Folik acid supplementation and fortification in Nova Skotia

Michiel Van den Hof Dalhousie University Halifax, Nova Scotia

History of Folate Research

1976-1991 - Numerous small studies suggesting benefit of folic acid supplementation - “Landmark” paper on benefit of folic acid supplementation to reduce the recurrence of NTDs* * MRC Vitamin Study Research Group: Lancet 1991

History of Folate Research

1992 -Research shows that folic acid supplementation reduces open NTDs in low-risk women* *Czeizel AE, Dudas I: N Engl J Med 1992

History of Folate Research

1991 - 1994 - Canadian recommendations about folic acid supplementation issued: - Health Canada - SOGC - Canadian Task Force on the Periodic Health Examination

Incidence of ONTD’S per 1000 births in Nova Scotia

Total Incidence of ONTD’S per 1000 Pregnancies

2.65

2.57

2.51

2.49

2.11

History of Folate Research

1993 - 1999 - < 45% of pregnant women taking folic acid before conception

History of Folate Research

March 1996 - US-FDA orders all enriched grain products to be fortified (.14/100gm) starting January 1, 1998

History of Folate Research

November 1, 1998 - Health Canada endorses similar fortification

Questions

Did recommendations for folic acid supplementation work? Did the “small” amount of fortification work?

Folic Acid Supplementation/Fortification

Methods: Nova Scotia Perinatal Database plus Nova Scotia Fetal Anomaly Database combined have information on all births and birth defects that occur in this province.

Folic Acid Supplementation/Fortification

Open neural tube defects: - spina bifida - anencephaly - other

Folic Acid Supplementation/Fortification

Pre-supplementation 1991-1994 Post-supplementation but pre-fortification 1994-1997 Pre-fortification 1991-1997 Post-fortification 1998-2000

Folic Acid Supplementation/Fortification

Risks for Folic Acid Fortification: Delay diagnosis of vitamin B12 deficiency which may result in neurologic effects.

Folic Acid Supplementation/Fortification

Spina Total Anencephaly* Bifida** NTDs*** Pre-supplementation 1.00 1.44 2.55 1991-1994 Post-supplementation .82 1.60 2.61 Pre-fortification 1995-1997 *RR0.82,95%CI 0.51-1.32; p=0.49 **RR1.11,95%CI 0.79-1.60; p=0.64 ***RR1.02,95%CI 0.77-1.35; p=0.87

Incidence of ONTD’S per 1000 Pregnancies

2.61

2.55

Folic Acid Supplementation/Fortification

Spina Total Anencephaly* Bifida** NTDs*** Pre-fortification .93 1.52 2.58 1991-1997 Post-fortification .38 .62 1.17 * RR 0.41, 95% CI 0.22-0.77; p=0.004 ** RR 0.40, 95% CI 0.25-0.67; p<0.001 ***RR 0.46, 95% CI 0.32-0.66; p<0.001

Incidence of ONTD’S per 1000 Pregnancies

2.57

1.16

Folic Acid Supplementation/Fortification

With the introduction of folic acid fortification, there was a 59% reduction in anencephaly 59% reduction in spina bifida and a 54% reduction in all NTDs. Calculated reduction ~ 20%

Folic Acid Supplementation/Fortification

Can prevention be further reduced? Chinese study suggested ~ .6/1000 in both high and low-risk population. Thus, further reduction may be possible, 1.0 ® .6 (40%).

Incidence of Anencephaly and Spina Bifida per 1000 Pregnancies in Nova

Scotia