Abstract
Background. In view of plans for dietary fortification with folic acid, there is a need to reassess the advice being given in primary care. Patients and professionals may assume that fortification will make preconceptional folic acid supplementation unnecessary, but this is unlikely to be correct.
Aim. To calculate the intake of total folic acid and folate at conception and to estimate the impact of fortification on the incidence of neural tube defect (NTD) conceptions.
Design. An in‐depth investigation of dietary folate intake of 18 women and a survey of preconception supplementation in a group of 130 women, including an assessment of the probable impact of mandatory fortification.
Method. Dietary folate intake of six infertile women and 12 age‐matched fertile controls was assessed using a 7‐day weighed diet diary. Mean values for this group were used as an estimate of local dietary folate intake. Questionnaires about periconceptional intake of supplements that included folic acid in their formulation were given to newly pregnant women attending district midwife clinics, a series of women attending an assisted conception unit and a self‐help group of lesbians who were either pregnant or planning a pregnancy.
Results. Of the 18 women in the dietary study there was suboptimal dietary folate intake in all infertile subjects and in eight of 12 controls. An approximate value for the combined intake of dietary folate and folic acid in the larger survey (n = 130) was calculated. We estimated that UK dietary fortification will double the number of pregnancies with adequate total folate intake. From previous data on folic acid intake and NTD births we estimate that this will prevent 226–343 conceptions per year in the UK from developing NTD malformations.
Conclusions. Fortification should prevent approximately 226–343 conceptions a year from developing NTDs, but 45% of women will still have an inadequate total folate intake, unless supplementation levels improve.