Lactating mothers have unique nutritional and hydration needs to support milk production, maintain their health, and ensure optimal growth and development for their infants. This post outlines the essential dietary and water requirements for breastfeeding women, their influence on breastmilk, and the potential impact on infant health.

Nutritional Requirements for Lactating Women

Energy and Macronutrients

Breastfeeding increases energy demands by approximately 500–670 kcal/day, especially in the first six months of lactation (Carretero-Krug et al., 2024; Talebi et al., 2024). Macronutrients like carbohydrates, proteins, and fats play critical roles:

• Protein: Essential for milk synthesis, lactating mothers require 1.05 g/kg body weight daily, a 159% increase over non-lactating women (Jeurink et al., 2019).
• Healthy Fats: Omega-3 fatty acids, such as DHA, improve infant neurodevelopment and retinal function. Higher maternal intake of fish or supplements enhances DHA levels in milk (Eidelman, 2021).
• Carbohydrates: Energy-dense and critical for milk production, they should comprise 45–65% of daily caloric intake (Talebi et al., 2024).

Micronutrients

Several vitamins and minerals directly affect maternal health and milk quality:

• Iodine: Supports infant thyroid function; supplementation is necessary for mothers with insufficient intake (Taylor et al., 2023).
• Iron and Calcium: Essential for maternal health, especially to compensate for lactation-associated bone loss, which typically reverses post-weaning (Talebi et al., 2024).
• Vitamin D: 
  • The vitamin D content of breastmilk is significantly influenced by the mother’s vitamin D status during pregnancy and lactation. Maternal vitamin D levels impact both the vitamin D status of the baby at birth and the ability of breastmilk to provide sufficient vitamin D for the infant.

    A 2003 study by the Thrasher Research Fund/US National Institutes of Health revealed that 81% of women of childbearing age have insufficient vitamin D levels. Insufficiency is typically defined as a blood level of less than 32 ng/mL, while levels below 20 ng/mL indicate a deficiency. This highlights a widespread need for improved vitamin D intake among mothers to ensure adequate levels in both themselves and their infants.

    Research indicates that high-dose maternal vitamin D supplementation (4,000–6,400 IU/day or a single monthly dosage of 150,000 IU) can effectively enrich breastmilk with sufficient vitamin D for the infant. This approach offers an alternative to direct infant supplementation and has shown strong efficacy in improving vitamin D status for both mother and baby. The Academy of Breastfeeding Medicine also endorses this strategy, stating that a dose of 6,400 IU/day ensures adequate vitamin D transfer through breastmilk to meet infant requirements.

    While the current safe upper limit for vitamin D intake is 4,000 IU/day, it is critical to consult with a healthcare provider and assess maternal vitamin D status through blood testing before beginning supplementation at higher levels. Pregnant and lactating women may require more vitamin D than the general adult population due to increased demands during these life stages.

    Mothers with low vitamin D levels should consider supplementation to support their own needs and enhance the vitamin D content of their milk. A study by Hollis et al. (2015),  concluded that “Maternal vitamin D supplementation with 6,400 IU/day safely supplies breast milk with adequate vitamin D to satisfy her nursing infant’s requirement.” This provides a viable alternative to direct infant supplementation, especially for mothers aiming to optimize their milk’s nutritional profile

Impact of Maternal Diet on Breastmilk

Milk Composition

While macronutrient levels remain stable across dietary patterns, certain nutrients are strongly influenced by maternal intake:

• DHA: Directly linked to maternal consumption of fish or fish oil (Eidelman, 2021).
• Micronutrients: Vitamins D, B12, and iodine in milk reflect maternal levels. For example, vitamin B12 levels are lower in vegan mothers who do not supplement (Karcz & Królak-Olejnik, 2021).
• Vitamin D: Studies indicate that taking high doses of vitamin D (4,000–6,400 IU per day or a single monthly dose of 150,000 IU) can effectively increase the vitamin D content of breastmilk to meet an infant’s needs. Maternal supplementation is often preferred as it supports both the mother and baby, offering a more convenient alternative to direct infant supplementation. While the current safe upper limit for daily vitamin D intake is 4,000 IU, it’s essential to consult a healthcare provider and have your vitamin D levels tested before supplementing at higher doses. The standard recommended daily intake is 600 IU, but research suggests that pregnant and lactating women may require more vitamin D than the general adult population to meet their unique needs.

Flavor Transfer

Maternal diet flavors breastmilk, exposing infants to diverse tastes. This “flavor bridge” can encourage acceptance of similar foods during complementary feeding, fostering long-term dietary diversity (Ventura et al., 2021).

Takeaways

None of the papers definitively claim that mothers must have a healthy diet to produce high-quality breastmilk. Instead, they emphasize that:

• Stability of Milk Quality: The macronutrient composition (fat, protein, and carbohydrates) of breastmilk is relatively stable, even when maternal diets are suboptimal. This is because the body prioritizes milk production to ensure infant nutrition, often drawing on maternal nutrient stores.
• Micronutrient Sensitivity: Certain micronutrients, such as vitamin D, iodine, DHA (an omega-3 fatty acid), and vitamin B12, are directly influenced by maternal intake. Low dietary levels or deficiencies in these nutrients can result in lower concentrations in breastmilk, potentially affecting infant health.
• Impact on Maternal Health: While a mother’s diet may not drastically affect the overall quality of her milk, prolonged nutritional deficiencies can deplete maternal stores, potentially compromising her health and, in severe cases, impacting milk volume or composition.

Key Insights:

• Balanced Diet Benefits: A healthy diet supports maternal well-being and ensures adequate levels of specific nutrients in breastmilk, particularly those that are diet-sensitive (e.g., omega-3s, fat-soluble vitamins, iodine).
• Adaptations in Milk Composition: The body has remarkable mechanisms to protect milk quality, prioritizing the infant’s nutritional needs, even in cases of maternal malnutrition.

In summary, while a healthy diet enhances maternal health and supports optimal nutrient levels in breastmilk, it is not an absolute requirement for producing nutritionally adequate milk. However, chronic deficiencies may impact both maternal health and specific aspects of milk composition.

Water Requirements for Lactating Women

Fluid Intake

Lactating mothers experience additional water loss of approximately 700–780 mL/day due to milk production (Mazur et al., 2024). Recommendations for total water intake (TWI) vary:

• European Food Safety Authority: 2.7 L/day.
• Institute of Medicine: 3.8 L/day.
• Chinese Guidelines: 3.2 L/day, with significant contributions from water-rich foods (Zhou et al., 2019).

Milk Supply and Composition

• Milk Supply: Adequate hydration supports milk production. Severe dehydration can reduce supply, although mild dehydration is often compensated by physiological adaptations (McKenzie et al., 2017).
• Milk Composition: Water content (87%) remains stable regardless of maternal hydration status, ensuring infants receive sufficient hydration through milk (Mazur et al., 2024).

Sources of Water

Water from beverages contributes 70–80% of TWI, while hydrating foods like fruits and vegetables account for 20–30% (Zhou et al., 2019). Soup-based diets also contribute significantly in some regions.

Special Considerations for Lactating Women

None of the papers definitively state that a specific amount of water is required for milk production. However, they provide important insights into the relationship between hydration and lactation:

• Hydration’s Role in Milk Production: While adequate hydration is important for overall health and milk production, the body can prioritize milk production even in mild states of dehydration through physiological adaptations, such as increased water retention. Severe dehydration may reduce milk production, but mild variations in fluid intake generally do not significantly affect milk volume.
• Guidelines for Total Water Intake (TWI): Recommendations for lactating women include higher TWI compared to non-lactating women to account for water lost through milk secretion (about 700–780 mL/day).
  • For example:
    • The Institute of Medicine (IoM) recommends 3.8 liters/day.
    • The European Food Safety Authority (EFSA) suggests 2.7 liters/day.
• Stability of Milk Composition: The water content of breastmilk (~87%) is tightly regulated and remains stable across a wide range of maternal hydration levels, ensuring infants receive adequate hydration through milk.
• Practical Findings from Studies: Fluid intake does not show a direct linear relationship with milk volume in the papers reviewed. Instead, hydration supports the mother’s overall health, which indirectly aids sustained lactation.

Key Insights:

The papers do not establish a specific threshold of water intake as a prerequisite for milk production. However, they highlight that adequate hydration is vital for maternal well-being and helps maintain consistent milk supply, particularly under normal physiological conditions. Severe dehydration, rather than precise fluid deficits, poses the greater risk to milk production.

Special Considerations for Lactating Women

Supplementation

Supplements for vitamin D, iodine, and DHA are crucial, particularly for mothers on restricted diets (Carretero-Krug et al., 2024). Over-supplementation, especially of iron, can lead to adverse effects like oxidative stress (Gila-Díaz et al., 2021).

Sociocultural and Environmental Factors

Barriers such as socioeconomic status, access to clean water, and dietary diversity impact maternal and infant health. Nutrition education and interventions tailored to local contexts can improve outcomes (Rajpal et al., 2021).

References

Carretero-Krug, A., et al. (2024). Nutritional status of breastfeeding mothers and impact of diet and dietary supplementation: A narrative review. Nutrients, 16(301), 1–28. https://doi.org/10.3390/nu16020301

Eidelman, A. I. (2021). The impact of the mother’s diet on breast milk quality and safety. Breastfeeding Medicine, 16(7), 507. https://doi.org/10.1089/bfm.2021.29185.aie

Institute of Medicine (IoM). (2011). Dietary Reference Intakes for Calcium and Vitamin D. National Academies Press. https://doi.org/10.17226/13050

Hollis, B. W., & Wagner, C. L. (2004). Vitamin D requirements during lactation: High-dose maternal supplementation as therapy to prevent hypovitaminosis D for both the mother and the nursing infant. The American Journal of Clinical Nutrition, 80(6), 1752S–1758S. https://doi.org/10.1093/ajcn/80.6.1752S

Jeurink, P. V., et al. (2019). Importance of maternal diet in the training of the infant’s immune system during gestation and lactation. Critical Reviews in Food Science and Nutrition, 59(8), 1311–1319. https://doi.org/10.1080/10408398.2017.1405907

Kolasa, K. M., et al. (2015). Diet for a healthy lactating woman. Clinical Obstetrics and Gynecology, 58(4), 893–901. https://doi.org/10.1097/GRF.0000000000000143

Mazur, D., et al. (2024). Impact of maternal body composition, hydration, and metabolic health on breastfeeding success. Medical Science Monitor, 30, e945591. https://doi.org/10.12659/MSM.945591

Rajpal, S., et al. (2021). Maternal dietary diversity during lactation and associated factors. PLOS ONE, 16(12), e0261700. https://doi.org/10.1371/journal.pone.0261700

Taylor, S. N., & The Academy of Breastfeeding Medicine. (2018). ABM clinical protocol #29: Iron, zinc, and vitamin D supplementation during breastfeeding. Breastfeeding Medicine, 13(6), 398–404. https://doi.org/10.1089/bfm.2018.29095.snt

Ventura, A. K., et al. (2021). Maternal diet during pregnancy and lactation and child food preferences. Current Nutrition Reports, 10(4), 413–426. https://doi.org/10.1007/s13668-021-00366-0

Wagner, C. L., Taylor, S. N., & Hollis, B. W. (2008). Does vitamin D make the world go ’round’? Breastfeeding Medicine, 3(4), 239–250. https://doi.org/10.1089/bfm.2008.9984

Zhou, Y., et al. (2019). Association between total water intake and dietary intake of pregnant and breastfeeding women. BMC Pregnancy and Childbirth, 19, 172. https://doi.org/10.1186/s12884-019-2301-z