Variation in intakes of calcium, phosphorus, magnesium, iron and potassium in 10 countries in the European Prospective Investigation into Cancer and Nutrition study

Abstract

Background/objectives:

Adequate mineral intake is important for the maintenance of bone health, cellular function and general metabolism, and possibly in the aetiology of cancer and other chronic diseases. This study aimed at investigating variation in intakes of selected minerals across 10 European countries participating in the EPIC (European Prospective Investigation into Cancer and Nutrition) study.

Methods:

Nutrient intakes for 36 034 subjects, aged between 35 and 74 years, in 27 centres were obtained using standardized 24-h dietary recall software (EPIC-SOFT). Mean intakes of calcium, phosphorus, magnesium, iron and potassium were calculated by centre and weighted by season and day of the week and were also stratified by age group. The contribution of food groups to total nutrient intake was calculated.

Results:

There was clear geographical variability in intakes, with differences ranging from 35% for magnesium to 90% for iron in men and 36% for potassium to 75% for calcium in women, and a twofold difference in sources of haem iron (meat and fish). There was a geographical gradient in iron intake, with higher intakes in Southern than in Northern Europe and also around a twofold north–south gradient in the contribution of fruits and vegetables to potassium intake. Compared with reference intakes, the majority of age groups and centres had intakes above the recommended levels. Dairy foods and products contributed the most to calcium and phosphorus intake in almost all centres. Cereals and cereal products contributed the most to magnesium and iron intakes, except in Greece and Germany.

Conclusions:

Intakes of minerals vary substantially throughout Europe, with some geographical variability in their food sources.

Introduction

Minerals are essential nutrients, and adequate intakes are important not only for the maintenance of bone health but also for cellular function and general metabolism. Aspects of mineral metabolism are also implicated in the aetiology of cancer, cardiovascular and other chronic diseases (WHO, 2003; WCRF/AICR, 2007). In vitro, calcium has been shown to have a growth-inhibiting effect on gastrointestinal tumour cells (Lamprecht and Lipkin, 2001) and its increased intake shows an inverse association with risk of colorectal cancer (Larsson et al., 2006; WCRF/AICR, 2007). However, its association with risk of other cancers is less clear, and it may even be positively associated with risk of prostate cancer (Rodriguez et al., 2003), although this is debatable (Baron et al., 2005). Iron is an essential nutrient and its inadequate intake can result in severe health consequences, particularly in some vulnerable populations such as young women and children. However, its potential role in catalysing the production of reactive oxygen species in vivo has stimulated speculation that higher intakes may be a risk factor for colorectal or other cancers (WCRF/AICR, 2007).

Evidence associating magnesium, potassium and phosphorus intakes with cancer risk is less well established (Folsom and Hong, 2006; Lin et al., 2006; Dai et al., 2007; van den Brandt et al., 2007; Wolf et al., 2007). Higher magnesium intakes have, however, been associated with reductions in systemic inflammation, blood pressure and metabolic syndrome, and hypomagnesemia has been identified in subjects with type II diabetes (Mizushima et al., 1998; Song et al., 2005a,2005b, 2007; Barbagallo et al., 2007; Larsson and Wolk, 2007). Furthermore, higher potassium intakes have been associated with lower blood pressure and reduced cardiovascular mortality (He and MacGregor, 2008).

Although intakes of minerals are likely to vary throughout Europe, few studies have investigated intakes systematically in individuals using the same methodology, that is, using data from individual estimates of food consumption, in contrast to estimates from food balance sheets, which are known to overestimate intakes of individuals (FAO, 2007). The purpose of this study was to investigate age- and gender-related dietary intakes of calcium, phosphorus, magnesium, iron and potassium within 27 redefined centres in 10 European countries participating in the EPIC (European Prospective Investigation into Cancer and Nutrition) study. The data presented in this paper are for intakes from food only, as quantitative data from vitamin and mineral supplements were unavailable, although the types of supplements consumed are described elsewhere (Skeie et al., 2009).

Materials and methods

EPIC is an ongoing prospective cohort study designed to investigate the associations between diet, lifestyle and cancer throughout 10 Western European countries: Denmark, France, Germany, Greece, Italy, Norway, Spain, Sweden, The Netherlands and the United Kingdom (Riboli and Kaaks, 1997; Riboli et al., 2002). The cohort comprises 370 000 women and 150 000 men aged 20–85 years, enrolled between 1992 and 2000. Participants were mostly recruited from the general population residing within defined geographical areas, with some exceptions: female members of a health insurance scheme for state school employees (France), women attending breast cancer screening (Utrecht, the Netherlands), blood donors (centres in Italy and Spain) and a cohort consisting predominantly of vegetarians (‘health-conscious’ cohort in Oxford, UK) (Riboli et al., 2002). Of the 27 EPIC centres, 19 had both female and male participants, and 8 centres had only female participants.

Data presented in this paper were derived from the EPIC calibration study, for which an 8% stratified random sample (36 994 participants) of the total cohort gave a standardized 24-h dietary recall (24-HDR) interview. A total of 36 034 subjects with 24-HDR data were included in this analysis, after a systematic exclusion of 960 subjects <35 and >74 years of age because of low participation in these age categories. Approval for the study was obtained from the ethical review boards of the International Agency for Research on Cancer (Lyon, France) and from all local recruiting institutions. All participants provided written informed consent.

Measurements of diet and other lifestyle factors

A computerized interview software program (EPIC-SOFT) was developed specifically for the calibration study (Slimani et al., 2000), which was designed to improve the comparability of dietary data across centres and to partially correct for dietary measurement error arising from centre-specific bias, and random and systematic within-person errors (Ferrari et al., 2004). Previous publications outline in detail the rationale, methodology and population characteristics of the 24-HDR calibration study (Slimani et al., 2002; Ferrari et al., 2004). The 24-HDR data were obtained from face-to-face interviews, except in Norway, where a telephone interview was conducted (Brustad et al., 2003).

Intakes (mg/day) of total calcium, phosphorus, magnesium, potassium and iron were estimated from the 24-HDRs, using country-specific databases that were developed to improve standardization across countries and which, when combined, are referred to as the ENDB (EPIC Nutrient Database) (Slimani et al., 2007). Within the ENDB, methods of expression of nutrients and conversion factors were standardized across countries and missing values were imputed (Slimani et al., 2007).

Data on other lifestyle factors, including education level, total physical activity and smoking history in this analysis, were collected at baseline through standardized questionnaires and clinical examinations, and have been described for the calibration sample elsewhere (Riboli et al., 2002; Slimani et al., 2002; Haftenberger et al., 2002a,2002b; Friedenreich et al., 2007). Data on age, as well as on body weight and height, were self-reported by participants during the 24-HDR interview. The mean time interval between these baseline questionnaire measures and the 24-HDR interview varied by country, from 1 day to 3 years later (Slimani et al., 2002).

Statistical analysis

Data of all participants within centres are presented as means and standard error (s.e.), stratified by gender and study centre and ordered according to geographical location from the south to the north, and these means were adjusted by age and weighted by day and season of recall using generalized linear models (this model is referred to as the ‘minimally adjusted model’). The weighting procedure was used to account for differences in the sampling procedures of the 24-HDR interviews that were conducted between centres. Data were also stratified by age groups and these means were weighted for day of the week and season without age adjustment. These minimally adjusted intake data are given in all papers across this supplement to ensure direct comparability.

In addition to the minimally adjusted model, intake data were analysed as fully adjusted models, including the additional covariates energy intake, height and weight. This model is referred to as the ‘fully adjusted model’ and the data are available in the Appendix (Tables A1–A5). If fewer than 20 persons were represented in a stratum defined by centre, gender and age group, descriptive data were omitted from the tables. The percentage contribution of nutrients by food group to total nutrient intake within a country was calculated.

Statistical analyses were carried out using SAS (version 9.0, SAS Institute, Cary, NC, USA) or STATA v10.0.

Results

Overall, when both genders were considered in the same model, women had significantly lower intakes of all nutrients than did men, after adjusting for centre, age, day of the week and season (P<0.001) (data not shown).

In general, although the results from the fully adjusted and minimally adjusted models differed, the differences were not substantial. The greatest differences between fully and minimally adjusted values were found in Greece: 8.7% for calcium, 8.4% for phosphorus and 8% for iron in men, and 12.3% for calcium, 10.8% for phosphorus and 11% for iron in women (Tables 1a,2a,3a,4a,5a and Appendix).

Table 1a Minimally adjusteda mean daily intake of calcium by centre ordered from south to north, gender and age group

The results sections that follow describe results from the minimally adjusted models.

Calcium

Nutrients

Mean intakes of calcium in men ranged from 804 mg/day in Ragusa (Italy) to 1190 mg/day in Greece, a difference of 48%. In women, the lowest intakes were also found in Ragusa (620 mg/day) and the highest in Utrecht (the Netherlands) (1086 mg/day), a difference of 75% (Table 1a).

The only significant trends with age, in men, were a reduction in intake in San Sebastian (Spain), Malmö (Sweden) and Florence (Italy), with a non-significant trend towards decreased intake with age in Umeå (Sweden). In women, there were significant trends towards decreased calcium intake with age in Granada (Spain), Malmö (Sweden) and Heidelberg (Germany) and a non-significant trend towards a decrease in Umeå (Sweden).

Foods

The main dietary source of calcium was dairy foods and products in all countries (range: 33–62.4% in men and 38.7–61.8% in women), with the exception of men in Greece, where more calcium was supplied by cereals and cereal products (Table 1b). The variability in the amount of calcium supplied by dairy foods was smaller than that for cereals and cereal products. Across the whole cohort, a greater percentage of calcium was supplied by dairy foods and products in women than in men. However, the contribution of cereals and cereal products to calcium intake was substantial in Greece (men 37.4%, women 30.8%) and in the United Kingdom (men 28.7%, women 24.1%), whereas in other countries, the maximum contribution was ≈14% (Table 1b). In Germany, a major source of calcium was non-alcoholic beverages (men 28.2%, women 34.4%).

Table 1b Contribution to calcium intake by food group (percentage) and gender

In women, in Greece, Italy, France and Germany, vegetables were the third most important source of calcium, contributing between 6.2 and 9.9% of intake, whereas in the UK general population, the third most important source of calcium was cakes (4.8%). However, in men, the contribution of vegetables was less obvious, being of importance only in Greece and Spain, although in the United Kingdom, cakes were also the third most important contributor to intakes (4.0%).

Phosphorus

Nutrients

In men, phosphorus intakes ranged from 1425 mg/day in health-conscious men in the United Kingdom to 2070 mg/day in Greece, a difference of 45%. In women, the lowest intakes were in Ragusa (Italy), 1089 mg/day, and the highest intakes were in Aarhus (Denmark), 1478 mg/day, a difference of 36% (Table 2a). In men, there were significant trends towards a decline in phosphorus consumption with age in Navarra (Spain) and trends towards a decline with age in San Sebastian (Spain), Ragusa (Italy), Florence (Italy), Turin (Italy), the UK general population, Malmö (Sweden) and Umeå (Sweden). In women, there were significant decreases in phosphorus intake by age group in Murcia (Spain), Varese (Italy), Umeå (Sweden) and North and East Norway.

Table 2a Minimally adjusteda mean daily intake of phosphorus by centre ordered from south to north, gender and age group

Foods

Overall, the greatest contributors to phosphorus intake were dairy foods and products, cereals and cereal products, and meats and products; and in all countries, in both men and women, this accounted for between ≈63% (in Spain) and ≈75% (in Denmark) of intake (Table 2b). Of cereals and cereal products, the percentage contribution to intake was highest in Denmark (men 35.9%, women 37.1%) and lowest in Spain (men 14.2%, women 12.1%). The highest contribution from dairy products was in Greece (men 29.3%, women 33.4%) and the lowest in Germany (men 19.0%, women 24.4%). Meat and meat products also contributed substantially to phosphorus intake, with the highest contributions in men in Spain (28.5%) and in women in France (21.9%), and the lowest contributions in both genders in Greece (men 10.9%, women 9.1%). In both Greece and Spain, the contribution from fish was >10%.

Table 2b Contribution to phosphorus intake by food group (percentage) by gender

Alcoholic beverages also contributed to 9.2% of phosphorus intake in men in Germany, 6.1% in the Netherlands and 5.0% in Italy. In Germany and the Netherlands (in men), the greatest contribution within the alcoholic beverages group was from beer (Germany 5.5%, the Netherlands 3.8%), whereas in Italy, it came from wine (3.5%) (data not shown). In women, the contribution from alcoholic beverages was <3%.

Magnesium

Nutrients

Intakes in men ranged from 347 mg/day in men in Malmö (Sweden) to 467 mg/day in Heidelberg (Germany), a difference of 34%. In women, intake ranged from 258 mg/day in Greece to 402 mg/day in North-West France, a difference of 52% (Table 3a).

Table 3a Minimally adjusteda mean daily intake of magnesium by centre ordered from south to north, gender and age group

In men, there were significant trends to a decline in intake with increasing age in Navarra (Spain), Potsdam (Germany), the United Kingdom and Umeå (Sweden), and a non-significant trend to a decline with increasing age in San Sebastian (Spain) and Malmö (Sweden). In women, there was a significant decrease with age in Heidelberg (Germany), Copenhagen (Denmark), Aarhus (Denmark) and Umeå (Sweden) and a non-significant trend to a decline in the UK general population cohort.

Foods

Overall, contributions to magnesium intake were greatest from cereals and cereal products, from non-alcoholic beverages, dairy foods and products, meats and products, and from fruits and vegetables (Table 3b).

Table 3b Contribution to magnesium intake by food group (percentage) by gender

In men, cereals and cereal products contributed the most to magnesium intake in all countries, except in Germany where non-alcoholic beverages made a greater contribution (in both men and women). In Spanish women, dairy foods and products as well as non-alcoholic beverages contributed more than cereals and cereal products, as did non-alcoholic beverages in France. Overall, except in Greek men and women, non-alcoholic beverages contributed >10% of intake. The greatest contribution to intake of magnesium from vegetables occurred in Greece. Generally, fruits and vegetables contributed more to magnesium intake in the southern than in the northern countries (Table 3b).

Iron

Nutrients

Generally, in men, mean intakes of total iron were higher in the Spanish centres and in Southern European countries (Greece, Italy and France) than in Northern Europe (the UK general population, Denmark, Sweden and Norway), except in the UK health-conscious cohort. Intakes were lowest in Malmö (Sweden) and highest in San Sebastian (Spain), a difference of 90% for men and 57% for women (Table 4a).

Table 4a Minimally adjusteda mean daily intake of iron by centre ordered from south to north, gender and age group

In men, there was a significant trend towards a decrease in iron intake with age in Greece, Turin (Italy), Varese (Italy), Navarra (Spain), Potsdam (Germany) and Umeå (Sweden), and in women in San Sebastian (Spain) and the UK general population. There was a non-significant trend to a decline in intake with age in men in Ragusa (Italy), Turin (Italy) and the UK health-conscious population, and in women in Copenhagen (DK).

Foods

The majority of iron was provided by cereals and cereal products, except for Swedish men and women and Spanish men, for whom meats and products were the greatest provider (Table 4b). In countries in which the principal iron source was cereals and cereal products, the second most important source was meat and products, except in Greece where vegetables were second and in Germany where non-alcoholic beverages were the second most important source.

Table 4b Contribution to iron intake by food group (percentage) by gender

When iron from meat and fish was combined (haem sources of iron), the lowest percentage contribution was in the United Kingdom (men 18.2%, women 14.5%) and the highest was in Sweden (men 37.0%, women 31.1%), a twofold difference in men and 1.9-fold in women. In all countries, the intake of food sources of haem iron was lower in women than in men.

Unlike the small variability for intake of total iron, there was much more variability in the sources of iron; around a fourfold difference for meat and meat products between intakes in Greece and Sweden in both men and women. However, when the percentage contributions from meat and fish were combined, the differences were around two-fold (between intakes in the United Kingdom and Sweden). In Greece and Spain, vegetables and fish contributed more to iron intake than in the northern countries. In Germany and the Netherlands, non-alcoholic beverages contributed 11–17%, whereas in other countries, the contribution was <5%.

Potassium

Nutrients

In men, the lowest intakes of potassium were found in Greece (3536 mg/day) and the highest in San Sebastian (Spain) (4870 mg/day), a difference of 38%. In women, the lowest intakes were also found in Greece (2730 mg/day) and the highest in Murcia (Spain) (3723 mg/day), a difference of 36% (Table 5a).

Table 5a Minimally adjusteda mean daily intake of potassium by centre ordered from south to north, gender and age group

There was a significant reduction with age for intakes of potassium in men in Navarra (Spain), Ragusa (Italy), the UK general population and Umeå (Sweden), and non-significant trends towards a decrease with age in Potsdam (Germany). In women, there was a significant increase with age in Navarra (Spain).

Foods

Overall, in men, meat and products, cereals and cereal products, non-alcoholic beverages and vegetables contributed to >12% of intake (Table 5b). In women, five food groups each contributed to >12% of intake: non-alcoholic beverages, vegetables, fruits, dairy foods and products, and cereals and cereal products (Table 5b).

Table 5b Contribution to potassium intake by food group (percentage) by gender

There was some geographical variability in contributions to potassium intake, with a greater percentage contribution from fruit and vegetables in Southern European countries (Greece, Spain and Italy) than in Northern Europe (Germany, the Netherlands, the United Kingdom, Denmark and Sweden), ranging from 14.7% in Sweden to 36.8% in Greece (a 2.5-fold difference) in men, and from 20.3% in Norway to 41.2% in Greece (a twofold difference) in women (see Figures 1a and b). However, the contribution from non-alcoholic beverages was greater in the northern countries, ranging from 3.3% in Spain to 19.8% in Denmark (a sixfold difference) in men, and from 5.2% in Spain to 20.8% in Germany (a fourfold difference) in women. In all countries, the main contributors to potassium intake in the non-alcoholic beverage group were coffee, tea and herbal teas (data not shown).

Figure 1
figure1

Intakes of potassium from food sources in the EPIC study (a) men and (b) women.

Discussion

The results of this study indicate clear geographical variability in intakes of calcium, phosphorus, magnesium, potassium and iron. Differences in centre-specific mean intakes ranged from 35% for magnesium to 90% for iron intake for men, and from 36% for potassium to 75% for calcium for women. In contrast to the total iron intake, there was a twofold difference in sources of haem iron (meat and fish) between countries, ranging from 16% in the United Kingdom to 34% in Sweden. In most centres, the majority of iron was supplied by cereals and cereal products, with the exception of Swedish men and women and Spanish men in whom meats and products provided the largest amounts. There was a north–south gradient in total iron intake, with higher intakes in Southern than in Northern Europe. There was also an approximately twofold higher contribution to potassium intake from fruits and vegetables in Southern than in Northern Europe, and a four- to sixfold higher difference in contributions from non-alcoholic beverages in the north than in the south. There were also some statistically significant and non-significant trends towards a decreased consumption of all nutrients with age. Intake of all nutrients was lower in women than in men after taking into account age, geographical and sampling differences.

Intakes for each centre and for each age group were compared with population Reference Nutrient Intakes (RNIs) from the United Kingdom, although in some cases, the values, for instance, for calcium, are the same as those for the European or World Health Organization recommendations (COMA, 1991; EC, 1998; WHO, 2003). The UK population RNI of 700 mg/day for calcium, of 550 mg/day for phosphorus, of 8.7 mg/day for iron and of 3500 mg/day for potassium was used (COMA, 1991). For magnesium, the figures used were 300 mg/day for men 50 years and 270 mg/day for women (COMA, 1991). If the mean of a group of individuals is lower than the RNI, there is a likelihood that certain individuals within the group will have lower than required intakes (COMA, 1991).

Using RNIs to assess group intakes for comparison purposes, the majority of centres and age groups had mean intakes above the recommended levels, apart from women in a few centres or age groups, and one age group of men, who had intakes below the recommendations. For calcium, all women in Ragusa (Italy) and women aged 45–54 years in Florence (Italy) had intakes below the UK and WHO RNI of 700 mg/day (COMA, 1991; WHO, 2003). For magnesium, several groups of women had intakes below the RNI: ‘all’ women in Greece and of the age subgroups 35–44, 55–64 and 65–74 years, ‘all’ women in Naples (Italy) and of the age subgroups 45–54 and 65–75 years, women in Varese (Italy) aged 65–75 years, women in the UK general population aged 65–75 years and women aged 65–75 years in Malmö (Sweden). For iron, women in Malmö aged 65–74 years were the only group that had intakes lower than the UK RNI. For potassium, 65- to 74-year-old men in Greece and Malmö (Sweden) had intakes below the RNI, whereas in women, all groups had intakes lower than the RNI except for women in Murcia (Spain), San Sebastian (Spain), Utrecht (the Netherlands) and in the UK health-conscious group. For iron, all groups consumed more than the RNI, with intakes ranging from 1.2 to 2.6 times the UK RNI in men, and from 1.0 to 1.8 times the RNI in women.

Compared with data published from different surveys and age groups in populations across eight countries available in the European Nutrition and Health Report (France, Denmark, Germany, Italy, Norway, Spain, Sweden and the United Kingdom), intakes of all the minerals in this study were of a similar order of magnitude for population groups aged 40 years (Elmadfa and Weichselbaum, 2005), although they were generally higher for magnesium, iron and potassium. However, as the majority of data in the Nutrition and Health Report were derived from diet records (weighed records, food diaries, 24-HDRs) as opposed to frequency methods, and were collected during the same time period, they should be relatively comparable. For Greece, there are very few studies for comparison with EPIC data, but intakes of a population of 951 third-year medical students, assessed by 24-HDR, were in general in agreement but slightly lower than those in our study, although the age group of the students was younger than that of our participants (Mammas et al., 2004). Intake estimates of the Dutch subjects in this study were on a similar scale to those obtained by the Dutch National Food Consumption Survey (1997–1998), but were generally higher for phosphorus, magnesium and iron, and lower for calcium (Voedingscentrum, 1999). The differences we found could be due to either dietary methodologies or the characteristics of the populations, as the EPIC cohorts were not designed to be representative of country populations, or due to variation in the age bands used; hence, it is reassuring to find that our data were broadly similar to those of other studies.

Cereals and cereal products were the major sources of magnesium, iron and potassium in most centres and age groups. Dairy foods and products were, mainly, the major sources of calcium and phosphorus. There were some geographical differences in the contribution of foods to nutrient intakes, with dairy foods supplying most to calcium intakes in all countries except Greece. For the United Kingdom and Greece, a relatively large percentage of calcium was supplied by cereals and cereal products. In the United Kingdom, this is in part due to mandatory supplementation of white flour with calcium carbonate (MAAF, 1998). In Greece, however, fortification of flour is not mandatory; therefore, the large percentage of calcium supplied by cereals may be an overestimation because of the inclusion of values from the UK food composition tables in the Greek National Database used in these analyses (UK food tables were used as there are no national values available) (Slimani et al., 2007). In Germany, non-alcoholic beverages are an important source of calcium and the large contribution to calcium intake may be because of the inclusion of values for tap water or mineral water, which contains minerals, whereas in most food composition databases, the values for beverages or composite foods are calculated assuming water does not contain minerals, but this practice varies between compilers.

The contribution to total potassium intake showed geographical differences, with an approximately twofold larger contribution from fruits and vegetables in Southern than in Northern European countries, and four- to sixfold higher contributions from non-alcoholic beverages in the north than in the south. The contribution of fruits and vegetables to magnesium and iron intake also showed geographical variation, with a greater contribution to intake in the south than in the north.

Within countries, dairy foods and products also made the greatest contribution to phosphorus intakes, followed by cereals and cereal products and meat and products. In Greece, fish and fish products made a greater contribution than did meat and products to phosphorus intake. For magnesium, cereals and cereal products contributed the most to intake, followed by non-alcoholic beverages, dairy foods and products, meat and products, and fruits and vegetables. Cereals and cereal products and then meat and products contributed the most to iron intake, except in Germany and Greece, where non-alcoholic beverages and fish, respectively, provided greater contributions. Variability in the sources of haem iron (meat and fish) to total iron intake was almost twofold, ranging from the lowest contributions in the United Kingdom (16.4%) to the highest in Sweden (34.0%), whereas variability in intakes was smaller (men 90% difference, women 57% difference).

There were some gender differences in the main sources of potassium. In women, non-alcoholic beverages, vegetables, fruits, dairy and cereals and cereal products all contributed to 12% of intake, whereas, in men, vegetables, cereals and cereal products, meat and products, and non-alcoholic beverages contributed to >12% of intake. The contribution of sources of haem iron in women was lower in all centres than for men, reflecting the tendency for women to eat less meat and fish (Linseisen et al., 2002; Welch et al., 2002).

One major advantage of this study is that these results are comparable across Europe because the same methodology and comprehensively developed food composition tables were used to calculate intakes (Slimani et al., 2007). Another advantage is that the EPIC-SOFT software was designed to standardize interviewing techniques, and the 24-HDR interviews were standardized with interviewers receiving substantial training in the use of the software (Slimani et al., 2000).

A disadvantage of this study is that there was only one 24-HDR per study subject, which limits the accuracy for estimating intakes of individuals. However, 24-HDRs are considered an acceptable method for estimating population mean intakes and for ranking them across centres, as shown by a series of validation studies using independent biomarkers (Slimani et al., 2003; Al-Delaimy et al., 2005; Ferrari et al., 2009; Saadatian-Elahi et al., 2009). Moreover, the contribution of dietary supplements to total intakes has not been taken into account because, although we had data for types of supplements consumed, quantitative data were unavailable (Skeie et al., 2009). However, one study found that the contribution to mineral intakes was small, ranging from 1% of intake for potassium to 16% for calcium (Welch et al., 1998). Also, as the mineral content of drinking and bottled water varies, but is not always comprehensively covered by food composition tables, the contributions from water may also be underestimated.

Apart from leading to a greater understanding of the variations in European intakes of minerals, these data could provide useful information to support the development of European food policies and recommendations, and for decisions on food enrichment programmes.

In conclusion, intakes of minerals vary substantially throughout Europe and there is some geographical variability in the food sources of these nutrients, which may have implications for the aetiology of cancer and other chronic diseases.

Conflict of interest

M Jenab has received grant support from the World Cancer Research Fund. S Bingham has received grant support from MRC Centre. The remaining authors have declared no financial interests.

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Acknowledgements

The work described in this paper was carried out with the financial support of the European Commission: Public Health and Consumer Protection Directorate 1993–2004; Research Directorate-General 2005; Ligue contre le Cancer (France); Société 3M (France); Mutuelle Générale de l’Education Nationale; Institut National de la Santé et de la Recherche Médicale (INSERM); Institut Gustave Roussy; German Cancer Aid; German Cancer Research Center; German Federal Ministry of Education and Research; Danish Cancer Society; Health Research Fund (FIS) of the Spanish Ministry of Health; Spanish Regional Governments of Andalucía, Asturias, Basque Country, Murcia and Navarra and the Catalan Institute of Oncology; and ISCIII RETIC (RD06/0020), Spain; Cancer Research UK; Medical Research Council, UK; the Stroke Association, UK; British Heart Foundation; Department of Health, UK; Food Standards Agency, UK; the Wellcome Trust, UK; Greek Ministry of Health; Hellenic Health Foundation; Italian Association for Research on Cancer; Italian National Research Council, Regione Sicilia (Sicilian government); Associazione Iblea per la Ricerca Epidemiologica—ONLUS (Hyblean association for epidemiological research, NPO); Dutch Ministry of Health, Welfare and Sport; Dutch Prevention Funds; LK Research Funds; Dutch ZON (Zorg Onderzoek Nederland); World Cancer Research Fund (WCRF); Swedish Cancer Society; Swedish Research Council; Regional Government of Skane and the County Council of Vasterbotten, Sweden; Norwegian Cancer Society; the Norwegian Research Council and the Norwegian Foundation for Health and Rehabilitation. We thank Sarah Somerville, Nicole Suty and Karima Abdedayem for assistance with editing and Kimberley Bouckaert and Heinz Freisling for technical assistance.

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Correspondence to A A Welch.

Additional information

Guarantor: AA Welch. Contributors: AAW carried out the statistical analyses and wrote the paper. NS was overall coordinator of this project and the EPIC nutritional databases (ENDB) project. HF, MCB, MT, UN and MO contributed to the interpretation of results and drafting of the paper. The other co-authors were EPIC collaborators involved in the design of the study and the data collection. ER is the overall coordinator of the EPIC study. All co-authors provided comments and suggestions on the paper and approved the final version.

Appendix

Appendix

Tables A1,A2,A3,A4,A5

Table A1 Fully adjusteda mean daily intake of calcium by centre ordered from south to north, gender and age group
Table A2 Fully adjusteda mean daily intake of phosphorus by centre ordered from south to north, gender and age group
Table A3 Fully adjusteda mean daily intake of magnesium by centre ordered from south to north, gender and age group
Table A4 Fully adjusteda mean daily intake of iron by centre ordered from south to north, gender and age group
Table A5 Fully adjusteda mean daily intake of potassium by centre ordered from south to north, gender and age group

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Welch, A., Fransen, H., Jenab, M. et al. Variation in intakes of calcium, phosphorus, magnesium, iron and potassium in 10 countries in the European Prospective Investigation into Cancer and Nutrition study. Eur J Clin Nutr 63, S101–S121 (2009). https://doi.org/10.1038/ejcn.2009.77

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Keywords

  • calcium
  • phosphorus
  • magnesium
  • iron
  • potassium
  • EPIC

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