Socioeconomic differences in micronutrient intake and status in Europe

The aim of this thesis was to evaluate micronutrient intake and status of socioeconomic disadvantaged populations, such as from Central and Eastern European (CEE) as compared to other European populations, and low socioeconomic status (SES) groups as compared to high SES groups within European countries. We addressed the micronutrients that have been prioritized because of their relevance for nutritional health by the EC-funded EURRECA Network of Excellence. Moreover, we assessed the association between folate intake and status which can be used in the process of setting folate DRVs. Micronutrient intake and status of CEE countries versus other European countries CEE countries have recently experienced rising income inequalities over a period of economic transition. There is some evidence that these reforms have been accompanied by health inequalities. Inadequacy in micronutrient intake and status may contribute to these inequalities. Because in more affluent Western European countries wide ranges in micronutrient intake and status are observed, we studied if low micronutrient intake and status levels are prevailing in CEE. The findings from this thesis signal no differences in micronutrient intake and status between CEE populations in comparison to those of other European regions with the exception of calcium intake in adults and iodine status in children that were lower in CEE than in other European regions. Since data from Western Europe indicate that inadequacies do exist among SES strata, more insight in the nutritional situation of lower SES populations in CEE and an understanding of both its determinants and consequences is needed. It is important to mention that evidence from grey literature added to that from open access sources. Fundamental to further studying of nutritional health in CEE, is suitable data. We underline the necessity for conducting nutritional surveillances on micronutrient intake and status in CEE as we have identified significant knowledge gaps for many life-stage groups. Differences in micronutrient intake between SES groups Considering that not enough studies have addressed the relationship between SES and micronutrient intake and status in their analyses of nutritional health, we performed a systematic review on this topic and we used data from the large European EPIC cohort to address that issue. To be able to conclude on socioeconomic, i.e. educational, occupational and income, inequalities associated with intake and status of prioritized micronutrients for all life stages in Europe, substantial knowledge gaps should be filled. Currently, data are mostly available for the intake of calcium, vitamin C and iron as collected from adults in Western European countries. When either of the above mentioned SES indicators was applied to estimate relative differences in micronutrient intake and status between the lowest and the highest SES category within one study, the results often, but not consistently, indicated a lower intake and/or status in low versus high SES groups. For example, in eight out of ten studies a lower intake for calcium intake was found with relative differences ranging from -2 to -14%. Similar patterns were found for vitamin C and iron: in eleven out of twelve studies relative differences ranged from -5 to -48% for vitamin C, whereas in nine of ten studies on iron relative differences went up to -14%. Studies on intake and/or status of folate, vitamin B12, zinc, iodine, and intake of vitamin D, selenium and copper were limited. Still, when differences were observed, it appeared that lower intake in low than in high SES groups was found except for vitamin B12 and zinc for which the findings were inconsistent. Furthermore, using education as a proxy for SES, we assessed differences in micronutrient intake between educational levels using the individual-participant data on European adults and elderly from the EPIC cohort. Based on data from 10 Western European countries it appeared that intake of calcium (except in France and a distinctive ‘health-conscious’ group in the UK), folate (except in Greece), and vitamin C was lower in the lowest than in the highest education groups: relative differences ranged up to 12, 13 and 23%, respectively. The intake of iron differed marginally, whereas the variation in intake of vitamins D and B12 was inconsistent. The observed association between educational level and intake of micronutrients was the same for men and women. Furthermore, differences in micronutrient intake were found to be larger between countries than between SES groups. With respect to SES differences in micronutrient intake and status, there are significant gaps in the open source literature for many life-stage groups in Europe, but particularly in CEE countries. There is a clear need for cross-country and within country comparative research and for the monitoring of trends in dietary intake across different SES groups and European countries. Relationship between folate intake and status to add complementary evidence for deriving folate dietary reference values (DRVs) DRVs are under continuous review and periodic revision as the cumulative evidence base and body of knowledge evolve. Folate is considered a public health priority micronutrient for which re-evaluation of DRVs is needed. For this micronutrient, a systematic review of observational studies on the relationship between intake and status was done followed by meta-analysis. The intake of folate was significantly associated with markers of folate status. The results of our meta-analysis showed that an average person with a folate intake of 100 µg/day has a serum/plasma folate status concentration that is 26% higher and a red blood cell folate status that is 21% higher than a person who has a folate intake of 50 µg/day; plasma homocysteine was found to be 16% lower. The difference between natural food folate and that from supplements and fortified foods (folic acid) significantly influenced the estimated relationship between folate intake and serum/plasma status. Associations were stronger when assessed as folate from the diet than as folate from diet and supplements. Dietary assessment method did not significantly influence the association, although pooled estimates were somewhat higher when FFQs were used as compared to 24-hour recalls combined with food records. To focus on the impact of poor intakes on related health outcomes, data modelling can be conducted to produce estimates for Average Nutrient Requirements. For this analysis datasets and statistical models developed within the EURRECA NoE are available and can be used. Overall, further research would benefit from methodologically comparable data on food intake in all age ranges, especially on so far understudied CEE populations. Both intakes obtained through diet and from supplements and fortified foods should be assessed. Monitoring of trends across SES strata should be done with standardized SES measurements that would also facilitate cross-country comparative research. The findings on the level and distribution of micronutrient intake and status could be used for development of food based dietary guidelines. To make them effective in meeting populations’ micronutrient needs, they should be created accounting for the country specific dietary patterns giving consideration to the socioeconomic context.