Foeniculum vulgare

The fruits of the plant are used. Contains essential oil (anethole 60-80%, estragole 5-10% and fenchone 7-15%), coumarins and flavonoids (Fitoterapia.net, Dosoky 2021, Badgujar 2014, Raffo 2011, WHO 2010 p127-140, WHO 2007 p136- 149). Ascribed properties: expectorant, antiseptic, spasmolytic and carminative.

The essential oil components (trans-anethole, estragole and fenchone) are excreted in breast milk in small amounts (Denzer 2015, Hausner 2008).
Administration of a commercial infusion containing anise, coriander, fenugreek and fennel to nursing mothers did not produce adverse effects in their nursing children (Wagner 2019).
Excess maternal consumption (2 liters/day) of a mixed infusion of anise, galega, fennel and licorice caused lethargy, vomiting and hypotonia in two infants and their mothers (Rosti 1994).

Anethole, at high doses, is neurotoxic and convulsive (Bahr 2019, Skalli 2011, Burkhard 1999) and has weak mutagenic activity.
Fennel has estrogenic activity (Dosoky 2021, Amir 2011, Türkyilmaz 2008, EMA 2007, Javidnia 2003, Albert 1980) and has caused premature thelarche in young girls who were taking it for treatment of abdominal cramps (Türkyilmaz 2008).
Estragole has a carcinogenic effect in animals. In humans, at recommended doses, this effect has not been found.
It has not been possible to demonstrate a greater antioxidant capacity in the milk of women who took mixed infusions of this and other plants (Kavurt 2013).
Essential oils rich in anethole should not be consumed during lactation, pregnancy and if you have estrogen-dependent cancer (Dosoky 2021).

There is no credible evidence that it increases milk production (Sibeko 2021, Foong 2020, ABM 2018 and 2011, Sachs 2013, Mortel 2013). The administration of infusions of fennel or a mixture of herbs containing fennel to nursing mothers did not result in an increase in prolactin (Vafaei 2018, Özalkaya 2018), nor greater weight gain in infants (Özalkaya 2018), although greater production was noted of milk than in the control groups (Özalkaya 2018).
Reinforcing maternal self-confidence, assessing and correcting breastfeeding problems, and effectively supporting breastfeeding mothers are the best galactogogues (ABM 2018, Mannion 2012).

It is one of the most widely used plants in numerous cultures, including during pregnancy and lactation (Sibeko 2021, Kaygusuz 2021, Sibeko 2021, Badgujar 2014, Sim 2013, Zaffani 2006).
Fennel has been used to treat infant colic (Harb 2018, Gordon 2018, Bruyas 2012, Abdulrazzaq 2009, Savino 2005) and as a galactogogue (Sim 2013, Muresan 2011, Ayers 2000) and there have been very few reported side effects (Gordon 2018).

The moderate consumption in quantity and duration of fennel infusions would be compatible with breastfeeding.

Culinary consumption as a food or aromatic condiment is safe.

Precautions when taking plant preparations:
1. Make sure they are from a reliable source: poisonings have occurred due to confusion of one plant with another with toxic properties, poisonings due to containing heavy metals extracted from the soil, and food poisoning due to contamination with bacteria or fungi (Anderson 2017).
2. Do not take in excess; follow the recommendations of expert phytotherapy professionals. “Natural” products are not good in any quantity: plants contain active substances from which much of our traditional pharmacopoeia has been obtained and can cause poisoning or act as endocrine disruptors (contain phytoestrogens: Powers 2015) if consumed in quantity or for an exaggerated time.