By Hilary Metcalfe
When I was breastfeeding, everyone talked to me about calories. “Eat more toast, have another bowl of porridge, you’re burning 500 calories a day.”
But no one warned me about what was really draining out of me: the invisible minerals. Zinc, selenium, iodine, magnesium, tiny nutrients you can’t see, can’t track on a fitness app, but which your baby depends on for immune defence, brain growth, and cellular repair.
Every feed was a transfer. Not just energy, but trace minerals moving from my body into hers. And while she thrived, I often felt brittle, hair shedding, nails weak, moods swinging, my thyroid wobbling. That’s when I realised: breastfeeding isn’t just about calories, it’s about micronutrient survival.
This blog is my attempt to shine a light on the overlooked mineral economy of breastfeeding, and why replenishing it is as essential as rest or hydration.
Zinc: The Builder of Milk and Immunity
Zinc is one of the most abundant trace minerals in breastmilk, and it’s essential for cell growth, wound healing, and immune defence. Babies rely on it for gut development and resistance to infection. For mothers, zinc supports tissue repair after birth and stabilises hormone receptors.
But here’s the catch: zinc isn’t stored well in the body, so levels depend on daily intake and absorption (King, 2000). Deficiency can mean slower healing, increased infection risk, and even reduced milk zinc content.
Nettle and oat straw, both in our Breastfeeding Herbata, are rich natural sources of zinc, gentle, bioavailable, and designed to restore what’s lost.
Selenium: The Antioxidant Shield
Selenium is less talked about, but it plays a critical role in reducing oxidative stress, regulating thyroid hormones, and enhancing immune defence. Babies need it for brain development and protection against cellular damage.
Low selenium has been linked with increased risk of postpartum thyroiditis and even higher susceptibility to certain cancers (Rayman, 2012). For lactating women, deficiency may affect the antioxidant capacity of milk, leaving both mother and baby more vulnerable.
Moringa leaves are a particularly rich source of selenium, alongside their iron and vitamin A content, which is why they’re a cornerstone of the Breastfeeding Herbata.
Iodine: The Thyroid Regulator
Breastfeeding women have higher iodine requirements than pregnancy, about 250–290 µg/day. Why? Because iodine fuels thyroid hormones, which regulate metabolism for both mother and baby. Adequate iodine in breastmilk is essential for infant brain and cognitive development (Zimmermann, 2009).
Yet mild to moderate deficiency is common, even in developed countries, especially when women cut back on iodised salt. Signs in mothers can include fatigue, hair loss, and low milk supply, symptoms often dismissed as “normal postpartum.”
While herbs like nettle and oat straw contain supportive minerals, pairing Herbata with iodine-rich whole foods, like seaweed, dairy, or eggs, ensures this critical nutrient makes its way into milk.
Magnesium: The Calmer & Stabiliser
Breastfeeding is a constant drain on magnesium, which is involved in over 300 enzymatic reactions: muscle relaxation, nerve signalling, blood sugar regulation, and stress response (Volpe, 2013).
Low magnesium can leave mothers anxious, sleepless, and tense, and it’s one of the quiet drivers behind postpartum fatigue. For babies, magnesium in milk supports bone growth and neuromuscular development.
Oat straw is a traditional galactagogue in part because it’s high in magnesium, supporting both let-down and maternal calm. Combined with tulsi and vervain in Breastfeeding Herbata, it creates a nervous system- friendly infusion that makes breastfeeding feel more manageable.
Why Trace Minerals Matter for Cancer Risk Too
Beyond milk supply, trace minerals are tied to long-term maternal health. Selenium and zinc, for example, play roles in DNA repair and antioxidant defence, lowering the risk of certain cancers. Iodine sufficiency has been linked with reduced risk of breast and endometrial cancer, likely through stabilising hormone pathways (Venturi & Venturi, 2009).
For me, this shifted the way I thought about “nourishing myself.” It wasn’t just about surviving the newborn months, it was about investing in my long-term resilience.
Breastfeeding isn’t just calorie-draining. It’s mineral-draining. Every drop of milk carries zinc, selenium, iodine, and magnesium to your baby, nutrients that are non-negotiable for growth, immunity, and development. And every drop leaves your own stores lower.
That’s why rituals matter. A daily infusion like Breastfeeding Herbata is more than a calming cup. It’s hydration plus trace minerals, supporting both digestion and micronutrient transfer into milk. Paired with mineral-rich foods, it builds the invisible scaffolding of recovery and supply.
ABOUT HILARY
Hilary is the Co-Founder of the SABI, a Holistic Nutritionist, natural, whole foods Chef, product developer and advocate for women getting to know their bodies, cycles and selves better. Born in Los Angeles, California and raised in Baja California, Mexico, she now lives in Los Cabos with her partner Kees, a curly-tailed rescue dog from Curacao, Flint and her rainbow babies Paloma and Bea.
HORMONAL & PROUD
Created as a brand to help women navigate the toughest moments in pregnancy, childbirth, postpartum — and practically every stage of life –– The SABI is changing the narrative around our hormones from one of taboo, embarrassment, and loneliness to awareness and even, pride. As more than a wellness brand, The SABI offers a carefully-crafted line of products to carry you through your hormonal journey, including rituals, supportive tools, and ancient herbal remedies that have been tested time and time again by women and now come backed by medicine. The SABI is a blend of science and nature conceived by women who have experienced the joys and deep struggles of bringing a child into the world, the pains of a heavy, difficult period, miscarriage, and difficulty conceiving.
We invite you to get to know your body and its cycles better –– to really understand what is going on inside. Learn to use your hormones to your advantage no matter your stage of life, and know that you can support and balance your hormone levels. We are here to help with the information, understanding and natural tools to support your body and the emotional process along with it.
DISCLAIMER
The SABI blog and articles are not meant to instruct or advise on medical or health conditions, but to inform. The information and opinions presented here do not substitute professional medical advice or consultations with healthcare professionals for your unique situation.
References
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King JC. Zinc: an essential but elusive nutrient. Am J Clin Nutr. 2000.
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Rayman MP. Selenium and human health. Lancet. 2012.
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Zimmermann MB. Iodine deficiency in pregnancy and lactation. Am J Clin Nutr. 2009.
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Volpe SL. Magnesium in disease prevention. Adv Nutr. 2013.
