Mecanismo de las Farmacointeracciones

6.1 Conclusion

In the present study, the women of child-bearing age had a population median urinary iodine concentration (UIC) of 64.7 mcg/l which represents mild ID according to the WHO (WHO/UNICEF/ICCIDD, 2007); and median urinary iodine excretion (UIE) of 116.8 mcg/day, which is classified as marginal iodine deficiency (Als et al., 2003). These results are consistent with other recent findings indicating moderate to mild ID amongst the NZ population, which also indicates the re-emergence of ID. Although the iodine intake of the present study is suboptimal, it is twice the intake of NZ women estimated by the 2003/04 NZTDS. The overall findings in the study show an improved iodine status and intake compared to previous studies, prior to fortification (Table 2.10). This improvement is most likely to have been influenced by the implementation of mandatory fortification of bread with iodised salt. However, the population is still considered as iodine insufficient, and there would still be potential adverse consequences if the participants were to become pregnant.

This suboptimal iodine intake amongst participants has been caused by several factors: inadequate intake of good food sources of iodine; consumption of processed foods; frequency of eating at food outlets; and usage of non-iodised salt at home. The low intake of iodine-fortified bread amongst the participants also contributed to their overall low iodine intake. The significant contribution of this iodine-fortified bread (to iodine intake) is clearly seen, when the consumption of bread is estimated based on the content of iodine prior- to and post-fortification (Figure 4.4). However, taking into account all major contributors of food to the participants’ overall iodine intake, milk is the greatest contributor, followed by bread, fish/seafood and egg. Participants are recommended to increase their iodine intake since the study population median intake of iodine did not achieve the RDI of 150 mcg/day. This can be done by increasing their bread consumption to more than their present average intake of 2.2 slices per day, in addition to using only iodised salt at home in order to improve their overall iodine intake. This is consistent with the NZ healthy eating guideline that recommends people eat bread and/or cereals of at least six servings per day (MOH, 2010a). On the other hand, fortifying other food with iodine could also be considered, in order to increase the iodine supply in the NZ diet.

Poor knowledge about iodine nutrition and the status of iodine deficiency on the population was found amongst the participants. There is a notable lack of awareness amongst the participants regarding the mandatory fortification of bread with iodine. However, the majority of the participants agreed with mandatory fortification of bread with iodised salt, but they required more information regarding fortification. Therefore, implementation of iodine fortification concurrently with good educational strategies that are aimed at increasing people’s awareness and iodine knowledge is necessary. This fortification and resulting awareness could encourage people to increase their iodine intake and it might eventually reduce the risk of ID amongst the NZ population.

The selenium status (31.6 mcg/day) of the study population is just above the lower limits of the safe range for women (30 mcg/day) proposed by the WHO (WHO & FAO, 2004). Both the participants’ selenium status and intake (Table 4.14) are identified as acceptable, since the population median values are above the requirement for the optimal function of IDIs and maximal GPxs. Nevertheless, if based on individual selenium status, the majority of the participants still did not meet the NZ EAR of 50 mcg/day (Figure 4.8). This suggests further investigation regarding selenium intake and status amongst the NZ population. This is important since selenium plays an important role as selenoproteins, iodothyronine deiodinases and GPx (Triggiani et al., 2009). Thus, an adequate selenium intake is important to help reduce the risk of ID and other health problems in NZ (Sheck, Davies, & Wilson, 2010). Moreover, previous studies have also reported the concerning risk of selenium deficiency amongst NZ people, due to few food sources of selenium in NZ (Thomson, 2004; Thomson et al., 2007).

Overall, the findings in this study show that the implementation of mandatory iodine fortification in bread has increased the iodine supply in the diet and it has improved the iodine status of the study population. Nevertheless, this mandatory fortification is still not sufficient to ensure that most women of childbearing-age achieve the RDI of 150 mcg/day for iodine intake, and this would be more difficult if they became pregnant, since the requirement is higher during pregnancy. This shows that iodine fortification in bread may only help to reduce the risk of ID, but it will not eliminate ID in NZ. Therefore, additional strategies such as implementing iodine fortification in other food vehicles should be considered in the future, since this might help to fully eliminate ID in NZ. Moreover, the prevention of IDD is critical, since it would reduce the risk of potential adverse consequences associated with moderate to mild ID, which have been identified in the NZ population especially amongst pregnant and breastfeeding women. Therefore, the recent introduction of subsidised iodine tablets together with

the introduction of iodine-fortified bread, can help women to increase their overall iodine intake during pregnancy and lactation. In general, the government’s strategies of introducing iodine supplementation and implementing iodine fortification, if combined with strong public education and extensive promotion on iodine nutrition, could help to improve the iodine status of the NZ population. Hence, this highlights the importance of continuous assessment of iodine status and the monitoring of iodine and selenium intakes in the NZ population, especially amongst women of childbearing-age, including pregnant and lactating women.

6.2 Recommendations

Further research involving a larger sample size is needed, in order to investigate the effectiveness of iodine-fortified bread in raising the levels of New Zealanders’ iodine intake. Other groups that should be included in future studies include pregnant and breastfeeding mothers and their infants, and various ethnic groups, in addition to people from low socioeconomic backgrounds. Further investigation is needed on the usage of iodine supplements and the level of iodine nutrition knowledge amongst these people, especially those living in deprived areas in NZ. More appropriate educational, promotional and marketing strategies on iodine nutrition should be developed for all age groups of people in NZ in order to increase their awareness of iodine deficiency.

Quality control in bread production is necessary to ensure the industry is always following the guideline of iodine fortification. Thus, monitoring the addition of iodised salt into bread is required to ensure correct levels of iodised salt is used for bread production in NZ. Moreover, the latest iodine content in all types of bread in NZ should be updated in the NZ food composition database. On the other hand, given that the average bread intake of the study population is considered low (2.2 slices of medium size bread), future study is required to evaluate the suitability of bread, as the most appropriate food vehicle for fortification. The other alternative is to consider implementing iodine fortification in another food vehicle, such as milk. Thus, more study is needed to investigate the appropriate food vehicle for iodine fortification, in addition to the public’s acceptance of fortification.

The NZ MOH recommends a daily iodine supplement for women during pregnancy and lactation (MOH, 2010c). However, the running program of subsidised iodine tablet by the NZ government is not available for non-pregnant women. Therefore, it is recommended that these subsidised iodine tablets are not limited only to pregnant or

breastfeeding women, but should also include women who are considering conception to encouraged their daily intake of iodine. In addition, information about iodine nutrition and availibility of iodine supplement in NZ could be included in the pregnancy testing kits to reach a wider audience including those of unplanned pregnancies. Hence, women of childbearing-age will always be informed about the importance of iodine through these measure. All these suggestion are important to be taken into consideration in order to maintain adequate iodine intake amongst women of reproductive age throughout the stage of their life to prevent any potential adverse consequences in the early stage of pregnancy.

Overall, continued evaluation on the effectiveness of the iodine fortification programme in improving the iodine intake of the NZ population is necessary. Therefore, regular assessment of the iodine and selenium status and continuous monitoring of the intake of these micronutrients is needed, especially amongst women of childbearing-age, particularly pregnant and breastfeeding women in NZ.