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Attachment 5 Current approach to increasing folate intake among women of child-bearing age
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Attachment 5Current approach to increasing folate intake among women of child-bearing ageAnalysis of the current approach to increasing folate intake among women of child-bearing age is based on limited data. The available data are generally from regional studies, from incomplete national data collections, or from dated national surveys. Despite these limitations, it is possible to obtain an overall picture of estimated changes in folic acid intake, folate status and the impact on NTD incidence. 1. Overview of folate campaigns implemented in Australia and New Zealand In Australia, between 1994 and 1999 three health promotion campaigns were implemented nationally (Table 1) in addition to State-based campaigns in Western Australia, South Australia, New South Wales, Victoria and Tasmania (Table 2). There has been no publicly funded awareness campaigns regarding folate and women of child-bearing age in New Zealand (NZMoH, 2003). The Australian campaigns have generally targeted women of child-bearing age and health professionals. In general, the main objectives of the campaigns have been to: increase awareness of the association between folate and NTDs; promote dietary sources of naturally-occurring folate and folic acid supplements; and increase folate intake. It should be noted that most of the campaigns promoted both increased consumption of folate rich foods and folic acid supplementation. Table 1: Summary of national folate health promotion campaigns in Australia to 2001
Adapted from (Abraham and Webb, 2001). Table 2: Summary of State and Territory folate health promotion campaigns in Australia
Adapted from (Chan et al., 2001; Abraham and Webb, 2001) 2. Dietary folic acid intakes The NHMRC and NZMoH (2006) recommend that ‘women capable of becoming or, or planning pregnancy, should consume additional folic acid as a supplement or in the form of fortified foods at a level of 400 µg/day’ in addition to consuming food folate from a varied diet. 2.1 Voluntary fortification Dietary modelling has been undertaken to assess the amount of folic acid consumed by the target population following the introduction of voluntary fortification, although an accurate determination is hampered by the lack of up-to-date information on the available fortified foods and food consumption patterns in the Australian and New Zealand populations. Despite these limitations, the mean increase in folic acid intake from voluntarily fortified foods among women of child-bearing age is estimated to be 95 µg and 58 µg in Australia and New Zealand, respectively. However, the median intake is much lower in both countries – just 57 µg and 21 µg in Australia and New Zealand, respectively, indicating that some women in the target population are probably consuming larger amounts of fortified foods (thus pushing up the mean intake) whereas a greater proportion are probably consuming relatively low amounts (hence the much lower median intake) (Table 3). The lower values for New Zealand reflect the lower uptake of voluntary fortification in that country. The 95th percentile of intakes indicates that very few women in the target population are consuming the recommended 400 µg/day of folic acid from fortified foods with younger women and women in New Zealand even less likely to do so. Interestingly, in Australia, younger women in the target age range (15-18 and 19-29 years) have a wider distribution of intake than older women (30-49 years); although this may simply reflect the smaller sample sizes in these age ranges. Higher median intakes of folic acid from voluntary fortification were recently reported by (Bower et al., 2005). Among women who had had a live born baby without birth defects in Western Australia between 1997 and 2000, 56.6% of these women obtained 100 µg or more from fortified foods54. In New Zealand, however, it is estimated that over 60% of women of child-bearing age had not received any additional folic acid as a result of voluntary fortification (Newton et al., 2001 cited in NZMoH, 2003). Table 3: Distribution of folic acid intake from fortified foods among women of child-bearing age since voluntary fortification in Australia and New Zealand*
* The data have been adjusted for within person variation. ** Median intakes for New Zealand are the same as the 5th percentile intakes because more than 50% of respondents did not consume foods containing folic acid based on a single day intake. However, after intakes are adjusted for a second day intake these respondents were assigned a small intake of 21 g/day which reflects daily variation in consumption patterns. Sources: FSANZ analysis of the Australian 1995 National Nutrition Survey and New Zealand 1997 National Nutrition Survey; Folic acid content of foods from analysis of labels and manufacturers’ data. 2.2 Folic acid supplements The promotion of folic acid supplements to women of child-bearing age in Australia and New Zealand has continued since the introduction of the voluntary folic acid fortification policy. The promotion of supplements offers a number of advantages over folic acid fortification; either voluntary or mandatory (Skeaff et al., 2003; NZMoH, 2003). These include:
Supplementation is of most benefit to women planning a pregnancy but to be effective supplements of sufficient dosage need to be taken consistently during the peri-conceptional period. Supplementation has not been recommended as a sole strategy to reduce the incidence of NTDs because:
Data from national surveys conducted up to 11 years ago, indicates that only a small proportion of women report taking folic acid supplements (Table 4). In New Zealand, Maori, Pacific women, women of low income, and women with unplanned pregnancies are less likely to consume supplements (NZMoH, 2003). Table 4: Supplement use among women in Australia and New Zealand, as indicated in historical national surveys
* Dosage on containers of supplements checked by interviewers Sources: 1. ABS 1995 in (Abraham and Webb, 2001). 2. Lawrence 1995 in (Abraham and Webb, 2001). 3. Adapted from NZMoH (2003) and Russell et al. (1999). More recent data, however, indicate that the proportion of women consuming folic acid supplements has increased substantially but this might be associated with health promotion campaigns encouraging supplement use. Bower et al. (2005) reported that 28.5% of women in their study population (women who had had a liveborn baby without birth defects in Western Australia between 1997 and 2000) had taken 200 µg or more of folic from supplements daily in the peri-conceptional period. In New Zealand, the proportion of women taking folic acid supplements during the peri-conceptional period ranges from 11-17% (Schader and Corwin 1999; Ferguson et al., 2000). There are no data on dosage in New Zealand. 3. Folate status The folate status of women of child-bearing age has risen since the introduction of voluntary folic acid fortification in Australia and New Zealand, due to increases in total folate intake, presumably due, in part, to fortification. From limited survey data, the change in food regulation in the mid 1990s appears to have generally increased folate status for both men and women (Metz et al., 2002d; Hickling et al., 2005f). Ideally, both serum and red blood cell folate are used to reflect blood folate status. Serum folate reflects recent folate exposure, whereas red blood cell folate is indicative of longer term folate exposure. Whilst serum folate in the individual reflects daily fluctuations in intake, at a population level it is a useful biomarker of folate status. Anticipated increases in serum folate levels from a series of defined folic acid doses have also been used in this report as the basis of quantifying the reduction in NTD risk (Daly et al., 1995). 3.1 Serum folate status Higher maternal serum folate levels have been associated with a lower risk of NTD-affected pregnancies (Kirke et al., 1993). However, the serum folate level that confers optimal protection against NTDs and other birth defects remains unknown (Lawrence et al., 2006). There are limited data that measure the impact on serum folate levels of strategies to increase folate intake in Australia and New Zealand (Ferguson et al., 2000; Metz et al., 2002b; Flicker et al., 2004c). One large study among Victorian adults aged 15-45 years in Victoria reported an increase in mean serum folate concentrations of approximately 19% for women and 16% for men, post voluntary fortification. However, no details were available on the level of folic acid supplement use and as such the change in serum folate levels cannot necessarily be attributed to voluntary fortification. The proportion of study participants with low serum folate levels decreased from 8.5% to 4.1% since fortification (Metz et al., 2002a). In a similar study in Perth involving adults aged 27-77 years, the authors (Hickling et al., 2005b) reported a 38% increase in mean serum folate between 1995-96 and 2001. Serum folate was consistently higher in participants who consumed at least one folate fortified food in the previous week compared with subjects who did not. Recent analysis of data from the Blue Mountains Eye Study (Flood et al., 2006) among an older population found that just 1.9% of women and 2.7% of men aged 49 years or older had ‘very low’ serum folate levels (< 6.8 nmol/L). De Jong et al. (2003) reported that 3% of older women aged 70-80 years in a small New Zealand study had low serum folate (<6.6 nmol/L). 4. Incidence of neural tube defects The impact of voluntary folic acid fortification on the incidence55 of NTDs, should consider the number of terminations affected by an NTD, as well as births and stillbirths. To accurately assess trends it is also important to compare data from extended periods of time (such as several years before the implementation of voluntary fortification in 1995 and several years after) rather than compare the variation in rates from one year to the next which can be quite misleading. South Australia, Western Australia and Victoria are the only Australian States or Territories with good quality data on terminations. In South Australia between 1991-95 and 1996-97, the incidence of NTDs fell from 1.8 to 1.6 per 1,000 births (Lancaster and Hurst, 2001). Western Australia has reported a 30% fall in NTD rates between the periods 1980-95 and 1996-00 (Bower, 2003a). In Victoria, the NTD rates remained relatively stable between 1999 and 2003, although they reported a fall of 20% between 1997 and 1998 (Victorian Perinatal Data Collection Unit, 2005). For the period 1999-03, the incidence of NTDs in Australia (based on data from Victoria, South Australia and Western Australia) was 1.32 per 1,000 total births, which leads to an all-Australian estimate of 338 cases annually with about 70% of these terminated (Bower and De Klerk, 200556). This incidence rate is higher than rates (including terminations) in the United States, Canada, England and Wales, and other European countries (Botto et al., 1999; CDC, 2004; USCDC, 2004; Liu et al., 2004a). The incidence of NTDs among Indigenous populations in Western Australia is nearly double that of the non-Indigenous population (Bower et al., 2004). Yüklə 2,26 Mb. Dostları ilə paylaş:
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