Regular Consumption of a High-Phytate Diet Reduces the Inhibitory Effect of Phytate on Nonheme-Iron Absorption in Women with Suboptimal Iron Stores,

Armah, Seth M.; Boy, Erick; Chen, Dan; Candal, Priscila; Reddy, Manju B.

doi:10.3945/jn.114.209957

Cited by 40 publications

(61 citation statements)

References 28 publications

(39 reference statements)

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“…Phytates coming from other parts of the subjects’ habitual diet may have nullified any effect of the low-phytate bread on iron bioavailability. Similar to our findings, an 8 week high-phytate diet had no effect on ferritin, transferrin receptor, and hepcidin concentrations in 28 females [ 34 ].…”

Section: Discussionsupporting

confidence: 91%

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

et al. 2018

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Purpose To investigate the effects of eating wholegrain rye bread with high or low amounts of phytate on iron status in women under free-living conditions. Methods In this 12-week, randomized, parallel-design intervention study, 102 females were allocated into two groups, a high-phytate-bread group or a low-phytate-bread group. These two groups were administered: 200 g of blanched wholegrain rye bread/day, or 200 g dephytinized wholegrain rye bread/day. The bread was administered in addition to their habitual daily diet. Iron status biomarkers and plasma alkylresorcinols were analyzed at baseline and post-intervention. Results Fifty-five females completed the study. In the high-phytate-bread group ( n = 31) there was no change in any of the iron status biomarkers after 12 weeks of intervention ( p > 0.05). In the low-phytate bread group ( n = 24) there were significant decreases in both ferritin (mean = 12%; from 32 ± 7 to 27 ± 6 µg/L, geometric mean ± SEM, p < 0.018) and total body iron (mean = 12%; from 6.9 ± 1.4 to 5.4 ± 1.1 mg/kg, p < 0.035). Plasma alkylresorcinols indicated that most subjects complied with the intervention. Conclusions In Swedish females of reproductive age, 12 weeks of high-phytate wholegrain bread consumption had no effect on iron status. However, consumption of low-phytate wholegrain bread for 12 weeks resulted in a reduction of markers of iron status. Although single-meal studies clearly show an increase in iron bioavailability from dephytinization of cereals, medium-term consumption of reduced phytate bread under free-living conditions suggests that this strategy does not work to improve iron status in healthy women of reproductive age.

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Section: Discussionsupporting

confidence: 91%

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

et al. 2018

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“…Furthermore, in contrast to older understanding [57], there appears to be adaptation to the inhibitory effects of phytate on iron absorption [58]. Therefore, acute absorption studies may underestimate the bioavailability of minerals from plant foods such as soy.…”

Section: Nutrient Contentmentioning

confidence: 99%

Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature

2016

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Soyfoods have long been recognized as sources of high-quality protein and healthful fat, but over the past 25 years these foods have been rigorously investigated for their role in chronic disease prevention and treatment. There is evidence, for example, that they reduce risk of coronary heart disease and breast and prostate cancer. In addition, soy alleviates hot flashes and may favorably affect renal function, alleviate depressive symptoms and improve skin health. Much of the focus on soyfoods is because they are uniquely-rich sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor modulators. Despite the many proposed benefits, the presence of isoflavones has led to concerns that soy may exert untoward effects in some individuals. However, these concerns are based primarily on animal studies, whereas the human research supports the safety and benefits of soyfoods. In support of safety is the recent conclusion of the European Food Safety Authority that isoflavones do not adversely affect the breast, thyroid or uterus of postmenopausal women. This review covers each of the major research areas involving soy focusing primarily on the clinical and epidemiologic research. Background information on Asian soy intake, isoflavones, and nutrient content is also provided.

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“…However, the evidence supporting this antinturient function have mostly been single meal studies utilizing hydrolyzable tannic acid or oligomeric epigallocatechin gallate found in tea. Studies that have explored long-term consumption of tannins [21, 22] and other antinutritional factors [23, 24], as well as epidemiological studies [25–27] have questioned whether potent tannin-non-heme iron inhibition is sustained over time.…”

Section: Introductionmentioning

confidence: 99%

Salivary proline-rich protein may reduce tannin-iron chelation: a systematic narrative review

et al. 2017

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BackgroundTannins are often cited for antinutritional effects, including chelation of non-heme iron. Despite this, studies exploring non-heme iron bioavailability inhibition with long-term consumption have reported mixed results. Salivary proline-rich proteins (PRPs) may mediate tannin-antinutritional effects on non-heme iron bioavailability.AimTo review evidence regarding biochemical binding mechanisms and affinity states between PRPs and tannins, as well as effects of PRPs on non-heme iron bioavailability with tannin consumption in vivo.MethodsNarrative systematic review and meta-analysis. Common themes in biochemical modeling and affinity studies were collated for summary and synthesis; data were extracted from in vivo experiments for meta-analysis.ResultsThirty-two studies were included in analysis. Common themes that positively influenced tannin-PRP binding included specificity of tannin-PRP binding, PRP and tannin stereochemistry. Hydrolyzable tannins have different affinities than condensed tannins when binding to PRPs. In vivo, hepatic iron stores and non-heme iron absorption are not significantly affected by tannin consumption (d = −0.64-1.84; −2.7-0.13 respectively), and PRP expression may increase non-heme iron bioavailability with tannin consumption.ConclusionsIn vitro modeling suggests that tannins favor PRP binding over iron chelation throughout digestion. Hydrolyzable tannins are not representative of tannin impact on non-heme iron bioavailability in food tannins because of their unique structural properties and PRP affinities. With tannin consumption, PRP production is increased, and may be an initial line of defense against tannin-non-heme iron chelation in vivo. More research is needed to compare competitive binding of tannin-PRP to tannin-non-heme iron complexes, and elucidate PRPs’ role in adaption to non-heme iron bioavailability in vivo.Electronic supplementary materialThe online version of this article (doi:10.1186/s12986-017-0197-z) contains supplementary material, which is available to authorized users.

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Regular Consumption of a High-Phytate Diet Reduces the Inhibitory Effect of Phytate on Nonheme-Iron Absorption in Women with Suboptimal Iron Stores,

Abstract: We found that habitual consumption of an HP diet can reduce the negative effect of phytate on nonheme-iron absorption among young women with suboptimal iron stores. Future studies are needed to explore possible mechanisms. This trial was registered at clinicaltrials.gov as NCT02370940.

Cited by 40 publications

References 28 publications

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

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

Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature

Salivary proline-rich protein may reduce tannin-iron chelation: a systematic narrative review

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