Vitamins are organic compounds that have various functions in the body and differ in their chemistry, biochemistry and food sources. They are either water soluble or fat soluble. Water soluble vitamins include the B vitamins and vitamin C, which are absorbed in the small intestine and excreted through urine. Fat soluble vitamins A, D, E and K are absorbed through the intestinal tract with dietary fats and stored in body tissues. Vitamins play essential roles in growth, metabolism and various bodily processes, and deficiencies can lead to structural and functional disorders.

2. Vitamins
Vitamins are a group of organic compounds
that have a variety of functions in the body
and are chemically different from each other.
They differ in their chemistry, biochemistry,
function, and availability in foods. Vitamins
facilitate biochemical reactions within cells
to help regulate body processes such as
growth and metabolism.

3. Vitamins are required in minute amounts
and their deficiency results in structural and
functional disorders of various organs in the
body
Vitamins are indispensable in our diets
because the body cannot synthesise them

4. Food sources of vitamins
The main sources of vitamin include:
Fruits
vegetables

5. Classification of vitamins
Vitamins are classified into two groups
namely;
Fat soluble vitamins
Water soluble vitamins

6. Physical properties of vitamins
As organic substances, vitamins in food are
susceptible to destruction and subsequent
loss of function. Individual vitamins differ
in their vulnerability to heat, light,
oxidation, acid and alkalis. For instance,
Thiamine (B1) is heat sensitive and is easily
destroyed by high temperatures and long
cooking times.

7. Cont’d
Riboflavin (B2) is resistant to heat, acid,
and oxidation but is quickly destroyed by
light. That is why riboflavin-rich milk is
sold in opaque, non transparent containers.
From 50% to 90% of folate in foods may be
lost during preparation, processing and
storage.
Vitamin C is destroyed by heat, air, and
alkali

8. FAT SOLUBLE VITAMINS

9. Fat soluble vitamins
These vitamins are soluble in fats therefore
these vitamins are utilised only if there is
sufficient amount of fat in the body
They are found in fats or oily parts of foods and
are therefore absent from foods without fat
They are stored in lipid fraction of the body like
adipose and lipid fractions of cells
Fat soluble vitamins include vitamin A, D, D2,
D3, E and K

10. Vitamin A
This is the term for the biologically active
compound retinol and its precursor
carotenoid. The liver stores Vitamin A in
sufficient quantities to supply the healthy
individual for several months.

11. Functions
Building and growth of all cells
normal structure of bones and teeth
maintenance of epithelium (outer layer) of
skin, and the mucous membranes lining the
nose, GIT mouth, eyes, respiratory tract
For formation of visual purple, enabling the
retina of the eye to adapt to dim light.

12. Functions cont’d
Recent data show that vitamin A fights
against cancer of the skin, lung bladder and
breasts
Carotenoids through their antioxidant
property reduce risk of CVDs

13. Absorption
The various forms of vitamin A are
solubilised ini micelles in the intestinal
lumen and adsorbed by intestinal mucosa
cells.
Both retinyl esters and provitamin A
carotenoids are converted to retinol, which
is oxidised to retinal and then to retinoic
acid

14. Storage
In food of animal origin, the major form of
vitamin A is an ester, primarily retinyl which
is converted to retinol (an alcohol) in the
intestine.
The retinol form functions as a storage form
of vitamin and can be converted to and
from its visually active form retinal

15. sources
liver of any animal
whole milk
Cream
Butter
Cheese
 eggs
Margarine
vegetables, (e.g., carrots, pumpkin, sweet
potatoes, mangoes, rape, etc.).

16. Dietary Allowance
Children 0-12 months – 350
microgram/day
1- 10 years- 500 micrograms/day
11-14 years – 600 micrograms/day
Above 14 years – 700 micrograms /day

17. Vitamin A deficiency
Xerophthalmia (dry eye) is the most specific
VAD–leading preventable cause of blindness
in children throughout the world
Night blindness- inability to see in dim light
Bitot’s spot- foamy and whitish cheese-like
tissue spots develop around the eye ball

18. Keratomalacia- erosion of roughened
corneal surface with softening and
destruction of cornea leading to total
blindness

19. Supplementation
Vitamin A supplementation of 50,00 iu is
given to newly born infants who are not
breastfeeding
Mothers are given 200,000 iu upon delivery
It is also supplemented t0 children less than
5 years
Less than 12 months- 100,000 iu
Above 12 months- 200,000iu

20. Vitamin D
Vitamin D is unique in that the body has
the potential to make all the vitamin D it
needs if exposure to sunlight is optimal and
liver and kidney functions are normal.
Vitamin D2 (ergocalciferol) is a plant
version of vitamin D while vitamin D3
(cholecalciferol) is an animal version

21. Functions
Maintains serum calcium and phosphorus
concentrations by stimulating GI
absorption
Stimulating the release of calcium from the
bones as needed to maintain normal serum
levels
Stimulating calcium absorption from the
kidneys

22. Storage
Like other fat soluble vitamins, vitamin D is
stored in the body’s adipose tissue.
This means the body can mobilise its own
reserves if daily intake falters temporarily,
but it also means that excessive doses of
vitamin D can build up to toxic levels.

23. Absorption
Vitamin D that is consumed from food or as
a supplement is absorbed in the part of the
small intestine immediately from the
stomach.
Stomach juices, pancreatic secretions bile
and the integrity of the wall of intestines
have some influence on how much of the
vitamin is absorbed

24. Sources
Vitamin D occurs naturally in only a few
foods: liver, fatty fish, and egg yolks.
Fortified foods are important sources: all
milks, most ready-to-eat cereals, and a few
brands of orange juice, yogurt, margarine,
and cereals

25. Dietary Allowance
Up to 70 years- 15 micrograms per day
Above 70 years – 20 micrograms

26. Deficiency
Rickets – calcium and phosphorus are not
deposited enough to form strong bones and
as a result leg bones become bent and
deformed. This condition usually occurs to
infants and children of poor families
Oesteomalacia – occurs among adults- this
is the softness of the bones due to
insufficient vitamin D intake. Pain,
softening and tenderness in the bones and
fractures are common

27. Vitamin E
Vitamin E is a generic term that describes a
group of at least eight structurally related,
naturally occurring compounds. Alpha-
tocopherol is considered the most
biologically active form of vitamin E and
considered a representative of all, although
other forms also have important roles in
maintaining health.

28. Functions
functions as the primary fat soluble antioxidant
in the body, protecting PUFAs and other lipid
molecules, such as LD cholesterol, from oxidative
damage. By doing so, it helps to maintain the
integrity of PUFA rich cell membranes
protects red blood cells against haemolysis, and
protects vitamin A from oxidation.
inhibiting cell division, enhancing immune
system functioning, regulating gene expression,
inhibiting platelet aggregation, and suppressing
tumor formation

29. Absorption and storage
Vitamin E is hydrophobic and is absorbed
similarly to other dietary lipids. After
mobilisation with bile acids, it is absorbed
into small intestinal epithelial cells,
incorporated into chylomicrons and
transported into the blood.
Vitamin E is stored within the fat droplets
of adipose tissue cells

30. Sources
Vegetables oil
Wheat germ
Leafy vegetable oil
Egg York
Margarine
Legumes

31. Dietary Allowance
Men- 10.6 mg
Women – 8.1 mg

32. Deficiency
Vitamin E deficiency is not common as
vitamin E is widely distributed in foods

33. Vitamin K
Vitamin K occurs naturally in two forms:
phylloquinone, found in plants, and
menaquinones, which are synthesized in
the intestinal tract by bacteria but anti-
biotics eliminate bacteria

34. Functions
Vitamin K is a coenzyme essential for the
synthesis of prothrombin and at least 6 of the
other 13 proteins needed for normal blood
clotting. Without adequate vitamin K, life is
threatened: even a small wound can cause
someone deficient in vitamin K to bleed to
death.
Vitamin K also activates at least three proteins
involved in building and maintaining bone.

35. Absorption
Like dietary lipids and other fat soluble
vitamins ingested vitamin K is incorporated
into mixed micelles via the action of bile
and pancreatic enzymes, and it is absorbed
by enterocytes of the small intestines.
Compared to the other fat soluble vitamins,
very small amounts circulate in blood

36. Storage
Vitamin K is stored in the liver and fatty
tissues and plays a role in the process of
coagulation and anticoagulation

37. Sources
Leafy green vegetables
Vegetable oils
Eggs
Meat
Dairy products

38. Dietary Allowance
Men -120 micrograms / day
Women - 90 micrograms/day

39. Deficiency
Dietary vitamin K deficiency is not
common.
Bleeding of the skin and mucous membrane
indicates the deficiency of vitamin K.
Deficiency of vitamin K among newborns,
especially among premature babies delays
clotting of blood.

40. WATER SOLUBLE VITAMINS

41. Water soluble vitamins
Water soluble vitamins are soluble in water
and can not be stored in the body
They are more readily lost during storage by
light and heat and during processing
Water soluble vitamins include B vitamins,
folic acid and vitamin C

42. Absorption of water soluble vitamins
Water soluble vitamins are packed into the
watery portions of the food eaten.
The B vitamins and vitamin C are absorbed
along with the water in the small intestines
and the circulate through the blood

43. Vitamin B12 and folic acid can be stored in
the body, but need to be replenished in few
days as they are easily eliminated through
urine
Kidneys continuously regulate levels of
water soluble vitamins shunting excess out
of the body

44. Vitamin B1 (thiamine)
This is a powder which is readily soluble in
water.
It is destroyed by alkali
It has a yeast like odour and is stable in its
own form

45.  FUNCTIONS
 Thiamine is a coenzyme in the metabolism of
carbohydrates and branched chain amino acid
 It is also important in nervous system functioning.
 SOURCES
 Pulses
 Nuts
 Yeast and yeast products
 Pork
 Vegetables
 Milk

46. Dietary Allowance
Adult RDA
Men: 1.2 mg
Women: 1.1 mg

47. Deficiency
Dry Beri-beri- characterised by tenderness
of the calf muscle,
Numbness in the toes, ankles and knees
Tingling and numbness of the legs and
hands are followed by wasting of muscles
and difficult in walking

48. Wet Beri- beri- all the symptoms of dry
beri-beri are seen in wet beri-beri
In addition to this, oedema in legs and in
between the cardiac muscle fibres. This
changes the heart beat
Later, oliguria and dyspnoea may develop
If untreated may cause death

49. Infantile beri beri- it affects infants within
6 months
The early symptoms are restlessness,
sleeplessness and loss of appetite
Vomiting and green coloured diarrhoea are
common
Among alcoholism thiamine deficiency is
common

50. Vitamin B2 (Riboflavin)
Riboflavin (vitamin B2) is an integral
component of the coenzymes flavin adenine
dinucleotide (FAD) and flavin
mononucleotide (FMN) that function to
release energy from nutrients in all body
cells.

51. Flavin coenzymes are also involved in the
formation of some vitamins and their
coenzymes and in the conversion of
homocysteine to methionine. Riboflavin
is unique among water-soluble vitamins in
that milk and dairy products contribute the
most riboflavin to the diet

52. Functions
Promotion of normal growth
Assist in synthesis of steroids, RBCs and
glycogen
Maintenance of mucosal membrane, skin,
eyes, and the nervous system
Assist in iron absorption

53. Sources
Eggs
Milk and milk products
Liver and kidney
Yeast
Fortified breakfast cereals

54. Dietary Allowance
Adult RDA
Men: 1.3 mg
Women: 1.1 mg

55. Deficiency
Riboflavin deficiency include;
Angular stomatitis
Dermatosis
Skin changes

56. Vitamin B3 (niacin)
Niacin (vitamin B3) exists as nicotinic acid
and nicotinamide. The body converts
nicotinic acid to nicotinamide, which is the
major form of niacin in the blood

57. Functions
Required for the breakdown of glucose in
metabolism.
Promotes normal nervous system
functioning

58. Sources
Beef
Pork
Chicken
Wheat and maize flour
Eggs
Milk

59. Dietary Allowance
Adult RDA
Men: 16 mg
Women: 14 mg

60. Deficiency
Deficiency of niacin leads to pellagra which
is referred to as the disease of the 3Ds due to
the following symptoms;
Diarrhoea
Dementia
Dermatosis
Other symptoms include vomiting and
mouth sores

61. Vitamin B6 (pyridoxine)
Vitamin B6 and pyridoxine are group names
for six related compounds that include
pyridoxine, pyridoxal, and pyridoxamine.
All forms can be converted to the active
form, pyridoxal phosphate, which is
involved in nearly 100 enzymatic reactions.

62. Functions
Coenzyme in amino acid and fatty acid
metabolism
Helps convert tryptophan to niacin
Helps produce insulin, haemoglobin and
antibodies

63. sources
 Meat
 Wholegrain cereals
 Fortified cereals
 Bananas
 Nuts
 Pulses
 DIETARY ALLOWANCE
 Adult RDA
 Men: 1.3–1.7 mg
 Women: 1.3–1.5 mg

64. Deficiency
Deficiency causes blood, skin and nerve
changes

65. Vitamin B12 (cobalamin)
FUNCTIONS
• vitamin B12 has an interdependent
relationship with folate: each vitamin must
have the other to be activated.
• Because it activates folate, vitamin B12 is
involved in DNA synthesis and maturation
of red blood cells.
• Like folate, vitamin B12 functions as a
coenzyme in homocysteine metabolism

66. Sources
Animal products: meat, fish, poultry,
shellfish, milk, dairy products, eggs
Some fortified foods
DIETARY ALLOWANCE
Adult RDA: 2.4 micrograms/day

67. Deficiency
Deficiency causes pernicious anaemia- in
this condition the life span of the red blood
cells reduces from 120 days to 60 days and
the size and shape changes.

68. Vitamin B5 (pantothenic acid)
FUNCTIONS
 Part of coenzyme A used in energy metabolism
SOURCES
• Yeast
• Offals
• Peanuts
• Meat
• eggs

69. Dietary Allowance
Adult AI: 5 mg

70. Deficiency
Deficiency of vitamin B5 is rare
Experimental production of its deficiency
shows loss of appetite, fatigue, dizziness
and impaired motor coordination

71. Vitamin B7 (biotin)
FUNCTIONS
Coenzyme in energy metabolism, fatty acid
synthesis, amino acid metabolism, and
glycogen formation
SOURCES
Widespread in foods; Eggs, liver, milk, and
dark green vegetables
Synthesized by GI flora

72. Dietary Allowance
Adult AI: 30 micrograms

73. Deficiency
Deficiency is not common
A study was taken in 1942 where a man was
30% of biotin. Dermatosis of varying types
on the neck, hands, arms and legs were
seen.
It was followed by muscle pain, anorexia,
nausea and anaemia
A rapid injection of biotin brought rapid
cure

74. Vitamin C (ascorbic acid)
FUNCTIONS
Collagen synthesis
Antioxidant
Promotes iron absorption
Involved in the metabolism of certain
amino acids
Thyroxin synthesis
Immune system functioning

75. Sources
Citrus fruits and juices, red and green
peppers, broccoli, cauliflower, sprouts,
strawberries, tomatoes
DIETARY ALLOWANCE
Adult RDA
Men: 90 mg
Women: 75 mg

76. Deficiency
In mild deficiency, fatigue, weakness
irritability and frequent infection occur
Pain in bones is common
In severe deficiency, scurvy occurs.
Symptoms of scurvy include; swollen/
bleeding gums, loose teeth, soft or
malformed weak bones, anaemia and
degeneration of muscle fibre
Iron is not properly absorbed in vitamin C
deficiency

77. Folate (folic acid)
FUNTIONS
Coenzyme in DNA synthesis; therefore vital
for new cell synthesis and the transmission of
inherited characteristics
Required for maturation of erythrocytes
SOURCES
Liver, okra, spinach, asparagus, dried peas and
beans, seeds, orange juice; breads, cereals, and
other grains are fortified with folic acid

78. Dietary Allowance
Adult RDA: 400 micrograms
Pregnant – 400-800 mcg

79. Deficiency
Lack of folic acid results in megaloblastic
anaemia; also known as macrocytic anaemia
Megaloblasts in the bone marrow do not
mature into erythrocytes therefore the
number of RBCs produced is reduced
The Hb level is also reduced