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The relation of soy intake and isoflavone levels in nipple aspirate fluid
Author(s) -
Maskarinec Gertraud,
Hebshi Sandra,
Custer Laurie,
Franke Adrian A.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a371-b
Subject(s) - isoflavonoid , chemistry , isoflavones , urine , pon1 , phytoestrogens , chromatography , food science , high performance liquid chromatography , estrogen , medicine , flavonoid , biochemistry , antioxidant , genotype , gene
Given the possible breast cancer preventive effects of isoflavones, substances with an estrogen‐like structure that are primarily found in soy beans, it is of interest to assess levels directly in the breast. The objective of this pilot study was to establish the presence of isoflavones in nipple aspirate fluid (NAF). In a pilot study with 11 women, NAF and urine samples were collected at baseline and after one month of consuming two servings of soy milk per day. In a parallel investigation, one woman donated NAF, blood, and urine on the same day after consuming different amounts of soy on nine different occasions. NAF was collected with an aspirator, diluted 1:11, and stored at −20°C. Isoflavonoids in 20 μL of NAF, as well as in serum and urine were liquid‐liquid extracted after enzymatic hydrolysis followed by liquid chromatography electrospray ionization high resolution tandem mass spectrometry (LC/ESI‐h‐MS‐MS) analysis using triply 13C labeled internal isoflavonoid standards. After the 30‐day soy intervention, median NAF yield, urinary isoflavonoid excretion, and isoflavonoid levels in NAF increased approximately two‐fold. For the nine samples collected in one subject, isoflavonoids measured in NAF, plasma, and urine were highly correlated with the number of daily soy servings and with each other. This pilot study indicated that isoflavonoids in NAF are ten times lower than in plasma and are closely related to soy intake and to levels of isoflavonoids in urine and plasma. Our findings indicate that isoflavonoids can be successfully measured in small amounts of NAF.