HarvestPlus

Nutrition Research Program:

Iron and Zinc

HarvestPlusInternational Food Policy Research Institute

Washington DC

Taking Stock of Evidence

on Biofortification of Food

Crops with Iron and Zinc:

Analysis of what we know

so far

BIOFORTIFICATION

Washington, DC

K. Michael Hambidge MD ScD

Progress to date

1. Genetic variation for nutrients exists.

2. Micronutrients can be bred into staple foods.

3. Iron and zinc are inherited together.

4. It is easier to breed for Vit A than Zinc/Iron

5. Neither yield nor farmer preferred traits are

compromised by breeding for micronutrients.

6. Micronutrient traits are NOT difficult to breed in.

7. Novel methods, protocols, and equipment for low-

cost, high throughput measurement (to the

microgram) had to be developed and implemented

by HarvestPlus.

2004 2010

HarvestPlus has established:

Taking Stock of Evidence

on Biofortification of Food

Crops with Iron and Zinc:

Analysis of what we know

so far

BIOFORTIFICATION

Washington, DC

K. Michael Hambidge MD ScD

Genetic Variation,

Baseline & Target Levels

45 Increment

30

88

Genetic Variation Discovered

Non-Biofortified Avg. Baseline

HarvestPlus Target

DEVELOPMENT

Estimate targets for Zn

and Fe so that

biofortified staple food

provides a meaningful

amount of these

micronutrients.

CONTRIBUTING GOALS TO

ASSESSMENT OF TARGET

• ESTIMATE USUAL INTAKE OF STABLE CROP.

• RETENTION OF IRON & ZINC DURING

PROCESSING.

• BIOAVAILABILITY OF BIOFORTIFIED IRON & ZINC.

• RELIABLE ESTIMATES OF PHYSIOLOGICAL REQUIREMENTS

Modified from Hotz & McClafferty, 2007

Estimate usual intake

of staple food

Challenge: availability of representative dietary intake data for target

populations

Examples of quantities of staple

crops consumeda

CROPa CHILDRENb WOMENc

Polished rice 120g 400g

Cassava 150g 500g

a. expressed as dry wt equivalents for rice and fresh wt for cassava. Derived from mutlticountry composite of household food expenditure data & estimated on basis of consumer equivalence

b. 4-6 yrs c young. Not pregnant or lactating

(Hotz & McClafferty Food & Nutr Bulletin 28 [2] S271-279)

FOOTNOTE

HUMAN NUTRITION RESEARCH 0F

HARVESTPLUS AND COLLABORATING

INSTITUTIONS MADE MORE ARDUOUS

BY LACK OF ESSENTIAL DATA THAT

MIGHT REASONABLY BE AVAILABLE

OR IN PROGRESS WITH SUPPORT

FROM OTHER SOURCES.

Zn and Fe

RETENTION

Amount of micronutrient [or increase in amount of

micronutrient] in the biofortified food in ready-to-eat form.

About 25% loss

G. Barry, IRRI 2009

Effect of polishing on grain zinc content (3 varieties)

14

16

18

20

22

24

26

28

30

32

Brown

rice

10 20 30 40 50 60

Polishing time (sec)

Zin

c c

on

ten

t (p

pm

)Areumbyeo IR 68144-2B-2-2-3-1-120 PSB Rc28

Pearl MilletZn & Fe content before cooking

μg Zn/g μg Fe/g

Whole

grain

27.7 110.5

Coarse

grind

30.0 110.0

Fine

grind

24.3 108.0

Zinc retention in wheat

converted to tortillas (μg Zn/g sample)

High Extraction Low Extraction

Whole grain Flour Tortilla* Flour Tortilla

High Zn 41.3 40.5 39.5 20.4 18.5

Control 23.6 23.0 21.8 10.6 10.0

*Tortillas made from flour, water, lard, salt

BIOAVAILABILITY

Definition: Proportion of micronutrient absorbed into the body and potentially available for biological function.

Challenges:

Zinc: now relatively simple to estimate effect of factor[s] inhibiting absorption.

Iron: complex with multiple inhibitors and facilitators.

Study

Serum

ferritin2

Bean

meal1Fractional iron

absorption2

Absorption

Ratio3 p4

µg/L %

Low vs

High Iron

9.3

(4.2- 20.6)

SER 16 6.8 (3.2; 14.2)

1.59<0.00

1MIB465 4.3 (1.8; 10.1)

Low vs

High PP

10.3 (5.4-

19.6)

SER 16 7.5 (4; 14.1)0.96 0.71

MIB 497 7.7 (4; 15.2)

1all A meals contained 0.4 mg Fe57 or 0.4 mg Fe58

2 values are geometric means; range in parentheses3 absorption ratio study 1 (SER16/ MIB465) and study 2 (SER16/ MIB497)4 paired Student’s t-test was used to compare differences in absorption on logarithmically transformed data

5-day % Fe absorption from test meals

(beans + rice or potatoes) by healthy

Rwandan university students

Combined Effects of Polyphenols

& Phytic Acid in Common Beans

Reduction of polyphenols in low

phytate beans or selection of beans

with low levels of polyphenols and

phytic acid necessary to achieve

substantial increase in fractional

absorption of iron.

(Perry N, et al, J. Nutr. 2010)

Dose dependent effect of phytic

acid on Fe absorption in humans

Adapted from Hallberg, et al. Am J Clin Nutr 1989

Model Conception and

Equation

TDZATDZAK

TDPKTDZA

K

TDPKTAZ MAXMAX

P

RMAX

P

R 4115.0

2

phytate

zinc

transport

receptor

diet

zinc-phytate

complex

unbound

zinc-receptor

complex

excreted

absorbed

KP1

KP2

KR1

KR2

Zn absorbed versus predicted at

actual phytate intakes

0 3 6 9 12 150

1

2

3

4

5

phytate0 mg/d

600800

23002500

80% High Zn

80% Control Zn

95% High Zn

95% Control Zn

Total Dietary Zn (mg/d)

To

tal

Ab

so

rbed

Zn

(m

g/d

)

Low-Phytate Cereal and Legume Germplasm and Breeding

“1st Generation Breeding”=Simply Crossing in Alleles or Introducing Genes

“2nd Generation Breeding”=1st Generation Followed by Selection for Performance, Emergence, Yield

Species

Current Genetic

Technologies Identification

Mature Seed

Phytic Acid/Phytase Status of Breeding and Comments

Maize Recessive Alleles lpa1, lpa2, lpa3 50% to 95% Phytate

Reduction

1st Generation Only, No 2nd Generation Selection;

Yields Range from Greatly Reduced to 95% of Control

Transgenic MRP4/ABC

Transporter

30% to 90% Phytate

Reduction

1st Generation Only, No 2nd Generation Selection;

Embryo-targeted Expression; Lack of Extensive Yield Data

Transgenic Fungal Phytase High Phytase and Normal to

~25% Phytate Reduction

Either Embryo or Endosperm Targeted Expression;

Lack of Extensive Yield Data

Barley Recessive Alleles lpa1, lpa2, lpa3,

lpa-M593

50% to 90% Phytate

Reduction

1st and 2nd Generation Breeding; Cultivars Available;

Yields Range From Greatly Reduced to Excellent, Depending on

Line and Environment

Wheat Recessive Alleles Js-12-LPA 35% Phytate Reduction 1st and 2nd Generation Breeding; Yields 80% to 100% of Control

Rice Recessive Alleles lpa1, lpaN15-186,

lpa-XS110-1

40% to 70% Phytate

Reduction

1st Generation Breeding Only;

Reduced Yields Indicated but Lack of Extensive Yield Data

Soybean Recessive Alleles pha1::pha2

lpa-ZC-2

LR 33-MIPS

50% to 80% Phytate

Reduction

For pha1::pha2: 1st and 2nd Generation Breeding, Yield Up To >90%

of Control; Germination/Emergence General Problem;

Lpa-ZC-2: Good Emergence

Transgenic “CAPPA: Bacterial

Phytase

High Phytase: 90% Phytate

Reduction

1st Generation Only; Lack of Extensive Yield Data

Common

Bean

Recessive Allele lpa-28-10 80% Phytate Reduction 1st Generation Only; Apparently Very Good Yield and

Germination/Emergence, But More Extensive Yield Data Needed

For most references, please see Cichy and Raboy. 2008. Pp. 177-200 in: “Modification of Seed Composition to Promote Health and Nutrition”. Agronomy

Monograph Series, American Society of Agronomy and Crop Science Society of America. Also see: Campion et al. 2009, Theor Appl Gene 118:1211;

Drakakaki et al. 2005, Plant Mol Bio 59: 869; Chen et al. 2007, Transgenic Res DOI 10.1007/s11248-007-9138-3.

HarvestPlus minimum target levels

for Zn

“An additional amount of

bioavailable Zn in the food supply

that is equivalent to 40% of the

physiological requirements for

absorbed Zn for non-pregnant

women and children of 4-6 yrs of

age”

C Hotz. Food Nutr Bull 2009:30(1);172-8

Zn Physiological Requirements:

Roles in Biofortification

• Establishing target goals.

• Interpretation of bioavailability of zinc

increment achieved with biofortification.

• Providing reference data for interpretation

of bioavailability of zinc from biofortified

crops

• First of 2 major steps in determining

dietary requirements of target populations.

• Determine the biological impact of biofortified foods on micronutrient status and health conditions under controlled conditions.

• Challenges:

• Identify adequate & sensitive biomarkers and other indices of host status that are dependent on iron or zinc status.

• Difficulkt to control for al environmental factors

EVALUATION:

EFFICACY

Hass JD, Beard JL, et al

IRON-BIOFORTIFIED RICE IMPROVES

THE IRON STORES 0F NON-ANEMIC

FILIPINO WOMEN.

(J. Nutr 135: 2823-2830, 2005)

1

1.5

2

2.5

3

3.5

4

4.5

Fin

al

ferr

itin

(ln

ug

/L)

1 2 3Ferritin tercile at baseline (ug/L)

Plasma ferritin after 9 months of consuming

high iron (IR68144) or control (C4) rice

non-anemic at baseline (n=137 )

C4 IR68144

1

1.5

2

2.5

3

3.5

4

4.5

Fin

al

ferr

itin

(ln

ug

/L)

1 2 3Ferritin at baseline (ug/L)

Plasma ferritin after 9 months of consuming

high iron (IR68144) or control (C4) rice

non-anemic at baseline (n=137 )

C4 IR68144

p=.01 p=.02 p=.13

Iron

deficiency

(<12ug/L)

EFFECTIVENESS,

DISTRIBUTION & ACCEPTANCE

• Effectiveness Trials: Pending

• Distribution, Acceptance, etc: Pending.

CONCLUSIONS

A LONG-TERM PROJECT WITH ENCOURAGING PROGRESS AND PLENTY OF WORK AHEAD WITH BREEDING, HUMAN STUDIES & DISSEMINATION, BUT WITH EMINENTLY WORTHWHILE GOALS ESPECIALLY FOR THIS PLANET’S RURAL POOR.