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01-09-2020 | Reply
Reply to the comments by Vorland et al. on our paper: “low-phytate wholegrain bread instead of high-phytate wholegrain bread in a total diet context did not improve iron status of healthy Swedish females: a 12-week, randomized, parallel-design intervention study”
Published in: European Journal of Nutrition | Issue 6/2020
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We thank Vorland et al. for their interest in our article and helpful comments relating to our statistical analysis and reporting. We have now reported the non-significant p values in Table 1 and agree that these will be useful for powering future studies in the area of phytate reduction and iron status. We acknowledge that we have discussed within-group differences more than between-group differences, mainly because the results were counter to our hypothesis that lowering the dietary phytate should lead to improved iron status and thus required further explanation. This is also related to the between-group findings, as it would have been expected that iron status would improve with reduced phytate. During re-analysis, we have detected a between-group difference for total body iron, which supports our overall conclusion that the low-phytate bread reduced iron status, most likely due to the strong acidic flavour which altered dietary habits.
Table 1
Data at baseline and after 12 weeks of intervention
|
High-phytate bread group (n = 31)
|
Low-phytate bread group (n = 24)
|
||||||
|---|---|---|---|---|---|---|---|
|
Baseline
|
Post-intervention
|
p value (within group)
|
Baseline
|
Post-intervention
|
p value (within group)
|
p value (betwee groups)
|
|
|
BMI
(kg/m2)
|
22.6 ± 0.6
|
22.8 ± 0.6
|
0.326
|
21.7 ± 0.5
|
21.8 ± 0.5
|
0.145
|
0.774
|
|
Hb
(g/L)
|
134 ± 1
|
136 ± 1
|
0.155
|
132 ± 1
|
134 ± 1
|
0.178
|
0.682
|
|
Hepcidin
(ng/ml)
|
11.8 ± 2.4
|
11.8 ± 2.0
|
0.704
|
13.6 ± 2.7
|
9.5 ± 2.8
|
0.433
|
0.343
|
|
Ferritin (µg/L)
|
31 ± 4
|
32 ± 4
|
0.859
|
33 ± 3
|
27 ± 6
|
0.018
|
0.251
|
|
TfR
(mg/L)
|
2.7 ± 0.1
|
2.7 ± 0.1
|
0.409
|
2.9 ± 0.1
|
2.9 ± 0.6
|
0.489
|
0.491
|
|
Body Fe a(mg/kg)
|
7.0 ± 0.4
|
7.0 ± 0.5
|
0.738
|
6.9 ± 0.4
|
5.4 ± 0.5
|
0.035
|
0.035
|
|
Alkyl-resorcinols
(mmol/L)
|
351 ± 52
|
467 ± 77
|
0.120
|
266 ± 68
|
522 ± 127
|
0.002
|
0.139
|
|
C17:C21 ratio
|
0.16 ± 0.02
|
0.23 ± 0.02
|
0.018
|
0.15 ± 0.02
|
0.29 ± 0.03
|
0.001
|
0.051
|