1. UNIVERSITY OF GONDAR
COLLEGE OF MEDICINE AND HEALTH SCINCES
Institute of Public Health
Department of Human Nutrition
Human Nutrition course
By: Lemlem D. (Bsc, MPH)
1
4/9/2024
3. Objectives
At the end of completing this chapter, the students are
expected to:
Describe the different types of vitamins
Describe the functions of vitamins in the body
Enumerate the food sources of vitamins
Describe the clinical manifestations of specific vitamin
deficiency
List The RDAs of Vitamins and health problems related to
over/under intake of vitamins
3
4/9/2024
4. Vitamins
Vitamins are organic compounds, needed in small
amounts in the diet of higher animals
‘Vita’- meaning life
‘Amin’- because it was believed that all types of vitamins
contain the chemical structure of an amine group
Essential, non caloric organic nutrients
Currently , there are 13 known vitamins
Without vitamins thousands of chemical reactions do not
occur 4
4/9/2024
8. Vitamins cont…
1. Water Soluble Vitamins
A. Vitamin B1 (Thiamin)
water-soluble vitamin
The substance initially called thiamine that corrected the
problems was first isolated from rice bran in 1912 by
Casmir Funk.
Plays a central role in energy yielding reactions
Coenzyme : Thiamin pyrophosphate(TPP)
Food source: The best dietary sources of thiamine are
whole-grain cereals, potato, fish, meat and Pork
8
4/9/2024
9. Vitamins cont…
Recommended Daily Allowance (RDA):
• Since it has central role in energy yielding reaction
specially of CHO metabolism, intake depends on the
amount of calorie intake from carbohydrates i.e.
0.5mg/1000Kcal
9
4/9/2024
10. Function of Thiamin
• Necessary for protein and carbohydrate metabolism
• Maintains normal function of nervous system, muscles, and
heart
• Replaces deficiency caused by alcoholism, cirrhosis,
infection, breast-feeding, pregnancy and prolonged diarrhoea
• Promotes normal growth and development
• Treats beriberi (thiamine-deficiency disease)
• Keeps mucous membranes healthy
10
4/9/2024
11. Deficiency of Thiamin
First observed among white rice eaters in the Far East
Beriberi : resulted from prolonged thiamin deficiency
Lactic acidosis : impaired conversion of pyruvate to acetyl-coA
which in turn results increased serum lactate and pyruvate
Wernicke-Korsakoff syndrome: Thiamin responsive condition
associated with alcoholism and patients on parentral nutrition
manifested with short term memory loss, motor problems, and
psychosis
Mild deficiency: Loss of appetite, Fatigue, Nausea, Vomiting,
Muscle tenderness and atrophy, constipation and GI disorders 11
4/9/2024
12. Type of beriberi Clinical manifestation
DRY Chronic Wasting disease, neuritis-paralysis of limbs
Thin, wasted, weak muscle
Feels pins and needles in feet and arms, tender calves
gradually paralysis of limb
Treatment- Paralysis does not respond to thiamine treatment.
Slowly little improvement
WET More acute form, whole body swollen, disturbance in the
Circulatory system - Sudden death from heart Failure
Pitting oedema in legs and may appear in face, trunks
Breathless, irregular rapid pulses and distended veins,
condition deteriorates.
Treatment- Patient recovers dramatically after 1 or 2 hours of
injection with thiamine.
INFANTILE Is common during 2nd and 5th months of life children who are
being breast-fed mothers eating beriberi-producing diet.
12
4/9/2024
13. Vitamin cont…
Treatment
Dietary management
• Fortification of staple cereal with Vitamin B1
• Adequate amounts of alternative foods rich in thiamine
• Decrease consumption of refined sugar and Alcohol
Therapeutic management
• Tablets: Take with meals or 1 to 1-1/2 hours after meals
• Injection: Injectable forms are administered by doctor or
nurse in the form of Thiamine hydrochloride
13
4/9/2024
14. Vitamin B2 (Riboflavin)
• Intense yellow in color as a result widely used as food
additive
• Easily destroyed by light, heat and acid
• pro-oxidant activity: The combination of light, oxygen
and riboflavin can lead to the formation of free
radicals
• Coenzymes forms: flavin mononucleotide (FMN) and
and flavin adenine dinucleotide (FAD)
14
4/9/2024
15. Vitamins cont…
FOOD SOURCES OF VITAMIN B2:
• Milk and other dairy products are good source of riboflavin
• Other food sources: eggs, meat, fish, Green leafy vegetables,
Brewer's yeast , Cheese , Organ meats, Chicken....
Tablets:
• A constituent of many multivitamin/mineral preparations
• Available as simple riboflavin or activated riboflavin
(riboflavin-5-phosphate)
• Should be taken with or immediately after food to decrease
stomach irritation 15
4/9/2024
16. Function of Riboflavin
• Acts as co-enzymes
• Aids in release of energy from food
• Necessary for the regeneration of glutathione
• Preserves integrity of nervous system, skin, eyes
• Aids for metabolism of iron
• Activates dietary vitamin-6
16
4/9/2024
17. Deficiency of riboflavin
• Cracks and sores in corners of mouth
• Inflammation of tongue and lips
• Eyes overly sensitive to light and easily tired
• Itching and scaling of skin around nose, mouth, scrotum,
forehead, ears, scalp
• Trembling, Dizziness, Insomnia, Slow learning, Itching,
burning and reddening of eyes
17
4/9/2024
19. Niacin (Vitamin B3)
Niacin was discovered as a nutrient during studies of the
deficiency disease pellagra.
• “Niacin” is used as a generic descriptor for both vitamers:
nicotinic acid and nicotinamide (niacin amide)
synthesized in the body from the essential amino acid,
Tryptophan
Acts as coenzyme: NAD(Nicotinamide adenine
dinucleotide) and NADP
19
4/9/2024
20. Vitamin cont…
Food sources of vitamin B3
• It is found in meat, liver, fish, poultry, Peanut, peas, beans,
and whole grains. However Milk, eggs, and cheese are poor
source; however, they are good source of Tryptophan
Tablet
• Available in the form of tablet or capsule and Injectable
forms as constituent of many multivitamin/mineral
preparations
20
4/9/2024
21. Function of vitamin B3
• As component of co-enzymes
• Aids in release of energy from foods (Carbohydrates, lipids
and proteins)
• Involved in the synthesis of sex and adrenal hormones
• Plays an important role in DNA repair mechanism
• Reduces cholesterol, triglycerides and raises HDL cholesterol
in the blood
• Helps to threat pellagra and arthritis and prevents
premenstrual headache
21
4/9/2024
22. Deficiency of niacin(vitamin B3)
• Common in the community where maize is staple food
• Pellagra is characterized by a photosensitive dermatitis, affecting
all parts of the skin that are exposed to sunlight such as the knees,
elbows, wrists, and ankles
• Advanced pellagra is also accompanied by dementia and there
may be diarrhea if Untreated, it would result death
Recommended Daily Allowance (RDA):
• 6mg/1000kcal for adult
• Excess intake (>500mg/d) can cause toxicity then to liver damage
22
4/9/2024
24. VITAMIN B6 (Pyridoxine)
• Generic descriptor of six vitamers
• All converted to the metabolically active form, pyridoxal
phosphate(PLP)
• Pyridoxal, pyridoxamine, and pyridoxine are all absorbed
rapidly by passive diffusion
• Unlike other water soluble vitamins, B6 stored in the
muscle
• 80% of the body’s total vitamin B6 is found in the muscle as
pyridoxal phosphate, mostly associated with glycogen
phosphorylase 24
4/9/2024
25. Vitamin cont…
Food sources of vitamin B6 :
avocado, banana, carrot, lentils, Rice, Soybean , Sunflower seeds
Tablet:
Available in the form of tablet as constituent of multivitamin tablet
Active forms: Pyridoxine hydrochloride and pyridoxal-5-
phosphate
Anti-TB drugs i.e. Isoniazide (INH) binds and inactivates the
vitamin, and increases renal excretion
As a result the vitamin should be supplemented while prescribing
INH 25
4/9/2024
26. Function of vitamin B6
• Acts as co-enzyme for metabolic functions affecting protein,
carbohydrates and fat utilization
• Coenzyme in the first step in the synthesis of heme
• Promotes conversion of tryptophan to niacin or serotonin
• Involved in the production of several body proteins and
neurot transmitters like serotonin, dopamine, melatonin and
norepinephrine
26
4/9/2024
27. Deficiency of vitamin B6
Symptoms of vitamin B-6 deficiency are non specific
Hormone-dependent cancer of the breast, uterus, and prostate
Mental confusion, Irritability, Nervousness , Insomnia, Poor
coordination walking, Hyperactivity, Anaemia ,Skin lesions ,
Discoloration of tongue , Muscle twitching , Kidney stones,
Depression, Convulsions, Glucose intolerance, Impaired nerve
function , Cracked lips
27
4/9/2024
28. Deficiency of vitamin B6 cont…
A hypo chromic, microcytic anaemia may also result from a
vitamin B6 deficiency due to impaired heme synthesis
Impairs niacin synthesis from tryptophan, and inhibits
metabolism of homocysteine. In turn results in hyper-
homocysteinemia, a risk factor for heart disease
28
4/9/2024
29. Vitamin cont…
RECOMMENDED DAILY ALLOWANCE (RDA)
Protein intake largely affects vitamin B6
requirement as a result the reference intakes are
based on 15–16 μg/g dietary protein
The therapeutic dose is between 50-100mg
29
4/9/2024
30. Vitamin cont…
Interaction with other substances
Alcohol: distracts and enhances excretion of B-6 in the
body (acetaldehyde)
Tobacco-decreases Vitamin B-6 absorption
Estrogens or oral contraceptives: increase requirements of
pyridoxine
Phenytoin: Large doses of B-6 accelerate break-down of
Phenytoin
Therefore individuals/clients taking these drugs require
regular vitamin B-6 supplementation 30
4/9/2024
31. Folic Acid (Vitamin B9)
One of water soluble vitamin which is also known as folacin or
Folate, important for cell division
As a supplement, folic acid is almost completely available
(especially if consumed on an empty stomach): 85% bioavailable.
Memory and abstract thinking appear to be influenced by folate.
Cognitive dysfunction and dementia have been shown to
correlate with plasma homocysteine concentrations, which in
turn are influenced in part by folate status.
31
4/9/2024
32. Function of folacin
1. It is critical to cellular division since it is necessary in DNA
synthesis:
2. Protein synthesis: conversion of homocysteine to methionine
3. Regulate embryonic and Foetal development of nerve cells:
4. Promotes normal red blood cell formation
32
4/9/2024
33. Folic acid cont…
FOOD SOURCES: generally fruits and vegetables are good
sources, Beans , Barley Brewer's yeast , Calves' liver, Fruits ,
Green, leafy vegetables, Lentils Peas , Rice , Soybeans , Split peas ,
Sprouts , Wheat ,Wheat germ , Orange juice , Oranges
Available as:
Tablets: in combination with iron and other multi-vitamins
Should be taken with meals or 1 to 1-1/2 hours after meals
33
4/9/2024
34. Deficiency of folic acid
1. Megaloblastic anaemia
During Folate deficiency there is release of immature
precursors of RBC and red blood cells are large and
uneven in size, have a shorter life span or are likely to
have cell membranes rupture
2. Neural tube defect in the foetus
34
4/9/2024
35. Folic acid cont…
Recommended dietary allowance
Pregnant women need to be supplemented with folic
acid at least 1 month before and 3 months after the
onset of pregnancy 400microgram of folic acid
Pregnant women who has previous experience of
giving birth of child with spina bifida 4gm of folic acid
35
4/9/2024
36. Cobalamin (Vitamin B12)
Cobalt containing vitamin which is found only in animal foods.
Absorption of vitamin-B12 is made possible by binding with the
intrinsic factor at the intestinal lumen
Intrinsic factor: are is a small glycoprotein secreted by the parietal
cells of the gastric mucosa
Vitamin B12 is absorbed from the distal third of the ileum
36
4/9/2024
37. Vitamin cont…
FOOD SOURCES
Vitamin B-12 is found from foods of animal origin : Milk, milk
products , Liver , Beef, Beef liver, Eggs , Kidney....
Available: in the form of tablet and Injectable forms
Tablets used as dietary supplements
Unlike other water-soluble vitamins, this vitamin is stored in the
body tissues, approximately 50% in the liver, so a deficiency can
take years to appear
37
4/9/2024
39. Function of Cobalamin
1. Treats pernicious anaemia
2. Promotes formation of blood-cell
3. Plays an important role in protein synthesis
4. In combination with folic acid, it is necessary for the synthesis of
DNA and for maintaining the myelin sheath that surrounds nerve
cells and facilitates the signals along the neurotransmitters
39
4/9/2024
40. DEFICIENCY OF VITAMIN B-12
1. Pernicious anaemia : commonly because of failure of the
absorption of vitamin B12, rather than dietary deficiency
Problem with absorption may be due to failure of intrinsic
factor secretion, as a result of autoimmune disease
2. Impaired brain and nervous system function: demylination of
nerve fibbers in Central Nervous System
40
4/9/2024
41. Vitamin cont…
Risk groups: vegetarians, people undergoes surgical removal
of the stomach (parietal cells) or terminal ileum
People with parasitic infections such as tapeworms may
develop a vitamin B12 deficiency because the parasite uses the
vitamin
Problems causing decreased HCL secretion and IF production
Recommended dietary allowance
Vegetarians are advised to obtain at least 100 mcg of B-12
each day
41
4/9/2024
43. Vitamin C (Ascorbic Acid)
Forms: Ascorbic acid and dehydroascorbic acid have
vitamin activity
There is no specific storage organ for ascorbate; apart
from leukocytes (which account for only 10% of total
blood ascorbate)
43
4/9/2024
44. Vitamin cont…
Food Sources
Citrus Fruits and Green Leafy vegetables are common
Sources Vitamin C like Oranges, Papayas , Potatoes ,
Tomatoes , Cabbage , Grapefruit , Green peppers , Lemons ...
Also available in the form of tablet (as constituent of other
multi-vitamins) and Injectable forms
44
4/9/2024
46. Function of Ascorbic Acid
1. Chief antioxidant
2. Helps to form collagen in connective tissue
3. Plays an important role in blood clotting system
4. Increases iron absorption from intestines
46
4/9/2024
47. Deficiency of vitamin C
1. Scurvy: muscle weakness, swollen gums, loss of teeth,
tiredness, depression, bleeding under skin, bleeding
gums, Swollen or painful joints, Nose bleeds, Changes
in personality and psychomotor performance
2. Anaemia and frequent infections
3. Delayed healing of wound and reopening of surgical wounds
47
4/9/2024
49. Vitamin cont…
RECOMMENDED DAILY ALLOWANCE (RDA):
Adjusted depending on age, sex and other physiological
factors
• RDA is 90mg/day for adult men and 75 mg/day for adult
women
• Smokers require more as smoking causes oxidative stress
Intake of 20 mg/day is required for optimum wound healing
49
4/9/2024
51. Vitamin-A
Fat soluble vitamin
There are two forms
1. Retinoid: Includes retinol, retinaldehyde,
retinoic acid and retinyl palmitate
Found only in foods of animal origin
Also known as Previtamin
Active and most absorbable type
51
4/9/2024
52. Con’t…
2. Carotenoids: Includes carotenes and related
compounds i.e. α, β,γ carotines and
cryptoxanthin
Mostly found in plants based food groups
Also known as provitamin A
Less absorbable type
52
4/9/2024
53. Cont…
50–80% of the total body content of retinol is stored in
the liver
Peoples with protein-energy malnutrition are at risk for
vitamin-A deficiency. WHY???
Vitamin A supplementation is found with reduction in
overall mortality and morbidity in children <5 years
53
4/9/2024
54. Cont…
Food sources
Plant sources: Vitamin A is generally found in
green leafy vegetables, yellow orange fruits in the
form of B-carotene
Animal sources: found in the form of retinol:
Liver , fish liver oil, Milk and Egg
54
4/9/2024
56. Function of vitamin-A
1. Essential for normal function of retina
2. Builds body's resistance to respiratory infections
3. Helps to treat acne, impetigo, boils, and carbuncles,
open ulcers when applied externally
4. Helps to form and maintain healthy skin, hair, and
mucous membranes
6. Has anti oxidant function
7. For reproduction, tissue growth and differentiation56
4/9/2024
57. Deficiency of vitamin-A
1. Increases Susceptibility to respiratory infection
2. Night blindness, eventual blindness if deficiency is severe and
untreated
3. Lack of tear secretion (due to destruction of goblet cell)
4. Poor bone growth, Weak tooth enamel, Diarrhea , Slow growth
5. Dry, rough skin
6. Changes in mucous membranes
57
4/9/2024
58. Clinical indicators of Vitamin A
deficiency
• Night blindness- the most common type
• Bitot’s spot
• Conjuctival xerosis
• Corneal ulcer
• keratomalacia
58
4/9/2024
59. Strategies to alleviate vitamin-A deficiency
Breast Milk: source of Vit A
Food diversification
Vitamin-A Supplementation : mothers, infants & children:
For infants 6-11 month: 100,000 IU (once)
For children 12-59 month: 200,000 IU (at every 4-6 month)
For lactating mothers: 200,000 IU
Food fortification
Public Heath Masures (Immunization, infection control)
59
4/9/2024
61. Vitamin D (1,25, Dihydroxycholecalciferol)
• The normal dietary form of vitamin D is Cholecalciferol (also
known as calciol). This is also the compound that is formed in the
skin by ultraviolet (UV) radiation of 7-dehydrocholesterol
Hence, can be synthesised under the skin it is not strictly an
essential vitamin
Vitamin D is absorbed in lipid micelles and incorporated into
Chylomicrons
Regulate the blood calcium level
61
4/9/2024
63. Function of vitamin-D
Regulates growth, hardening and repair of bone by
controlling absorption of calcium and phosphorus from
small intestine
Prevents rickets and other vitamin-D related deficiency
disease
Promotes normal growth and development of infants and
children, particularly bones and teeth
Food source: Sunlight plus subcutaneous fat, Vitamin D-
fortified milk, Butter, Egg yolks , liver oil
63
4/9/2024
64. Deficiency of vitamin-D
1. Rickets: under mineralization of bone as a result of poor
absorption of calcium in the absence of adequate amounts
of calcitriol. It is common problem among childhood and
adolescents
Mostly black children
• Symptoms: Bowed legs and knocked knees, malformations
of joints or bones, late tooth development, weak muscles,
double maleolus, Rachitic Rossary
64
4/9/2024
67. Cont…
2. Osteomalacia (adult rickets): resulted from
demineralization of bone and common among
adult, old ages and women of reproductive age
(pregnant women)
3. Osteoporosis: due to loss of bone matrix
Sign and symptom: pain in ribs, lower spine, pelvis
and legs, muscle weakness and spasm, brittle, easily
broken bones.
67
4/9/2024
68. Vitamin E
Vitamin E is the generic descriptor for two families of compounds,
the tocopherols and the tocotrienols
The tocotrienols have lower vitamin activity than tocopherols
Alpha-tocopherol, commonly known as Vitamin E, is the form
found most in nature and the most biologically active
68
4/9/2024
69. Cont…
Food Sources
Vegetable oils are rich sources of vitamin E, but significant
amounts are also found in nuts and seeds, most green leafy
vegetables and a variety of fish
All vegetable oils(Apricot oil , Corn oil, Cottonseed oil, Peanut oil
Wheat germ, Whole-wheat flour , Margarine, Sunflower seeds
69
4/9/2024
70. Functions
Unlike other vitamins, no unequivocal physiological function
for vitamin E has been defined; since many of its functions
can be replaced by synthetic antioxidants but is a known
Chief antioxidant.
70
4/9/2024
71. Cont…
Deficiency
Dietary deficiency of vitamin E in human beings is unknown,
• Premature infants and children: Irritability , Edema , Hemolytic
anemia
Adults: Lethargy, Apathy, Muscle weakness, Causes infertility
71
4/9/2024
72. Vitamin K
It is often suggested that about half of the requirement for vitamin
K is met by intestinal bacterial synthesis.
Food sources: because of its role in photosynthesis, it is found in
all green leafy vegetables, Soybeans, Cabbage , Green leafy
vegetables, Oats
Available as:
• Tablets: Take with meals or 1 to 1-1/2 hours after meals
• Injectable : administered by a health professional.
NOTE: Vitamin K is not usually included in most
multivitamin/mineral preparations
72
4/9/2024
73. Functions
Prevents abnormal bleeding
Promotes health and strength of bone:
Prevents hemorrhagic disease of the newborn
Treats bleeding disorders due to Vitamin K deficiency
73
4/9/2024
74. Deficiency
Infants:
• Failure to grow and develop
• Hemorrhagic disease of the newborn: characterized by blood
vomiting and bleeding from intestine, umbilical cord, circumcision
site. Symptoms begin 2 or 3 days after birth
Adults:
• Abnormal blood clotting that can lead to nosebleeds, blood in
urine, stomach bleeding, bleeding from capillaries or skin causing
spontaneous black-and-blue marks, prolonged clotting time
74
4/9/2024
75. CONT...
RECOMMENDED DAILY ALLOWANCE (RDA):
No RDA has been established. Adequate and safe range is 2
mcg/kg body weight per day
Overdose/ toxicity
Signs and symptoms:
In infants: Brain damage.
In all: Large doses may impair liver function
75
4/9/2024
