Written by Marelize Wilke
7th Mar 2023 • 5 minute read
Team Aisling
Reviewed by
Aisling Moran BSc (Hons) Nutritional Science

Like pregnancy, your breastfeeding diet requires more calories and nutrients to support your body and baby. There’s no need to include any special foods in your diet — except for vitamin D, a varied and balanced diet can usually give you what you need. In some cases, a supplement might be recommended. 

Which nutrients are essential for breastfeeding?

When breastfeeding, your body requires a higher amount of certain nutrients and calories — 300-500 more a day. This helps support your milk supply and provides you and your baby with essential nutrients. And a balanced diet can usually provide you with what you need. 

Besides getting enough proteins, carbohydrates, and unsaturated fats, some vitamins and minerals are particularly important while breastfeeding.

You can do a post-birth blood test at home to check your nutrient levels.

Vitamin D
Your risk of vitamin D deficiency increases while breastfeeding. This can affect your sleep, energy levels, and mood. Unlike other nutrients, national guidelines recommend a daily 10 mcg vitamin D supplement while breastfeeding. 

Vitamin B12
Vitamin B12 is important to keep your brain and nervous system healthy. It’s also needed to make red blood cells — which is important for your energy levels. 

Your vitamin B12 requirements increase while breastfeeding. If you’re deficient, it might affect the quality of your breast milk and affect your baby’s levels — this can affect their brain development. If you don’t eat meat or dairy, you’re at higher risk of a vitamin B12 deficiency

Good sources of vitamin B12 include:

  • organ meats
  • beef
  • fish
  • dairy products
  • eggs
  • fortified foods

Folate (vitamin B9) helps your body make red blood cells. While breastfeeding, your folate requirements increase — which increases your risk of a folate deficiency. Low folate levels can lead to anaemia, which can cause low energy levels. 

Good sources of folate include:

Omega-3 fats

These fatty acids are essential for brain development, cell structure, and hormone production. During pregnancy, omega-3 also plays a key role in the development of your baby’s cells. Omega-3s found in breast milk help support your baby’s brain and eye development.

Oily fish, like salmon, trout, mackerel, tuna, and sardines, are the best sources of omega-3s. 

During pregnancy, your body requires more iron. Blood loss during birth can also cause you to be more at risk of low iron. Low iron levels can affect your energy and sleep. 

Red meat, seafood, dark leafy green vegetables, and dried fruit are good sources of iron. 

If you’re not getting enough calcium from your diet, your body will leech calcium from your bones. To help protect your bone health, it’s important to include calcium-rich foods like dairy products, tofu, fortified foods, and almonds in your diet. 

What should you eat while breastfeeding?

You don’t need to include any special foods in your diet while breastfeeding.  Instead, focus on including a wide variety of healthy foods, like:

  • lean meat and poultry — or other protein sources like peas, beans, and lentils
  • nuts and seeds
  • oily fish — limit your intake to 2 portions of fish a week (avoiding more than 1 portion of fish with a high mercury level like shark and swordfish)
  • whole grains — like oats, wholemeal bread, brown rice, quinoa and vegetables
  • milk and cheese — or other calcium-enriched foods

You should also aim for at least 1500-1800 calories a day. If your calorie intake is too low, your milk supply can drop and you might not be able to get all the nutrients you need. 

Things to avoid while breastfeeding

There are a few things experts recommend limiting or avoiding while breastfeeding. 

An occasional drink is unlikely to cause harm to your baby, but no amount of alcohol in breast milk is considered safe. When you do have a drink, avoid breastfeeding for 2-3 hours for each drink you have to ensure there’s no alcohol in your breast milk.

As your alcohol levels fall, the levels in your milk will fall — so there’s no need to express after alcohol.

Small amounts of caffeine can pass into your breast milk — this can keep your baby awake. Caffeine is found in tea, coffee, energy drinks, fizzy drinks, and chocolate. 

It’s recommended to avoid more than 200 mg a day  — equivalent to having 1 cup of filter coffee and a chocolate bar.

Certain medicines
Some medicines aren’t recommended while breastfeeding, including:

  • aspirin
  • some nasal congestions
  • codeine phosphate 

Paracetamol, most antibiotics, medication to treat postnatal depression, and asthma inhalers are safe while breastfeeding. But always check with your GP or midwife if you’re unsure about a medication. 

Keep in mind that there’s no need to avoid potential allergy-causing foods while you’re breastfeeding — this doesn’t reduce the risk of your baby developing an allergy. 

Nutrient deficiencies and breastfeeding

Because of your increased nutrient requirements, your risk of a nutrient deficiency can increase. 

But even if you do develop a deficiency, your breastmilk still tends to be high in the nutrients your baby needs. This is because your body will prioritise providing nutrients for your baby. 

Should you take a supplement while breastfeeding?

If you have a deficiency or are at high risk of developing a deficiency, a food supplement might be recommended. These might include:

  • vitamin D supplements — national guidelines recommend considering a 10 mcg supplement if breastfeeding 
  • omega-3 supplements — if you don’t eat oily fish, an omega-3 supplement that contains EPA and DHA might be beneficial for you and your baby
  • vitamin B12 supplements — if you don’t eat meat or dairy, you might need to take a supplement or get vitamin B12 injections

It’s a good idea to speak to your GP or pharmacist before starting a supplement. 

If you think you might have a nutrient deficiency, you can do a post-birth blood test to measure your levels of a range of nutrients.