• 19+ years male 120 mcg per day
• 19+ years female 90 mcg per day
• <18>
• >19 years pregnancy or breastfeeding 90 mcg per day

Sources of Vitamin K

Here is foods rich in Vitamin K:

• cabbage
• cauliflower
• cereals
• green leafy vegetables (spinach)
• soybeans
• oil
• organ meets
• cereals
• kiwi
• banana
• milk
• eggs

Too much Vitamin K

Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone) are not toxic in large doses.
Vitamin K3 (menadione) overdose causes oxidant damage to cell membranes and:

• liver toxicity
• jaundice
• hemolytic anemia

No UL (tolerable upper level) had been defined for Vitamin K.

What is Vitamin K?

Vitamin K is fat-soluble vitamin that plays role in blood clotting (coagulation).
There are two common forms of Vitamin K

• Vitamin K1 also known as phylloquinone (synthesized by plants)
• Vitamin K2 also known as menaquinone (synthesized by animals)
• Vitamin K3 also known as menadione

Vitamin K functions are:

• Coagulation (clotting)
• Bone mineralization
  
• Cell growth
• Plays key role in vascular biology

Vitamin E deficiency

Vitamin E deficiency is uncommon in human but can occur in following cases:

• persons with disorders of fat metabolism
• rare genetic anomalies in the alpha-tocopherol transfer protein
• premature
• very low birth weight infants
• persons with Zinc deficiency

Vitamin E deficiency symptoms are:

• ataxia
• nerve degeneration in hands and feet
• decreased sensation to vibration
• paralysis of eye muscles
• nyctalopia (night blindness)

Vitamin E dosage (RDA)

RDAs (Recommended Daily Allowance) for vitamin E (alpha-tocopherol form):

• 1-3 years 6 mg per day (9 IU)
• 4-8 years 7 mg per day (10.5 IU)
• 9-13 years male 11 mg per day (16.5 IU)
• 9-13 years female 11 mg per day (16.5 IU)
• 9-13 years pregnancy 15 mg per day (22.5 IU)
• 9-13 years lactating 19 mg per day (28.5 IU)
• 14+ years male 15 mg per day (22.5 IU)
• 14+ years female 15 mg per day (22.5 IU)
• 14+ years pregnancy 15 mg per day (22.5 IU)
• 14+ years lactating 19 mg per day (28.5 IU)

Vitamin E sources

Foods rich with Vitamin E:

• Nuts
  
• Wheat germ
• Olives
  
• Corn
• Seeds
• Green leafy vegetables (Spinach, Broccoli)
• Asparagus
• Vegetable oils (corn, sunflower, soybean, cottonseed)
• Kiwi
• Mango

Vitamin Pills may increase death risk

A review of 67 studies involving 230000+ people found that the vitamin supplements mayn't cut risk of dying. Even more, some supplements may increase mortality.
The study examines effect of Vitamin A, Vitamin C, Vitamin E and selenium intake with varying doses.

The study found that Vitamin A, Vitamin E and beta-carotene increases death risk. Vitamin C and selenium seem to not affect death risk.
Also Vitamin C is reported to not increase longevity.

(Sources: http://www.news-medical.net/?id=37402, http://news.sky.com/skynews/article/0,,91251-1313009,00.html)

Too much Vitamin E

The risk of too much Vitamin E is low.

Possible symptoms of a vitamin E overdose are:

• fatigue
• diarrhea
• weakness
• headache
• blurred
• nausea
• vision
• flatulence

Tolerance Upper Intake levels (UL):

• 1-3 years female 200 mg/day (300 IU)
  
• 1-3 years male 200 mg/day (300 IU)
• 4-8 years female 300 mg/day (450 IU)
  
• 4-8 years male 300 mg/day (450 IU)
• 9-13 years female 600 mg/day (900 IU)
  
• 9-13 years male 600 mg/day (900 IU)
• 14-18 years female 800 mg/day (1200 IU)
  
• 14-18 years male 800 mg/day (1200 IU)
• 19-70 years female 1000 mg/day (1500 IU)
  
• 19-70 years male 1000 mg/day (1500 IU)
• > 70 years female 1000 mg/day (1500 IU)

• > 70 years male 1000 mg/day (1500 IU)

What is Vitamin E?

Vitamin E is fat-soluble vitamin with antioxidant properties. It exists in eight forms: tocopherols and tocotrienols. Most common form of Vitamin E is alpha-tocopherol in case of highest bio-availability.

Vitamin E acts as antioxidant and protects cells from free radicals' influence.

Vitamin E also plays role in:

• DNA repair
• metabolism
• immune function
• red blood cells formation

Vitamin D deficiency

Vitamin D deficiency can be caused by:

• inadequate intake with inadequate sunlight exposure
• liver and kidney disorders
• hereditary disorders
• fat malabsorption

The deficiency leads to:

• bone mineralization
• bone softening
• rickets in children
• osteomalacia
• osteoporosis

Vitamin D malnutrition may also cause following chronic diseases:

• high blood pressure
• cancer
• chronic pain
• depression
• periodontal disease
• schizophrenia
• type 1 diabetes
• multiple sclerosis

Vitamin D dosage (RDA)

Adequate Intake (AI) of Vitamin D:

• Children 0-13 years 5 mg per day (200 IU)
• Adolescents 14-18 years 5 mg per day (200 IU)
• Adults 19-50 years 5 mg per day (200 IU)
• Mature 50-70 years 10 mg per day (400 IU)
• 71+ years 15 mg per day (600 IU)

Vitamin D sources

Following foods are rich in Vitamin D:

• Fish liver oils
• Fatty fish (catfish, salmon, mackerel, sardines, tuna, eel)
• Mushrooms
• Eggs
• Milk
• Cheese

However, sun exposure is most important source of vitamin D. Most human receives their vitamin D requirement by exposure to sunlight.

Too much Vitamin D

Vitamin D is fat-soluble and stored in body as calcidiol. However Vitamin D toxicity appears only if excessive doses are taken.
Sunlight does not cause Vitamin D toxicity.

Vitamin D toxicity can cause:

• nausea
• vomiting
• poor appetite
• constipation
• weakness
• weight loss
• raise blood levels of calcium (causing confusion, heart rhythm abnormalities)

What is Vitamin D

Vitamin D is a group of fat-soluble prohormones. Most active forms of vitamin D are ergocalciferol (also known as vitamin D2 ) and Calciferol (Vitamin D3). Skin produces vitamin d3 after exposure to ultraviolet rays.

The major function of Vitamin D is keeping blood levels of calcium phosphorus. Vitamin D play role in formation and maintaining strong bones. Vitamin D also helps to maintain healthy immune system and plays role in immunomodulation.

Vitamin D was discovered In 1922 by Edward Mellanby while researching a rickets disease.

Vitamin C deficiency

Scurvy caused by Vitamin C lack.

Scurvy leads:

• liver spots on the skin
• anemia
• decreased ability to fight infection
• possible weight gain because of slowed metabolism
• spongy gums
• Gingivitis (inflammation of the gums)
• rough, dry, scaly skin
• decreased wound-healing rate
• easy bruising
• nosebleeds
• weakened tooth enamel
• swollen and painful joints
• death

Vitamin C dosage (RDA)

Recommended Daily Allowance (RDA) for Vitamin C:

• Infants 0 - 6 months 40 mg per day

• Infants 7 - 12 months 50 mg per day

• Children 1 - 3 years 15 mg per day

• Children 4 - 8 years 25 mg per day

• Children 9 - 13 years 45 mg per day

• Adolescent female 14 - 18 years 65 mg per day

• Adolescent male 14 - 18 male 75 mg per day

• Adult male 90 mg per day

• Adult female 75 mg per day

Sources of Vitamin C

Vegetables and fruits are richest natural sources of Vitamin C.

Following vegetable food are rich in Vitamin C (sorted by amount):

• Kakadu plum
• Camu Camu
• Rose hip
• Acerola
• Amla
• Seabuckthorn
• Jujube
• Baobab
• Blackcurrant
• Red pepper
• Parsley
• Guava
• Kiwifruit
• Broccoli
• Loganberry
• Redcurrant
• Brussels sprouts
• Wolfberry
• Lychee
• Cloudberry
  
• Elderberry
  
• Persimmon
• Papaya
• Strawberry
• Orange
• Lemon
• Melon
• Cauliflower
• Grapefruit
• Raspberry
• Tangerine
• Mandarin orange
• Passion fruit
• Spinach
• Cabbage raw green
• Lime
• Mango
• Potato
• Melon
• Mango
• Cranberry
• Tomato
• Blueberry
• Pineapple
• Plant source
• Pawpaw
• Grape
• Apricot
• Plum
• Watermelon
• Banana
• Carrot
• Avocado
• Crabapple
• Cherry
• Peach
• Apple
• Blackberry
• Beetroot
• Pear
• Lettuce

Animal sources of Vitamin C are liver, oysters, milk, tongue.

Too much Vitamin C

Vitamin C is not-toxic because it is water-soluble and it is excreted regularly.

High doses (more then 2000 mg per day) can cause:

• diarrhea
• gas
• stomach upset
• iron overload

What is Vitamin C

Vitamin C (also known as L-ascorbate) - water-soluble vitamin essential for higher primates.

Vitamin C is essential for growth and development.
Vitamin C plays role in:

• collagen formation (hydroxylation) (necessary for make blood vessels, tendons, skin, ligaments, scar tissues)
• synthesis of carnitine
• antioxidant
  
• dopamine beta hydroxylase
• tyrosine metabolise

Vitamin C was isolated in 1928. In 1932 it was discovered that Vitamin C deficiency causes scurvy.

Vitamin B12 deficiency

Vitamin B12 deficiency can cause brain and nervous system damage.

Vitamin B12 deficiency signs, symptoms:

• anemia
• fatigue
• weakness
• constipation
• weight loss
• loss of appetite
• depression

Usually deficiency treatment includes cyanocobalamin injections.

Vitamin B12 dosage (RDA)

Recommended Dietary Allowances (RDA) for Vitamin B12:

• children 1-3 years 0.9 mg per day
  
• children 4-8 years 1.2 mg per day
  
• children 9-13 years 1.8 mg per day
  
• 14-18 years 2.4 mg per day
  
• 14-18 years pregnant 2.6 mg per day
  
• 14-18 years lactating 2.8 mg per day
  
• adult 2.4 mg per day
  
• adult pregnant 2.4 mg per day
  
• adult lactating 2.4 mg per day

Sources of Vitamin B12

Vitamin B12 is naturally found in foods of animal:

• meat
• liver
• shellfish
• milk
• eggs

• Mollusks
• Liver
• Fortified breakfast cereal
• Trout
• Salmon
• Beef
• Yogurt
• Haddock
• Clams
• Tuna
• Pork
• Chicken
  

It also exists in brewer's yeast.

Too much Vitamin B12

Vitamin B12 is water-soluble and not toxic in big doses.

What is Vitamin B12

Vitamin B12 (B-12) term can be defined in two ways. Formally Vitamin B12 is collection of calamines - cobalt and corrin ring molecules.
In the narrow sense Vitamin B12 means Cyanocobalamin - one of calamines.

Vitamin B12 plays role in following processes:

• brain functioning
• nervous system functioning
• formation of blood

It was isolated from liver by Karl A. Folkers in 1948. Vitamin B-12 was first synthesised by Robert Burns Woodward in 1973.

Folate deficiency (Vitamin B9 deficiency)

General folate deficiency symptoms:

• Diarrhea
• loss of appetite
• weight loss
  

Additional signs:

• sore tongue
• heart palpitations
• weakness
• headache
• irritability

The deficiency may cause:

• fatigue
• acne
• sore tongue

Folic acid dosage (RDA)

Recommended Daily Allowance of folic acid is 400 mg per day (for adult male, female, pregnant and lactating women).

National Academy of Sciences: intake of folic acid should not exceed 1000 mg / day.

Sources of Vitamin B9 (folic acid)

Vitamin B9 exists in foods in folate and folic acid forms.

Food rich in folate:

• green leafy vegetable (like spinach)
• oranges
• lentils
• pinto beans
• broccoli
• liver
• brewer's yeast

Good sources of folic acid:

• asparagus
• beets
• broccoli
• avocados
• beans
• soybeans
• lentils
• oranges
• peas
• turkey
• cabbage
• savoy
• spinach

Too much Folic Acid (Vitamin B9)

Risk of toxicity is low because folic acid is water soluble.

Regular intake of large doses of Vitamin B9 can cause:

• digestive upset
• energy loss
• insomnia

Also it can mask a Vitamin B12 deficiency.

What is Folic Acid (Vitamin B9)

Vitamin B9 is water-soluble vitamin exists in tow forms: folic acid and folate.

Folate is necessary for:

• cell division and replication
• protein metabolism
• DNA replication
• red blood cells construction
• anemia prevention
  

Folic acid was discovered by Lucy Wills in 1931. It was firstly extracted from spinach in 1941. It was synthesised in 1946.

Vitamin B6 deficiency

Vitamin B6 deficiency is very uncommon but can be caused malnutrition or poor quality diet.

Clinical symptoms include:

• dermatitis
• atrophic glossitis
• depression
• confusion
• angular cheilitis
• convulsions
• conjunctivitis
• neuropathy

Vitamin B6 dosage (RDA)

RDA (Recommended Daily Allowance) for vitamin B6:

• 1.3 mg per day for male
• 1.3 mg per day for female
• 1.8 mg per day for pregnant
• 2.0 mg per day for lactating

Sources of Vitamin B6

Vitamin B6 exists in in a wide set of foods: beans, fortified cereals, meat, poultry, fish, fruits and vegetables.

Food rich in Vitamin B6:

• Potato
• Banana
• Turkey
• Chicken

• Garbanzo beans
• Oatmeal
• Pork loin
• Cereal
• Spinach
• Hazelnuts
• Vegetable juice cocktail
• Soybeans
• Lima beans
• Avocado
• Salmon
• Tuna
• Peanut butter

Too much Vitamin B6

Although vitamin B6 is a water-soluble vitamin very high doses (over 1000 mg per day) of pyridoxine can cause sensory neuropathy.

Sensory neuropathy symptoms are:

• pain and numbness of the extremities
• difficulty walking

Daily intake over 500 mg can cause sensory neuropathy.

What is Vitamin B6

Vitamin B6 is water-soluble vitamin exists in several chemical forms: pyridoxine (PN), pyridoxal (PL), and pyridoxamine (PM).

Vitamin B6 plays role in:

• nervous system function (serotonin, dopamine, GABA synthesis)
• red blood cell function
  
• niacin formation
• hormone function
• nucleic acid synthesis

Vitamin B6 was discovered in 1930s.

Vitamin B5 deficiency

Deficiency of Vitamin B5 hasn't been studied adequately because deficiency is very rare.

Deficiency of Vitamin B5 (pantothenic acid) can cause following symptoms:

• fatigue
• headaches
• allergies
• cardiac instability
• nausea
• abdominal pain
• sleep disturbance
• neurological disorders

Vitamin B5 dosage

The recommended dosage of pantothenic acid (Vitamin B5) is:

• infants 0-6 months 1.7 mg per day
• infants 7-12 months 2 mg per day
• children 4-8 years 3 mg per day
• children 9-13.5 years 4 mg per day
• adolescents 14-18 years 5 mg per day
• adults (male and female) 5 mg per day
• pregnant women 6 mg per day
  
• lactating women 7 mg per day

Sources of Vitamin B5 (Pantothenic acid)

Pantothenic acid are found in most foods.

Following foods are most rich in Vitamin B5:

• whole grain
• eggs
• brewer’s yeast
• beef
• kidney
• nuts
• liver
• pork
• fresh vegetables
• saltwater fish
• legumes
• mushrooms
• royal jelly
• torula yeast
• whole rye flour

Too much vitamin B5

Vitamin B5 is not toxic in high dosage.

Intake exceeding 10g/day can cause:

• diarrhea
• water retention
• digestive disturbances
• increased teeth sensitivity

What is Vitamin B5 (Pantothenic acid)

Vitamin B5 also known as pantothenic acid is water-soluble vitamin, essential nutrient.

Pantothenic acid is essential for:

• secretion of hormones (cortisone, adrenal gland support)
  
• metabolism of carbohydrates (like most B group vitamins)
• metabolism and synthesis of fats, proteins
• synthesis of CoA (coenzyme A)

Vitamin B5 was discovered by R.J. Williams about 1919. In 1933, it was isolated from yeast.

Niacin deficiency

Pellagra is disease also known as niacin deficiency.

Most often causes of Pellagra are:

• chronic alcoholism
• malnutrition
• multiple vitamin deficiencies

Niacin deficiency can cause following disease conditions:

• dermatitis
• diarrhoea
• dementia

Most common symptoms of niacin deficiency are:

• rash on skin (thick, scaly, darkly)
• burning mouth, bright red tongue, mouth sores

Niacin dosage (RDA)

The recommended dietary intake (RDA) of niacin is:

• 19 mg/day for adult males
• 13 mg/day for adult females
• 15 mg/day for pregnant
• 18 mg/day for lactating females
  

Niacin dose should be taken as 2-3 daily doses.

Source of Niacin (Vitamin B3)

Following products are good sources of Niacin (Vitamin B3)

Animal products:

• eggs
• beef
• milk
• fish (salmon, tuna, swordfish)
• chicken
• liver
• heart
• kidney
• pork
• turkey

Vegetative sources:

• peppermint
  
• mullein
• rose hips
  
• oat straw
  
• leaf vegetable
• red clover
• yellow dock
  
• broccoli
• tomatoes
• carrots
• slippery elm
  
• nettle
• raspberry leaf
  
• dates
• parsley
  
• sweet potatoes
• asparagus
• avocados
  

Seeds:

• nuts
• salt-bush seeds
• whole grain
• legumes

Also Niacin contains in mushrooms and brewer's yeast.

Too much Niacin

Intake of large niacin (Vitamin B3) doses can cause:

• Liver damage (75 mg or more)
  
• Peptic ulcers
  
• Flushing
• Gout
  
• Tingling skin
• Skin rashes
• Low blood pressure
• Diabetes-like symptoms
  
• Glucose tolerance (very large doses above 3 g/day)

Too much Niacin

Intake of large niacin (Vitamin B3) doses can cause:

• Liver damage (75 mg or more)
  
• Peptic ulcers
  
• Flushing
• Gout
  
• Tingling skin
• Skin rashes
• Low blood pressure
• Diabetes-like symptoms
  
• Glucose tolerance (very large doses above 3 g/day)

What in Niacin (B3)

Niacin also called Vitamin B3 or nicotinic acid is water-soluble vitamin.

Niacin is essential for energy metabolism of carbohydrates, fats, proteins, DNA repair, functioning of the nervous system, healthy skin, removing toxic chemicals, production of steroid hormones.

It was discovered in 1937 by Conrad Elvehjem.

Riboflavin Deficiency

Riboflavin Deficiency is caused by

• Dietary lack of Vitamin B2
• Liver disease
• Chronic alcoholics
• Parenteral nutrition (TPN) with inadequate riboflavin
• HIV
• Chronic heart disease
• Bowel disease

Signs and symptoms of Vitamin B2 deficiency:

• Red and cracked lips (cheilosis)
• Fluid in the mucous membranes
• Angles of the mouth are cracking (angular stomatitis)
• Scaly skin rashes
• Inflammation of the tongue
• Red, itchy eyes
• Numbness of the hands

Riboflavin dosage

The RDA (recommended daily allowance) for riboflavin is 1.7 mg/day(adult man) and 1.3 mg/day for woman.

Vitamin B2 Intake for pregnant women is 1.6 mg/day and 1.8 for lactating women.

Sources of riboflavin (vitamin b2)

Foods high in riboflavin:

• milk
• yogurt
• whole grains
• meat
• eggs
• fish asparagus
• bananas
• legumes
• okra
• chard
• cottage cheese
• green leafy vegetables
• nuts

Too much riboflavin

Overdose of riboflavin is impossible because of riboflavin is water-soluble.

Possible results of overdose are burning and numbness sensations.

What is Riboflavin

Riboflavin is also known as Vitamin B2. Riboflavin is water-soluble B-group vitamin. It is easily absorbed and cannot be stored in body.

Vitamin B2 plays role in maintaining health, cellular processes, energy metabolism. Riboflavin is necessary for metabolism of fats, carbohydrates and proteins. Also Vitamin B2 acts as antioxidant.

Riboflavin was first synthesized in 1935 by Kuhn and Karrer.

Sources of Thiamine

Thiamin (Vitamin B1) can be found naturally in following foods:

• Fortified breads
• Cereals
• Pasta
• Whole grains
• Lean meats
• Fish
• Dried beans
• Peas
• Soybeans
• Spinach
• Liver
• Beef
• Pork
• Navy beans
• Nuts
• Pinto beans
• Bananas
• Goji berries
• Unpolished rice
• Legumes

Thiamine/Thiamin deficiency

Thiamine (Vitamin B1) deficiency can be caused by:

• Malnutrition
• Alcoholism
• Thiaminase-rich nutrition (raw fish, raw shellfish)
• Diet high in anti-thiamine factors (betel, coffee, tea, nuts)
• Diabetes

Thiamine deficiency leads:

• beriberi
• irritability
• enlarged liver
• edema
• constipation
• extreme fatigue
• nervousness
• severe weight loss
• weak and sore muscles
• general weakness
• poor coordination
• numbness of the hands and feet
• tingling sensations

Thiamine dosage

RDA (Recommended Dietary Allowance) for thiamine is:

• 1.4 mg/day for adult men
• 1.0 mg/day for adult women

Because of low vitamin B1 toxicity dosage under 50 mg is used in vitamin supplements.

What is Thiamine(Thiamin or Vitamin B1)

Thiamine or thiamin (Vitamin B1) is water-soluble vitamin. Thiamine is one of B vitamins.

Thiamine (vitamin B1) is essential for carbohydrates metabolism. It plays role in growth, development. Also it's necessary for hearth, nervous, muscles and digestive systems.

Vitamin B1 was discovered by Umetaro Suzuki in Japan in 1910. It was first crystallized in 1926. Synthesis was reported in 1935.

Foods rich in Vitamin A

Following foods are rich in vitamin a:

• Carrots 34317.4 IU
• Spinach 14742 IU
• Turnip greens 7917.12 IU
• Kale 9620 IU
• Parsley 631.8 IU
• Bell peppers 5244 IU
• Mustard greens, 4243.4 IU
• Romaine lettuce 2912 IU
• Calf's liver 30485.26 IU
• Swiss chard 5493.25 IU
• Sweet potato 13107.7 IU
• Cayenne pepper 1470.24 IU
• Collard greens 5945.1 IU
• Cantaloupe 5158.4 IU
• Winter squash 7291.85 IU
• Apricots 914.2 IU
• Broccoli 2280.72 IU
• Basil 281.24 IU
• Tomato 1121.4 IU
• Oregano 207.08 IU
• Asparagus 970.2 IU
• Chili pepper 531.6 IU
• Green beans 832.5 IU
• Brussel sprouts 1121.64 IU
• Cucumbers, slices 223.6 IU
• Summer squash 516.6 IU
• Watermelon 556.32 IU
• Grapefruit 318.57 IU
• Celery 160.8 IU
• Prunes 844.48 IU
• Papaya 863.36 IU
• Green peas 955.2 IU
• Cabbage 198 IU
• Plum 213.18 IU
• Oranges 268.55 IU
• Cow's milk 500.2 IU

How much Vitamin A?

According to Recommended Dietary Allowance (RDA) (http://www.nal.usda.gov/fnic/etext/000105.html) recommended daily intake of Vitamin A is 5000 IU for man, 4000 IO for woman.
5000 IU is approximately 3 mg of beta carotene. 4000 IU is 2.4 mg beta carotene.

Daily upper limit of retinol is 3000 mg (3g or 10000 IU).

Upper limit doesn't refer to carotene forms (from dietary source). Carotene forms (foods of plant) are not toxic.

Daily intake above 20000-25000 IU is toxic for adults.

Top Vitamin A foods

Top Vitamin A foods are:

• liver
• sweet potatoes
• carrots
• mangoes
• spinach
• cantaloupe
• dried apricots
• milk
• egg yolks
• mozzarella cheese

Vitamin A Deficiency

Vitamin A deficiency is not common disease. But it's most common in underdeveloped countries.

Vitamin A deficiency can lead to blindness.

Symptoms:

• Reduced night vision
• Night blindness
• Dry eyes
• Eye inflammation

Causes:

Most common cause of deficiency of Vitamin A is insufficient intake of foods high in vitamin A or carotene.

Less common causes are:

• malabsorption
• massive urinary excretion
• hepatic disease decreased storage and transport of vitamin A

Treatment:

Vitamin A deficiency can be cured with oral and injectable forms of Vitamin A.

What is Vitamin A

Vitamin A (Retinol) - a fat-soluble vitamin. It exists in several forms: retinol, retinal and retinic acid.
Provitamins (prescures) of Vitamin A are carotenoids - animal form of Vitamin A. Carotenoids can be found in foods of plant.

Vitamin A is necessary for vision, growth, development, healthy skin, hair, immunity, reproduction and more.

Was discovered by Lafayette Mende, Thomas Osborne and Elmer McCollum in 1917.