Folic Acid Fortification. Alan A Jackson National Institute for Health Research Southampton Biomedical Centre

Transcription

1 NIHR Southampton Biomedical Research Centre in nutrition Folic Acid Fortification Alan A Jackson National Institute for Health Research Southampton Biomedical Centre The NIHR Southampton Biomedical Research Centre in nutrition is funded by the National Institute for Health Research (NIHR) and is a partnership between University Hospital Southampton NHS Foundation Trust and the University of Southampton

2 History 1991 Clinical trials report increased folic acid prevents NTD-affected pregnancies 1992 Department of Health recommends all women planning a pregnancy take folic acid daily Voluntary fortification of cereals encouraged 1998 USA/ Canada introduce mandatory fortification 2000 Committee on the Medical Aspects Food Policy publish Folic acid and the Prevention of Disease 2006 Scientific Advisory Committee on Nutrition publish Folate and disease Prevention 2009 SACN Report to Chief Medical Officer, England: Folic acid and colorectal cancer risk

3 NEURAL TUBE DEFECT - commonest developmental abnormality - failure of brain and spinal cord to develop normally - first 4 weeks of pregnancy to 900 affected conceptions/year - therapeutic termination - incompatible with independent life - lifelong disability

4 Neural Tube Defects: Evidence 1991: Randomised controlled trial preconceptual supplement Folic acid significantly reduced NTD affected pregnancy by about 70% Wald N, Sneddon J, Densem J, Frost C, Stone R. Prevention of neural tube defects: results of the MRC Vitamin Study. Lancet 1991; 338: : USA and Canada: mandatory folic acid fortification of flour Reduced NTD by up to 50% No demonstrable adverse effects in population No formal systems in place to identify possible adverse effects

5 Current advice Folate status of population poor Women who are trying to conceive or who are likely to become pregnant are advised to: take a daily supplement of 400μg of folic acid. eat foods voluntarily fortified with folic acid and folate rich foods. Younger mothers and those from the most socio-economically deprived areas were the least likely to report taking any action.

6 Mandatory fortification with folic acid: Need for risk benefit analysis Folate status Benefit Harm Neural tube defects Cancer?? Heart disease?? Clinically manifest vitamin B12 deficiency

7 Modelling: effect of fortification with folic acid. Reference Nutrient Intake: 200 μg/d Supplement for pregnancy: 400 μg/d Guidance/Safe Upper Level: 1 mg/d (B-12 interaction) Currently: women at risk of pregnancy less than 200 μg/d people consuming foods voluntarily fortified with folic acid or supplements containing folic acid > 1mg/d

8 Above safe level, % Below Reference Nutrient Intake, % Effect of Folic Acid Fortification of Flour 13,261,000 (23%) 2,200,000 (3-7%) below RNI above safe level ,000 (0.2%) 1,235,000 (2%) fortification mg/100g 4.0

9 Do nothing: voluntary increase in intake not effective, voluntary fortification increases intake of those least likely to need greater intake, does not reach those most likely to need greater intake. continue with part of population not getting enough and other part of population getting more than desirable (may increase with time if voluntary fortification increases)

10 Mandatory fortification; - reduces those at risk of inadequate intake, - increases numbers possibly at risk of excess, those consuming more than the safe upper level

11 Mandatory fortification with limit on voluntary fortification and use of supplements. - reduces those at risk of inadequate intake, - limits the numbers possibly at risk of excess those consuming more than the safe upper level.

12 Recommended mandatory fortification of flour with folic acid alongside action to control voluntary fortification and advice on the appropriate use of supplements

13 2009 SACN Report to Chief Medical Officer, England Folic acid and colorectal cancer. No evidence that supplemental folic acid increases either the risk or progression of cancer

14 SACN recommendations All women who could become pregnant should take 400μg/day folic acid prior to conception and until the twelfth week of pregnancy. (5mg/d for women with a previous NTDaffected pregnancy.) Mandatory fortification should only be introduced in the UK if it is accompanied by: - action to reduce folic acid intakes from voluntarily fortified foods - measures for monitoring emerging evidence on effects of long-term exposure to intakes above the GL/UL per day including postulated adverse effects. Clear guidance is needed on the use of supplements containing folic acid by the general population.

15 CONCLUSION 1. Clear evidence of benefit from fortification of flour with folic acid in terms of reduction in risk of the development of neural tube defects formal ethical advice to FSA. (estimate up to 7,000 terminations of pregnancy and 14,000 affected pregnancies) 2. No evidence that fortification of flour with folic acid leads to any adverse effects in any group of the population.