Breastfeeding mums are at risk of silent nutritional deficiency, says a clinical nutritionist and food scientist.
Kristy Petersen said omega-3 and vitamin D deficiencies during lactation were more common than most people realised.
When a breastfeeding mother doesn’t consume enough omega-3 fatty acids, particularly docosahexaenoic acid (DHA), her body will draw on its own stores, often from the brain and eyes.
“This can leave the mother depleted, leading to increased fatigue, mood disturbances, poor immune function, and even longer-term cognitive issues,” Kristy said.
“Unfortunately, the signs of nutritional depletion are not overtly obvious.”
For babies, omega-3s are essential for healthy brain, eye, and nervous system development.
Insufficient DHA in breast milk has been associated with slower cognitive growth, reduced visual acuity, and potential behavioural challenges in early childhood.
“Many women avoid oily fish, don’t supplement, or simply don’t know how critical omega-3 intake is while breastfeeding,” Kristy said.
“It’s a hidden nutritional risk with long-lasting effects.”
Ensuring adequate DHA intake – about 200 to 300mg per day – can protect both mother and baby from deficiency-related complications.
“Whether through carefully chosen food sources or supplementation, omega-3s should be a non-negotiable part of every breastfeeding mum’s diet,” Kristy said.
“It’s not just about milk supply or calories, it’s about the right nutrients, at the right time, in the right form.”
Kristy said vitamin D was also essential for breastfeeding mums.
“Many mothers don’t eat enough vitamin D-rich foods and aren’t supplementing. They simply don’t know they’re at risk,” she said.
“Low vitamin D can cause severe fatigue, increased postnatal depression risk, poor calcium absorption, and long-term consequences like osteoporosis.
“Because vitamin D is fat-soluble, if a mother was already deficient before pregnancy, breastfeeding will deplete her even further.”
Kristy said that during breastfeeding, a mother’s body was their baby’s only source of vitamin D.
“If she’s deficient, the baby is too, and that can lead to developmental delays, weakened bones, impaired immunity, and increased disease risk later in life,” she said.
Kristy said nutrition management wasn’t something new mothers should activate once they started breastfeeding, but prior to conception, during pregnancy and breastfeeding, and after breastfeeding ended.
“Nutrition remains critically important for mothers even after breastfeeding has ended because their bodies are still in a recovery and rebuilding phase,” she said.
“Pregnancy and breastfeeding place significant demands on a woman’s nutrient stores, especially iron, calcium, DHA, iodine, and B vitamins.
“After weaning, mothers often experience ongoing hormonal shifts, fatigue, and sometimes disrupted sleep, all of which can affect energy levels, mood, and overall wellbeing.
“Put simply, nutrition doesn’t stop being important just because breastfeeding does.
“It’s a foundation for a mother’s ongoing vitality and wellbeing.”
