Breastfeeding promotes physiological recovery from pregnancy, can act as a natural contraceptive for some women in the first few months after birth, encourages psychological attachment between mother and child and can help parents save time and money. There is evidence that breastfeeding may also have long-term benefits for the mother, such as reducing the risk of hypertension, diabetes and cancer-related death.(1, 2)

A woman’s total energy and nutrient needs while breastfeeding are greater than at any other time in her adult life, even greater than during pregnancy, with the exception of iron. It is challenging to set nutrient recommendations as some women combine breastfeeding with infant formula feeding. The Nutrient Reference Values (NRV) and Australian Dietary Guidelines (ADG) are based on exclusive breastfeeding for the first six months of a baby’s life.(3, 4)

Energy requirements

The energy required to produce breast milk is sourced from both diet and fat deposits laid down during pregnancy. The energy intake recommendation during lactation is an additional 2,000–2,100 kJ/day (~500 kcal/day) based on the production of 780 mL breast milk/day.(3)

Modest weight loss of around 2 kg/month by the mother while breastfeeding is not associated with reduced milk supply or infant growth.(3) Women who are breastfeeding can safely engage in moderate exercise and gradual weight reduction of ~2 kg/month, as long as they remain in the healthy weight range.

Food groups

The ADGs recommend that additional energy intake comes from 2½ extra serves of vegetables and 3 extra serves of grain products. Table 1 shows the ideal distribution of intake from the food groups during breastfeeding.

Table 1. Recommended daily servings of the five food groups for adult women compared to breastfeeding women aged 19–50 years.(4)

Breastfeeding women with very high activity levels may require additional serves from the five food groups to maintain a healthy body weight. On the other hand, it is rare for breastfeeding women to require any less than the serves shown in Table 1.

Protein

Protein requirements are higher during breastfeeding than during pregnancy. The additional serves of grain recommended in the ADGs are likely to increase protein intake adequately, but the guidelines additionally allow up to 2½ serves from any food group per day. Women who are struggling to meet their protein requirements may benefit from these additional servings coming from the lean meats and alternatives or dairy food groups.\

Recommended Dietary Intakes (RDIs) for protein at different stages (3):

• Non-pregnant or lactating women: 0.75 g/kg body weight per day
• Pregnant women 19–50 years: 1.0 g/kg body weight per day
• Breastfeeding women 19–50 years: 1.1 g/kg body weight per day

Fluid and fibre

It is very important for breastfeeding women to stay hydrated to meet increased fluid needs and prevent constipation. Fluid recommendations for women aged 19–50 years increase from at least 2.3 L/day during pregnancy to at least 2.6 L/day during breastfeeding.(3) The ADGs recommend drinking plenty of water, especially in warm climates and during physical activity.(4) Fibre needs also increase during breastfeeding to 27–30 g/day.(3) The additional serves of fruit, vegetables and grain products are usually sufficient to meet this requirement.

Vitamins

Lactating women have higher requirements for some vitamins to account for losses through breast milk and increased energy use in the body. These can usually be met through diet alone. Table 2 outlines changes in requirements for key vitamins.

Table 2. Recommended Dietary Intakes of vitamins for women aged 19–50 years.(3)

Minerals

Iodine

The recommendation for iodine is greater than during pregnancy and is difficult to achieve through dietary intake. The National Health and Medical Research Council (NHMRC) recommends taking a daily iodine supplement of 150 µg during lactation to help meet the RDI of 270 µg/day.(3, 5) Dietary sources of iodine include milk and dairy products, fortified bread, shellfish, and iodised salt.

Iron

The ADGs recommend that breastfeeding women aged 19–50 years who have not resumed their menstrual cycle consume at least 9 mg of iron daily.(3) This is lower than what is recommended for pregnant (27 mg/day) and menstruating (18 mg/day) women. There are minimal iron losses for breastfeeding mothers before menstruation resumes, as only a small amount passes into breast milk. When their menstrual cycle begins again, this requirement increases back to 18 mg/day. Sources of iron include lean meats and alternatives, leafy-green vegetables, legumes, wholegrains, and fortified foods.

Calcium

There are physiological changes during breastfeeding that supply the calcium needed for breast milk without increasing dietary intake. Calcium requirements remain the same as for non-lactating women at 1,000 mg/day (for ages 19–50). Although not increased, it is still important for breastfeeding women to meet their calcium requirements. Breastfeeding women experience a temporary decrease in bone mineral density that is slowly restored after ~4–6 months. High calcium intake in this period does not seem to affect this process. Dietary sources of calcium include milk and other dairy products, and calcium-fortified alternatives such as soy milk.(3, 6)

Zinc

The amount of dietary zinc needed is slightly increased during breastfeeding to 12 mg/day for women aged 19–50.(3) Dairy, lean meats, wholegrains and legumes are good sources of zinc. Often the additional serves of grains are enough to meet this requirement.

Common nutrition concerns

Fatigue

The energy and nutrient needs during breastfeeding are greater than at any other time in a woman’s life, but it is also a very busy time for new parents. Women may not have the time or energy to shop for and prepare nutrient-dense meals. It is important to support women, especially in the initial months of breastfeeding, to have enough nutritious food available. Supermarket delivery services may be a useful resource during this time, in addition to support from friends and family. Maternal support networks, such as mothers’ groups, can have many benefits for this period and are associated with continuation of breastfeeding.(7)

Vitamin D

Infants born to vitamin D-deficient mothers are more likely to be deficient themselves. Consuming enough vitamin D while breastfeeding (5.0 µg/day) helps ensure infants receive a supply via breast milk, but the amount that passes into milk is only very small. Infants will still need some sun exposure to build adequate vitamin D levels. When doing so, sensible sun-protection strategies should be followed, such as avoiding exposure when ultraviolet (UV) light levels are high and limiting the duration.(3)

Other considerations

Breastfeeding mothers are recommended to avoid alcohol consumption at any level. Alcohol passes into breast milk, where it can remain for hours after drinking. This can harm the developing baby. The NHMRC’s Infant Feeding Guidelines state, “not drinking is the safest option” for breastfeeding women. All household members, including breastfeeding women, are also recommended to stop or reduce smoking to limit the infant’s exposure.

In the Infant Feeding Guidelines, there are few contraindications recognised for breastfeeding, including when a mother is HIV positive, severely unwell, or taking certain medications. Many other maternal conditions do not prevent women from breastfeeding safely, if managed appropriately. There are a few infant conditions where breast milk is not appropriate and special formula must be provided; however, these circumstances are rare. Breastfeeding compatibility should be assessed by health professionals on a case-by-case basis.(5)