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(1) Present in wholegrain foods, but not refined foods, nor other food sources |
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Quantitative analytical methods for grains and food | GC | [9, 83] |
HPLC | [16, 84, 85] |
Colorimetry | [86–88] |
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Not present in other foods | In food plants, only found in wheat, rye and barley, and genetically related crops, and in low amounts in mango flesh. Very low amounts in beer and animal fat. | [9, 19, 70] |
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Not affected by food processing | AR stable during baking and pasta production | [9, 15] |
Limited effect of fermentation and germination in rye | [89, 90] |
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Variation in raw material | Wheat (350–900 μg/g) | [9, 15, 91, 92] |
Rye (500–1300 μg/g) | [83, 93, 94] |
Barley (30–100 μg/g) | [17, 18] |
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(2) Intake, absorption, distribution, metabolism, and elimination |
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Quantitative analytical methods for biological samples | GC-MS (plasma, erythrocytes, adipose tissue, urinary metabolites) | [41, 55, 57] [46, 59] |
GC-MS/MS (plasma, erythrocytes) | [58] |
LC-MS/MS (plasma) | [56] |
HPLC-CAED (metabolites) | [48, 49] |
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Intake | Average intake in the UK and Sweden estimated to be 12 and 23 mg/d, respectively | [20] |
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Absorption | Pigs: 60–79% depending on dose | [44] |
Humans: 58% ileal absorption | [43] |
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Distribution | Rats: negligible accumulation 100 h after a single dose | [44] |
Adipose: AR-measured in rat and human adipose | [29, 46] |
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Metabolism | Main AR metabolites in humans: DHBA and DHPPA | [47] |
DHBA and DHPPA also measured in human plasma | [49] |
DHPPA extensively glucuronidated in human urine | [59] |
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Elimination | 61% and 31% of a single dose eliminated in faeces and urine in rats | [44] |
Urinary recovery 45–89% depending on dose | [45] |
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(3) Dose response and pharmacokinetics |
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Dose response | Increased dose of AR leads to decreased absorption in pigs | [44] |
Urinary recovery % lower with increased AR dose | [45] |
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Pharmacokinetics | Pigs: : 3 h; : 4 h | [50] |
Humans: : 2.8 h; : 6.7 h; : 4.8 h | [23] |
Plasma metabolites: : 6 h; : 10–16 h Urinary metabolites: : 6 h; : 10–12 h | [52, 53] |
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(4) Determinants of biological concentrations, variation, and reproducibility |
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Determinants of plasma alkylresorcinol concentration | Gender: males have generally higher concentrations | [62, 63] |
Triglycerides and lipoproteins | [27, 63] |
Nonesterified fatty acids | [63] |
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Variation in different populations | Healthy subjects, fasting plasma | |
Mixed results for females with hormone-related cancers | [37, 70] |
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Reproducibility and validity | Intervention studies: good-to-moderate ICC | [54, 63] |
Free-living studies: low ICC | [62] |
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(5) Application in clinical and epidemiological studies |
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Surrogate endpoint for WG intake | Endometrial cancer case-control study: no difference in nonfasting plasma AR | [38] |
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Validation of dietary assessment tools | WG FFQ: correlation with FFQ: 0.53 | [76] |
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Biomarker of compliance to an intervention | WG interventions | [51, 63, 74] |
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