Vitamin A Deficiency in Developing Countries - PowerPoint PPT Presentation

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Vitamin A Deficiency in Developing Countries

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(43, 70, and 44 in the placebo, vitamin A, and b-carotene groups, respectively) ... With the maximum vitamin A dosage, response usually evident within one week ... – PowerPoint PPT presentation

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Title: Vitamin A Deficiency in Developing Countries


1
Vitamin A Deficiency in Developing Countries
HSERV 590/NUTR 600 20 April 2007
2
Global Distribution of Vitamin A Deficiency
20 April 2007
3
Under-5-mortality distribution of countries with
vitamin A survey information
Schultink, 2002
20 April 2007
4
Functions
  • Vision (night, day, colour)
  • Epithelial cell integrity against infections
  • Immune response
  • Haemopoiesis
  • Skeletal growth
  • Fertility (male and female)
  • Embryogenesis

20 April 2007
5
Malnutrition and child death
VAD ?
20 April 2007
6
Association between xerophthalmia and mortality
Sommer, Hussaini, Tarwotjo, 1983
20 April 2007
7
Impact of vitamin A supplementation on child
mortality
20 April 2007
8
Impact of vitamin A on measles mortality
Sommer, West, 1996
20 April 2007
9
Maternal HIV-1 infection and vitamin A status
20 April 2007
10
Vitamin A status and some major childhood
infections
  • benefit is greatest on measles
  • fewer attendances in clinics
  • fewer admissions to hospital
  • little effect on respiratory infections
  • Shigella gut infection reduced
  • malaria reduced
  • reduced mortality in children with HIV

20 April 2007
11
Impact of supplementation on mortality related to
pregnancy up to 12 weeks post partum
West, Katz, Khatry et al, 1999
20 April 2007
12
Stages of deficiency
Increasing deficiency
  • Subclinical
  • reducing stores
  • lowering serum level
  • metaplasia
  • Clinical
  • xerophthalmia
  • - non-blinding
  • - blinding

20 April 2007
13
Tests for assessment of vitamin A status
Decreasing status
  • Subclinical
  • relative dose-response test
  • serum retinol
  • retinal rod function
  • conjunctival impression cytology (CIC)
  • Clinical
  • night blindness
  • conjunctival and corneal eye signs

20 April 2007
14
Increasing impairment of retinal rod function,
illustrating the subclinical-clinical divide
20 April 2007
15
Progressive changes in conjunctiva and cornea,
illustrating the subclinical-clinical divide
20 April 2007
AS06
16
Biological indicators of subclinical vitamin A
deficiency in children 6-71 months of age
20 April 2007
17
Xerophthalmia classification by ocular signs
  • Night blindness (XN)
  • Conjunctival xerosis (X1A)
  • Bitots spot (X1B)
  • Corneal xerosis (X2)
  • Corneal ulceration/keratomalacia (X3A)
  • lt1/3 of corneal surface
  • Corneal ulceration/keratomalacia (X3B)
  • ?1/3 of corneal surface
  • Corneal scar (XS)
  • Xerophthalmic fundus (XF)

20 April 2007
WHO, 1982
18
WHO criteria of a public health problem of VADD
  • Night blindness (XN) gt 1
  • Bitots spot (X1B) gt 0.5
  • Corneal sclerosis/ (X2, X3A, X3B) gt 0.01
    ulceration/keratomalacia
  • Corneal scar (XS) gt 0.05
  • Retinol gt 5 lt0.35 mmol/l (10 mg/dl)

WHO, 1982
20 April 2007
19
Scheme for the classification of night blindness
by interview
  • Does your child have any problem seeing in the
    daytime?
  • Does your child have any problem seeing at
    nighttime?
  • If yes, is this problem different from other
    children in your community?
  • Note this question is particularly appropriate
    where VAD is not very prevalent
  • Does your child have night blindness?
  • Use local term that describes the symptom

WHO, 1996
20 April 2007
20
Conjunctival xerosis (X1A) and corneal xerosis
(X2)
20 April 2007
21
Bitots spot (X1B)
20 April 2007
22
Characteristics of vitamin A-responsive Bitots
spots (X1B)
  • Subject usually a child less than 6 years of age
  • With the maximum vitamin A dosage, response
    usually evident within one week
  • Usually accompanied by generalised conjunctival
    xerosis and night blindness
  • Males more commonly affected than females

20 April 2007
23
Characteristics of vitamin A- unresponsive
Bitots spots (X1B)
  • Commonly occur in children over 6 years and in
    otherwise healthy adults
  • Usually a small, single spot
  • No accompanying evidence of VAD
  • Largely responsible for the apparent increase of
    X1B prevalence with increasing age

20 April 2007
24
Conjunctival and corneal xerosis (X1A and X2)
20 April 2007
25
Keratomalacia (X3A, X3B)
20 April 2007
26
Keratomalacia
20 April 2007
27
Corneal scarring (XS)
20 April 2007
28
Why do children become vitamin A deficient?
  • Mothers of poor children often have VAD and
    produce deficient breast milk
  • Childrens diets provide too little vitamin A
  • Children spend a large part of their
    childhood being sick
  • Provitamin A carotenoids in vegetables and
    fruits are less readily bioavailable than
    previously thought
  • Early weaning is often onto foods low in vitamin
    A
  • Growth velocity, and therefore vitamin
    A requirement, is higher during pre-school age
    than at any other time postnatally

20 April 2007
Humphrey, Katz et al, 2002
29
Major food sources
  • Dark green leafy vegetables
  • Yellow fruits
  • Carrots
  • Palm oils
  • Liver and liver oils

20 April 2007
30
Examples of common vegetable/fruit-carotenoid
sources
mg RE/100 g edible portion Red palm
oil 30000 Buriti palm (pulp)
3000 Carrots 2000 Dark green leafy
vegetables 685 Sweet potato, red and yellow
670 Mango golden 307 Apricot
250 Papaya 124 Tomato 100
20 April 2007
31
Examples of common animal vitamin A sources
mg retinol/100 g edible portion Fatty fish
liver oils Halibut 900,000 Shark 180,0
00 Cod 18,000 Herring and
mackerel 50 Dairy
produce Margarine - fortified
900 Butter 830 Cheese, fatty type
320 Eggs
140 Milk 40 Meats Liver of sheep
and ox 15,000 Beef, mutton, pork
0-4
20 April 2007
32
Hierarchy of carotenoid bioavailability
20 April 2007
33
Retinol Activity Equivalent (RAE)
1 mg RAE 1 RE of retinol 1 mg retinol 2
mg b-carotene in oil 12 mg b-carotene in mixed
foods
20 April 2007
34
Children being taught about foodstuffs rich in
vitamin A
20 April 2007
35
Food supply of vitamin A - from provitamin A
carotenoids and preformed vitamin A food sources
20 April 2007
36
Control of VADD
  • Supplementation
  • Fortification
  • Diet diversification
  • Infectious disease control
  • Disaster relief
  • Plant breeding

20 April 2007
37
A child receiving a vitamin A capsule
20 April 2007
38
Periodic oral supplementation, IVACG 2001
  • Infants 0-5 months 50,000 IU
  • With each of the three infant doses of DPT/Polio
  • Young children 6-11 months 100,000 IU
  • Every 4-6 months
  • Children 12-59 months 200,000 IU
  • Every 4-6 months
  • Women 15-44 years 200,000 IU
  • Within 6 weeks of delivery, two doses gt24
    hours apart for a total of 400,000 IU

IVACG, 2001
20 April 2007
39
Coverage of vitamin A supplementation in children
6-59 months old, Nicaragua
20 April 2007
40
Prevalence of VADD (serum retinol lt 20mg/dl) in
children 6 - 59 months old, Nicaragua
20 April 2007
41
Treatment schedule (orally)
Immediately on diagnosis lt6 months 50,000
IU 6-12 months 100,000 IU gt12 months 200,000
IU Next day Same age-specific dose At least
two weeks later Same age-specific dose Women of
reproductive age 200,000 IU with
xerophthalmia with milder eye signs 10,000
IU/d or 25,000 IU/week for 4 weeks
20 April 2007
WHO, 1997
42
Prevention 2 Food fortification
Scientific rationale Economic
viability Industrial capacity Community
acceptance Training Sustainability
Advocacy Monitoring Legislative support
Quality control
  • Economic viability
  • Community acceptance
  • Sustainability
  • Monitoring
  • Quality control

20 April 2007
43
Vitamin A-fortified sugar
20 April 2007
44
Prevention 3 Dietary diversification
Advantages Ultimate solution Community
involvement Generating income Provides other
nutrients Components Production (home,
school) Consumption (by vulnerable
groups) Problems Long-term cooperation Difficult
in slums and desert areas
20 April 2007
45
Promotion of training and education
20 April 2007
46
Nepali women and children during a vitamin A
distribution campaign
20 April 2007
47
Recent insights into dietary control of VADD in
developing countries
  • Mean daily provitamin A intake is only 470 mg
    RE/day and not 720 as earlier calculated
  • Provitamin A activity 40 lower than previously
    stated
  • Solely vegetarian diet probably not protective
  • Recent research explains why VADD have persisted
    despite abundant provitamin A food supplies

West, McLaren, 2002
20 April 2007
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