Vitamins

Vitamins are a group of organic substances that mammals and humans are not able to produce consequently they are necessary for life. They regulate our metabolism through enzyme system. A single deficiency can endanger the whole body.Vitamins can be easly supplied through a varied andbalanced diet as they are needed only in small amounts. They can be divided into two main groups:fat-soluble vitamins (A, D, E, and K) and water-soluble vitamins (the B group of vitamins and vitamin C). Unlike fat-soluble vitamins , water soluble-vitamins are not stored by the body and can be lost from food through the processes of storing, preparation and cooking ( they can also be temperature-dependent). It is therefore necessary that adequate amounts of the water-soluble vitamins are included in the daily diet .The exact requirement of most vitamins for an adult of average size is known, althoughmore may be required during lactation, pregnancy, illness and strenous work. Growing children need more than in proportion to body weight. There are a variety of factors that influence vitamin deficiency other than diet intake:

Physiologic factor	Vitamin affected	Comments
Endogenus synthesis	D, K, B6, Biotin
Enteroepatic circulation	A, polar metabolites of vitamin D, folic acid, cobalamin
Dietary intake	All except K, B6, biotin	K, B6, and biotin are probably produced by enteric bacteria
Decreased storage capacity	Cobalamin, A	Stored in liver
Increased utilization	Folic Acid	Used in increased amounts during pregnancy, hemolysis
Increased loss from body	All	During malabsorption

Nowdays is very difficult to found in developed countries an absolute inadequacy of any vitamins, although it is possible to find any partial deficiency. Vitamin are classed in micro-nutrients since weneed only very small amounts of them in our diet. Historically vitamins have been classified in simple alfabetic order (although vitamin B is actually a group of vitamins rather than a single vitamin).

Vitamin

Major causes of deficiency

Manifestation of deficiency

Sources

Fat malabsorption, alcoholism

Poor dark adaptation,

xerophthalmia, bryness of

skin

cod liver oil, spinach, carrot,

cheese, butter, eggs,

margarine fortified

B1 thiamin

Inadequate intake, alcholism

Cardiac failure, peripheral

neurophaty, Wernicke's

encephalopathy

Brazil nouts, brown rice,

wholemeal bread, peas, beans,

and other pulses

B2 riboflavin

Inadequate intake

Angular stomatitis, sore

lips, cheilosis, geographic

tongue, seborrheic

dermatitis

Milk, cheese, yogurt, eggs,

meat and offal such as liver,

green leafy vegetables. Richest

source yeast extract

Niacin

Inadequate intake, alcoholism,

carcinoid syndrome

Dermatitis (photosensitive),

dementia, diarrhea

Meat, poultry, oily fish, cheese,

milk, bread, fortified breakfast

cereals. Richest sources: yeast

extract, and brewer's yeast

B6 pyridoxine

Inadequate intake, old age,

alcoholism

Glossitis, cheilosis,

peripheral

neuritis, seborrheic

dermatitis

Wholemeal bread, wheatbran,

liver, bananas, fish and nuts.

Richest sources dried brewers'yeast

and yeast extract

B12 cobalamin

Malabsorption, pernicious

anemia, vegetarian diet

Fatigue, anemia, sore tongue,

paresthesias

Animal foods: offal, meat, poultry,

fish, eggs

Biotin

Total parenteral nutrition

Scaly dermatitis, alopecia

Dried brewer's yeast, offal, yeast

extract, wheatgerm, wholemeal

bread, milk, brown rice, cheese,

yogurth

Folic acid

Inadequate intake, alcoholism,

malabsorption, hemolysis,

pregnancy, drugs such as

anticonvulsivants,

methotrexate, sulfasalazine

Anemia, sore tongue,

diarrhea

Liver, broccoli and green cabbage,

wheatgerm, pulses, nuts, and

yeast extract

Panthotenic

acid

Spontaneous human

deficiency is not clearly

recognized

Loss of appetite, abdominal

pain, tenderness in the feet

Dried brewer's yeast, yeast

extract, kidney, nuts, soya flour,

wheatgerm, eggs, pulses, dried

fruit

C ascorbic

acid

Alcoholism, inadequate

intake (destroies through poor

handling, cooking, processing)

Fatigue, ecchymoses,

bleeding gums, anemia

Citrus fruits, blackcurrants, kiwi

strawberries, broccoli, raw

cabbage, peas, potatoes

Fat malabsorbtion, lack of

sunlight, breast milk-fed

newborn

Osteomalacia, rickets,

vertebral fractures, muscle

weakness

Cod liver oil, kippers, mackerel,

canned salmon, eggs and milk.

Sunlight on uncovered skin

Premature infants, cystic

fibrosis, fat malabsorbtion,

chronic biliary obstruction

Areflexia, anemia,

ophthalmoplegia

Wheatgerm, nuts, vegetable oils,

eggs, green leafy vegetables,

wholemeal bread

Fat malabsorbtion, excessive

warfarin dose

Bleeding

Cauliflower, brussels sprouts,

broccoli, spinach, liver, lean

meat, potatoes, cow's milk