Vol.3, No.11, 672-676 (2011)
doi:10.4236/health.2011.311113
C
opyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Health
Estimation of mi neral and trace element int ak e in vegans
living in Japan by chemical analysis of duplicate diets
Munehiro Yoshida*, Noriko Ôgi, Yuki Iwashita
Laboratory of Food and Nutritional Sciences, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita, Japan;
*Corresponding Aut hor:
Received 10 September 2011; Revised 5 October 2011; Accepted 21 October 2011.
ABSTRACT
Thirty-six daily duplicate diet samples were col-
lected from 12 healthy female Japanese vegans
and sodium, potassium, calcium, magnesium,
phosphorus, iron, zinc, copper, manganese,
iodine, selenium, chromium and molybdenum in
the diets were measured to estimate mineral
and trace element intake by Japanese vegans.
Significantly higher intake of potassium, mag-
nesium, phosphorus, iron, copper, manganese
and molybdenum was observed in vegans than
in general Japanese women, but no difference
was observed in sodium, iodine, selenium and
chromium intake. Vegan calcium intake tended
to be low compared to that of general women
but the difference was not significant. Since
high potassium, magnesium and iron intakes
cannot be achieved by general Japanese diets
and high intake of potassium and magnesium
may preven t hyperex tensio n and cardi ovascula r
disease in vegans, there are few problems with
Japanese vegan diets regarding mineral and
trace element intake, except for calcium intake,
which is low as it is in the general Japanese
people.
Keywords: Vegan; Mine ral intake; Trace Element
Intake; Duplicate Diets; Japan
1. INTRODUCTION
Vegetarian diets, essentially excluding animal foods,
have become increasingly popular in developed coun-
tries [1]. These diets are classified according to the types
of animal foods consumed, and strict vegetarians con-
suming no foods of animal origin are known as vegans.
Although vegan diets cause lower serum cholesterol,
lower blood pressure and a reduced risk of cardiovascu-
lar diseases, eliminating all animal foods from the diet
increases the risk of several micronutrient deficiencies,
including vitamin B12, vitamin D and n-3 fatty acids [2].
Regarding the intake of minerals and trace elements,
vegetarians, including vegans, show low intakes of cal-
cium, zinc and selenium because the main sources of
these micronutrients are animal foods in Western diets
[3,4].
Traditional Asian diets are predominately p lant-based,
differing from Western diets. In Japan, although the
consumption of meat and dairy products has increased
along with the Westernization of society, more than
three quarters of the energy intake still depends on plan t
foods [5]. Accordingly, it is thought that the effect of
adopting a vegan diet on the nutrient intake pattern is
different between the West and Japan. However, little
research has examined the nutrient intake of vegetarians
in Japan [6], and research on the intake of minerals and
trace elements by Japanese vegans is scarce. In the pre-
sent study, to evaluate mineral and trace element intake
by Japanese vegans, duplicate diet samples were col-
lected from Japanese vegans, and concentrations of so-
dium, potassium, calcium, magnesium, phosphorus, iron,
zinc, copper, manganese, iodine, selenium, chromium
and molybdenum were measu red.
2. SUBJECTS AND METHODS
2.1. Subjects and Duplicate Diet
Sampling
In the present study, vegans were defined as people
eating food of plant origin only. Twelve healthy female
vegans were recruited through a vegetarian food shop
located in Chiba Prefecture, Japan. The characteristics of
the subjects are described in Table 1. Duplicate meals,
beverages and between-meal snacks were collected over
24 h period; 36 duplicate diets from 12 subjects were
sampled for 3 consecutive days between September and
November 2010. All subjects gave informed consent for
the use of their personal information in this study.

M. Yoshida et al. / Health 3 (2011) 672-6 76
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
673673
Table 1. Characteristics of vegan subjects (n = 12).
Mean ± SD Median
Age (y) 48.4 ± 12.9 47.5
Duration of vegan d ie t (y) 20.7 ± 14.5 12.0
Height (cm) 156.4 ± 7.7 157.0
Weight (kg) 49.1 ± 8.9 48.5
Body mass index (kg/m2) 19.9 ± 2.4 19.7
2.2. Treatment of Samples
The daily duplicate diet sample was freeze-dried, ho-
mogenized and milled. Approximately 1 g of the dried
sample was mixed with 200 mL of 1% HCl, shaken for
30 min and centrifuged. The supernatant was filtrated
with 0.45-µm membrane filter. Filtrate thus obtained
was used for the determination of sodium and potassium.
Another 1 g of the dried sample was heated with 10 mL
metal-free HNO3 until the disappearance of insoluble
components, and then, 2 mL metal-free HClO4 was
added to the digestion mixture, which was further heated
until the appearance of white vapor of HClO4. The vol-
ume of the digest was made up to 10 mL with pure water.
Diluted digest thus ob tained was used for the determina-
tion of calcium, magnesium, phosphorus, iron, zinc,
copper, manganese, selenium and molybdenum. For the
analysis of chromium, approximately 1 g of the dried
sample was heated in an electric furnace (F-B1414M; As
One, Osaka, Japan) at 550˚C for 16 h [7]. After dry in-
cineration, the remaining ash was dissolved in 10 mL of
0.1 M HNO3. Iodine in the dried samples was extracted
with 0.5% tetramethylammonium hydroxide (TMAH)
[8]. Two hundred milligrams of the dried samples was
mixed with 40 mL of 0.5% TMAH and left overnight.
The mixture was heated at 60˚C for 6 h and centrifuged.
The supernatant was filtrated through a 0.45-µm mem-
brane filter.
2.3. Analysis
Sodium, potassium, calcium, magnesium, iron, zinc,
copper and manganese were measured using atomic ab-
sorption spectrometer (AA-6300; Shimadzu, Kyoto, Ja-
pan). Iodine, selenium, chromium and molybdenum were
determined by inductively coupled plasma mass spec-
trometry (ICPMS) with direct nebulization. The ICPMS
operating conditions were as fo llows: instrumen t, ICPM-
8500 (Shimadzu); forward power, 1200 W; coolant gas
flow rate, 7.0 L/min; auxiliary gas flow rate, 1.5 L/min;
nebulizer gas flow rate, 0.58 L/min; sampling depth, 5.0
mm; integration time, 2.0 s; number of run, 20; mode of
analysis, pulse; isotopes monitored, 52Cr, 82Se, 95Mo,
97Mo, 98Mo and 127I. Rhodium (103Rh) and tellurium
(126Te, 128Te and 130Te) were used as internal standards.
Phosphorus was determined with vanadomolybdate ab-
sorption spectrometry [9]. Protein, total lipid and energy
were analyzed by a commercial service system (Japan
Functional Food Analysis and Resear ch Center , Fukuoka,
Japan).
2.4. Statistical Analysis
For each subject, mean daily intake was calculated
from the analytical results of duplicate diet samples from
3 consecutive days. The mean and median of the daily
intake for 12 subjects were then calculated. For iodine,
the mean and median were also calculated when each
value was logarithmically transformed because values
highly varied. Mean daily intake for 12 subjects was
statistically compared with the mean daily intake by
general Japanese women aged 30 to 49 y described in
the National Health and Nutritional Survey in Japan
(NHNSJ) [10] by calculation of the Z-score; in which
women aged 30 to 49 y in NHNSJ, 2008 (n = 1053)
were regarded as a population.
3. RESULTS AND DIS CUS SION
In Table 2, daily intake of major nutrients, minerals
and trace elements by 12 Japanese female vegans was
summarized and compared with those by general Japa-
nese women and several criteria in the Dietary Reference
Intakes for Japanese (DRIJ) [11]. For the intake of en-
ergy, protein and total lipids, no difference was observed
between vegan s and general women.
Among major mineral intake, calcium intake by ve-
gans was below the estimated average requirement
(EAR) and tended to be low compared to that by the
general population. In several Western researches, cal-
cium intake by vegans was markedly lower than that by
omnivores [12] and lacto-vegetarians [13]. In the present
analysis, vegan calcium intake was somewhat low but
was not significantly lower than in the general Japanese
calcium intake. Since calcium intake by general Japa-
nese people is always low due to the low consumption of
dairy products, the low calcium intake of Japanese ve-
gans may be inconspicuous.
Phosphorus intake by vegans was markedly higher
than by general women. In Western research, a vegan
diet contains low phosphorus and is appropriate for pa-
tients with renal failure [14]. In the West, because the
major source of phosphorus in general diets is dairy
products, vegan phosphorus intake is comparatively low;
however, Japanese people ingest phosphorus mainly
from plant foods [5]. The difference in the source of

M. Yoshida et al. / Health 3 (2011) 672-6 76
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674
Table 2. Intake of energy, protein, lipids, minerals and trace elements in Japanese vegans.
Vegans ( n = 1 2 ) NHNSJ, 20081) DRIJ, 20102)
Mean ± SD Median Mean ± SD MedianEAR RDA AI DG UL
Energy (kcal) 1847 ± 141 1840 1682 ± 469 1645 1750 - - - -
Protein (g) 56.2 ± 8.1 58.4 60.2 ± 19.0 58.7 40 50 - - -
Lipids (% energy) 20.8 ± 7.3 21.0 24.5 ± 14.1 22.6 - - - 20 - 25-
Sodium (mg) 3649 ± 1719 3029 3696 ± 14153) 3538
3) 590 3) - - <29503) -
Potassium (mg) 3610 ± 1272* 3217 1983 ± 777 1891 - - 2000 2800 -
Calcium (mg) 361 ± 122 389 440 ± 224 406 550 650 - - 2300
Magnesium (mg) 494 ± 112* 462 214 ± 80 204 240 290 - - -
Phosphorus (mg) 1225 ± 311* 1197 8 54 ± 284 830 - - - - 3000
Iron (mg) 13.0 ± 2.4* 12.2 6.9 ± 3.0 6.5 9.0 11.0 900 - 40
Zinc (mg) 8.3 ± 1.6 9.1 7.1 ± 2.4 6.9 8 9 - - 35
Copper (mg) 1.75 ± 0.37* 1.66 1.00 ± 0.35 0.96 0.6 0.7 - - 10
Manganese (mg) 7.5 ± 2.2 7.9 - - - - 3.5 - 11
Iodine (µg) 1865 ± 1934 1158 - - 95 130 - - 2200
788 (255 - 2441)4) 7465)
Selenium (µg) 87 ± 34 76 - - 20 25 - - 230
Chromium (µg) 27 ± 8 28 - - 25 30 - - -
Molybdenum (µg) 540 ± 207 563 - - 20 25 - - 500
*Signif i can t differen ce f r o m NHNSJ da t a was obs er v ed at p < 0.001 by calculation of Z-score; 1)Values for general Japanese women aged 30 to 49 y (n = 1053)
quoted from the National Health and Nutrition Survey in Japan, 2008 [10]; 2)Criteria for Japanese women aged 30 to 49 y in Dietary Reference Intakes for
Japanese, 2010 [11]; EAR, estimated average requirement; RDA, recommended dietary allowance; AI, adequate intake; DG, tentative dietary goal for prevent-
ing lifestyle-related diseases; UL, tolerable upper intake level; 3)Calculated from the values for salt; 4)Geometrical mean with SD range in parentheses; 5)Median
calculated after logarithmic transformation of data for each daily duplicate diet sample.
phosphorus may contribute to the difference in phos-
phorus intake between Western and Japanese vegans. In
addition, phytate may contribute to the high phosphorus
intake in vegans because whole grains and beans contain
it at a high level.
No difference was observed between vegans and gen-
eral women in sodium intake. On the other hand, vegan
potassium intake was markedly higher than by general
women and far exceeded the tentative dietary goal for
preventing lifestyle-related diseases (DG) in DRIJ.
Similarly, markedly higher magnesium intake was ob-
served in vegans than in general women. This high in-
take of potassium and magnesium is probably due to the
high consumption of vegetables and fr ui t .
Among trace element intake, significantly higher iron
and copper intake was observed in vegans than in gen-
eral women. Similarly, manganese and molybdenum
intake by vegans was markedly higher than by general
Japanese, as described in several reports [15,16]. Intake
of these four trace elements far exceeded the recom-
mended dietary allowance (RDA) or the adequate intake
(AI) in DRIJ. High intake of copper and manganese is
also reported in Western researches [17], probably, be-
cause the high consumption of whole grains and beans
results in high intake of these trace elements. The mean
and median of vegan molybdenum intake exceeded the
tolerable upper intake level of this element in DRIJ. This
is also caused by high consumption of cereals and beans
since they particularly soybean, contain molybdenum at
a high level [16].
Although vegan zinc intake has been reported to be
low [12], there was no difference between vegans and
general women; however, because it has been reported
that the serum zinc level in Japanese vegetarians tends to
be low [18], it is necessary to examine whether phytate
and/or dietary fiber, which are contained in whole grains
and beans at a high level, decrease the bioavailability of
zinc in Japanese vegan diets.
Since the main sources of selenium in general Japa-
nese diets are fish, meats and eggs [19], the low sele-

M. Yoshida et al. / Health 3 (2011) 672-6 76
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
675675
nium intake by Japanese vegans is concern; however,
selenium intake by Japanese vegans was comparable to
that by general Japanese described in several previous
reports [19-21]. Japanese vegans may ingest selenium
from imported wheat and soybeans, which contain sele-
nium at a high level [22]. Similarly to selenium intake,
iodine and chromium intake by vegans was also compa-
rable to general Japanese people described in the litera-
ture [20,23].
In conclusion, Japanese vegans are estimated to ingest
high potassium, magnesium, phosphorus, iron, copper,
manganese and molybdenum compared to general Japa-
nese people. In particular, high potassium, magnesium
and iron intake cannot be achieved by ingesting general
Japanese diets. High intake of potassium and magnesium
may lead to the preventing of hyperextension and car-
diovascular disease in vegans [24]. Accordingly, there
are few problems with Japanese vegan diets regarding
mineral and trace element intake, except for calcium
intake, which is low as it is in general Japanese people.
4. ACKNOWLEDGEMENTS
This study was supported by a grant for comprehensive research on
cardiovascular and lifestyle disease from the Ministry of Health, La-
bour and Welfa re of Japan.
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