Breastfeeding: what to eat while nursing

What should a mother eat while breastfeeding?

Eating during breastfeeding does not require special meals. It means eating a varied diet, based on fresh foods and enough to meet your needs.

Each day, combine complex carbohydrates such as rice, potatoes, oats, wholemeal bread or pulses with seasonal vegetables and fresh fruit. Add extra-virgin olive oil and a portion of protein to each meal, such as fish, eggs, pulses, lean meat or dairy. According to the Autoridad Europea de Seguridad Alimentaria, producing milk uses around 500 kcal more per day during the first six months of exclusive breastfeeding [1]. This extra energy comes from what you eat and the fat your body stored during pregnancy.

Do you need iodine or other supplements while breastfeeding?

In Spain, iodine is the nutrient that needs most attention during breastfeeding. It is needed to make thyroid hormones and support the baby’s brain development. If your baby is exclusively breastfed, your milk is their only source. During breastfeeding, make sure you get enough iodine [2].

There is no single recommendation on how to meet this need. Spanish endocrinologists recommend supplements for all breastfeeding mothers [3]. Primary care paediatricians recommend them for those whose diet does not meet their needs [4]. Use iodised salt as your usual source and avoid seaweed while breastfeeding, as AESAN recommends. Your midwife or doctor can assess whether you need a supplement.

If you are vegetarian or vegan, make sure you get enough vitamin B12 [5]. If you are vegan, a supplement is essential and should be prescribed by your doctor or dietitian-nutritionist. A mother’s B12 deficiency can cause serious neurological harm to the baby. Your midwife or doctor assesses whether you need additional DHA, an omega-3 that is important for the baby’s brain and retina [6]. If you do not eat fish, ask them about it.

Eat at least three portions of fish a week, prioritising small oily fish. During breastfeeding, avoid swordfish or emperor fish, shark, bluefin tuna and pike because of their mercury content [7].

For the baby, a paediatrician prescribes 400 IU of vitamin D a day from the first days of life for breastfed babies under one year of age [8].

How much should you drink while breastfeeding?

For adult women, EFSA sets a reference intake of 2 litres of total water a day, including water from food. While breastfeeding, drink according to your thirst. Drinking litres of water does not increase milk supply. Milk production mainly depends on the baby suckling and how often they feed. Forcing yourself to drink more is not helpful and may be uncomfortable.

It is common to feel very thirsty just as a feed begins. This is when oxytocin, the hormone that triggers milk let-down, is released.

If you want to lose weight while breastfeeding

The postnatal period is not the time for restrictive diets or drastic calorie cuts. Losing weight quickly can cause fatigue and irritability, and may reduce your milk supply.

Weight loss after childbirth is usually gradual, and breastfeeding itself helps use the reserves stored during pregnancy. If you want to lose fat, do it slowly, without going hungry and with support. The advice in our weight-loss diet guide can be a starting point, but it needs to be adapted during breastfeeding so you get enough energy and nutrients.

Can foods give the baby gas or change the taste of breast milk?

This is one of the questions we hear most often in appointments. Many mothers avoid pulses, cauliflower, broccoli, garlic or asparagus for fear of causing colic. The gas these foods produce in your gut does not pass into your milk, so there is no need to avoid them as a precaution. If you notice clear, repeated discomfort in your baby whenever you eat a particular food, talk to their paediatrician before removing it from your diet.

Some foods, such as garlic, artichoke or spices, do slightly change the aroma and taste of breast milk. This is good for the baby: they become familiar with the flavours of family meals and may find them easier to accept when they start complementary feeding.

Do caffeine and alcohol pass into breast milk?

Yes, both do. For caffeine, up to 200 mg a day is not considered a safety concern for a breastfed baby, equivalent to one or two cups of coffee [9]. Above this amount, it may build up in a newborn, who clears it very slowly, and cause irritability or difficulty sleeping.

For alcohol, there is no safe amount for health (OMS): the less, the better. While breastfeeding, the safest choice is not to drink. Alcohol passes into breast milk, does not increase milk production and, in larger amounts, makes let-down more difficult [10]. If you exceptionally have a glass of wine or a beer, wait two to two and a half hours per drink before breastfeeding again [10]. See “Alcohol and breastfeeding”. See “Do any foods increase breast milk? Myths and what does help”.

What is breast milk made of, and how does it change over time?

Breast milk changes as your baby grows. In the first few days, you produce colostrum, a thick, yellowish fluid. It is rich in protective substances such as immunoglobulins and lactoferrin, which help protect a newborn’s gut.

Next comes transitional milk, with a greater volume and more fat and lactose. By around the second week, mature milk is established. It is mostly water, with easy-to-digest proteins, oligosaccharides that feed the baby’s microbiota and essential fatty acids.

Milk also changes during a feed. The milk at the start is more watery, while the milk towards the end is richer in fat. If you are planning another pregnancy, see our guidance on eating during pregnancy.

What common mistakes do we see in appointments?

• Skipping breakfast and lunch because the baby leaves you no time, then reaching the evening with hunger that is difficult to manage. Wholemeal toast with a hard-boiled egg or hummus takes a minute to prepare.
• Switching to organic dairy because you think it is better for the baby. It often contains less iodine because those cows are not given enriched feed [4].
• Changing your meals to make your milk “more nutritious”. If you are worried that the baby is not gaining weight, your midwife or paediatrician can assess them.