## 3 Results and Discussion
### Analysis of Phytoestrogens in Food, Serum and Urine  
As part of the validation process, regional commercial food (\(n\) = 6, Table 4), urine (12 h) and serum samples from healthy women (\(n\) = 10, Table 5) were analyzed. The CVs of samples processed in duplicate ranged from 2-13% for food, 2-8% for serum and 1-13% for urine (except for resveratrol with 20%), thus the proposed method presents adequate repeatability. A representative MS chromatogram of a commercial food sample (turkey ham), serum and urine from a healthy woman is illustrated in Figure 3.  
compared to previous studies (0.02-10.02 ug/100 g [22; 46] and not detected-66 ug/100 g [22; 28; 46], respectively). The high levels of naringenin in beans could be explained by the use of chili, onion, tomato and other vegetables as conditions. The high levels in turkey ham could be explained by the use of soy as an additive to reduce the price of processed food while adjusting protein levels, with isoflav content similar to soy-based meat products (465-4430 ug/100 g) [48; 49]. The Mexican consumer omnudsman has recently published notifications that some ham products in Mexico do not comply with the percentage of meat advertised, omit the added soy on their labels, and could represent a risk as allergens for consumers [50]. Our study reported the first comprehensive phytoestrogens content of highly consumed Mexican food items that are a source of wide types of phytoestrogen. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Lettuce,** & **Beefsteak** & **Tomato,** & **Mandarin,** & **Pinto Beans,** & **Turkey Ham** \\  & **Raw** & **Tomato,** & **Cooked** & **Puree** & **Raw** & **Cooked** & **Turkey Ham** \\ \hline Resveratrol & - & - & - & - & - & - \\ Biochanin A & - & - & - & 0.06 & 0.04 & - \\ Seciosolariciresionol & 0.64 & - & - & 2.51 & 14.24 & - \\ Luteolin & - & 0.15 & 0.6 & 0.1 & - & - \\ Cournestrol & - & 0.18 & 0.05 & 0.02 & 0.59 & - \\ Formonontein & - & 0.41 & 0.36 & 0.04 & - & - \\ Daidzein & 0.04 & - & 0.7 & - & 3.5 & 395.24 \\ Enterodiol & 0.21 & - & - & 4.87 & - & - \\ Equol & - & - & - & 11.6 & - & - \\ Kaempferol & 0.01 & 0.07 & 1.95 & - & 406.41 & 0.64 \\ Glycitein & - & - & - & 0.53 & - & 172.39 \\ Matairesinol & - & 1.32 & 1.91 & 0.02 & - & - \\ Naringenin & 0.06 & 140.6 & 322.39 & 83.9 & 81.97 & 13.17 \\ Quercetin & 0.02 & 0.33 & 16.5 & 0.99 & 1 & - \\ Enterolactone & - & - & 0.02 & 0.03 & - & 0.09 \\ Genistein & 0.03 & 0.24 & 0.89 & - & 1.96 & 356.24 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Phytoestrogen content (ug/100 g of wet weight) of regional food from North Mexico. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Phytoestrogen**} & \multirow{2}{*}{**Serum (ng/mL)**} & \multicolumn{2}{c}{**Urine**} \\ \cline{3-4}  & & **(ng/mL)** & **(ng/mmol Creatinine)** \\ \hline Resveratrol & 0.28 \(\pm\) 0.36 & 1.53 \(\pm\) 1.63 & 0.20 \(\pm\) 0.21 \\ Biochanin A & 0.53 \(\pm\) 0.38 & 1.15 \(\pm\) 0.75 & 0.15 \(\pm\) 0.10 \\ Seciosolarisiresinol & \textless{}LOD & 1.81 \(\pm\) 1.96 & 0.24 \(\pm\) 0.26 \\ Luteolin & 7.08 \(\pm\) 1.54 & 2.51 \(\pm\) 1.59 & 0.33 \(\pm\) 0.21 \\ Coumestrol & 0.65 \(\pm\) 0.44 & 1.01 \(\pm\) 1.54 & 0.13 \(\pm\) 0.20 \\ Formonontein & 0.03 \(\pm\) 0.09 & 1.74 \(\pm\)1.87 & 0.23 \(\pm\) 0.24 \\ Daidzein & 4.50 \(\pm\) 4.80 & 148.77 \(\pm\) 193.00 & 19.51 \(\pm\) 25.31 \\ Enterodiol & 0.07 \(\pm\) 0.20 & 0.91 \(\pm\) 2.04 & 0.04 \(\pm\) 0.08 \\ Equiol & 8.51 \(\pm\) 4.55 & 36.38 \(\pm\) 37.60 & 4.77 \(\pm\) 4.93 \\ Kaempferol & 20.14 \(\pm\) 6.43 & 48.61 \(\pm\) 97.48 & 6.37 \(\pm\) 12.78 \\ Glycitein & 0.56 \(\pm\) 1.44 & 52.71 \(\pm\) 71.2 & 6.91 \(\pm\) 9.35 \\ Matairesinol & \textless{}LOD & 1.58 \(\pm\) 4.15 & 0.21 \(\pm\) 0.54 \\ Naringenin & 1.76 \(\pm\) 0.68 & 78.43 \(\pm\) 89.57 & 10.28 \(\pm\) 11.75 \\ Quercetin & 5.53 \(\pm\) 3.29 & 1.40 \(\pm\) 1.17 & 0.18 \(\pm\) 0.15 \\ Enterolactone & 0.61 \(\pm\) 0.47 & 36.03 \(\pm\) 27.31 & 4.72 \(\pm\) 3.58 \\ Genistein & 4.85 \(\pm\) 5.12 & 56.52 \(\pm\) 76.27 & 7.41 \(\pm\) 10.00 \\ \hline \hline \end{tabular}
\end{table}