Challenges in setting Dietary Reference Values. Where to go from here? Inge Tetens & Susan Fairweather-Tait

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1 Challenges in setting Dietary Reference Values. Where to go from here? Inge Tetens & Susan Fairweather-Tait EFSA symposium on DRVs at FENS Berlin, 22 October 2015

2 Conflict of interest regarding this presentation: We have no conflicts of interest to report in relation to this presentation. 2

3 DRV OPINIONS ADOPTED BY 22 OCT 2015 Work carried out Year Opinion 2010 Principles for deriving DRVs Guidance on translation of nutrient-based recommendations into food-based dietary guidelines Carbohydrates and dietary fibre Fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol Water 2012 Protein 2013 Energy 3

4 DRVS NEED SOLID FOUNDATIONS Average Requirements (ARs) and Population Reference Intakes (PRIs) have been set for some nutrients Adequate Intakes (AIs) have usually been set in older infants (7-11 months) and in other population groups for many nutrients The setting of a Dietary Reference Value was not considered appropriate for chromium 4

5 WHERE DO WE START? In principal, a decision tree approach can be used to begin the process of deriving DRVs but in practice, it s not that simple! 5

6 . APPROACHES FOR DERIVING DRVS Dose-response data Measured intake Status/intake biomarker Balance study data Dietary intake and excretion (steady state) Factorial calculations Requirements for pregnancy, lactation, growth Endogenous (obligatory) losses Health or functional outcome Dietary bioavailability 6

7 DERIVING THE AVERAGE REQUIREMENT FOR CALCIUM Age Approach 7-11 months Factorial (high uncertainty hence AR not set) 1-17 years Factorial (no balance or other useful data) Adults years Adults 25 years Intermediate value between ARs for children aged years and adults 25 years Balance data (null balance when intake equals excretion: 715 mg/d) plus dermal losses (insufficient data for factorial approach, no useful biomarkers for health effects) 7

8 CALCIUM BALANCE DATA IN ADULTS Estimated mean at null balance: 715 mg/day (balance data from Grand Forks, USA) Upper bound of prediction interval of estimated mean at null balance: 904 mg/day PRI 950 mg/day (upper bound of prediction interval plus allowance for dermal losses) 8

9 BIOAVAILABILITY AS PART OF FACTORIAL APPROACH Estimating iron bioavailability based on data on iron intake and status in a representative sample of UK adults Dainty et al. PLOS ONE 2014;9:e

10 SETTING THE PRI: IRON AS AN EXAMPLE Age Approaches for the Population Reference Intake Infants and children up to 11 years years (boys) Based on 20% CV Based on 20% coefficient of variation very varied growth rates, uncertainty over iron losses, and differences in dietary patterns that may affect iron bioavailability years (girls) Intermediate value between calculated PRI for girls based on 20% CV and PRI for premenopausal women Men 18 years Women 18 years Premenopausal Meets 97.5% of the population s obligatory iron losses according to the distribution model Meets 95% of the population s obligatory iron losses according to the distribution model women with very high menstrual losses were not included Postmenopausal Same as adult men 10

8 mg/day Assuming dietary iron absorption of 18% (at a serum ferritin

11 MODELLING IRON LOSSES TO ESTIMATE THE POPULATION REFERENCE INTAKE In premenopausal women the 95 th percentile of iron losses is 2.8 mg/day Assuming dietary iron absorption of 18% (at a serum ferritin of 30 µg/l) this translates into a Population Reference Intake of 16 mg/day 11

12 DRVS FOR FOLATE: HOW TO DEAL WITH LACK OF DATA Age Approach PRI 7-11 months Extrapolating upwards from estimated folate intake in exclusively breast-fed infants 1-17 years Extrapolating downwards from AR for adults using allometric scaling and growth factors, considering reference body weight Adults 18 years Pregnancy Folate intake required to maintain functional folate adequacy Maintenance of serum and red blood cell folate concentration as in adults, but few data AI AR x 1.3, i.e. use of a CV of 15% AR x 1.3 Lactation AR plus amount to cover losses in breast milk AR x 1.3 AI Health outcomes considered but found to be insufficient to establish DRVs 12

13 DRVS FOR VITAMIN B12: APPROACH Selecting a combination of biomarkers and their dose-response relationship 13

14 DRVS FOR VITAMIN B12: POPULATION GROUPS Adults: Adequate Intake (AI) set at 4 µg/day Infants and children: AI extrapolated from adult value by using allometric scaling and applying growth factors Pregnant and lactating women: factorial approach to cover accumulation in fetal tissues and transfer into breast milk 14

15 WORK IN PROGRESS 15

16 DRVS FOR VITAMIN D: INTAKE-STATUS RELATIONSHIP Two-step approach: - vitamin D status and health outcomes relationship - vitamin D intake and status relationship Total vitamin D intake - µg/d One example of a meta-regression model Multivariable log-linear model with adjustment for relevant covariates. Data points shown for illustrative purposes. /Prediction interval Predicted mean /95% CI Mean Achieved 25(OH)D - nmol/l 16

17 OPINIONS ON DRVS FOR MICRONUTRIENTS Adopted by 22 October 2015 Type of DRV Minerals calcium, iron, zinc AR/PRI copper, magnesium, phosphorus, fluoride, iodine, manganese, molybdenum, selenium chromium Vitamins A, C, folate biotin, cobalamin, E as α-tocopherol, pantothenic acid AI none AR/PRI AI 17

18 ONGOING WORK ON DRVS Minerals: Sodium Chloride Potassium Vitamins: Vitamin D Vitamins B1, B2, B6 Vitamin K Choline 18

19 WHERE TO GO FROM HERE? In the long term all Adequate Intakes should be converted to Population Reference Intakes More data needed on micronutrient requirements in older infants, children, and older adults effects of different physiological states (e.g. obese, pregnancy) on requirements the relationship between biomarkers of micronutrient body content and function and related health outcomes Improved and expanded food composition and European food/nutrient intake databases Contribution of micronutrient supplements, additives and food fortificants to dietary intake Effects of common polymorphisms on micronutrient requirements 19

20 CONCLUSIONS Different approaches between nutrients but also for one nutrient, that determine the robustness and choice of DRV Still limited data for various population groups Aim when possible to set a PRI based on estimated requirements of majority of population not on statistical models Adequate Intake (AI) is proposed when it is not possible to derive an Average Requirement (AR) Targeted research needed to be able to refine some of the DRVs in the future 20

21 ACKNOWLEDGEMENTS EFSA Working Groups on DRVs for Minerals and Vitamins Hearing experts: Peter Laurberg, Linda Harvey, Leland Miller Provision of data: Gerald Combs, Linda Harvey, LuAnn Johnson EFSA staff in NUTRI, AMU and DATA units Stakeholders submitting comments 21

EFSA s work on Dietary Reference Values and related activities

EFSA s work on Dietary Reference Values and related activities Dr Juliane Kleiner Head of Unit, NDA EFSA 12 th Stakeholder Consultative Platform Meeting, 13-14 April 2010, Brussels 1 Overview on EFSA s