To the Editor: In their study of phytoestrogens and risk of lung cancer, Dr Schabath and colleagues report on the intake of lignans in a US population. Their results, while interesting, are discrepant with those of other studies. In their article, the total intake of lignans was calculated as the sum of the plant lignans secoisolariciresinol and matairesinol and the mammalian enterolignans enterodiol and enterolactone. Enterolignans are not present in foods but can be determined via in vitro fermentation. Enterolignans are formed by bacteria in the colon at the expense of plant lignans. Summing plant lignans and enterolignans counts food contribution to the lignan intake twice. As a result, the estimates of total lignan intakes and the odds ratios based on these (in Tables 2, 4, and 6) may be biased. Apart from secoisolariciresinol and matairesinol, other plant lignans can also be converted to enterolignans. We determined the intake of secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol in a Dutch population using a comprehensive food composition database and found a mean intake of 1240 μg/d. Although we included these additional plant lignans, which made up 75% of the total intake, this intake is still much lower than the 5400 μg/d (or approximately 5000 μg/d not including enterolignans) reported by Schabath et al. Regarding previously published intakes of secoisolariciresinol and matairesinol, daily intakes of 175 to 645 μg/d have been reported in a US population. Similar intakes were reported by us (303 μg/d) and by a Finnish group (434 μg/d). Boker et al reported higher intakes in a Dutch population (1110 μg/d), but they used category scores based on the highest values reported in the literature, which certainly leads to overestimation. In the study by Schabath et al, tea and coffee contributed 80% of the intake of secoisolariciresinol, whereas in the other studies their contribution never exceeded 44%. This high contribution suggests that the secoisolariciresinol contents of tea and coffee that were used are not correct. Pillow at al reported tea to contain 1090 μg/100 mL and coffee 520 μg/ 100 mL, whereas in our laboratory, contents obtained with liquid chromatography mass spectrometry were only 6 μg/ 100 mL for tea and 12 μg/100 mL for coffee. These discrepant lignan contents for coffee and tea may also have led to misclassification of participants and erroneous odds ratios.