Have you heard of high lipase in breast milk? Lipase is an enzyme that helps break down fat in breast milk. The breakdown of the fat in breastmilk by lipase is normal but not noticeable when the baby is feeding directly at the breast. When lipase occurs in excess, this process happens much more rapidly and can make the milk taste off or soapy after a period of time. Milk with excess lipase is safe to drink, but some babies dislike the taste and refuse it.

 

How do you know if you have high lipase?

• Test prior to freezing – Before freezing large amounts of breast milk, you can test it for odor and taste changes due to lipase. Collect and freeze 1-2 bags or small containers of breast milk for at least 5 days and then evaluate the odor to see if your baby will drink it.

What can you do if you have high lipase?

• Freeze milk as soon as you pump it whenever possible
• Reduce intake of polyunsaturated fatty acids
• Scald you’re milk prior to freezing 
• To scald fresh milk: Heat it in a pot until tiny bubbles form around the edges of the pan (approximately 180° F) but don’t boil it. Remove the milk from the stove and allow it to cool before freezing.

Scalding fresh milk will stop the enzymes from breaking down the fat, preventing that soapy smell and taste. Scalding milk does reduce some of the beneficial components in breast milk, however, so give your infant fresh breast milk whenever possible.

To scald milk:

• Heat milk to about 180 F (82 C), or until you see little bubbles around the edge of the pan (not to a full, rolling boil with bubbles in the middle of the milk).
• Quickly cool and store the milk.

Scalding the milk will destroy some of the immune properties of the milk and may lower some nutrient levels, but this is not likely to be an issue unless all of the milk that baby is receiving has been heat-treated.

Per Lawrence & Lawrence, bile salt-stimulated lipase can also be destroyed by heating the milk at 144.5 F (62.5 C) for one minute (p. 205), or at 163 F (72 C) for up to 15 seconds (p. 771).

Lawrence R, Lawrence R. Breastfeeding: A Guide for the Medical Profession, 6th ed. Philadelphia, Pennsylvania: Mosby, 2005: 156-158, 203-205, 771, 781.

Lawrence RA. Storage of human milk and the influence of procedures on immunological components of human milk. Acta Paediatr Suppl. 1999 Aug;88(430):14-8.

Have a ton of freezer milk with high lipase? Some babies don’t mind the flavor and will drink it anyway. If you’re won’t, Before pitching it, consider trying the following:

• Mix frozen milk with fresh milk to make it more appetizing to baby
• Some moms find adding a few drops of alcohol free vanilla extract can mask the lipase flavor. 
• Use it for a milk bath which can help with dry skin

Milk taste rancid or metallic? That's not lipase, the cause may be chemical oxidation (Mohrbacher, p. 461). Reducing intake of polyunsaturated fats may help. Certain minerals or metals in drinking water may also be to blame like copper or iron ions. When this happens, Mohrbacher has a few suggestions to try:

• Avoid your usual drinking water (either drinking it or having milk come into contact with it) by using bottled or reverse osmosis filtered water instead
• Avoid fish-oil and flaxseed supplements, and foods like anchovies that contain rancid fats
• Increase antioxidant intake (including beta carotene and vitamin E like berries, spinach, beets, and beans).

Mohrbacher N. Breastfeeding Answers Made Simple. Amarillo, Texas: Hale Publishing, 2010: 460-461.