Breastfeeding vitamins: what you need to know

Your breastfeeding diet

There are two factors which determine the quality of your breast milk – your diet and your body’s reserves of key nutrients.

Estimates suggest that breast milk contains as many as 300 different components, so eating a balanced, varied diet is key. Every day, aim to include two to three portions of protein foods such as lean meat, fish, beans, nuts and seeds; a minimum of five portions of fruit and vegetables; wholegrain cereals such as brown rice and oats and enough water to satisfy your thirst. Those on a plant-based diet should include fortified foods such as plant milks and spreads.

The good news is that most of the dietary restrictions you adopted during pregnancy won’t necessarily apply when you’re breastfeeding. However, be aware that caffeine does pass into breast milk and may disrupt your baby's sleep. If this happens, limit or avoid tea, coffee, chocolate and cola. Alcohol is also passed into the milk, so allow 2-3 hours per alcoholic drink before you breastfeed.

What you need to know about breastfeeding

• When planning a breastfeeding diet, there are a few things to consider. Interestingly, not all the nutrients in breast milk are directly influenced by what you eat, but some are. These include some of the B vitamins (B1, B2, B6, B12 and choline). This means if your diet is lacking in any of these vitamins, your baby won’t be getting sufficient amounts either.
• As a new mum, you will have a greater need for some key nutrients. It’s these extra requirements that persuade some mums to continue taking a pre-natal supplement, especially if they’re a new mum of twins. Although supplements may help, they are not a replacement for a well-balanced and varied diet.
• When breastfeeding, your energy needs will increase by as much as 500 calories per day. If you continue to carry some baby weight, some of these stores will be used to support your milk production. Otherwise, you may notice an increase in your appetite in an attempt to address these extra needs.
• Some nutrients are present in breast milk regardless of your diet. These include calcium, folate, iron and zinc. If these nutrients are not adequately supplied by your diet, they will be taken from your reserves (bone and tissue) leaving you potentially at risk of depletion.
• Your breast milk needs to supply all the protein your baby needs for growth, so you will need an additional 25g of protein per day. This shouldn’t be a problem as long as you choose nutrient-dense foods and include an extra portion of protein each day. Aim for 2-3 protein sources (lean meat, dairy, beans, pulses, nuts and seeds) daily to satisfy your own needs and that of your baby – as an example a 100g portion of baked white fish supplies 24g protein, while two boiled eggs supply 14g protein.

When might you need to supplement?

1. Vitamin D is used by the body for a number of different functions, including how a baby utilises calcium for the formation of strong bones and teeth. Vitamin D also helps regulate your baby’s immune and respiratory function. In the UK, the NHS recommends all pregnant and breastfeeding women supplement with 10mcg of vitamin D, and an exclusively breastfed baby should receive a daily supplement of 8.5-10mcg vitamin D. This is because vitamin D levels tend to be low in the UK population, especially amongst certain groups.

Food sources of vitamin D are limited in number, with most of our vitamin D being produced by sunlight on the skin. Useful food sources include oily fish, egg yolks and fortified spreads.

Supplement savvy: Vitamin D is available in two forms (D2 and D3). Look for cholecalciferol (D3) because it is considered more stable in supplement form. Vegan mums need to look for a suitable vegan-friendly version such as that made from lichen.

2. Fats are important to support the absorption of fat-soluble vitamins like vitamin D and also to provide essential fatty acids like docosahexaenoic acid (DHA), which is needed for your baby’s visual and brain development. The best dietary sources of DHA include oily fish like salmon, trout and sardines – but don’t forget, just as in pregnancy, you are advised to limit varieties of fish that are high in mercury. For this reason and while you are breastfeeding, limit oily fish intake to no more than two portions per week.

Plant foods like walnuts and flaxseeds supply omega-3 in the form of alpha-linoleic acid (ALA). However, your body needs to convert this form into DHA. This conversion tends to be inefficient which is why vegetarians, vegans and those unable to eat fish should consider a daily omega-3 supplement.

Supplement savvy: During pregnancy and lactation, women are advised to take 2.6mg of omega-3 fatty acids of which 100-300mg should be DHA per day. Those who are vegan or avoid fish may supplement with a natural algae formula.

3. The need for vitamin B12 increases during pregnancy and breastfeeding. This vitamin is important for the formation of a baby’s blood cells, as well as their brain development and function. It may also help support your memory, mood and energy levels. Food sources include meat, fish, dairy and eggs, as well as fortified plant milks and yeast extract.

Vegan and strict vegetarians who don’t eat meat, dairy or eggs, should speak with their GP about taking a daily B12 supplement which supplies 10mcg.

Supplement savvy: There are two forms of vitamin B12 – cyanocobalamin, which is a synthetic version, or methyl-cobalamin, the natural form. Studies suggest both forms are effective.

4. Vitamin C plays an important role in tissue growth and repair, as well as bone and teeth development, so your needs will increase during breastfeeding. Most mums get good amounts by including plenty of fresh fruit and vegetables such as citrus fruit, kiwis, peppers and tomatoes in their diet.

Supplement savvy: If your GP or dietitian has suggested adding a supplement, look for a ‘buffered’ form of vitamin C. This supplies a highly absorbable vitamin C along with a buffering mineral and is thought to be gentler on the gut. Calcium ascorbate would be an example – ideally aim for a supplement providing 100-250mg.

5. Although your body will ensure adequate calcium is supplied in your breast milk, it can be useful if you follow a restricted diet, or don’t eat dairy, to increase your intake of calcium-rich foods. Useful food sources include green leafy vegetables, dried fruit, nuts and seeds, fortified plant milks and calcium-set tofu. Breastfeeding mums have been seen to lose 3-5% of their bone density while breastfeeding, so including plenty of calcium-rich food sources is very important.

Supplement savvy: If advised to supplement, look for a product providing about 700-800mg of calcium. Calcium citrate may be a more convenient form as it can be taken at any time of day, whereas calcium carbonate should be taken with meals.

6. Low levels of iodine during pregnancy and when breastfeeding may cause thyroid problems and impact brain development and cognition. Food sources include seafood, sea vegetables and dairy. Daily requirements in the UK are 140mcg iodine, which for most of us is adequately met by consuming dairy and fish.

Supplement savvy: Vegans and those on a restricted plant-based diet should seek advice from their GP or dietitian with regards supplementation.

Last words

If you’re considering any major dietary changes, or are thinking about taking supplements, please consult your GP or a registered dietitian to ensure you do so without risk to your baby or your own health.

Speak to your midwife, doula or health visitor if you have any concerns about feeding your baby.

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Check out our Vitamins and Minerals Information Hub to learn more about key nutrients – from whether you’re getting enough vitamin D to the top 10 healthiest sources of vitamin C, plus vital minerals you need in your diet.

This article was reviewed on 22 January 2024.

Kerry Torrens is a qualified Nutritionist (MBANT) with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.

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