Foremilk and Hindmilk

Fat Content of Milk

You may have heard people talking about two kinds of milk – foremilk and hindmilk. This suggests that when we are lactating we produce two distinct kinds of milk, which is not the case. Your milk-making cells all produce the same kind of milk.

Foremilk is the milk available when your baby starts feeding, hindmilk is the milk your baby gets at the end of a feed. Foremilk is not necessarily low in fat: fat content of the milk that is removed varies according to how long the milk has been collecting in the ducts and how much of your breast is drained at the time.

As milk is made, fat sticks to the sides of the milk-making cells and the watery part of the milk moves down the ducts toward your nipple, where it mixes with any milk left there from the last feed. The longer the time between feeds, the more diluted the leftover milk becomes. This ‘watery’ milk has a higher lactose content and less fat than the milk stored in the milk-making cells higher up in your breast.

You can’t tell how much fat your baby has received from the length of a feed. Some babies take a full feed in five minutes while others take 40 minutes to get the same amount. As long as your baby is breastfeeding effectively, you can let them decide how long to feed for and they will get all the fat they need.

Lactose Overload

 Lactose overload used to be known as foremilk/hindmilk imbalance.

Lactose is sugar (carbohydrate) in human (and all mammals’) milk. It is a large molecule and the body has to break it down to be able to absorb it. It is broken down in the body by an enzyme called lactase.

Most healthy babies can break down the lactose in normal volumes of milk. Fat slows down milk as it passes through your baby’s gut. If your baby has a lot of milk that is relatively low in fat, it can rush through their digestive system more quickly than the lactose can be digested. This can happen when a baby drinks a very large amount of breastmilk – either because  the time between feeds is long, or because of an oversupply of milk.

Babies with lactose overload can appear like they’re suffering from a digestive disorder. They may have a lot of flatulence/gassiness (wind), green, foamy or frothy, explosive stools and pain which will usually be noticeable with lots of screaming, not just grumbling or occasional complaining.

If your baby seems comfortable and has yellow stools, they do not have a problem with the amount of fat in his milk.

Damage to a baby’s intestines, including inflammation caused by cow’s milk allergy and infection, can stop the production of enough of the enzyme lactase. This means milk isn’t digested as it moves through the intestine and instead ferments in the lower bowel causing pain, gas and green stools.

Please note: there are other reasons why a baby might have green stools, including being ill, taking medications, insufficient total milk intake and allergy. In a healthy baby who is gaining weight well, occasional green stools can be ignored.

If your baby seems to be suffering with lactose overload the following tips may help:

• Check your baby’s latch: sometimes a deeper latch can help baby manage the milk flow better.
• Try different positions: a laid-back position, or lying on your side, might help your baby manage a faster milk flow more easily.
• Allow your baby to feed for as long as they want to on each breast.
• Try offering more frequent feeds: they can help baby take in more manageable amounts and avoid a build-up of large volumes of relatively ‘lower-fat milk’.

Despite common advice, it is neither necessary nor helpful to reduce the amount of dairy products in your diet in order to reduce the lactose in your milk. This is because the amount of lactose in your milk has nothing to do with your diet; your body manufactures it especially for your baby. If limiting dairy products in your diet improves your baby’s condition, your baby was probably reacting to the proteins found in cow’s milk that can appear in your milk.

Find more information about cow’s milk protein intolerance (CMPI) here.

Lactose intolerance

You may know adults who don’t drink dairy milk because they are ‘lactose intolerant’, a medical condition that occurs when the body no longer makes enough of the enzyme lactase, which is needed to digest lactose.

Lactose intolerance is not a problem for babies. They are born with the ability to produce lots of lactase because they depend on their mother’s milk for nutrition in the first year of life and the lactose in human milk is needed for brain development. Lactase production decreases as children get older, because in the world of mammals, milk is a food for babies, not adults. True lactose intolerance in infants is called galactosemia, an extremely rare genetic condition (approximately 1 in 30,000 US births) that is present from birth and fatal if not treated; a baby with this disorder would not gain weight well and would have clear symptoms of malabsorption and dehydration.

Further Reading

Allergies
CMPI – Cow’s Milk Protein Intolerance 
Breastfeeding and Galactosemia
Oversupply
LLLGB  – The Unhappy Breastfed Baby
LLLGB – Fat Content of Breastmilk FAQs