Changes in the mineral and trace element contents of cereals, fruits and vegetables in Finland

Abstract

The contents of calcium, potassium, magnesium, phosphorous, aluminium, cobalt, copper, iron, manganese, nickel, selenium, zinc, cadmium and lead in cereal products, fruits and vegetables were analysed and the results were compared with those obtained 30 years previously in food samples from Finland. There were significant changes in the trace elements. In most cases trace elements contents are now lower than before. Only the selenium content of foods had clearly increased in Finland, through the use of selenium-supplemented fertilizers. There was a change in average mineral element content only for potassium, whose content was significantly lower than in the middle of the 1970s. We found that trace element density in vegetable foods has decreased over the past three decades. Per capita daily intakes of mineral elements in the 2000s were lower than in the 1970s, although the consumption of fruits and vegetables has increased since 1970s.

Full text

JOURNAL OF
FOOD COMPOSITION
AND ANALYSIS
Journal of Food Composition and Analysis 20 (2007) 487–495
Original Article
Changes in the mineral and trace element contents of cereals,
fruits and vegetables in Finland
Pa
¨ivi Ekholm
a,
, Heli Reinivuo
b
, Pirjo Mattila
c
, Heikki Pakkala
b
, Jani Koponen
d
,
Anu Happonen
d
, Jarkko Hellstro
¨m
c
, Marja-Leena Ovaskainen
b
a
Department of Applied Chemistry and Microbiology, University of Helsinki, Finland
b
National Public Health Institute, Department of Epidemiology and Health Promotion, Finland
c
MTT Agrifood Research Finland, Food Research, Finland
d
Food and Health Research Centre, Department of Clinical Nutrition, University of Kuopio, Finland
Received 12 June 2006; received in revised form 31 January 2007; accepted 1 February 2007
Abstract
The contents of calcium, potassium, magnesium, phosphorous, aluminium, cobalt, copper, iron, manganese, nickel, selenium, zinc,
cadmium and lead in cereal products, fruits and vegetables were analysed and the results were compared with those obtained 30 years
previously in food samples from Finland. There were significant changes in the trace elements. In most cases trace elements contents are
now lower than before. Only the selenium content of foods had clearly increased in Finland, through the use of selenium-supplemented
fertilizers. There was a change in average mineral element content only for potassium, whose content was significantly lower than in the
middle of the 1970s. We found that trace element density in vegetable foods has decreased over the past three decades. Per capita daily
intakes of mineral elements in the 2000s were lower than in the 1970s, although the consumption of fruits and vegetables has increased
since 1970s.
r2007 Elsevier Inc. All rights reserved.
Keywords: Mineral element content; Trace element content; Cereal product; Fruits; Root vegetables; Vegetables; Berries; Intake
1. Introduction
The mineral and trace element contents of plants are
known to be affected by the cultivar of plant, soil
conditions, weather conditions during the growing, use of
fertilizers and the state of the plants maturity at harvest
(Koivistoinen, 1980;Pietola and Salo, 2000;Ba
´lint et al.,
2001;Hattori and Chino, 2001). During the past 30 years
many agricultural practices have changed in Finland. The
total amount of major plant nutrients has decreased 25%
and the use of phosphorous (P) in fertilizers has decreased
66% since 1975 (National Board of Agriculture, 1986,
2003). Cereal cultivars have also changed completely.
Likewise, many new cultivars of peas, potatoes and other
vegetables have appeared and the growing of older
cultivars has either ended or clearly decreased (Grain
Research Committee and State Granary, 1978;Kinanen,
1981;Kangas and Tera
¨va
¨inen, 2004). The cadmium
content of cereals in Finland is known to be low by
reason of the phosphate raw material used in fertilizers
(Tahvonen, 1995). Selenium supplementation of fertilizers
has changed the Se content of all vegetable foods in
Finland (Eurola et al., 1989, 1990;Ekholm et al., 1995).
Geological origin also affects minerals, since these vary in
different countries (Sanches-Castillo et al., 1998). In
Finland, however, food marketing includes foods from
different parts of the country so that no regional
differences are present in the foodstuffs sold (Mattila,
1995;Ekholm, 1997). Consequently, the mineral and trace
element contents of plant foods may have changed since
the 1970s when they were studied by Koivistoinen (1980).
At that time the mineral and trace element contents of
Finnish cereal products, fruits, berries and vegetables were
analysed extensively at the Department of Food Chemistry
and Technology in the University of Helsinki. The samples
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
Corresponding author. Tel.: +358 9 191 58409; fax: +358 9 191 58475.
E-mail address: paivi.ekholm@helsinki.fi (P. Ekholm).

consisted of many sample items from cereal, cereals
products, vegetables, fruits and berries. Six mineral
elements and 19 trace elements were analysed from the
samples. Since then no systematic study has been under-
taken in Finland concerning the mineral and trace elements
in foods.
Besides the changes in agricultural practices in our
country, the importance of imported food has increased
since Finland became a member of the European Union in
1997 (National Board of Customs, 2005). Cereal imports
have varied annually during the last 40 years, depending on
the amount of domestic crop yield, but the consumption of
other vegetable foods from other European countries has
increased. These facts may affect the mineral and trace
element contents of foods consumed in Finland and the
intakes of minerals also.
Fruits and vegetables have low energy content, while the
nutrient densities are very high. Increased consumption of
fruits and vegetables can help replace foods high in
saturated fats, sugar and salt and thus improve the intake
of most micronutrients and dietary fibre. Daily consump-
tion of fresh fruits and vegetables (4400 g/d) is recom-
mended to help prevent major non-communicable diseases
such as cardiovascular diseases and certain cancers (WHO,
2003). Therefore, updating the mineral and trace element
contents of vegetable foods is important. We wanted also
to know how the intakes of minerals have changed since
the mid-1970s.
In the present study, the contents of four biologically
essential mineral elements were analysed: calcium (Ca),
potassium (K), magnesium (Mg) and phosphorous (P), and
eight essential or potentially essential trace elements: cobalt
(Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni),
selenium (Se) and zinc (Zn), as well as three toxic elements:
aluminium (Al), cadmium (Cd) and lead (Pb) from samples
of 18 cereal products, ten root vegetables, 16 vegetables or
vegetable products , 16 fruits and berries or their products.
These results were compared to the results of Koivistoinen
(1980) and also the intakes of these elements was estimated
by the consumption statistics.
2. Materials and methods
The samples were collected in a research project dealing
with bioactive phenol compounds (Mattila et al., 2005;
Mattila and Hellstro
¨m, 2006). The sampling of cereal
products is described by Mattila et al. (2005) and Mattila
and Hellstro
¨m (2006). Briefly, representative samples of
products of wheat, rye, barley, oats, buckwheat and millet
were collected from three retail food stores (four sub-
samples weighing from 0.25 to 2 kg of each item)
representing the three major food chains in Finland in
2003. For pooling, equal amounts (100 g) of each primary
sample were combined to form a single composite sample
of a given grain product. The most important vegetables,
fruits and berries available in Finland were selected. All
samples were purchased from retail stores, supermarkets
and market squares in the Forssa and Helsinki areas in
2003 and three major food chains were represented.
Vegetables were purchased at the peak of their season.
Berries (cultivated and wild) were purchased from whole-
sale trade near Kuopio in the central Finland (see Fig. 1 for
map showing where samples were taken). A total of 10–12
subsamples (2–10 of berries) weighing 0.5–2.0 kg was
obtained of each food item. One pooled sample was
prepared representing each item and the samples were
determined as for consumption, i.e. only the edible parts
were analysed. The apples were peeled and core removed.
All samples were freeze-dried, homogenized and stored at
20 1C until analysis. The remaining moisture was
removed by storing the samples at +70 1C overnight just
before the determination.
The moisture content of the samples was determined in
Agrifood Research Finland by weighing the samples before
and after drying at 97 1C for 16 h (Mattila et al., 2005;
Mattila and Hellstro
¨m, 2006).
Most of the samples were produced in Finland; however,
all buckwheat (USA), rice, millet (USA), aubergine, garlic
(Spain, China, France), green sweet pepper, peach (Italy),
orange and apple juice samples were imported. For celery
root, strawberry and raspberry jams, red sweet pepper,
yellow sweet pepper and organic onion, 88%, 75%, 70%,
50%, and 20%, respectively, were produced in Finland; all
other samples were produced entirely in Finland.
The organic matter of all samples was wet-digested with
concentrated nitric acid (Instra-Analyzed, J.T. Baker). The
0.5 g of dry sample was weighed into a wet digestion tube
and 10 ml of concentrated HNO
3
were added. The tubes
were allowed to stand at room temperature overnight and
later processed in a wet digestion apparatus (2040 Digestor
Foss). The tubes were first heated at 70 1C until the brown
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Fig. 1. Map showing where samples were taken.
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495488

fumes had disappeared and all the dry matter was
dissolved. The temperature was then slowly elevated to
130 1C and the acid was evaporated until 2–3 ml of solution
remained. Digestion was further completed by maintaining
the tubes at 160 1C for 30 min. The tubes were cooled and
the sample moved into a 25 ml volumetric flask with freshly
purified water (Milli Q equipped with an ICP cartridge).
All glassware was washed with acid and rinsed with
purified water.
The mineral and trace element contents, except for Se,
were determined with inductively coupled plasma-mass
spectrometer equipment (ICP-MS; Perkin Elmer Sciex
Elan 6000). Rhodium was used as an internal standard to
eliminate instability during measurements. Quantitation
was performed using external standards (Merck IV, multi-
element standard solution) and all the standard curves were
obtained at 5 different concentrations. The total mineral
and trace elements determined were measured using their
most abundant isotopes.
Se was analysed using an electrothermal atomic absorp-
tion method previously described for food samples
(Kumpulainen et al., 1983). The dried samples were
digested in a mixture of concentrated HNO
3
,HClO
4
and
H
2
SO
4
. Se was reduced to Se IV with 3 M HCl, chelated
with ammonium pyrrolidine dithiocarbamate and ex-
tracted into methylisobutylketone for the determination.
All determinations were made in triplicate. The accuracy
and precision of the methods were tested by determining
a certified reference material NBS 1567 wheat flour
(National Institute of Standards & Technology, Standard
Reference Material 1567a Wheat flour, Gaithersburg, MD,
USA) and 3 in-house control materials (wheat flour, rye
flour and green feed meal) in each determination set; the
results are shown in Table 1. The in-house control samples
were vacuum-packed in polyethylene bags and stored at
+4 1C. The stability of these samples was tested regularly.
For comparing the results between the present study and
the Finnish Mineral Elements study by Koivistoinen
(1980), we selected food items which were present in both
studies. There were together 28 pairs of foods (Table 2).
The pairs were tested with exact Wilcoxon signed-rank test
using SPSS for Windows 13.0 statistical program (SPSS
Inc., Chicago, IL, USA). A level of Po0.05/two-tailed)
was considered statistically significant. Before the statistical
test the new results were standardized to eliminate the
analytical differences. We used shared samples in both
studies (in-house control samples: wheat flour and green
feed meal) and calculated the relative contents of every
mineral and trace element determined here. The results of
these shared samples are presented in Table 1. These
standardized results were used only in comparing the
present results with the older ones by Koivistoinen (1980).
The average daily mineral intakes were calculated using
the Finnish Food Balance Sheets. The used consumption
figures were 3-years averages from the 1970s and the 2000s
(Agricultural Economics Research Institute, 1975, 1976,
1977;Information Centre of the Ministry of Agriculture
and Forestry, 2001, 2002, 2003).
ARTICLE IN PRESS
Table 1
Accuracy and precision of analytical method
Element NBS 1567a Wheat flour
a
In-house control samples
Wheat flour Green feed meal Rye flour
Present study
b
Certified value
b
Present study
c
Old result
1
Present study
c
Old result
1
Present study
c
Eurola
2
nmg/kg DM nmg/kg DM nmg/kg DM nmg/kg DM
Mg 7 39579 400720 7 1139724 1180 7 1747772 1840 7 1275731
K 7 1330727 1330730 7 3285 785 3600 7 251907609 24800 7 55767109
Ca 7 18978 19174 7 25779 291 7 55697525 7140 7 35478
P 7 1305734 1340760 7 28997334 3610 7 29727303 3390 7 35327494
Mn 7 9.670.4 9.470.9 7 297131 7637267 73771 32.772.4
Zn 7 10.770.6 11.670.4 7 297135 7297137 73171 32.870.4
Cu 7 2.170.1 2.170.2 7 4.370.1 4.8 7 6.170.8 7.7 7 5.071 5.670.7
Fe 7 15.271.7 14.170.5 7 3173 51 7 142710 188 7 2673
Al 7 7.672.0 5.771.3 7 7.171 8.4 7 5677 174 7 6.671.2
Co 7 0.01470.006 0.006 7 28718 19 7 0.2370.03 0.23 7 0.07470.0
Ni 7 0.1170.02 7 0.2670.04 0.22 7 0.2770.07 0.22 7 0.04370.006
Se 9 1.170.1 1.170.2 13 4071 36 7 ND 13 0.02771
Pb 7 0.0270.001 o0.02 7 0.0270.001 o0.05 7 1.1070.09 1.25 7 0.07870.03 0.0237.006
Cd 7 0.02570.004 0.02670.002 7 0.05170.003 0.06 7 0.06470.004 0.082 7 0.00870.004 0.00970.0004
n¼number of samples.
DM ¼dry matter.
a
National Institute of Standards & Technology, Standard Reference Material 1567a Wheat flour, Gaithersburg, MD.
b
mean7standard deviation.
c
mean7uncertainty.
1
Koivistoinen, 1980.
2
Eurola et al., 1996.
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495 489

3. Results and discussion
The mineral and trace element contents of the samples
are given in Tables 3a–h. Their profiles in the fruits,
vegetables, berries and cereal products were typical for
these types of foods (Koivistoinen, 1980;Sanches-Castillo
et al., 1998). The highest content of any elements in all the
samples was shown by K. Cereal products had higher
contents of most mineral and trace elements than other
sample items, and berries had the lowest. The Mn content
of wild berries was extremely high as was also shown earlier
(Koivistoinen, 1980). The mineral element contents of
vegetable foods vary widely in different countries. In
general our results were similar to those obtained elsewhere
in Europe, especially in Germany, although the P content
was clearly higher in samples from Finland than these from
Germany, the UK or Mexico (Sanches-Castillo et al.,
1998).
The mineral and trace element contents of the exact same
samples items were compared with the results for Finland
as reported by Koivistoinen (1980). The changes occurring
over three decades in the average standardized results of
cereals, vegetables, root vegetables and berries are pre-
sented in Table 4.
Remarkable changes were found in the average of trace
element contents of food groups such as cereal products,
root vegetables, vegetables, cultivated and wild berries
(Table 4), most of which showed decreases. The contents of
Mn, Zn, Cu, Al, Pb, Cd and Ni have decreased
significantly. The contents of Fe and Co remained un-
changed and Se was the only trace elements showing
increased content. Instead the average mineral element
contents have found to be almost unchanged (Table 4).
Only the K content was decreased significantly. This
change was mainly caused by the decrease in K content
of cereals and the change in other food items was only
moderate.
The reasons for some of these changes are clear. The use
of Se supplemented fertilizers was initiated in 1985 in
Finland and the Se contents of all Finnish foods have
increased significantly since then (Ekholm, 1997). Emission
of Pb from traffic has decreased enormously during the last
30 years, due to the increasing use of unleaded fuels
(Melanen et al., 1999). This was seen as a decrease in the Pb
contents of samples. However, the Pb content of cereals
was found to increase compared to the results of
Koivistoinen (1980). Finland occasionally imports grain
due to inadequate or low-quality harvest, and Finnish
grain and imported grain are mixed for milling. In 2003,
the amount of imported grain was high, which may explain
the high Pb content of cereal samples. Fe supplementation
of wheat flour was terminated in 1994 and this has
naturally decreased the Fe contents in them. But this is
not seen in the general comparison. Anyway there are still
changes with no clear explanation such the clear decrease
in the Al content of all sample types. The decreasing use of
P in fertilizers has not resulted in lowering of the P content
of food items. This may indicate better fertilization
practices, in which the nutrients are more available for
the plants and leaching is minimized.
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Table 2
The compared food items
Food item
Wheat flour
Rye flour
Barley flour
Rolled oats
Potato, new, Solanum tuberosum
Carrot, Daucus carota
Beet root, Beta vulgaris
Parsnip, Pastinaca sativa
Celery root, Apium graveolens
Turnip, Brassica rapa
Swede, Brassica napus
Radish, Raphanus sativus
Onion, Allium cepa
Cauliflower, Brassica oleracea var. botrytis
Broccoli, Brassica oleracea var. italica
Cabbage, white, Brassica oleracea var. capitata ‘‘f. alba’’
Cabbage, red, Brassica oleracea var. capitata
Beans, green, Phaseolus vulgarus
Sweet pepper, red, Capsicum annuum
Tomato, Lycopersicon
Cucumber, Cucumis sativus
Strawberry, Fragaria x ananassa
Blackcurrant, Ribes nigrum
Redcurrant, Ribes rubrum
Bilberry, Vaccinium myrtillus
Lingonberry, Vaccinium vitis-idaea
Cranberry, Vaccinium oxycoccos
Apple, Malus sp.
Table 3a
Mineral elements contents of cereal products
Sample nWater K Ca Mg P
% mg/100 g dry matter
Rye flour 1 10 480 32 102 260
Rye flour, organic 1 8.7 540 30 131 300
Rye bran 1 10 1340 60 397 880
Rye bread 1 39.9 510 33 123 280
Wheat flour 1 11.8 200 19 39 140
Wheat flour, organic 1 8.7 190 15 48 160
Wheat bran 1 9.6 1740 72 602 1220
Wheat bread 1 31.2 200 60 38 150
Barley flour 1 9.7 340 19 78 240
Rolled oats 1 9.1 390 43 130 370
Rolled oats, instant 1 8.8 380 44 132 360
Oat bran 1 9.7 550 63 211 530
Buckwheat 1 9.4 360 14 159 270
Millet 1 10.6 200 8 116 250
Rice 1 10.4 160 79 30 150
Rice, brown 1 10.9 220 9 96 240
Rice brown, boiled 1 70.8 230 15 120 240
Pasta 1 9.7 240 27 50 180
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495490

The dry matter content of the samples has not changed,
only radishes and celery now have clearly less dry matter
than earlier. The mineral and trace element contents of
radishes showed the most change of any of the samples.
The results are here reported in dry matter, so that the
changes in water content should not be seen. However,
so great changes in water content of samples indicate
changes in whole plant and probably also in its nutrient
composition.
All the changes in agricultural practice: new cultivars,
different fertilizers and so on, has together caused the
decrease in the trace element contents of vegetable food.
Plant breeding has developed better cultivars for yield and
disease resistance, but the nutrient content of these
cultivars had not been in focus. The samples in the Finnish
Mineral Element study from the 1970s were almost
completely obtained from foodstuffs produced in Finland,
but in the present study the proportion of imported food
items was remarkable. The imported food widens the
variation of growing circumstances and plant cultivars and
may affect the mineral and trace element contents of foods.
The number of samples in both compared studies was
limited and in this study we had to use pooled samples, so
that the variation within the sample item was lost. Because
of that it is difficult to come to conclusions, but the results
of this study will indicate the trend of the change. The
trend seems to be so that the contents of the mineral
elements have remained nearly steady, but the trace
element density in cereal and vegetable foods is now lower
than it was 30 years ago. This trend was also seen in other
studies (Mayer, 1997;Davis et al., 2004;Kirchmann, 2005)
and previous results from Finland (Eurola, 2001). Conse-
quently, there is a need for extensive study with a sufficient
number of sample items and samples. Valid knowledge
about the nutrient contents of foods is required by
nutritional authorities and researchers.
The average daily mineral and trace element intakes
from cereal, fruit and vegetable foods are presented in
Table 5. Some changes were shown in the intakes of many
minerals, only the Mg and K intakes were similar to those
seen in the mid-1970s. The Ca intake clearly increased,
while the P intake showed only moderate decrease. With
regard to trace elements, the intakes of Zn, Fe, Co, Ni, and
Cd were 25% or lower in the 2000s than in the 1970s. On
the contrary, intakes of Se and Pb were higher in the 2000s
than in the 1970s. The same kind of increase in Se intake
has found also in the Finnish Se monitoring program
(Eurola et al., 2003). The intake of Al showed moderate
increase although the Al content of samples was decreased;
ARTICLE IN PRESS
Table 3b
Trace element contents of cereal products
Sample nWater Fe Cu Mn Zn Co Ni Se Al Cd Pb
% mg/100 g dry matter
Rye flour 1 10 2.1 0.3 2.7 2.4 0.001 0.01 0.05 0.6 0.001 0.011
Rye flour, organic 1 8.7 2.2 0.5 3.8 3.6 0.002 0.018 0.001 0.4 o0.001 0.009
Rye bran 1 10 3.3 1.0 5.6 5.7 0.006 0.027 0.008 0.5 0.001 0.023
Rye bread 1 39.9 3.3 0.5 2.9 2.8 0.001 0.018 0.008 0.8 0.001 0.007
Wheat flour 1 11.8 1.3 0.2 0.8 1.1 o0.001 0.006 0.011 0.5 0.003 0.009
Wheat flour, organic 1 8.7 1.5 0.2 1.0 1.4 o0.001 0.011 0.003 0.4 0.002 0.009
Wheat bran 1 9.6 11.0 1.4 14.4 8.9 0.01 0.081 0.016 0.8 0.01 0.009
Wheat bread 1 31.2 1.6 0.2 0.9 1.1 0.002 0.013 0.009 0.5 0.003 0.008
Barley flour 1 9.7 1.9 0.4 1.0 1.8 o0.001 0.006 0.012 0.7 0.001 0.007
Oats, rolled 1 9.1 3.2 0.4 4.5 3.3 0.002 0.139 0.016 0.6 0.002 0.005
Oats, rolled instant 1 8.8 3.7 0.5 4.7 3.4 0.003 0.172 0.017 0.5 0.002 0.013
Oats, bran 1 9.7 6.1 0.5 5.7 4.3 0.003 0.186 0.022 0.4 0.003 0.005
Buckwheat 1 9.4 1.9 0.4 1.1 1.7 0.006 0.156 0.008 0.8 0.003 0.01
Millet 1 10.6 2.2 0.5 0.9 2.2 0.006 0.216 0.022 0.9 0.003 0.022
Rice 1 10.4 0.8 0.2 0.7 0.8 o0.001 0.021 0.003 0.5 o0.001 0.006
Rice, brown 1 10.9 0.9 0.2 2.0 1.5 0.001 0.02 0.004 0.9 0.001 0.005
Rice brown, boiled 1 70.8 1.0 0.5 2.1 1.6 0.001 0.022 0.005 0.6 0.001 0.006
Pasta 1 9.7 1.6 0.3 0.9 1.3 0.001 0.018 ND 0.9 0.005 0.004
Table 3c
Mineral element contents of root vegetables
Sample nWater K Ca Mg P
% mg/100 g dry matter
Potato, new, Solanum tuberosum 2 79.3 1940 37 116 220
Carrot, Daucus carota 1 87.9 2650 214 121 200
Carrot, organic 1 89.2 2330 225 150 240
Beet root, Beta vulgaris 1 86.8 2610 97 156 180
Parsnip, Pastinaca sativa 1 80.2 3020 232 177 300
Celery root, Apium graveolens 1 88.8 4870 359 122 610
Turnip, Brassica rapa 1 91.6 3540 378 166 350
Swede, Brassica napus 1 90.2 2550 372 136 360
Radish, Raphanus sativus 1 96.5 7780 431 249 460
Jerusalem artichoke, Helianthus
tuberosus
1 83.4 3210 89 112 280
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495 491

ARTICLE IN PRESS
Table 3d
Trace elements composition of root vegetables
Sample nWater Fe Cu Mn Zn Co Ni Se Al Cd Pb
% mg/100 g dry matter
Potato, new, Solanum tuberosum 2 79.3 3.4 0.6 0.7 1.0 0.008 0.049 0.003 2.7 0.007 0.005
Carrot, Daucus carota 1 87.9 3.0 0.5 2.7 2.3 0.004 0.06 0.002 0.8 0.028 0.013
Carrot, organic 1 89.2 3.4 0.6 1.2 2.1 0.003 0.048 o0.001 1.2 0.012 0.010
Beet root, Beta vulgaris 1 86.8 2.9 0.6 3.0 1.6 0.012 0.089 0.002 1.0 0.014 0.006
Parsnip, Pastinaca sativa 1 80.2 3.0 0.6 1.0 2.1 0.003 0.056 0.002 0.9 0.010 0.008
Celery root, Apium graveolens 1 88.8 5.5 1.2 1.5 3.7 0.003 0.067 0.002 0.7 0.057 0.007
Turnip, Brassica rapa 1 91.6 4.0 0.4 1.0 2.4 0.015 0.073 0.018 0.6 0.012 0.012
Swede, Brassica napus 1 90.2 3.4 0.3 1.1 1.9 0.007 0.059 0.009 1.0 0.008 0.007
Radish, Raphanus sativus 1 96.5 6.5 0.3 1.0 3.1 0.013 0.055 o0.001 3.2 0.008 0.036
Jerusalem artichoke, Helianthus tuberosus 1 83.4 1.8 1.0 0.2 1.4 0.001 0.154 0.002 0.7 0.003 0.007
Table 3e
Mineral element contents of vegetables
Sample nWater K Ca Mg P
% mg/100 g dry matter
Cauliflower, Brassica oleracea var. botrytis 1 92.7 4250 312 195 620
Broccoli, Brassica oleracea var. italica 1 88.3 3480 275 189 550
Squash, Cucurbita pepo 1 95.2 4660 359 319 600
Aubergine, Solanum melongena 1 93.7 2780 127 198 400
Cabbage, white, Brassica oleracea var. capitata ‘‘f. alba’’ 1 93.5 3110 490 147 350
Cabbage, red, Brassica oleracea var. capitata 1 91.9 3090 422 165 330
Onion, Allium cepa 1 87.3 1500 170 85 275
Onion, organic, Allium cepa 1 87.3 1640 156 97 300
Onion, red , Allium cepa 1 85.5 1480 151 80 290
Beans, green, Phaseolus vulgarus 1 88.9 2780 940 208 320
Sweet pepper, green, Capsicum annuum 1 94.3 2740 98 142 230
Sweet pepper, yellow, Capsicum annuum 1 93.3 2620 75 119 240
Sweet pepper, red, Capsicum annuum 1 92 2440 69 120 230
Tomato, Lycopersicon esculentum 1 94.5 3830 111 145 400
Cucumber, Cucumis sativus 1 96.4 4820 451 265 610
Table 3f
Trace element contents of vegetables
Sample nWater Fe Cu Mn Zn Co Ni Se Al Cd Pb
% mg/100 g dry matter
Cauliflower, Brassica oleracea var. botrytis 1 92.7 5.9 0.4 2.1 3.7 0.011 0.080 0.013 0.9 0.005 0.004
Broccoli, Brassica oleracea var. italica 1 88.3 6.4 0.5 2.1 4.6 0.018 0.081 0.027 1.1 0.007 0.014
Squash, Cucurbita pepo 1 95.2 7.3 0.9 2.7 4.0 0.013 0.141 0.004 0.8 0.010 0.014
Aubergine, Solanum melongena 1 93.7 3.1 0.5 2.4 1.5 0.003 0.002 o0.001 0.4 0.002 0.012
Cabbage, white, Brassica oleracea var. capitata ‘‘f. alba’’ 1 93.5 5.3 0.2 4.7 1.5 0.006 0.014 0.023 1.0 0.005 0.005
Cabbage, red, Brassica oleracea var. capitata 1 91.9 5.3 0.2 1.8 1.6 0.005 0.037 0.02 0.3 0.005 0.007
Onion, Allium cepa 1 87.3 2.8 0.4 1.4 1.6 0.004 0.028 0.011 0.5 0.007 0.009
Onion, organic, Allium cepa 1 87.3 2.4 0.5 0.8 1.3 0.003 0.015 o0.001 0.6 0.003 0.011
Onion, red, Allium cepa 1 85.5 2.5 0.5 1.8 2.2 0.006 0.038 0.011 0.4 0.015 0.011
Beans, green, Phaseolus vulgarus 1 88.9 6.7 0.6 1.8 2.4 0.007 0.183 0.003 1.3 0.004 0.014
Sweet pepper, green, Capsicum annuum 1 94.3 4.3 0.5 1.9 2.5 0.002 0.005 o0.001 0.8 o0.001 0.003
Sweet pepper, yellow, Capsicum annuum 1 93.3 4.1 0.4 1.6 2.0 0.007 0.041 o0.001 0.6 0.003 0.005
Sweet pepper, red, Capsicum annuum 1 92 3.9 0.5 1.6 2.0 0.001 0.022 o0.001 0.9 0.001 0.004
Tomato, Lycopersicon esculentum 1 94.5 2.9 0.4 1.8 1.2 0.003 0.002 o0.001 0.5 o0.001 0.002
Cucumber, Cucumis sativus 1 96.4 5.5 0.5 3.2 2.4 0.005 0.012 0.002 1.0 0.002 0.003
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495492

the increased consumption caused the increase of the
average Al intake. The results of this study reflect only the
Al content of agricultural products and the intake
estimation is not showing the whole situation in Al intakes,
because the use of Al containing food additives is so wide
that these additives are the main source of Al in the diet
(Saiyed and Yokel, 2005).
Consumption of fruits and vegetables has increased
significantly, which may compensate for the decrease in
mineral and trace element contents. The average per capita
consumption of vegetables has increased to two-fold
amounts from 1970s to 2000s. Other changes are the
increased consumption of wheat and decreased consump-
tion of rye and increased consumption of juices and
decreased consumption of citrus fruit. The proportion of
total daily energy intake was one-third from cereal,
vegetables and fruits in 1970s and 45% in 2000s
(Agricultural Economics Research Institute, 1975, 1976,
1977;Information Centre of the Ministry of Agriculture
and Forestry, 2001, 2002, 2003).
4. Conclusions
Most mineral and trace element contents of cereal
products, fruits and vegetables have changed significantly
in Finland during the past 30 years, showing a trend
ARTICLE IN PRESS
Table 3g
Mineral elements contents of fruits and berries
Sample nWater K Ca Mg P
% mg/100 g dry matter
Strawberry, Fragaria x ananassa 2 91.0 1550 200 140 220
Blackcurrant, Ribes nigrum 1 83.3 1800 220 130 290
Redcurrant, Ribes rubrum 1 85.6 1910 290 100 360
Raspberry, Rubus idaeus 1 86.3 1300 160 160 240
Bilberry, Vaccinium myrtillus 1 88.7 680 140 60 130
Lingonberry, Vaccinium vitis-idaea 1 86.0 570 100 50 80
Cranberry, Vaccinium oxycoccos 1 87.1 700 110 70 100
Sea buckthorn, Hippophae rhamnoides 1 83.7 980 50 60 150
Apple, peeled Malus sp. 2 88.6 960 40 50 80
Apple peel 2 86.4 1250 50 70 130
Peach, Prunus persica 1 89.1 1890 60 90 200
Rosehip, Rosa sp. 1 78.8 160 760 160 190
Orange juice 1 ND 90 90 90 150
Apple juice 1 ND 40 60 40 60
Strawberry jam 1 46.7 10 30 10 30
Raspberry, jam 1 48.8 20 20 20 30
Tomato ketchup 1 75.6 1450 60 60 130
Table 3h
Trace element contents of fruits and berries
Sample nWater Fe Cu Mn Zn Co Ni Se Al Cd Pb
% mg/100 g dry matter
Strawberry, Fragaria x ananassa 2 91.0 2.5 0.5 4.2 1.0 0.011 0.024 0.001 0.9 0.004 0.005
Blackcurrant, Ribes sp. 1 83.3 3.3 0.4 1.4 0.7 0.006 0.022 0.001 1.1 o0.001 0.012
Redcurrant, Ribes sp. 1 85.6 4.8 0.4 1.8 0.8 0.003 0.024 0.001 0.6 0.002 0.011
Raspberry, Rubus idaeus 1 86.3 3.1 05 4.1 2.0 0.005 0.088 0.001 0.5 0.003 0.014
Bilberry, Vaccinium myrtillus 1 88.7 3.1 0.5 28.9 0.8 0.002 0.041 o0.001 2.3 o0.001 0.008
Lingonberry, Vaccinium vitis-idaea 1 86.0 1.7 0.4 17.5 0.8 0.002 0.027 o0.001 2.8 o0.001 0.009
Cranberry, Vaccinium oxycoccus 1 87.1 1.7 0.5 18.4 1.1 0.002 0.038 o0.001 0.7 0.004 0.016
Sea buckthorn, Hippophae rhamnoides 1 83.7 2.2 0.5 1.2 1.3 0.002 0.038 o0.001 1.1 0.003 0.004
Apple, Malus sp. 2 88.6 1.1 0.3 0.2 0.1 0.002 0.007 o0.001 0.7 o0.001 0.013
Apple peel 2 86.4 1.9 0.5 0.4 0.2 0.003 0.026 o0.001 1.7 o0.001 0.015
Peach, Prunus persica 1 89.1 2.3 1.0 0.6 1.0 0.006 0.075 0.001 0.9 o0.001 0.012
Rosehip, Rosa sp. 1 78.8 4.8 0.4 2.6 1.6 0.004 0.038 o0.001 3.2 0.001 0.005
Orange juice 1 ND 1.1 0.4 0.3 0.2 0.003 o0.001 o0.001 0.5 o0.001 0.008
Apple juice 1 ND 2.2 o0.1 0.4 0.1 0.003 0.014 o0.001 2.0 o0.001 0.014
Strawberry jam 1 46.7 0.9 o0.1 0.5 0.1 0.002 0.018 o0.001 1.0 0.002 0.008
Raspberry, jam 1 48.8 1.0 o0.1 1.3 0.3 0.004 0.005 o0.001 1.3 0.002 0.007
Tomato ketchup 1 75.6 1.9 0.4 0.5 0.6 0.006 0.023 0.001 0.8 0.005 0.011
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495 493

towards decrease, especially in the trace element contents
of vegetable foods. Consequently, the average daily
mineral and trace element intakes seemed to have
decreased, although the consumption of vegetable foods
has clearly increased. A thorough research of mineral and
trace element contents of foods would be needed.
Acknowledgements
We would like to thank the Finnish Food and Drink
Industries’ Federation (FFDIF) for financial support.
References
Agricultural Economics Research Institute, 1975. Balance sheet for food
commodities, Helsinki.
Agricultural Economics Research Institute, 1976. Balance sheet for food
commodities, Helsinki.
Agricultural Economics Research Institute, 1977. Balance sheet for food
commodities, Helsinki.
Ba
´lint, A.F., Kovacs, G., Erdei, L.J., 2001. Comparison of the Cu, Zn, Fe,
Ca and Mg contents of the grains of wild, ancient and cultivated wheat
species. Cereal Research Communications 29, 375–382.
Davis, D.R., Epp, M.D., Riordan, H.D., 2004. Changes in USDA food
composition data for 43 garden crops, 1950–1999. Journal of the
American College of Nutrition 23, 669–682.
Ekholm, P., 1997. Effects of selenium supplemented commercial fertilizers
on food selenium contents and selenium intake in Finland. University
of Helsinki, EKT-series 1047, Helsinki.
Ekholm, P., Ylinen, M., Koivistoinen, P., Varo, P., 1995. Selenium
concentration of Finnish foods: Effects of reducing the amount of
selenate in fertilizers. Agricultural Science in Finland 4, 377–384.
Eurola, M., 2001. Mineral and trace elements. In: Kumpulainen, J. (Ed.),
Suomalaisten Elintarvikkeiden Ravitsemuksellinen Laatu Ja Kemialli-
nen Turvallisuus. MTT, Jokioinen, pp. 29–33.
Eurola, M., Ekholm, P., Ylinen, M., Koivistoinen, P., Varo, P.,
1989. Effects of selenium fertilization on the Se content of selected
Finnish fruits and vegetables. Acta Agriculturæ. Scandinavica 39,
345–350.
Eurola, M., Ekholm, P., Ylinen, M., Koivistoinen, P., Varo, P.,
1990. Effects of selenium fertilization on the Se content of cereal
grains, flour, and bread produced in Finland. Cereal Chemistry 67,
337.
Eurola, M., Pa
¨a
¨kko
¨nen, K., Varo, P., 1996. Raskasmetallit Sienissa
¨.
Elintarvikevirasto tutkimuksia 7/1996, Helsinki.
Eurola, M., Alfthan, G., Aro, A., Ekholm, P., Hietaniemi, V., Rainio, H.,
Rankanen, R., Vena
¨la
¨inen, E.-R., 2003. Results of the Finnish
selenium monitoring program 2000–2001. Agrifood Research Reports
36, Jokioinen.
Grain Research Committee, State Granary. 1978. Research Report,
Helsinki.
Hattori, H., Chino, M., 2001. Growth, cadmium, and zinc contents of
wheat grown on various soils enriched with cadmium and zinc.
Developments in Plant and Soil Sciences 92, 462–463.
Information Centre of the Ministry of Agriculture and Forestry, 2001.
Balance sheet for food commodities, Helsinki.
Information Centre of the Ministry of Agriculture and Forestry, 2002.
Balance sheet for food commodities, Helsinki.
Information Centre of the Ministry of Agriculture and Forestry, 2003.
Balance sheet for food commodities, Helsinki.
Kangas, A., Tera
¨va
¨inen, H. (Eds.), 2004. Peltokasvilajikkeet 2004.
Maaseutukeskustenliiton julkaisuja no. 1001. Pro Agria, Helsinki.
Kinanen, M. (Ed.), Peltokasvilajikkeet 1981. Maaseutukeskustenliiton
julkaisuja no. 646. MTTK, Helsinki.
Kirchmann, H., 2005. Trace elements in long term experiments in Iceland
and Sweden. Essential trace elements for plants, animals and humans.
NJF seminar no. 370. Reykjavik 15.-17.8.2005.
Koivistoinen, P., 1980. Mineral element composition of Finnish foods.
Acta Agriculturæ. Scandinavica suppl 22.
Kumpulainen, J., Raittila, A.-M., Lehto, J., Koivistoinen, P., 1983.
Electrothermal atomic absorption spectrometric determination of
selenium in foods and diets. Journal of the Association of Official
Analytical Chemists 66, 1129–1135.
Mattila, P., 1995. Analysis of cholecalciferol, ergocalciferol and their
25-hydroxylated metabolites in foods by HPLC. University of
Helsinki, EKT-series 995, Helsinki.
Mattila, P., Hellstro
¨m, J., 2006. Phenolic acids in potatoes, vegetables, and
some of their products. J. Food Comp. Anal. 20, 152–160.
Mattila, P., Pihlava, J.-M., Hellstroem, J., 2005. Contents of phenolic
acids, alkyl- and alkenylresorcinols, and avenanthramides in commer-
cial grain products. Journal of Agricultural and Food Chemistry 53,
8290–8295.
Mayer, A.-M., 1997. Historical changes in the mineral content of fruits
and vegetables. British Food Journal 99, 207–211.
ARTICLE IN PRESS
Table 4
Paired comparison of minerals and trace elements in 28 foods (items in
Table 2) between 1970s and 2000s
Mineral or trace
element
Test score (z)PChange
Mg 1.025 0.316
K2.072 0.038 k
Ca 1.252 0.218
P1.389 0.171
Mn 1.958 0.050 k
Zn 3.780 0.000 k
Cu 1.981 0.048 k
Fe 1.617 0.109
Al 3.347 0.000 k
Pb 2.027 0.043 k
Cd 2.573 0.009 k
Co 0.068 0.951
Ni 3.530 0.000 k
Se 3.302 0.001 m
Wilcoxon signed-rank test score (z), exact significance (two-tailed), and
direction of significant change (Po0.05; mpositive, knegative).
Table 5
The average daily mineral and trace element intakes per capita from cereal
and vegetable foods in Finland
Element Average daily
intake, 2000s,
mg d
1
10 MJ
1
Average daily
intake, 1970s,
mg d
1
10 MJ
1
Change
Mg 161 144 12% m
K 1590 1390 15% m
Ca 116 76 52% m
P 422 441 4% k
Mn 3.2 3.8 14% k
Zn 3.0 4.0 25% k
Cu 0.7 0.8 20% k
Fe 4.4 6.3 30% k
Al 2.0 1.7 20% m
Co 0.005 0.007 25% k
Ni 0.047 0.088 45% k
Se 0.032 0.002 1600% m
Pb 0.019 0.012 60% m
Cd 0.007 0.01 35% k
P. Ekholm et al. / Journal of Food Composition and Analysis 20 (2007) 487–495494

Melanen, M., Ekqvist, M., Mukherjee, A.B.,Aunela-Tapola,L.,Verta,M.,
Salmikangas, T., 1999. Raskasmetallien pa
¨a
¨sto
¨t ilmaan Suomessa 1990-
luvulla. Suomen ympa
¨risto
¨329, Suomen ympa
¨risto
¨keskus, Helsinki.
National Board of Agriculture, 1986. Official statistics of Finland III:82.
Yearbook of farm statistics 1983, Helsinki.
National Board of Agriculture, 2003. Official statistics of Finland,
Yearbook of farm statistics, Helsinki.
National Board of Customs, 2005. Import Statistics 1985–2004. National
Board of Customs, Helsinki.
Pietola, L., Salo, T., 2000. Response of P, K, Mg and NO
3
-N contents of
carrots to irrigation, soil compaction, and nitrogen fertilization.
Agricultural and Food Science in Finland 9, 319–331.
Saiyed, S.M., Yokel, R.A., 2005. Aluminium content of some foods and
food products in the USA, with aluminium food additives. Food
Additives and Contaminants 22, 234–244.
Sanches-Castillo, C.P., Dewey, P.J.S., Aguirre, A., Lara, J.J., Vaca, R.,
Barra de la, P.L., Ortiz, M., Escamilla, I., James, W.P.T., 1998. The
mineral content of Mexican fruits and vegetables. Journal of Food
Composition and Analysis 11, 340–356.
Tahvonen, R., 1995. Contents of Lead and Cadmium in Foods in Finland.
Food Chem, University of Turku, Department of Biochemistry and
Food Chemistry, Turku.
WHO, 2003. Diet, Nutrition and the Prevention of Chronic Diseases.
WHO, Geneva.
ARTICLE IN PRESS
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