Dr. Muslim N.Saeed Community
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Nutrition Lecture 5
Learning objective:
At the end of this lecture student would be able to :
1-Determine vitamins general characteristics .
2-Classify vitamins .
3-Determine essential facts about vitamins A,E,K & B complex .
4-Outline clinical presentation of vitamin A deficiency & toxicity .
5-Identify directions of action of vitamin D , clinical features of vitamin D
deficiency .
6-Discuss clinical presentation of vitamins B1,B2,nicotinic acid , folic acid , B12
, & vitamin C deficiency .
To a level accepted to the accreditation standard of the College .
Vitamins
:
Vitamins are group of organic compounds that are needed in small amounts
for maintaining normal metabolism of nutrients and thus promoting the
physiological well being of human body.
It cannot be synthesized by human body.
Vitamins vary in their composition and functions.
Its presence in various kinds of food is in a variable amounts.
No optimal food is present i.e. there is no food that contain all essential
vitamins to satisfy the daily requirement .
Vitamins are usually required in a relatively small quantities.
Vitamins Primarily have a catalytic function i.e. it enter in the enzymatic
system components which play an important role in facilitating essential
metabolic reactions.
The early investigative work concern was to search for any unknown
accessory dietary factor that can prevent classical nutritional deficiency health
problems .
The purpose of preventing nutritional deficiency health problems , is to find
an alternative nutrient that can result in a prolonged existence of human being
through depending on a limited artificially altered diet
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Classification
According to its solubility , vitamins are classified in to :-
A-) Fat soluble vitamins
It include vitamins A,D,E and K.
B-)Water soluble vitamins.
It include vitamins B and C.
Vitamin A (Retinol):
Although vitamin A can be destroyed easily by oxidation ,it is relatively heat
stable material.
To a great extent , it is found naturally in its precursors form i.e. carotenoid pro-
vitamins alpha, beta and gamma carotene .
It is present in the yellow and orange pigments of most fruits and vegetables.
Sources are liver , dairy products ,eggs ,green vegetables and carrot . Fish liver
is the most concentrated natural source.
Importance of vitamin A
1.It is necessary for the growth of children.
2.It play an important role in the eyes perception to light specially at night (rods and
cones photo receptors).
3.It has a protective function for surface tissues e.g. respiratory tract and eye
(cornea).
4.It play a certain role in steroids metabolism.
Vitamin A deficiency
Clinically patient will develop:-
1.Night blindness i.e. poor adaptation for dark.
2.Xerosis i.e. changes in the outer layer of sclera resulting in xeropthalmia .
3.Keratomalacia i.e. corneal affection.
4.Cutaneous lesions around the hair follicles.
5.Epithelial changes .
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6.Sterility from genitourinary tract affection.
7.Certain pathological changes in the teeth and bones.
Vitamin A toxicity
Patient clinically will have:-
1.Anorexia .
2.Dry itchy skin .
3.Coarse hair.
4.Swelling over the long bones.
The daily recommended allowances is 5000 I.U.
Additional daily requirement is 1000 I.U. for pregnant woman and 3000 I.U. for
lactating woman.
Vitamin D
Vitamin D play a major role in increasing the utilization and retention of calcium
and phosphorus in the body.
Directions of action:-
1.It increase the absorption of dietary calcium and phosphorus from intestinal
lumen.
2.It reduce phosphorus excretion in urine through enhancing renal reabsorption of
it .
3.It maintain proper calcium and phosphorus levels in blood .This will ensure normal
mineralization condition for mature bones.
4.Conversion of organic phosphorus into inorganic phosphorus in bones
Vitamin D deficiency
In children leads to Rickets.
In adults leads to Osteomalacia.
Both parathyroid and calcitonin hormones with vitamin D are concerned
with maintenance of calcium and phosphorus -plasma levels .
Sources are cod liver oil,fish ,egg ,milk and milk products.
During summer ,dairy products contain more vitamin D than during winter.
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Sunlight act on skin and subcutaneous fat and help in the oxidation and
formation of vitamin D.
Vitamin E
It has some influence on fertility.
Sources are green vegetables, milk and milk products.
Vitamin K
It Play a role in prothrombin formation .Thus it is essential for normal
clotting of blood.
It is found in green plants.
Bacterial flora of intestine synthesize vitamin K.
Vitamins B complex (vitamins B group)
Vitamin B1 (thiamine):-
Unstable at high temperature .
Destroyed by alkaline materials.
Vitamin B1 deficiency usually presented as :
1.Affection of children growth.
2.Neuritis.
3.Irritability and depression (psychological symptoms)
4.Beriberi disease :
wet type (in cases of extreme deficiency)
dry type
Sources are seeds,green plants, potato and milk.
Vitamin B2 (riboflavin)
It is easily destroyed by heat, ultraviolet and alkaline materials.
Sources are liver,meat,eggs and milk.
Features of vitamin B2 deficiency are:-
1.Affection of children growth.
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2.Cracks at corners of mouth and nose.
3.Glossitis .
Nicotinic Acid
Features of nicotinic acid deficiency are:
1. Affection of children growth .
2.Skin affection result in red rough skin.
3.Digestive disturbances and diarrhea.
4.Mental disturbances.
5.Pellagra in sever deficiency states .
Folic Acid
Its deficiency result in macrocytic anemia.
Sources are liver,green vegetables and formed by intestinal flora.
Vitamin B12
Its deficiency lead to pernicious anemia.
Its minimal daily requirements is 0.1
gm.
Its liver store depleted in 3-6years.
Sources are liver,meat,milk,and fish.
Vitamin C
It can be easily destroyed by heat.
Its main sources are fruits,fresh vegetables ,fresh liver ,meat and milk.
Features of its deficiency include:-
1. Affection of children growth.
2.Bleeding around hair follicles.
3.Inflamation and swelling of gums.
4.Failure of wounds healing.