03-Dec-14 1 DR ALEXIS HURE PhD, AdvAPD, BND (Hons I) HMRI Public Health Postdoctoral Fellow School of Medicine and Public Health, University of Newcastle [email protected]DOHaD for Doctors, 25 th November 2014 Micronutrients in Preconception and Pregnancy No Conflict of Interest FULL DISCLOSURE Personal Vested Interest • 32.5 weeks gestation and 2 year old daughter Professionally • An unpaid consultant for DANONE-Nutricia since 2009 2 Philosophical Standpoint Hippocrates • “Let food be thy medicine and medicine be thy food” • “First do no harm” 3 Overview 1. Dietary intakes for pregnancy – ‘Nutritional Epi 101’ 2. Public health guidelines – Critical appraisal 3. Mandatory fortification – Public health nutrition in action 4. Micronutrient supplements – Risks and benefits – Naming and shaming 5. Evidence into practice 4 Nutritional Epidemiology • Under-reporting is very common – People change the foods they eat because they know they will be asked about it – Misrepresentation (deliberate, unconscious or accidental) to make diets appear ‘healthier’ or quicker to report • Quantitative bias analysis – For groups: use energy cut-points (e.g. 4500-20,000 kJ/day) – For individuals: Energy Intake to Basal Metabolic Rate (EI:BMR) ratio • 1.55 is a normally active population (e.g. 1.27 - 2.1) • Population-based surveys tend to under-estimate food and nutrient intakes by around 20% – Australian Health Survey (2011-2012) 5 Nutritional Requirements • Consumers, healthcare professionals are most familiar with the term “RDI” - but what does this really mean? – Recommended Daily Intake? XXX – Recommended DIETARY Intake (with intakes averaged over 3-4 days) • “RDIs exceed the actual nutrient requirements of practically all healthy persons and are not synonymous with requirements." https://www.nrv.gov.au/home/introduction • RDIs are mathematically derived: RDI = EAR +2SD EAR – i.e. two standard deviations or twice the coefficient of variation above the Estimated Average Requirement (EAR) • EARs are what we should be using to: – examine the probability that an individual’s usual intake is inadequate – or estimate the prevalence of inadequate intakes within a group 6
Transcript
03-Dec-14
1
DR ALEXIS HURE
PhD, AdvAPD, BND (Hons I)
HMRI Public Health Postdoctoral Fellow
School of Medicine and Public Health, University of Newcastle
• An unpaid consultant for DANONE-Nutricia since 2009
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Philosophical Standpoint
Hippocrates
• “Let food be thy medicine and medicine be thy food”
• “First do no harm”
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Overview
1. Dietary intakes for pregnancy – ‘Nutritional Epi 101’
2. Public health guidelines – Critical appraisal
3. Mandatory fortification – Public health nutrition in action
4. Micronutrient supplements – Risks and benefits
– Naming and shaming
5. Evidence into practice
4
Nutritional Epidemiology
• Under-reporting is very common – People change the foods they eat because they know they will be
asked about it
– Misrepresentation (deliberate, unconscious or accidental) to make diets appear ‘healthier’ or quicker to report
• Quantitative bias analysis – For groups: use energy cut-points (e.g. 4500-20,000 kJ/day)
– For individuals: Energy Intake to Basal Metabolic Rate (EI:BMR) ratio
• 1.55 is a normally active population (e.g. 1.27 - 2.1)
• Population-based surveys tend to under-estimate food and nutrient intakes by around 20% – Australian Health Survey (2011-2012)
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Nutritional Requirements
• Consumers, healthcare professionals are most familiar with the term “RDI” - but what does this really mean? – Recommended Daily Intake? XXX
– Recommended DIETARY Intake (with intakes averaged over 3-4 days)
• “RDIs exceed the actual nutrient requirements of practically all healthy persons and are not synonymous with requirements." https://www.nrv.gov.au/home/introduction
• RDIs are mathematically derived: RDI = EAR +2SDEAR – i.e. two standard deviations or twice the coefficient of variation above
the Estimated Average Requirement (EAR)
• EARs are what we should be using to: – examine the probability that an individual’s usual intake is inadequate
– or estimate the prevalence of inadequate intakes within a group 6
• Data from the ALSWH (2003) + AHS (2011-12) are consistent – Almost 10 years between the two surveys
– Differences in populations (pregnant vs. all women)
– Dietary assessment methods (FFQ vs. 24 hr recall)
• Exceptions include: – Low dietary fibre intake and low iron
– EAR for iron during pregnancy is very high: 22mg/day for pregnancy vs. 8mg/day for menstruating women
• Intakes of folic acid have increased with fortification to now meet the EAR but this is separate to the recommendation for preconception and first trimester supplementation
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Take Home Message
• Pregnant women in Australia are generally meeting their nutritional requirements (as we currently understand them) through diet alone
• High fibre foods should be encouraged
– Wholegrain breads and cereals
– Vegetables and fruits
• Good sources of iron include:
– Lean red meat, fish, poultry
– Eggs
– Legumes, including baked beans
– Fortified foods and beverages
• Breakfast cereals: Sultana bran, Weetbix, Special K etc.
• Milo
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PUBLIC HEALTH GUIDELINES
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Folic Acid to Prevent NTD
• Supplementation with 500 mg per day for 12 weeks (or at least 1 month) pre-conception and throughout the first 12 weeks of pregnancy
• Increase to 5 mg per day in women at high risk NTDs:
– Those with a family history or who have had a previous pregnancy affected by NTD, anti-epileptics, diabetes, and body mass index ≥30 kg/m2
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What you should know about
this recommendation
• Grade A: can be trusted to guide clinical practice – Based on a systematic review and meta-analysis of randomised
controlled trial data; the highest level evidence
• Clear clinical benefit: reduced incidence of NTD
• NT closes over ~ 6 wks gestation – Guidelines include a buffer for potential dating inaccuracies
• Recommendations were always accompanied by a warning that periconceptional supplementation with other vitamins was not necessary and there was potential for harm (for e.g. from excess vitamin A)
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Iodine for Child Cognition
From January 2010
• Pregnant and breastfeeding women are advised to take an iodine supplement of 150 mg/day
• Women with pre-existing thyroid conditions should seek advice from their medical practitioner before taking a supplement
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• NHMRC developed this recommendation via a review of the literature and consultation with an expert group – Consensus-based recommendation
– Formulated in the absence of quality evidence
• There is only 1 iodine-only supplement available in Australia to allow women to meet this recommendation without taking a multi-nutrient preparation
• Main dietary sources: – Fortified bread, dairy,
seafood and iodised salt
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What you should know about
this recommendation
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MANDATORY FORTIFICATION
Public Health Nutrition in Action - A population-based safety net
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Folic Acid Added to Foods
• 1998: Voluntary folic acid fortification of foods
• September 2009: mandatory fortification of wheat-flour used for bread making (120-135mg FA / 100g bread)
• Expected to reduce the number of NTD-affected pregnancies by 14 to 49 cases(or up to 14%) each year
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Added Iodine
• Salt used in bread-making (rolls, buns, etc. except organic bread) is required to contain iodised salt
– 40-50mg iodine / 100g bread
• Under review: mandatory fortification with folic acid & iodine http://www.foodstandards.gov.au/science/monitoringnutrients/monitoringfort/pages/default.aspx
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Diet and Pregnancy Outcomes • Dietary intervention during pregnancy increases birth weight
and length, and reduces the incidence of low birth weight and preterm delivery
• Largest gains in birth size were in underweight and nutritionally at-risk populations in both high- and low-income countries and using dietary interventions that focused on whole diet or macronutrients
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MICRONUTRIENT SUPPLEMENTS
Did you know…
Women taking any vitamin supplements prior to or early in
pregnancy are ~40% more likely to have a multiple pregnancy
- RR 1.38, 95% CI 1.12 to 1.70, 3 trials, n=20,986 women Rumbold et al (2011). Vitamin supplementation for preventing miscarriage.
Cochrane Database of Systematic Reviews.
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Australian Health Ministers’ Advisory Council 2012, Clinical Practice Guidelines: Antenatal Care - Module 1. Australian Government Department of Health and Ageing, Canberra. http://www.health.gov.au/antenatal
• When prescribing a nutritional supplement, what is the outcome you are aiming for?
– Clinical benefit • E.g. Reduced incidence of rickets
– Surrogate marker • E.g. Increase in serum Vitamin D
– No evidence that routine vitamin D supplementation for healthy women improves pregnancy outcomes but supplementation may be beneficial in groups of women at risk of deficiency
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Market Leaders
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Evidence Into Practice
• Use supplements to correct nutritional deficiency or when there are clinical benefits that outweigh the potential for harm – Not as a blanket recommendation or magic-bullet approach
• GPs can help to improve the micronutrient intakes of pregnant women by promoting the importance of having a good diet for pregnancy
• Food avoidance recommendations (listeria, mercury) may cause harm by reducing micronutrient intakes from consuming a wide variety of nutritious foods (Pezdirc, 2012, PHN)
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Refer to an Accredited Practising Dietitian for individual dietary assessment if you or your patients are interested or concerned http://daa.asn.au/for-the-public/find-an-apd/
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Having a baby born a good size and at the right time is the strongest predictor of long term health
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Key Resources
• Australian Longitudinal Study on Women’s Health
• Australian Bureau of Statistics, Australian Health Survey Data (2011-2012)
• Nutrient Reference Values for Australia and New Zealand
• Clinical Practice Guidelines: Antenatal Care – Module 1, Australian Government, Department of Health and Ageing, Canberra. http://www.health.gov.au/antenatal
• Food Standards Australia and New Zealand (FSANZ)
