Hambidge nutrition fe zn

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Hambidge nutrition fe zn

  1. 1. HarvestPlus Nutrition Research Program: Iron and Zinc HarvestPlus International Food Policy Research Institute Washington DC
  2. 2. 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
  3. 3. 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:
  4. 4. 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
  5. 5. Genetic Variation, Baseline & Target Levels 45 Increment 30 8 8 Genetic Variation Discovered Non-Biofortified Avg. Baseline HarvestPlus Target
  6. 6. DEVELOPMENT Estimate targets for Zn and Fe so that biofortified staple food provides a meaningful amount of these micronutrients.
  7. 7. 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
  8. 8. Estimate usual intake of staple food Challenge: availability of representative dietary intake data for target populations
  9. 9. 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)
  10. 10. 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.
  11. 11. Zn and Fe RETENTION Amount of micronutrient [or increase in amount of micronutrient] in the biofortified food in ready-to-eat form.
  12. 12. 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) Zinccontent(ppm) Areumbyeo IR 68144-2B-2-2-3-1-120 PSB Rc28
  13. 13. Pearl Millet Zn & 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
  14. 14. 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
  15. 15. 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.
  16. 16. Study Serum ferritin2 Bean meal1 Fractional 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 1 MIB465 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 parentheses 3 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
  17. 17. 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)
  18. 18. Dose dependent effect of phytic acid on Fe absorption in humans Adapted from Hallberg, et al. Am J Clin Nutr 1989
  19. 19. Model Conception and Equation TDZATDZA K TDP KTDZA K TDP KTAZ 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
  20. 20. Zn absorbed versus predicted at actual phytate intakes 0 3 6 9 12 15 0 1 2 3 4 5 phytate 0 mg/d 600 800 2300 2500 80% High Zn 80% Control Zn 95% High Zn 95% Control Zn Total Dietary Zn (mg/d) TotalAbsorbedZn(mg/d)
  21. 21. 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.
  22. 22. 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
  23. 23. 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.
  24. 24. • 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
  25. 25. Hass JD, Beard JL, et al IRON-BIOFORTIFIED RICE IMPROVES THE IRON STORES 0F NON-ANEMIC FILIPINO WOMEN. (J. Nutr 135: 2823-2830, 2005)
  26. 26. 1 1.5 2 2.5 3 3.5 4 4.5 Finalferritin(lnug/L) 1 2 3 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 Finalferritin(lnug/L) 1 2 3 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)
  27. 27. EFFECTIVENESS, DISTRIBUTION & ACCEPTANCE • Effectiveness Trials: Pending • Distribution, Acceptance, etc: Pending.
  28. 28. 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.

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