Lactational transfer of sulforaphane-N-acetylcysteine in vivo and in human breast milk

Abstract

Sulforaphane (SFN) is a bioactive phytonutrient found in cruciferous vegetables. There is a lack of detailed information on the lactational transfer of SFN and SFN metabolites, and potential pharmacological effects on breastfeeding infants. We carried out two maternal supplementation studies in a mouse model, wherein lactating dams received either vehicle, 300 or 600 ppm SFN from postnatal day (PND) 1 to 5, or in a second experiment, vehicle or 600 ppm SFN from PND 1 to 14. The parent compound was only detectable in milk and plasma from dams receiving 600 ppm SFN for five days. The predominant metabolite SFN-N-acetylcysteine (SFN-NAC) was readily detected in milk from dams receiving 300 and 600 ppm SFN for five days or 600 ppm for 14 days. Maternal SFN-NAC plasma levels were elevated in both 600 ppm groups. Maternal hepatic and pulmonary expression of NRF2-related genes, Nqo1, Gsta2, Gstm1, and Gstp1, were significantly increased, generally following a dose-response; however, offspring induction varied. PND5 neonates in the 600-ppm group exhibited significantly elevated expression of Nqo1, Gsta2, and Gstp1 in liver, and Gstm1 and Gstp1 in lung. Findings support maternal dietary supplementation with SFN induces NRF2-related gene expression in neonates via lactational transfer of SFN-NAC. However, NQO1 enzyme activity was not significantly elevated, highlighting the need to optimize dosing strategy. Additionally, in a pilot investigation of lactating women consuming a typical diet, without any purified SFN supplementation, 7 out of 8 breast milk samples showed SFN-NAC above the limit of quantification (LOQ). Notably, the one sample below the LOQ was collected from the only participant who reported no consumption of cruciferous vegetables in the past 24 h. The parent compound was not detected in any of the human breast milk samples. Overall, these data indicate lactational transfer of SFN-NAC at dietary relevant levels. Future studies are needed to evaluate pharmacokinetics and pharmacodynamics of lactational transfer for potential preventive or therapeutic effects in breastfeeding children.

Keywords: Breast milk; Cruciferous vegetables; Lactational transfer; NRF2; Nutraceutical.

Figure 1.

Sulforaphane-N-acetylcysteine (SFN-NAC) metabolite levels (mean ± SD) detected in murine milk and plasma following 5 days of 0, 300 or 600 ppm maternal dietary SFN supplementation post-delivery, i.e., offspring postnatal day (PND) 5 (A-B, analyzed via ANOVA) or 2 weeks of 0 or 600 ppm maternal SFN dietary supplementation, i.e., offspring PND 14 (C-D, analyzed via t test). Experimental groups represent 2–5 dams/group. *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001.

Figure 2.

Fold change of Nqo1 in murine maternal (A-B) and neonate (C-D) liver and lung tissue collected following 5 days of 0, 300 or 600 ppm maternal dietary sulforaphane (SFN) supplementation post-delivery, i.e., offspring PND 5. Error bars represent SD. Experimental groups represent 2–5 dams/group and at least 3 neonates per group (across litters). Data analyzed via ANOVA. *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001.

Figure. 3.

Fold change of Gsta2, Gstm1, and Gstp1 in murine maternal (A-B) and neonate (C-D) liver and lung tissue collected following 5 days of 0, 300 or 600 ppm maternal dietary sulforaphane (SFN) supplementation post-delivery, i.e., offspring PND 5. Error bars represent SD. Experimental groups represent 2–5 dams/group and at least 5 neonates per group (across litters). Data analyzed via ANOVA. *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001.

Figure 4.

Fold change of Nqo1 in murine maternal (A-B) and neonate (C-D) liver and lung tissue collected following 2 weeks of 0 or 600 ppm maternal dietary sulforaphane (SFN) supplementation post-delivery, i.e., offspring PND 14. Error bars represent SD. Experimental groups represent 3 dams/group and at least 6 neonates per group (across litters). Data analyzed via t test. *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001.

Figure 5.

Fold change of Gsta2, Gstm1, and Gstp1 in murine maternal (A-B) and neonate (C-D) liver and lung tissue collected following 2 weeks of 0 or 600 ppm maternal dietary sulforaphane (SFN) supplementation post-delivery, i.e., offspring PND 14. Error bars represent SD. Experimental groups represent 3 dams/group and at least 6 neonates per group (across litters). Data analyzed via t test. *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001.