In epidemiological and clinical studies, the most common nutritional tool to assess dietary flavonol intake is the food frequency questionnaire (FFQ), which needs to contain a detailed list of plant-based foods and be previously validated. Our study aimed to assess the accuracy of dietary flavonol (quercetin, kaempferol, and isorhamnetin) intake from a food frequency questionnaire (FFQ) compared to fasting plasma flavonol concentrations, as biomarkers of exposure, in breast cancer patients. In a consecutive case series, newly diagnosed patients with breast cancer (n = 140) were recruited at Nour-Nejat Hospital, Tabriz, Iran. Flavonol intake was assessed using a validated FFQ. Plasma flavonol concentrations were measured using high-performance liquid chromatography-ultraviolet detection. The accuracy of dietary status was evaluated using a receiver operating characteristic (ROC) and area under the ROC curve (AUC). Dietary status was shown in dichotomous using ROC-cutoff point. The plasma concentrations of quercetin were moderately correlated with dietary intake of quercetin (Spearman's correlation coefficient (r_s) = 0.188, P < .05; r_partial= 0.330, P < .01) and plasma concentrations of isorhamnetin (r_s = 0.337, P < .001). A linear correlation between dietary levels and plasma concentrations of kaempferol was attained (r_partial = 0.240, P < .05). Using a ROC-cutoff of 61.9 nmol/L for plasma quercetin (test reference), we were able to differentiate between lower and higher consumers of quercetin with an AUC_{ROC-based reference} =0.65 (P < .01, sensitivity = 61.8%, and specificity = 60.0%). Using a plasma kaempferol concentration of 60.1 nmol/L (ROC-cutoff), it was possible to detect significant differences between higher and lower intakes of kaempferol (AUC_{ROC-based reference} = 0.64, P < .05). The correlations and diagnostic performance with plasma concentrations could present a significant accuracy rate (validity), which seems acceptable for a nutritional questionnaire (FFQ) to assess intakes intake levels of quercetin and kaempferol. An improvement in the accuracy of the flavonol exposure can provide more precise relationship with health outcomes, which may increase their clinical significance.

在流行病学和临床研究中，评估膳食黄酮醇摄入量的最常见营养工具是食物频率问卷 (FFQ)，该问卷需要包含植物性食物的详细清单并事先经过验证。我们的研究旨在评估食物频率问卷 (FFQ) 中膳食黄酮醇（槲皮素、山奈酚和异鼠李素）摄入量与作为暴露生物标志物的乳腺癌患者空腹血浆黄酮醇浓度相比的准确性。在连续的病例系列中，在伊朗大不里士的 Nour-Nejat 医院招募了新诊断的乳腺癌患者 (n = 140)。使用经过验证的 FFQ 评估黄酮醇的摄入量。使用高效液相色谱-紫外检测器测量血浆黄酮醇浓度。使用接受者操作特征 (ROC) 和 ROC 曲线下面积 (AUC) 评估饮食状态的准确性。使用 ROC 截止点以二分法显示饮食状态。槲皮素的血浆浓度与槲皮素的膳食摄入量呈中度相关（Spearman 相关系数（r_s ) = 0.188, P < .05; r _partial = 0.330, P < .01) 和血浆异鼠李素浓度 (r _s  = 0.337, P < .001)。膳食水平与山柰酚血浆浓度之间存在线性相关性（r_偏 = 0.240，P < .05）。使用血浆槲皮素的 ROC 截止值为 61.9 nmol/L（测试参考），我们能够区分较低和较高的槲皮素消费者，基于 AUC _{ROC 的参考}=0.65（P< .01，敏感性 = 61.8%，特异性 = 60.0%）。使用 60.1 nmol/L 的血浆山柰酚浓度（ROC 截止值），可以检测到山柰酚摄入量较高和较低之间的显着差异（基于 AUC _{ROC 的参考} = 0.64，P < .05）。与血浆浓度的相关性和诊断性能可能呈现出显着的准确率（有效性），这对于评估槲皮素和山奈酚摄入量的营养问卷 (FFQ) 似乎是可以接受的。黄酮醇暴露准确性的提高可以提供与健康结果更精确的关系，这可能会增加其临床意义。