edta
DESCRIPTION
EDTATRANSCRIPT
-
Journal of Trace Elements in Medicine and Biology 26 (2012) 227 233
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Bioavailability
EDTA disodium zinc has superior bioavailability cor chelated zinc compounds in rats fed a high ph
Jesse Bertinato , Lindsey Sherrard, Louise J. PlouffeNutrition Resea ReseaK1A 0K9
a r t i c l
Article history:Received 25 JaAccepted 12 A
Keywords:BioavailabilityEDTA disodiumPhytic acidRatZinc
uniquacid (ay-ol
Zn/k diso
with oxiderow
rats for Zn orotate. Rats fed EDTA disodium Zn showed enhanced growth compared to rats fed Zn oxide orZn gluconate and had higher Zn concentrations in plasma and femur compared to rats fed all other Zncompounds. Only the haematological prole of rats fed EDTA disodium Zn did not differ from controlrats fed normal Zn. These data indicate that in rats fed a high PA diet, bioavailability of commonly usedinorganic or chelated Zn compounds does not differ appreciably, but Zn supplied as an EDTA disodium
Introductio
Nutritiois particularAfrica and Sstrated benchildren. A infants, presupplemensupplemeneases such aand reduce
Zn fortiZn decien
Abbreviatiomean corpuscution; MCV, mecell distributio
CorresponBranch, HealthFrederick BantTel.: +1 613 95
E-mail add
0946-672X/$ http://dx.doi.osalt has superior bioavailability.Crown Copyright 2012 Published by Elsevier GmbH. All rights reserved.
n
nal zinc (Zn) deciency is a global health problem thatly prevalent in developing countries in the Middle East,outh America [1,2]. A number of studies have demon-ecial effects of Zn supplementation in Zn-decientrecent meta-analysis of Zn supplementation trials withschoolers and prepubertal children showed that Zntation increased linear growth and weight gain [3]. Zntation also decreased the incidence of infectious dis-s diarrhoea and acute lower respiratory tract infection
d child mortality in children over 1 year of age [3].cation is used as a strategy to reduce the prevalence ofcy [4]. Despite the large number of countries with Zn
ns: Ca, calcium; Fe, iron; Hb, haemoglobin; HCT, haematocrit; MCH,lar haemoglobin; MCHC, mean corpuscular haemoglobin concentra-
an corpuscular volume; PA, phytic acid; RBC, red blood cell; RDW, redn width; WBC, white blood cell; Zn, zinc.ding author at: Nutrition Research Division, Health Products and Food
Canada, Sir Frederick G. Banting Research Centre, PL 2203E, 251 Siring Driveway, Ottawa, Ontario, Canada K1A 0K9.7 0924; fax: +1 613 941 6182.ress: [email protected] (J. Bertinato).
fortication programmes, there is a lack of data on the efcacy ofthese programmes. Recent studies using inorganic Zn compounds(i.e., Zn oxide or Zn sulphate) have suggested that Zn consumed as asupplement is more efcacious than Zn from Zn-fortied foods rais-ing concerns regarding the value of Zn fortication programmes.Brown et al. [5] showed that plasma Zn increased in young Peruvianchildren receiving a Zn supplement, but not in children receiv-ing a marginally higher amount of Zn added to porridge. Similarresults were reported in young children from Senegal [6]. PlasmaZn increased in children that received a liquid Zn supplement, butnot in children that received a similar amount of Zn as a Zn-fortiedcomplementary food. Furthermore, fat-free mass accrual increasedin stunted young Peruvian children with Zn administered as a liq-uid supplement, but not with a similar amount of Zn in fortiedporridge [7]. A possible explanation for these observations is thatZn absorption was decreased by the presence of anti-absorptivecomponents in the foods.
Two main factors affect absorption of Zn from a meal, theamount of Zn consumed in the meal or a previous meal [8], andthe quantity of inositol hexakisphosphate or phytic acid (PA) inthe meal. PA or phytate (when in salt form) is a phosphorous stor-age compound in plants. It is found in large amounts in unrenedcereals and legumes that are consumed as staple foods in manycountries [9]. PA binds minerals such as Zn, iron (Fe) and calcium
see front matter. Crown Copyright 2012 Published by Elsevier GmbH. All rights reserved.rg/10.1016/j.jtemb.2012.04.008rch Division, Health Products and Food Branch, Health Canada, Sir Frederick G. Banting
e i n f o
nuary 2012pril 2012
zinc
a b s t r a c t
Different zinc (Zn) compounds have particularly in the presence of phytic its bioavailability. In this study, 30-dwith PA (0.8%) and low levels (8 mggluconate, Zn acetate, Zn citrate, EDTAgroups were fed diets supplementedadded PA. Control rats fed the low Znexacerbated the Zn deciency in rats. Gin plasma and tissues were similar inr .de / j temb
ompared to common inorganicytic acid diet
rch Centre, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, Canada
e properties that may inuence the amount of Zn absorbedPA), a common food component that binds Zn and decreasesd male rats (n = 12/diet group) were fed diets supplementedg diet) of inorganic (Zn oxide, Zn sulphate) or chelated (Zndium Zn, Zn orotate) Zn compounds for 5 weeks. Two control
low or normal (30 mg Zn/kg diet) Zn (as Zn oxide) without diet showed depressed Zn status. Addition of PA to this diet
th (body weight gain and femur length) and Zn concentrationsed Zn oxide, Zn sulphate, Zn gluconate, Zn acetate, Zn citrate
-
228 J. Bertinato et al. / Journal of Trace Elements in Medicine and Biology 26 (2012) 227 233
(Ca) making them unavailable for absorption [9,10]. The strong abil-ity of PA to chelate minerals can lead to mineral deciencies inpeople that consume a diet high in PA.
Mass fortication programmes usually involve fortifying sta-ple foods soften have monly usedfavourable other Zn cocant in certforms of Znthese compZn orotate)numerous ccompounds
Since cetain high amof the fortihighly bioaticant for fis less inubenet of dtied Zn resfoods.
Differenity, afnitybound moleat least in pin Zn absoricant in theIn this studganic or cheinconsistention [12,14disodium Z
Materials a
Animal prot
Thirty-dSt. Constandiet groupsin each diewere housesteel platfohad free acplemented (P8810-500low level o500G, SigmZn gluconatUSA), Zn acrate dihydrethylenediaSigmaAldrton Chem IPA and supdiets were eAdditional a potential in egg-whit
Diets weof food intasured on da
the wire-bottom cages was collected on metal grills and weighed.To obtain food consumption, the amount of spilled food was sub-tracted from the amount of food missing from the feeder. Bodyweight was measured twice per week. After 5 weeks of feeding the
ats wl isogs w
on dnalysge ant K2icro
of plativelan Cl pro
Ani05).
lengt
urs n andur h
lyses
ts, fe withe as ic salashesd aso meectrom, Urd culogyUrfurcecy. Eed.
cs
erened by
signlot 1
s
posed Z
thet in t
the 0.t in ter dd coes d
se 4 2). Fd notuch as cereal ours (e.g., wheat or maize our) thata high PA content [4]. Zn oxide is by far the most com-
compound for fortication [4] because of its low cost,sensory properties and comparable bioavailability tompounds [1113]. Zn sulphate is also used as a forti-ain products such as infant formulas. Although chelated
are generally not used for fortication, a number ofounds (e.g., Zn gluconate, Zn acetate, Zn citrate, and
are available to consumers in supplements. There arelaims of improved Zn bioavailability from chelated Zn, most of which are unsubstantiated.real ours used in Zn fortication programmes can con-ounts of PA, absorption and consequently the efcacyed Zn is compromised. A Zn compound that provides
vailable Zn in the presence of PA would be best as a for-oods with a high PA content. Using a Zn compound thatenced by the inhibitory effect of PA could also have theecreasing the variability in the effectiveness of the for-ulting from differences in PA consumption from other
t Zn compounds have unique properties (e.g., solubil- for food components, and dissociation constants ofcules). Thus, the amount of Zn absorbed may depend,art, on the specic Zn compound ingested. Differencesption from different compounds may be more signif-
presence of anti-absorptive components such as PA.y, we compared the bioavailability of 6 common inor-lated Zn compounds in a high PA diet in rats. Given thet results concerning the effect of EDTA on Zn absorp-17], we also investigated the bioavailability of EDTAn.
nd methods
ocol and diets
ay-old male Sprague Dawley rats (Charles River Canada,t, Canada) were assigned based on body weight to 19
(n = 12/group) so that mean body weights for ratst group were similar at the start of the study. Ratsd individually in wire-bottom cages with a stainlessrm and shelter and put on a 12-h day/night cycle. Ratscess to deionised water and 1 of 7 test diets sup-with 8 g/kg diet of PA sodium salt hydrate from riceG, SigmaAldrich Canada Ltd., Oakville, Canada) and af Zn (8 mg elemental Zn/kg diet) as Zn oxide (Z0385-aAldrich), Zn sulphate heptahydrate (Z0635-500G),e (CAS No.: 4468-02-04, Canton Chem Inc., Clarksville,etate dihydrate (96459-250G, SigmaAldrich), Zn cit-ate (480762-500G, SigmaAldrich), IDRANAL II-Znminetetraacetic acid (EDTA) disodium Zn salt (34553,ich) or Zn orotate dihydrate (CAS No.: 5970-45-6, Can-nc.). Two control groups were fed diets without addedplemented with 8 or 30 mg Zn/kg diet (as Zn oxide). Allgg white-based to ensure low background levels of Zn.d-biotin (4 mg/kg diet) was added to the diets to avoidbiotin deciency resulting from the high avidin contente protein.re pelleted to allow for more accurate measurementke. Food eaten in a 24-h period by each rat was mea-ys 8, 15, 22 and 29 of the study. Food spilled through
diets, rgeneraand legen oruntil aa syrinElemena BD Mlation respecBeckmimentaBranch2010-0
Femur
Feming skithe fem
Zn ana
Dieashingfurnacisotontissue ubiliseprior ttion spWalthastandaTechnoBaie Drate soaccurareport
Statisti
DifffollowtisticalSigmaP
Result
ComAnalysexceptpresentent into 10.8contenthe oth
Foorate timfor the(Tablealso diere killed (in the morning) by exsanguination underurane anaesthesia after an overnight fast (12 h). Liver
ere extracted and immediately frozen in liquid nitro-ry ice, respectively. Liver and legs were stored at 80 Cis. Blood was collected from the abdominal aorta withd immediately dispensed into a BD Vacutainer TraceEDTA tube (368381, VWR, Mississauga, Canada) and
tainer tube with K2EDTA (VT365974, VWR) for iso-sma and measurement of haematological parameters,
y. Haematological parameters were measured using aoulter AcT 5 Diff CP haematology analyser. The exper-tocol was approved by the Health Products and Foodmal Care Committee of Health Canada (protocol No.:
h measurement
were isolated from the right leg and cleaned by remov- esh using a scalpel. Femur length was measured fromead to the medial condyle using a dial calliper.
murs and livers were ashed using a combination of wet- concentrated nitric acid and dry-ashing in a mufe
described [18]. Prior to ashing, liver was washed withine [0.9% (w/v) NaCl] to remove excess blood. Diet and
were solubilised in 1 mol/L nitric acid. Plasma and sol-hes were appropriately diluted with deionised waterasurement of Zn concentration by ame atomic absorp-scopy (AAnalyst 400, Perkin-Elmer Cetus Instruments,SA). Zn concentrations were determined relative to arve generated using National Institute of Standards and-certied atomic absorption standards (SCP Science,, Canada). Certied reference materials from sepa-s were analysed alongside samples to verify analyticalach sample was measured in triplicate and the mean
ces between diet groups were compared using ANOVA Tukeys test. Data were reported as means SEM. Sta-icance was set at P < 0.05. Data were analysed using1.2 (Systat Software Inc., Chicago, USA).
itions of the control and test diets are shown in Table 1.n content in a mock diet containing all ingredients
Zn compounds showed that 2 mg Zn/kg diet washe diet ingredients (data not shown). Analysed Zn con-control 8ZnO diet and 7 test diets ranged from 9.3 0.42 mg Zn/kg and did not differ signicantly (Table 1). Znhe control 30ZnO diet was 3-fold higher compared toiets.nsumption for a 24-h period was measured at 4 sepa-uring the study for each rat. Average food consumptiondays did not differ between rats fed the different dietsood consumption at each of the 24-h measurements
differ for rats fed the different diets (data not shown).
-
J. Bertinato
et al.
/ Journal
of Trace
Elements
in M
edicine and
Biology 26 (2012) 227 233
229
Table 1Composition of diets.
Component (g/kg diet) Diet groups
30ZnO 8ZnO 8ZnO + PA 8ZnSO4 + PA 8Zn-Glu + PA 8Zn-OAc + PA 8Zn-Cit + PA 8Zn-EDTA + PA 8Zn-Oro + PA
Zn source Zn oxide Zn oxide Zn oxide Zn sulphate Zn gluconate Zn acetate Zn citrate EDTA disodium Zn Zn orotateFixed ingredientsa 775.9 775.9 775.9 775.9 775.9 775.9 775.9 775.9 775.9Cornstarch 220.35 223.10 215.10 215.10 215.10 215.10 215.10 215.10 215.10Phytic acid 8 8 8 8 8 8 8Zn premixb 3.75 1 1 1 1 1 1 1 1Zn content (mg/kg diet)c 32.5 0.3a 10.8 0.2b 10.4 0.6b 9.8 0.5b 9.3 0.4b 9.3 0.4bd 10.5 0.3b 10.2 0.2b 9.6 0.2ba Fixed ingredients (g/kg diet): egg white solids (sprayed-dried), 200; sucrose, 200; soybean oil, 140; dextrinised cornstarch, 135; bre, 50; AIN93G mineral mix without Zn, 35; AIN93G vitamin mix, 10; l-cystine, 3; choline
bitartrate, 2.5; d-biotin premix (10 mg d-biotin/g cornstarch), 0.4.b Zn premixes were formulated to contain 8 mg elemental Zn/g cornstarch.c Values are means SEM, n = 4. Values in the row without a common letter differ, P < 0.05.d n = 3.
Table 2Growth and food consumption of rats.
Parameter Diet groups
30ZnO 8ZnO 8ZnO + PA 8ZnSO4 + PA 8Zn-Glu + PA 8Zn-OAc + PA 8Zn-Cit + PA 8Zn-EDTA + PA 8Zn-Oro + PA
Initial BW (g) 109 3a 109 3a 108 3a 108 3a 109 3a 109 3a 109 3a 109 3a 109 3aFinal BW (g) 298 9a 275 7ab 248 8b 279 8ab 247 14b 266 8ab 281 6ab 304 8a 266 9abTotal BW gain (g) 188 10a 166 7ab 140 7b 171 10ab 138 13b 157 8ab 172 5ab 194 9a 157 10abFemur length (mm) 32.8 0.3ab 32.2 0.3ab 31.5 0.2b 32.2 0.3ab 31.6 0.4b 32.1 0.3ab 32.8 0.2ab 33.1 0.3a 32.4 0.3abFC (g/day)a 17.5 0.6a 16.7 0.5a 15.5 0.8a 16.8 0.6a 15.6 0.6a 16.4 0.8a 16.4 0.4a 17.5 0.4a 15.5 0.9aFC (g/100 g BW)b 8.0 0.1a 8.4 0.2a 8.5 0.4a 8.4 0.3a 8.8 0.5a 8.6 0.5a 8.0 0.2a 7.9 0.1a 8.1 0.4a
Values are means SEM, n = 12. Values in a row without a common letter differ, P < 0.05. BW, body weight; FC, food consumption.a Average food consumption determined from 4 separate 24-h food consumption measurements at days 8, 15, 22 and 29 of the study.b Food consumption per 100 g body weight was determined for each rat on days 8, 15, 22 and 29. The average of these 4 measurements is reported.
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230 J. Bertinato et al. / Journal of Trace Elements in Medicine and Biology 26 (2012) 227 233
Fig. 1. Growthstudy. Each po
Furthermorrats was sim
Growth of rats werstudy (Tablwere highepared to raweights an8ZnO + PA, 88Zn-Oro + Pfed the 8Znpared to rat
Femur Zlowed by rand plasmathat rats fecompared tdifferencesin rats fed t8Zn-Cit + PAliver Zn con
Haemogwere higherfed the 8ZnCit + PA or 8(Table 4). Hwere highediet. Haemthe 8Zn-EDhad lower HWhite bloomean corpufer between
Discussion
Bioavaiportion of imetabolic pfrom 7 Zn coPA diet by aciency incluplasma. Thewith the safor several w
O
8ZnO
+
PA
8ZnSO
4+ PA
8Zn-G
lu
+
PA
8Zn-O
Ac
+
PA
8Zn-C
it
+
PA
8Zn-E
DTA
+
PA
8Zn-O
ro
+
PA
4
5b
103
3d
107
3d
103
2d
113
6d
111
3d
143
3c
108
3d4
29ab
874
38c
954
37c
865
36c
924
32c
950
27c
1177
31b
899
29c
3
4a
101
4a
99
2a
96
2a
97
2a
96
3a
95
3a
95
3a
com
mon
letter
diffe
r,
P
<
0.05
. DW
, dry
wei
ght. curves. Body weights of rats fed the control and test diets during theint represents the mean, n = 12.
e, food consumption normalised to body weight of theilar for all groups (Table 2).
curves for the rats are presented in Fig. 1. Body weightse similar for all diet groups at the beginning of thee 2). Final body weights and total body weight gainsr for rats fed the 30ZnO or 8Zn-EDTA + PA diets com-ts fed the 8ZnO + PA or 8Zn-Glu + PA diets. Final bodyd weight gains did not differ for rats fed the 8ZnO,ZnSO4 + PA, 8Zn-Glu + PA, 8ZnOAc + PA, 8Zn-Cit + PA orA diets. Consistent with the larger body weight of rats-EDTA + PA diet, these rats also had longer femurs com-s fed the 8ZnO + PA or 8Zn-Glu + PA diets (Table 2).n content was highest in rats fed the 30ZnO diet, fol-ats fed the 8ZnO diet (Table 3). Comparison of femur
Zn concentrations in rats fed the 7 test diets showedd the 8Zn-EDTA + PA diet had higher concentrationso rats fed diets containing other Zn compounds. No
in femur or plasma Zn concentrations were observedhe 8ZnO + PA, 8ZnSO4 + PA, 8Zn-Glu + PA, 8ZnOAc + PA,
or 8Zn-Oro + PA diets. There were no differences incentrations in rats fed the control or test diets (Table 3).lobin (Hb) and mean corpuscular haemoglobin (MCH)
and red cell distribution width (RDW) was lower in ratsO + PA, 8ZnSO4 + PA, 8Zn-Glu + PA, 8ZnOAc + PA, 8Zn-Zn-Oro + PA diets compared to rats fed the 30ZnO dietaematocrit (HCT) and mean corpuscular volume (MCV)r in many test groups compared to rats fed the 30ZnOatological parameters did not differ between rats fed
TA + PA or 30ZnO diets. Rats fed the 8Zn-EDTA + PA dietb and HCT compared to rats fed the 8Zn-Glu + PA diet.
d cell (WBC) counts, red blood cell (RBC) counts andscular haemoglobin concentration (MCHC) did not dif-
rats fed the different diets.
lability of a nutrient can be broadly dened as the pro-ntake that is absorbed and can be used for storage orrocesses. In this study the relative bioavailability of Znmpounds was evaluated in rats in the context of a highssessing differences in parameters sensitive to Zn de-ding growth and Zn concentrations in bone (femur) and
main goal of this study was to determine if rats fed dietsme amount of Zn coming from different Zn compounds
eeks would show measurable differences in Zn status Table
3Zn
conce
ntr
atio
ns
in
fem
ur,
pla
sma
and
live
r
of
rats
.
Para
met
er
Die
t
grou
ps
30Zn
O
8Zn
Fem
ur
Zn
(g/
g
DW
)
357
10a
21Pl
asm
a
Zn
(g/
L)
1412
47a
127
Live
r
Zn
(g/
g
DW
)
108
5a
10
Val
ues
are
mea
ns
SEM
, n
=
12. V
alues
in
a
row
withou
t
a
-
J. Bertinato et al. / Journal of Trace Elements in Medicine and Biology 26 (2012) 227 233 231
Table
4Hae
mat
olog
ical
mea
sure
men
ts
of
rats
.
Para
met
er
Die
t
grou
ps
30Zn
O
8ZnO
8ZnO
+
PA
8ZnSO
4+
PA
8Zn-G
lu
+
PA
8Zn-O
Ac
+
PA
8Zn-C
it
+
PA
8Zn-E
DTA
+ PA
8Zn-O
ro
+
PA
WBCs
(109
/L)
5.7
0.4a
4.9
0.4a
4.8
0.4a
4.1
0.5a
3.8
0.5a
5.0
0.6a
4.9
0.5a
5.2
0.
4a
4.3
0.7a
RBCs
(101
2/L
)
8.0
0.1a
8.2
0.1a
7.9
0.1a
7.8
0.1a
8.0
0.1a
7.9
0.1a
7.9
0.1a
8.0
0.
1a
7.9
0.1a
Hb
(g/L
)
136
1a
140
1ab
146
1bc
144
1bc
148
2c
145
1bc
143
2bc
141
2a
b
144
1bc
HCT
0.41
0
0.00
4a
0.42
1
0.00
4ab
0.43
6
0.00
4bc
0.42
9
0.00
3abc
0.44
3
0.00
5c
0.43
2
0.00
4bc
0.42
7
0.00
4abc
0.42
3
0.00
4ab
0.43
2
0.00
5bc
MCV
(fL)
51.3
0.7a
51.3
0.7a
55.3
0.4b
55.4
0.5b
55.6
0.4b
54.7
0.5a
b
54.2
0.7a
b
53.2
0.6a
b
54.3
0.7a
bM
CH
(pg)
17.0
0.2a
17.1
0.3a
b
18.5
0.2c
18.5
0.2c
18.6
0.2c
18.4
0.2c
18.0
0.3b
c
17.7
0.2a
bc
18.1
0.2c
MCHC
(g/L
)
331
1a
333
2a
335
1a
335
1a
334
1a
336
1a
334
2a
333
1a
334
1aRDW
(%)
14.3
0.5a
13.8
0.6a
b
11.1
0.1c
11.5
0.2c
11.4
0.2c
11.4
0.2b
c
11.9
0.4b
c 11
.9
0.3a
bc
11.8
0.3b
c
Val
ues
are
mea
ns
SEM
, n
=
12. V
alues
in
a
row
withou
t a
com
mon
letter
diffe
r,
P
<
0.05
. WBCs,
white
bloo
d
cells;
RBCs,
red
bloo
d
cells;
Hb,
hae
mog
lobi
n; H
CT,
hae
mat
ocrit;
MCV, m
ean
corp
usc
ula
r
volu
me;
MCH, m
ean
corp
usc
ula
rhae
mog
lobi
n;
MCHC, m
ean
corp
usc
ula
r
hae
mog
lobi
n
conce
ntr
atio
n;
RDW
, red
cell
distr
ibution
wid
th.
markers and functional outcomes of Zn deciency. Previous studieshave shown that PA reduces Zn absorption in rats similar to humansindicating that rats are a suitable animal model to investigate theeffects of PA on the bioavailability of Zn compounds [1921].
Zn compquate to mwas chosennal Zn absoabsorption accurately these homeand metabo
Test dieamount is sand legumePA diets repexperimentthe test dietrats and deca severe Zn
Zn concof Zn decimarker to compoundstrol diets vlow Zn dietmal Zn dietthe diet witconcentratideciency iconcentrati
Of the superior oncentrationsdisodium Zfed EDTA digains, nal oxide or Zn EDTA disodoutcome ofcate that ZnZn. Howevefed Zn oxidorotate indinot vary apstudies demsulphate [1Zn concentsimilar for aindicating tZn decien
Rats fed parameterschanges indand larger The lower Rsize. These delevated HCtradictory rhave suggeintracellulamay partly water meta[25,29]. In asuggest thaZn-decienounds were added to the test diets at amounts inade-aintain optimal Zn status. This experimental approach
because Zn overload is controlled by decreasing intesti-rption. As the amount of Zn intake increases, fractionaldecreases [22]. Therefore, Zn bioavailability is morequantied at suboptimal Zn supply when activities ofostatic mechanisms are minimised and Zn absorptionlic need is high.ts were supplemented with 0.8% PA sodium salt. Thisimilar to the quantity of PA present in common cereals
grains and is only marginally higher than typical high-orted to contain 0.480.55% PA [23]. Based on previouss in growing rats [24], the Zn concentration chosen fors was expected to induce mild growth retardation in therease Zn content in sensitive tissues without producing
deciency.entration in bone is regarded as a sensitive biomarkerency [24]. Bone Zn concentration is therefore an idealassess differences in Zn bioavailability from different. Femur Zn concentration in rats fed the Zn oxide con-alidated our experimental model. Control rats fed the
had lower femur Zn compared to control rats fed a nor- (30ZnO vs. 8ZnO) indicating that supplementation ofh 8 mg Zn/kg diet was insufcient to maintain bone Znon. Addition of PA to the 8ZnO diet exacerbated the Znn rats as evidenced by a further reduction in femur Znon (8ZnO vs. 8ZnO + PA).7 Zn compounds examined, Zn bioavailability wasly when supplied as an EDTA disodium salt. Zn con-
in both femur and plasma were higher in rats fed EDTAn compared to rats fed the other 6 Zn compounds. Ratssodium Zn also showed superior growth (larger weightbody weight and femur length) compared to rats fed Zngluconate. This superior growth strongly suggested thatium Zn provided more bioavailable Zn since a functional
Zn deciency was improved. These data may also indi- oxide and Zn gluconate provided the least bioavailabler, none of the measured parameters differed for rats
e, Zn sulphate, Zn gluconate, Zn acetate, Zn citrate or Zncating that Zn bioavailability from these compounds didpreciably. These data are consistent with human traceronstrating similar Zn absorption from Zn oxide and Zn
113]. Since liver is a primary organ for Zn metabolism,ration in liver was also measured. Liver Zn content wasll diet groups including control rats fed a normal Zn diethat liver Zn concentration is an insensitive measure ofcy in rats.the test diets showed changes in several haematological
compared to control rats fed normal Zn. The observedicated that Zn-decient rats had higher HCT and Hb
RBCs with a greater amount of haemoglobin per cell.DW indicated that the RBCs were also more uniform inata are in agreement with other studies demonstratingT and Hb in Zn-decient animals [2527], although con-esults have been reported [28]. Experiments in chickssted that a redistribution of water from extracellular tor compartments resulting in a smaller plasma volumeaccount for the increased HCT and Hb [25]. This alteredbolism may be explained by changes to cell membranesddition to an effect on water metabolism, studies alsot Zn deciency causes a haematopoietic defect [27,30].t rats have been reported to have altered red and white
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232 J. Bertinato et al. / Journal of Trace Elements in Medicine and Biology 26 (2012) 227 233
blood cell counts, lower absolute reticulocyte numbers, changedleucocyte population and lower plasma erythropoietin [27,28,30].In our study, red and white blood cell counts were unaffected inZn-decient rats. It should be noted, however, that rats in ourstudy had aaccounting of Zn-deciZn status opounds, onin the haem
Althougentire studyeach rat at for any foomeasuremeconsumptiogested that Zn was notwhen food were very s
Human sEDTA on Zneffect [141discrepanciexperimentsition of thealso been sEDTA was aexpected tothe intestinabsorption be requiredtoxicity per
Althougrior bioavaifemur Zn cplemental disodium sthe PA on Znability in thand therefoof the testedbetter Zn bion the preseaction withavailable fohypothesis is absorbedgested whea higher eqto intestinawould expemagnied i
Fe from pared to othhave demoning the preadvocated for wheat efcacy andulatory issuissues be reCa disodium
EDTA exEDTA in foophytases in
approach for increasing mineral bioavailability from foods high inPA [34]. Phytases have been shown to be effective in increasing Znbioavailability from high PA diets in animals and humans [3538].The potential health benets of improved mineral bioavailability
e usk of tum, d aslatio
othet imundsable presanimive eing f Zn
shoes arent
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sma zlytes Hson R
calc-inco0;31:lberg iron aman Scation
absotz C, D
from differez deducts3;78:ndozacant mcessed mild Zn deciency. Although the exact mechanismsfor the observed changes in the haematological proleent rats are unclear, these data further suggest betterf rats fed EDTA disodium Zn. Of rats fed the 7 Zn com-ly rats fed EDTA disodium Zn did not show differencesatological prole compared to rats fed normal Zn.
h we did not measure food consumption throughout the, food consumption was measured for 24-h periods for4 separate times during the study. We also accountedd spilled by the rats which resulted in more accuratents of actual food eaten. The lack of differences in foodn between rats fed the different diets strongly sug-the better Zn status observed for rats fed EDTA disodium
explained by larger food consumption. Furthermore,consumption was normalised to body weight, valuesimilar across all diet groups.tudies have reported conicting results for the effect of
absorption. Some studies have reported an enhancing6], while others have not [12]. The reason for thesees is not clear but may be due to differences in theal design of the studies or differences in the compo-
test meals. Differences in the EDTA:Zn ratio used haveuggested as a possible explanation [4]. In this study,dded to the diet as a chelated Zn compound. This was
result in a high proportion of Zn bound to EDTA inal lumen. EDTA may be more efcient at increasing Znif it is ingested prebound to Zn. Thus, less EDTA may
to enhance Zn absorption, which is appealing from aspective.h Zn in the form of an EDTA disodium salt showed supe-lability compared to other Zn compounds, the higheroncentration in rats fed the 8ZnO diet (without sup-PA) strongly suggested that Zn supplied as an EDTAalt did not completely abolish the inhibitory effects of
bioavailability. It should also be stressed that bioavail-is study was assessed in the context of a high PA dietre we cannot comment on the relative bioavailabilities
Zn compounds in lower PA diets. It is possible that theoavailability from EDTA disodium Zn may be dependentnce of PA. EDTA-bound Zn may be protected from inter-
PA in the intestinal lumen increasing the amount of Znr uptake by absorptive enterocytes. Consistent with thisis a study in rats suggesting that the Zn-EDTA complex
intact [17]. An alternative mechanism has been sug-re Zn dissociates from EDTA prior to uptake because ofuilibrium dissociation constant for Zn-EDTA comparedl mucosal receptors [4]. In either of these scenarios, onect the enhancing effect of EDTA on Zn absorption to ben the presence of PA.sodium Fe EDTA (NaFeEDTA) is better absorbed com-er Fe compounds [31] and a number of human studiesstrated this compound to be highly effective in reduc-valence of Fe deciency [32]. It has recently been
that NaFeEDTA should be the Fe compound of choiceour fortication programmes given its demonstrated
acceptable organoleptic properties [32]. Although reg-es have slowed its use, it has been urged that thesesolved [32], particularly given the history of safe use of
EDTA as a food additive.hibits low toxicity; however, more widespread use ofds could raise concerns of overexposure [33]. The use of
the processing and manufacturing of foods is another
with ththe ris
In ssupplieprechetion todid nocompofavourin the vious a positexaminlence ostudiesgrammin diffe
Ackno
The(Food tologicwork wCanada
Refere
[1] Hesedg
[2] BronatAsscon
[3] Broam200
[4] Brorec
[5] Broisoon chi
[6] Lo Ntrain y
[7] Arstionincmo
[8] Hamplatro
[9] Gibandlow201
[10] Halon
[11] Hertiiron
[12] Hotionnot
[13] Loppro200
[14] Metiproe of EDTA or phytases will have to be weighted againstoxicity and other practical considerations such as cost.we showed that Zn bioavailability is improved when
EDTA disodium Zn in rats fed a high PA diet. Whereasn of Zn with EDTA enhanced Zn bioavailability, chela-r molecules such as gluconate, acetate, citrate or orotateprove bioavailability compared to common inorganic
(Zn oxide and Zn sulphate). These data indicate ainteraction of Zn with EDTA but not other moleculesence of PA. Given the data presented here and in pre-al [39,40] and human studies [1416] demonstratingffect of EDTA on Zn absorption/bioavailability, studiesthe efcacy of EDTA disodium Zn in reducing the preva-deciency are justied. It is important to note that theseuld be conducted in areas where Zn fortication pro-re intended, since diet composition and PA intakes vary
areas of the world and may inuence the results.
gements
ors would like to thank the Animal Resources Divisiontorate, Health Canada) for assistance with the haema-easurements and feeding and weighing of the rats. Thisfunded by the Bureau of Nutritional Sciences, Health
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EDTA disodium zinc has superior bioavailability compared to common inorganic or chelated zinc compounds in rats fed a high...IntroductionMaterials and methodsAnimal protocol and dietsFemur length measurementZn analysesStatistics
ResultsDiscussionAcknowledgementsReferences