Transcript
Taking Stock of the Evidence on
Biofortification of Food Crops with
Provitamin A Carotenoids: Situation
Analysis of What We KnowSherry A. Tanumihardjo
Associate Professor
University of Wisconsin-Madison, USA
Department of Nutritional Sciences
Parker, FASEB J 10:543, 1996
Definitions
Bioaccessibility: how much carotenoid is released from the food matrix and available for absorption.
Bioavailability: fraction of ingested nutrient available for utilization or storage.
Bioconversion: proportion of bioavailable carotene converted to retinol.
Bioefficacy: efficiency ingested carotenoids are absorbed and converted to retinol.
Intestinal
wall
b-Cabsorbed
Cleaved
Retinal
Reduced
Retinol
Food
b-Ctotal
b-Cfreed
Bioaccessibility = b-Cfreed / b-Ctotal
Bioavailability = b-Cabsorbed / b-Ctotal
Bioconversion = Retinol / b-Cabsorbed
Bioefficacy = Retinol / b-Ctotal
Tanumihardjo, IJVNR 72: 41, 2002
SLAMENGHI - 1996
Species of carotenoids
molecular Linkage
Amount of carotenoids consumed in a meal
Matrix in which the carotenoid is incorporated
Effectors of absorption and bioconversion
Nutrient status of the host
Genetic factors
Host-related factors
mathematical Interactions
Advantages of Biofortification:
Enhancing micronutrients in crops
Targets the poor: eat high levels of food
staples
Rural-based: complements fortification
and supplementation
Cost-effective: research at a central
location can be multiplied across countries
and time
Sustainable: investments are front-loaded,
low recurrent costs
The Sherry Factors!!!
S – Species of carotenoid
H – Host related factors
E – Effectors of absorption
R – Relative amounts of carotenoids
R – Resistant starch
Y – Yet to be determined
S – Species of carotenoid
Hydrocarbon or not…
S – Species of carotenoid
OH
OH
-carotene
b-carotene
b-cryptoxanthin
retinol
-Carotene equivalents
5.5 mg:1 mg
Treatment
group
n Serum retinol
(mmol/L)
Liver retinyl
palmitate
(mmol/g)
Liver total retinol2
(mmol/g)
Baseline3 6 1.30 + 0.35 0.123 + 0.024b 0.170 + 0.027b
Vitamin A 9 1.44 + 0.21 0.198 + 0.051a 0.267 + 0.071a
-Carotene 9 1.39 + 0.09 0.110 + 0.026b 0.155 + 0.033b
b-Carotene 9 1.40 + 0.17 0.109 + 0.051b 0.153 + 0.066b
Oil control 5 1.57 + 0.38 0.061 + 0.029c 0.091 + 0.041c
Tanumihardjo & Howe. J. Nutr. 135: 2622–6, 2005
Bioconversion for
b-cryptoxanthin
was 2.8 mg to 1 mg
retinol and almost
identical to b-
carotene.
aab
bc
c
ab
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Base Ctl bC bCX VA
µm
ol
RE
/ g
liv
er
ab
c
bc
a
a
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Base Ctl bC bCX VA
µm
ol
RE
/ l
iver
Davis et al., BJN, 2008
Biofortified b-cryptoxanthin maize
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6m
mo
l R
E / liv
er
Base Control bC Maize VA
bc bc
c
b
a
Davis et al., BJN, 2008
Bioefficacy of biofortified b-carotene maize
High-b-carotene maize did not differ from b-carotene .
Bioconversion: ~3 mg b-carotene to 1 mg retinol.
0.0
0.5
1.0
1.5
2.0
Control Maize BC VA
Treatment
Liv
er
VA
(m
mo
l)
a
bb
c
What about bioconversion
factors in human studies? Li et al. Am J Clin Nutr 2010
• 6.48 ± 3.51 mg bC:1 mg retinol in 6 young
women in Iowa
Muzhingi et al. FASEB J. 2009
• 3.0 ± 1.5 mg bC:1 mg retinol in 9 healthy
Zimbabwean men
S – Species of carotenoid
Cis or trans
Cassava: Comparable to
b-carotene supplement
even with substantial
cis-b-carotene
a
bb
c
bc
0
0∙2
0∙4
0∙6
0∙8
1
1∙2
1∙4
1∙6
1∙8
Base Control BC Cassava VA
Treatments
mm
ol V
itam
in A
/ liv
er
A
a
bcb
c
bc
0
0∙1
0∙2
0∙3
0∙4
0∙5
0∙6
0∙7
0∙8
Base Control BC Cassava VA
Treatments
mm
ol V
itam
in A
/ g
liv
er
B
c c ca b
b b
a
a
b
0
1
2
3
4
5
6
7
8
9
Base Control BC Cassava VA
Treatments
nm
ol b
-Caro
ten
e / liv
er
trans
cis
C
Erdman’s group All-trans b-carotene appears to be more
bioavailable than 9-cis or 13-cis b-carotene in
gerbils given single oral doses of each isomer
• Deming et al., J. Nutr. 132: 2700-8, 2002.
The relative vitamin A value of 9-cis b-carotene
is less and that of 13-cis b-carotene may be
greater than the accepted 50% that of all trans-
b-carotene in gerbils
Deming et al., J. Nutr. 132: 2709-12, 2002.
Cis/trans b-carotene
Bresnahan et al. FASEB J 2011
a
c bc bc b b
H – Host related factors
Polymorphisms
Single nucleotide polymorphisms in the
human BCMO1 gene have been
discovered causing observably reduced
BCMO1 activity.
We do not know how this will influence
biofortification efforts at the population
level.
Lietz et al., Arch Biochem Biophys, 2010
R = 0.885
0
5
10
15
20
25
0 0.5 1 1.5 2
Co
nv
ers
ion
fa
cto
r (m
g:m
g)
Total vitamin A liver reserves (mmol)
Vitamin A status of the host
High b-carotene
orange carrots
Orange and
purple carrots
Kale, spinach,
and brussels
sprouts
Sweet Potato
Red carrots and Cassava
Maize
Total vitamin A liver reserves (mmol)
Co
nvers
ion
facto
r (m
g:m
g)
H – Host related factors
Other nutrient status
How are iron and vitamin A related?
Hematopoiesis and erythropoiesis: formation
of red blood cells
Modulation in the anemia of infection
Iron absorption and metabolism: iron
mobilization and transport
Immune modulation: Reduced morbidity and
mortality of some infectious diseases
Vision retinol retinal
Zn
monooxygenase
Digestion b-carotene 2 retinal
Zn
Protein synthesis
Zn retinol binding protein retinol:RBP in blood
(RBP)
Synergism between vitamin A and Zn
dehydrogenase
E – Effectors of absorption
Fat
Ribaya-Mercado et al. AJCN
2007;85:1041-9
Schoolchildren fed 4.2 mg provitamin A
carotenoids in the form of vegetables for
9 weeks with 2.4, 5 or 10 g fat/meal.
Low liver reserves (< 0.07 mmol/g) fell
from 35% to 7% and the amount of fat
did not influence the results.
Influence of fat on bioconversion Mills et al. J. Nutr. 139: 44-50, 2009
mg b
-caro
ten
e to
ret
inol
Emerging data: Type of fat
Dietary fats with increased unsaturated
to saturated fat enhance absorption of
carotenoids by increasing efficiency of
micellarization and lipoprotein secretion
Unsaturated fat enhances carotenoid
bioavailability
• Chitchumroonchokchai et al., FASEB J.
2010; Abstract 539.3.
R – Relative amounts of carotenoids
Conversion factors
ranged from 9 to 11
mg b-carotene to 1 mg
retinol for typical
orange and 23 mg b-
carotene to 1 mg
retinol for biofortified
carrots.
0
50
100
150
200
250
300
350
high orange orange purple white
To
tal li
ver b
-caro
ten
e (
nm
ol)
a
b
b
c
(A)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
high orange orange purple white
To
tal
liv
er v
ita
min
A (m
mo
l)
a
b b
c
(B)
Dosti et al., BJN. 2006
Cassava:Varying the level
of cassava
a
abab
b
aa
0
0∙3
0∙6
0∙9
Base Control 15% #2 17% #1 35% #2 40% #1Treatments
mm
ol V
itam
in A
/ liv
er
A
abab
ab
b
ab a
0
0∙1
0∙2
0∙3
Base Control 15% #2 17% #1 35% #2 40% #1Treatments
mm
ol V
itam
in A
/ g
liv
er
B
bb a
bb
a
a
bb
cc
a
0
1
2
3
4
5
6
7
8
Base Control 15% #2 17% #1 35% #2 40% #1
Treatments
nm
ol b
-Caro
ten
e / liv
er
trans
cis
C
b-Carotene assessment
0
10
20
30
40
Control Maize BC VA
Treatment
Liv
er b
-caro
ten
e (
nm
ol)
a
b
Liver bC is ~100%
greater in maize
treatment group
VA status with increasing b-carotene. Liver
VA from orange maize was greater than
yellow, regardless of % (P < 0.05).
0
0.2
0.4
0.6
0.8
30% typical 60% typical 30% high BC 60% high BC
Maize Treatment
Liv
er
VA
(m
mo
l)
abbc
c
a
Provitamin A from
cassava, maize, or
supplements of
vitamin A, β-carotene,
and β-cryptoxanthin
Conclusions:
Not all provitamin A carotenoids are equivalent,
one conversion factor does not fit all foods and is
related to vitamin A status.
Biofortified maize not only maintained vitamin A
status, but was as efficacious as b-carotene
supplements.
In populations consuming maize, using orange
instead of white maize may impact vitamin A
status.
A male child eating maize
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.5 1 1.5 2 2.5 3 3.5 4 4.5
Age of child (y)
Liv
er
vit
am
in A
ac
cu
mu
lati
on
m
mo
l/g
)
Sugar
Maize
Supplements
Bioconversion slows
Tanumihardjo, Comp. Rev. Food Sci. & Food Safety, 2008;7:373-81.
Setting up kitchens
Grinding the maize
Food Details
Standardized recipes
with a rotating menu
Cooking the maize
Stirring and stirring….
Food Details
Serving sizes weighed
for each menu item
Food Details
Children Eating!
All uneaten food weighed for each subject
Cleaning up the mess
And the data!
**
A
B
C
D
R – Resistant starch
Sweet potato, Golden Rice and
banana
Orange Fleshed Sweetpotato
• Using the paired isotope dilution test, final
vitamin A was higher in the spinach, vitamin A and
b-carotene groups compared to the control group.
• Vitamin A equivalency factors were estimated:
~13:1 for sweet potato
~10:1 for Indian spinach
~6:1 for b-carotene
Vitamin A provided with meals
Haskell et al. Am J Clin Nutr. 2004;80:705-14
Mills et al. J. Nutr. 139: 44-50, 2009
Influence of dry matter on bioconversion
mg b
-caro
ten
e to
ret
inol
South African Trial Supervised feeding; 125 g x 5 d/wk for 10.5 wk; 1030 mg RAE OFSP
vs 0 mg RAE WFSP; 90% compliance; 250% RDA
Infants eating sweet potato
Sweet potato
Sachets or tablets
?
0
0.2
0.4
0.6
0.8
6 7 8 10 11 12 13
Age of child (mo)
Liv
er
vit
am
in A
ac
cu
mu
lati
on
(mm
ol/
g)
Sweet potato
Tablets or sachets
Tanumihardjo, Comp. Rev. Food Sci. & Food Safety, 2008;7:373-81.
-0.004
0.004
-0.006-0.005-0.004-0.003-0.002-0.0010.0000.0010.0020.0030.0040.0050.006
Intervention effect: -0.008 (-0.015, -0.001)
P = 0.0203
Change in liver stores of vitamin A
Intervention Control
Sweet potato in Mozambique
Effectiveness study using an integrated
agricultural and nutrition intervention
2 year intervention covering 2 agricultural
cycles
90% of intervention households produced
sweet potato
Intervention children (n = 498) ate more sweet
potato and had higher serum retinol than
controls (n = 243)
Low et al. J Nutr. 2007;137:1320-7.
.
Towards Sustainable Nutrition Improvement
in Rural Mozambique
Taste tests were conducted at every adaptive trial
harvest to determine preferences of local consumers.
.
Towards Sustainable Nutrition Improvement
in Rural Mozambique
Sweet potato bread maker making his bread at home and
selling it in the nearby market of Lualua. Bread is marketed
under the name of Golden Bread.
Orange sweet potato
in Africa – a Success Story
Active behavior change
Agronomic ‘equality’ crucial
Assistance to understanding and overcoming constraints to adoption crucial
• Farmer participation in breeding and varietal selection
• Seeds systems, product, and market development
Progress with Golden Rice
Ready for golden rice?
Bioconversion factor:
The conversion factor for Golden Rice
was 3.8 + 1.7 mg to 1 mg with a range of
1.9–6.4:1 in 5 healthy adults
• Tang et al. Am J Clin Nutr 2009;89:1776–83
Pure βC, GR βC, and spinach βC to
retinol were 2.0, 2.1, and 7.3 mg to 1 mg,
respectively
• Tang et al. FASEB J 2010 Abstract
Do favorable bioconversion
factors result in efficacy to
improve vitamin A status?
No change in serum retinol
Both groups lost liver stores as
predicted by the numbers
What do the numbers predict?
6 mg/g X 0.75 retention factor
4.5 mg/g X158 g/day
711 mg with an optimistic 3:1
conversion
237 mg with a 275 mg/d EAR = - 38 mg
Potential loss during the trial is 28
mg/g liver with maize feeding
MRDR versus liver reserves
Liver reserves in mg/g liver
MR
DR
va
lue
BN MN OR TN PP VA
Vit
am
in A
(μ
mo
l / li
ve
r)V
ita
min
A (μ
mo
l / g
liv
er)
Values are means + SD; n = 10. Means with different letters are
different, P < 0.05. ND, not detected
VA Concentration
Total Liver VA
All fruits maintained
baseline liver VA
concentrations.
All fruits prevented VA
depletion as compared to
control, except banana.
Liver carotenoids
present in respective
groups.
Arscott et al., Exp. Biol. Med, 2009
Fruit – Banana?
r = 0.88
Banana r = 0.44 with banana
Dark orange carrot
Orange and
purple carrots
Kale, spinach
brussels Red carrots
sprouts Maize
Mango, orange, tangerine, papaya
Conversion efficiency improves as VA status declines
Interesting Observations
Daily Diet and VA Intake
DietDaily Diet Intake
(g)VA Intake (nmol)
VA- 6.77 0.00
VA+ 6.64 19.11
VA+ Banana 8.12 30.38
60CG 9.16 32.47
60CR 8.99 37.50
60LG 8.28 29.72
60LR 7.67 48.84
15KBG 7.55 56.16
30KBG 7.61 103.70
More studies with banana
All gerbils vitamin A deficient!
Study 2:
Total liver vitamin A (nmol)
Y – Yet to be determined
Another
reason to feed
whole foods!
Mills et al. J. Nutr.
2008.;138:1692-8
c
aababab
bc
d
0
2
4
6
8
10
12
Bas
eline
Contr
olPO O O
RPO
R VA
mm
ol T
EA
C/g
Hydrophilic Extracts Lipophilic Extracts
ba a a a a a
0
1
2
3
4
5
6
Bas
eline
Contr
olPO O O
RPO
R VA
mm
ol T
EA
C/L
Vision retinol retinal
Zn
monooxygenase
Digestion b-carotene 2 retinal
Zn
Protein synthesis
Zn retinol binding protein retinol:RBP in blood
(RBP)
Biofortification: vitamin A and Zn
dehydrogenase
LET’S FEED PEOPLE:
Jejunal Morphology
ORAL TPN
Peterson, C.A. et al. Am J Physiol 272:G1100, 1997
Supports biofortification efforts!
Situation analysis of what we know
The Current VAAL Team
Sara Arscott
Kara Bresnahan
Ashley Valentine
Emily Nuss
Chris Davis
Harold Furr
David Liu
Napaporn Riabroy
Margertha McLean
Sammie Schmalzle
Jacob Tanumihardjo
Collaborators:
Philipp Simon
Torbert Rocheford
Kevin Pixley
Natalia Palacios
Past members whose
work was cited:
Mandy Porter Dosti
Hua Jing
Julie Howe
Jordan Mills
Thanks for your attention
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