Activity 3. The impact of maternal diet on breast milk composition (fatty acids, vitamins, minerals) (10 mins)
Impact of maternal diet on breast milk composition
Mothers can produce milk of sufficient quality and quantity to support infant growth and health, generally independent of maternal nutrient intake.20 However, milk production normally affects maternal body composition and nutritional status, and lactating women have increased nutrient demands. This is because lactation is partly supported by mobilisation of fat stores, with major macronutrients such as calories, protein, certain minerals and trace elements maintained at a satisfactory concentration for the infant at the expense of maternal stores.20
A mother’s diet can, however, influence her milk composition, In particular concentrations of fatty acids and certain water-soluble and fat-soluble vitamins.20-24 Allen 24 and Sakurai’s team 25 categorised nutrients into 2 groups during lactation:
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Group I nutrients (e.g., thiamine, riboflavin, vitamin B6, vitamin B12, choline, retinol, vitamin A, vitamin D, selenium, and iodine) are most critical, as their secretion into milk is rapidly and/or substantially reduced by maternal depletion. So, where diet is inadequate, maternal supplementation with these nutrients can increase breast milk concentrations and improve infant status.
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Group II nutrient concentrations in breast milk (e.g., folate, calcium, iron, copper, and zinc) are relatively unaffected by maternal intake or status.24 In this case, if the mother gradually becomes more depleted when intake is less than the amount secreted in milk, maternal supplementation benefits the mother rather than the infant. Table 2 provides further detail on the impact of maternal diet on key vitamins.
Vitamins
Table 4. Impact of maternal diet on key vitamins 21-25
| Vitamin | Maternal diet, milk, and infant effects |
|---|---|
| B group vitamins | Most B group vitamins, particularly B1, B2, B3, B6, are not stored, so are necessary in the maternal diet.24,25 The exception to this is folic acid, where concentrations in milk don’t depend on maternal diet. Folate is secreted into milk at the expense of maternal stores. 19,20,24 Maternal folate supplementation in lactation may therefore be important for preserving maternal stores, which are especially important for subsequent conception and pregnancy. |
| Vitamin A | The recommended daily intake is approximately 1.5 times higher during lactation than in adult women.11 It is estimated that over the first 6 months of lactation, infants receive 60 times the amount of vitamin A that they receive during gestation. Note: supplementation has shown no consistent health benefits and may have side effects in young infants. |
| Lutein | Lutein is important in infant brain and retinal development. This antioxidant is highly concentrated in breast milk and actively transported into breast milk. Concentrations of lutein in breast milk vary depending on maternal intake. While studies advise that women consume adequate dietary lutein or supplements, there is currently no RDI for lutein. There are no studies demonstrating supplementation in the absence of deficiency. |
| Vitamin D | An important factor for the development of vitamin D deficiency in adults is maternal vitamin D status. The RDI for lactating women equates to non-lactating women. The concentration of vitamin D in breast milk will be deficient if the mother is also deficient in vitamin D. Note: breast milk is a poor source of vitamin D. Infants who are at risk of vitamin D deficiency may need supplementation. |
| Vitamin C | The RDI for vitamin C is approximately 1.8 times higher during lactation than for non-lactating women. Mothers should be encouraged to consume a healthy diet that is high in vitamin C. |
| Vitamin E | The RDI for vitamin E is approximately 1.6 times higher during lactation than for non-lactating women. Levels appear to be affected by maternal diet. |
Minerals
Levels of most minerals of human milk i.e. (calcium, phosphate, magnesium, sodium, potassium, iron, copper and zinc) are relatively independent of serum concentrations and are not substantially influenced by variations in maternal dietary intake.19,21-23 However, intake of some trace minerals, iodine and selenium does affect breast milk levels.
Table 5. Minerals: maternal diet, milk, and infant effects
| Mineral | Maternal diet, milk, and infant effects |
|---|---|
| Iodine | Iodine is essential for thyroid and developmental function. The RDI for lactating women is approximately 1.5 times higher than in non-lactating women. |
| Calcium | Calcium levels in breast milk is regulated in the mammary gland and is unrelated to dietary intake of calcium or vitamin D. The RDI for calcium is the same for lactating or non-lactating women, with about 200mg per day of calcium secreted in milk. RDI is not increased as lactation-induced loss in bone mass is not prevented by increased calcium intake, and bone mass recovers after weaning.26 |
| Iron | The RDI for lactating women is approximately half that of non-lactating adult women. Exclusive breastfeeding for 6 months uses approximately half the iron that would normally be lost through menstruation for that time. Post-partum use of iron supplementation (including pre-natal vitamins) is not required unless the woman is known to be iron deficient.20 |
Recommended resources
Diet, nutrition, and breastfeeding
Vitamin D + breastfeeding mothers and babies (with a word about pregnancy too)
References
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Butte NF, Stuebe A. Maternal nutrition during lactation. UpToDate Aug 2017 Available at: https://www.uptodate.com/contents/maternal-nutrition-during-lactation
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Institute of Medicine, USA, Academy of Science. Nutrition during lactation. Washington DC: National Academy Press, 1991. Chapter 7 – Maternal nutrition and infant growth.
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Innis SM. Impact of maternal diet on human milk composition and neurological development of infants. Am J Clin Nutr 2014; 99:734S–41S.
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Lonnerdal B. Effects of maternal dietary intake on human milk composition. J Nutr 1986;116:499–513.
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Allen LH. B vitamins in breast milk: relative importance of maternal status and intake, and effects on infant status and function. Adv Nutr 2012;3(3):362–9.
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Sakurai T, Furukawa M, Asoh M, Kanno T, Kojima T, Yonekubo A. Fat soluble and water-soluble vitamin contents of breast milk from Japanese women. J Nutr Sci Vitaminol (Tokyo) 2005;51:239–47.
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Kalkwarf HJ, Specker BL, Bianchi DC, Ranz J, Ho M. The effect of calcium supplementation on bone density during lactation and after weaning. N Engl J Med 1997; 337:523-8.