Haas nutrition fe zn

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Haas nutrition fe zn

  1. 1. Jere D. Haas Cornell University Ithaca, NY, USA First Global Conference on Biofortification Washington, DC November 9, 2010
  2. 2. (From Hotz & McClafferty, Food and Nutrition Bulletin, 2007;28:S271-79) 2
  3. 3. Challenges for Iron and Zinc Biofortification  Measuring biological response to changes in iron and zinc ingestion  Testing efficacy and effectiveness of iron and zinc biofortification interventions  Demonstrating benefits versus costs of iron and zinc biofortification intervention strategies 3
  4. 4. Measuring biological response to changes in iron and zinc ingestion Constraints to observing significant improvements in iron and zinc status from consumption of biofortified staple foods  Low concentrations of nutrients in biofortified staple crops  Post harvest processing reduces iron and zinc content in some staple foods  Low bioavailability of iron and zinc in plant based diets 4
  5. 5. Assessing Bioavailability  Methodological constraints for assessing bioavailability  Conceptual constraints affecting the assessment bioavailability  Conceptual constraints affecting response to low nutrient bioavailability 5
  6. 6. Methodological constraints to assessing bioavailability  Intrinsic versus extrinsic labeling with stable isotopes  Use of animal models and in vitro methods to screen staple crop varieties  Use of algorithms to evaluate diets containing biofortified foods 6
  7. 7. Conceptual constraints for assessing bioavailability  Should we concentrate only on the upper small intestine?  Are there other methods that can estimate bioavailability?  Do we have sufficient information on bioavailability for the high risk populations and high risk segments of these population? 7
  8. 8. Conceptual constraints affecting the response to low nutrient bioavailability  How much can food processing of staple foods affect mineral bioavailability ?  Should plant breeding objectives focus more on modifying inhibitors and enhancers of absorption? 8
  9. 9. Measuring biological response to biofortification  Wide array of iron status indicators reflecting various stages of iron metabolism  Very limited biomarkers to assess zinc status  Some conventional markers are not sufficiently sensitive to changes in status in response to increased iron and zinc intakes  intrinsic environmental factors like inflammation and parasitic infections confound interpretation of biomarkers  Measuring functional outcomes of changes in iron and zinc status 9
  10. 10. Figure 1 Fe stores Ferritin Hemoglobin anemia IDNA IDNA=Iron Deficient Non-Anemic FEP & sTfR TS Relationship between various indicators of iron status and the body’s level of iron stores Modified from Guthrie and Picciano, Human Nutrition, 1995
  11. 11. Measuring biological response to biofortification  Wide array of iron status indicators reflecting various stages of iron metabolism  Very limited biomarkers to assess zinc status  Some conventional markers are not sufficiently sensitive to changes in status in response to increased iron and zinc intakes  intrinsic environmental factors like inflammation and parasitic infections confound interpretation of biomarkers  Measuring functional outcomes of changes in iron and zinc status 11
  12. 12. Assessing efficacy and effectiveness  Efficacy requires strict controls on the experimental situation which is required given low nutrient density and bioavailability  Efficacy must be shown in order to justify effectiveness studies.  How can we expand the scope of efficacy studies to better inform subsequent effectiveness studies?  Efficacy studies could be the best place to study the relation of functional outcomes to change in biomarkers  Can populations consume enough of the biofortified staple food under real life conditions to achieve a measurable difference in iron or zinc status?  What are reasonable expectations for response to biofortification in effectiveness studies? How much time is required to observe effectiveness? 12
  13. 13. Assessing efficacy and effectiveness  Efficacy requires strict controls on the experimental situation which is required given low nutrient density and bioavailability  Efficacy must be shown in order to justify effectiveness studies.  How can we expand the scope of efficacy studies to better inform subsequent effectiveness studies?  Efficacy studies could be the best place to study the relation of functional outcomes to change in biomarkers  Can populations consume enough of the biofortified staple food under real life conditions to achieve a measurable difference in iron or zinc status?  What are reasonable expectations for response to biofortification in effectiveness studies? How much time is required to observe effectiveness? 13
  14. 14. 14 1 1.5 2 2.5 3 3.5 4 4.5 Finalferritin(lnug/L) 1 2 3 Ferritin 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 Iron deficiency (<12ug/L) 15 33 65 p=.01 p=.02 p=.13 14.4 18.9 28.4 59.7 49.9 35.4
  15. 15. 15 Changes in body iron (mg/kg) by level of iron intake from rice over nine months -10 -5 0 5 10 0 0.5 1 1.5 2 2.5 3 Iron Intake from Rice (mg/day ) ChangeinBodyIron (mg/kg) O X Control Rice High Iron Rice O,X = mean change in body iron at the mean value of iron intake from rice r=.35
  16. 16. Assessing efficacy and effectiveness  Efficacy requires strict controls on the experimental situation which is required given low nutrient density and bioavailability  Efficacy must be shown in order to justify effectiveness studies.  How can we expand the scope of efficacy studies to better inform subsequent effectiveness studies?  Efficacy studies could be the best place to study the relation of functional outcomes to change in biomarkers  Can populations consume enough of the biofortified staple food under real life conditions to achieve a measurable difference in iron or zinc status?  What are reasonable expectations for response to biofortification in effectiveness studies? How much time is required to observe effectiveness? 16
  17. 17. Production efficiency (PE) of Chinese female cotton mill workers before and after 12 weeks of iron suplementation 1.6 1.7 1.8 1.9 2 2.1 2.2 Baseline After 12 weeks PE(yuan/MJ) Placebo Control Iron Supplemented From Li et al., AJCN 59:908;1994 1.86 1.83 1.85 2.15 P=.001 5% increase in earnings 16% improvement in PE
  18. 18. Assessing efficacy and effectiveness  Efficacy requires strict controls on the experimental situation which is required given low nutrient density and bioavailability  Efficacy must be shown in order to justify effectiveness studies.  How can we expand the scope of efficacy studies to better inform subsequent effectiveness studies?  Efficacy studies could be the best place to study the relation of functional outcomes to change in biomarkers  Can populations consume enough of the biofortified staple food under real life conditions to achieve a measurable difference in iron or zinc status?  What are reasonable expectations for response to biofortification in effectiveness studies? How much time is required to observe effectiveness? 18
  19. 19. 19 Dietary source of iron during 9 month feeding trial in Philippine women 0 2 4 6 8 10 12 14 16 18 Control High Iron Rice group Ironconsumption (mg/day) Rice iron Non-rice iron RDA for women 44% to 46% of RDA 46% to 56% of RDA +0.36 mg +1.77 mg n=138
  20. 20. 20 Fe required (mg/d) 0 2 4 6 8 10 12 14 16 18 20 0 10 20 30 40 50 60 70 80 90 100 Estimated percentile of Requirement Ferequirement(mg/d) range of habitual intakes in Filipino women The distribution of Fe requirements is modeled from a factorial accounting for body size, age, menstrual blood loss, and contraceptive use (IOM 2001). A Monte Carlo simulation with n>1000 was used. 8 mg/d intake is sufficient for only 50% of women 10 mg/d is sufficient for 73% of women Meeting dietary iron requirements at two levels of intake from rice
  21. 21. Assessing benefits relative to costs  There is a need to updated estimates from previous ex ante analysis of the impact of biofortification  Better measures of benefit (functional outcomes) can strengthen assumptions and calculations of benefit-cost ratios  Policy makers need thoughtful and understandable translation of good science to inform their decisions. 21
  22. 22. Relationship between work output and work input in iron deficient and healthy subjects. Constant Work Output Lo Work input (kcals) Hi Workoutput(watts) Healthy Fe Def  An iron deficient person performs the same amount of work as a healthy person but at higher energetic cost (effort)  It follows that for the same amount of effort the iron deficient person produces less than the healthy person  Iron deficiency effects on work output (productivity) must also consider work input (kcals) and efficiency
  23. 23. 23 Differences in dietary iron intake between control and high iron rice groups Iron concen- tration1 (ppm) Rice intake1 (g/d) Iron intake from rice1 (mg/d) Iron intake- total diet1 (mg/d) Control Rice (n=69) 0.57+0.08 623+133 0.36+0.09 8.3+1.8 High Iron Rice (n=69) 3.21+0.26 553+120 1.77+0.41 10.0+1.9 Difference (relative to control rice) 2.80 ppm 5.6-fold increase -70 g 11% less 1.41 mg 5-fold increase 1.69 mg 20% increase 1Means+SD JB
  24. 24. 24 Probability of inadequate intake v. usual intakes 0 2 4 6 8 10 12 14 16 18 20 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 probability of inadequate intake Feintakes(mg/d) without biofortification 43% probability of inadequate intake 21% probability of inadequate intake with biofortification The probability of an inadequate intake of iron is reduced as iron intake increases. The “gain” however is not equivalent in all parts of the distribution curve. a probability of 1 has been assigned for all usual intakes<2.5% of requirement and a probability of 0 has been assigned to all usual intakes >97.5 percentile of requirement. Probability of inadequate total daily iron intake at two levels of iron from rice

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