HIGH LIPASE IN BREASTMILK: What You Need to Know

By Andrea Chamberlain, IBCLC

If you’ve noticed that your stored breastmilk smells soapy, metallic, or even rancid after some time in the fridge or freezer, you’re not alone. This change in odor or taste is often caused by high lipase activity. While it can be frustrating or discouraging, especially if your baby refuses stored milk, there are solutions. Here’s what you need to know.

What Is Lipase and Why Is It Important?

Lipase is a natural enzyme found in breastmilk that helps break down fats into smaller components, making them easier for your baby to digest and absorb. All human milk contains lipase, but some individuals produce higher levels. In these cases, the enzyme continues breaking down fats even after the milk is expressed, leading to a noticeable change in smell or taste over time.

Importantly, high lipase activity does not make milk unsafe. The milk still retains its nutritional and immunological benefits, even if the flavor has changed.

How to Test for High Lipase Activity

If you suspect high lipase is affecting your milk, try the following:

1. Express and store 1–2 oz of freshly pumped breastmilk in a sealed container.

2. Refrigerate it without freezing.

3. Smell and taste a small amount each day over the next 3–4 days.

4. If the milk develops a soapy, metallic, or rancid smell/taste within that time, high lipase activity is likely.

Note how long the milk remains fresh before the flavor changes. This can guide how long you can refrigerate milk before freezing or using it.

Why Some Babies Refuse High-Lipase Milk

Some babies are sensitive to the altered flavor and may reject the milk, especially if they are used to freshly expressed milk. Others may not mind the change. This is a preference issue, not a safety one.

Tips if Your Baby Refuses High-Lipase Milk

• Serve it cold or slightly warmed: Some babies are more likely to accept altered milk when it is cold.

• Mix with freshly expressed milk: Diluting with fresh milk can help mask the flavor.

• Try during sleepy or dream feeds: Babies may be less aware of taste changes during these times.

• Offer in a different bottle: A change in nipple or bottle flow can sometimes reduce resistance.

• Freeze milk immediately after pumping: This may reduce the breakdown of fats and preserve taste.

• Use the milk for milk baths or other topical uses if your baby still refuses.

• Consider milk donation if the milk meets guidelines for donation and your baby won’t drink it.

Scalding Breastmilk to Prevent Flavor Changes

Scalding breastmilk can deactivate the lipase enzyme, preventing further fat breakdown and preserving the original taste. This is often a last-resort strategy, but it can be effective.

How to Scald Milk:

1. Pour expressed milk into a clean saucepan.

2. Heat on the stove until small bubbles form around the edges (approximately 180°F / 82°C).

3. Remove from heat immediately.

4. Cool the milk quickly by placing the container in an ice water bath.

5. Store or freeze immediately.

Note: Scalding may slightly reduce some of the immune and nutritional properties of breastmilk. Use this method only when necessary.

Frequently Asked Questions

Is high-lipase milk harmful? No. High-lipase milk is safe and retains its nutritional and immune-supporting properties.

Will I always have high lipase? High lipase levels are typically consistent across a lactation, though some report changes over time. Testing every few months can be helpful.

Can I test lipase levels at a lab? While research labs can measure lipase levels, this testing is not readily available for consumer use and is not usually necessary.

Can freezing right after pumping help? Yes. Freezing milk immediately may help prevent taste changes by halting lipase activity.

Emotional Support Matters

Discovering that your baby refuses your stored milk can be incredibly disheartening. It's okay to feel frustrated. Remember: there is nothing wrong with your milk or with you. You’re doing an amazing job, and there are strategies to work through this.

Need Help? If you’re navigating high lipase challenges or bottle refusal, reach out for personalized lactation support. Working with an IBCLC can help you troubleshoot feeding issues and create a plan that works for your family.

Additional Resources

• KellyMom: High Lipase in Breastmilk

• Healthline: What to Know About High Lipase Breast Milk