Raw Milk vs Pasteurized Milk: What’s the Difference?

What Pasteurization Does to Milk

Pasteurization is a process that heats milk in order to reduce bacteria that may be present.

In modern dairy processing, milk is typically heated to about 161°F for around 15 seconds and then rapidly cooled. This allows milk to remain stable longer and makes it easier to distribute through large supply chains.

However, heating milk also changes several natural components found in fresh milk. Pasteurization reduces naturally occurring beneficial bacteria, enzymes, and some sensitive vitamin activity that exist in raw milk.

While the core nutrients in milk remain, these changes can influence how milk behaves during digestion.

Raw Milk vs Pasteurized Milk

Raw Milk	Pasteurized Milk
Contains naturally occurring beneficial bacteria	Most bacteria removed through heating
Natural enzymes remain active	Many enzymes reduced or inactivated
Minimal processing	Heat processed to extend shelf life
Cream naturally separates	Usually homogenized for uniform texture
Often consumed close to where it is produced	Designed for large-scale distribution

Understanding these differences helps explain why people can have very different experiences with dairy depending on how the milk is produced and processed.

Raw Milk Contains Beneficial Bacteria and Enzymes

Raw milk naturally contains bacteria and enzymes that exist in fresh milk.

Some of these are beneficial bacteria that support gut health and help break down parts of the milk during digestion. These bacteria are similar to the ones involved in fermentation, such as those found in yogurt or kefir, which are discussed in more detail in our guide to health benefits of fermented foods.

When milk is pasteurized, most of these beneficial bacteria and enzymes are removed.

For some people, this difference may help explain why they tolerate raw dairy better than heavily processed milk.

Research supports a connection between unprocessed milk and certain health outcomes. In a five-country study following nearly 1,000 infants, raw cow’s milk consumption was associated with about 30% fewer respiratory infections and fever than heat-treated milk. The researchers note their goal is minimally processed milk that is also pathogen-free, rather than a recommendation to drink milk raw.

Why Some People Digest Raw Dairy More Easily

Many people assume that discomfort after drinking milk is always caused by lactose intolerance. Lactose can certainly play a role, but it is not the only factor that affects how dairy is digested.

Several things influence how the body responds to milk, including beneficial bacteria that help break down milk during digestion, the type of milk protein, and how the milk has been processed.

When these factors change, the digestive experience can change as well. This helps explain why some individuals report tolerating raw dairy better than highly processed milk.

A1 vs A2 Milk Proteins

Milk contains a protein called beta-casein.

There are two common forms of this protein: A1 beta-casein and A2 beta-casein. Different breeds of cows naturally produce different types of milk.

Some research suggests that certain people may digest A2 milk more comfortably than milk containing A1 proteins. This difference may be another reason why some individuals tolerate certain forms of dairy better than others.

Why Some People Can Eat Yogurt or Cheese but Not Milk

Many people who feel uncomfortable after drinking milk can still eat foods like yogurt, kefir, or aged cheeses.

These foods are fermented dairy products. During fermentation, beneficial bacteria break down much of the lactose and other components in milk.

As a result, fermented dairy foods often contain less lactose and more beneficial bacteria that support digestion. This helps explain why yogurt and aged cheeses are often easier to tolerate than regular milk.

How Modern Processing Changed Milk

When people compare raw milk and store-bought milk, the conversation usually focuses on pasteurization. But modern milk often goes through several processing steps.

Common processing steps include pasteurization, homogenization, ultra-pasteurization for extended shelf life, and large-scale storage and transportation.

Each of these steps changes milk in different ways and can influence how the body responds to it.

What Homogenization Does

Homogenization is a process that breaks the fat molecules in milk into very small particles so the cream does not separate.

This creates the uniform texture most people expect from store-bought milk. Before homogenization became common, milk naturally separated in the container, with cream rising to the top.

While homogenization improves consistency and shelf stability, it also changes the physical structure of milk fat, which may influence how the body processes it.

How Milk Was Traditionally Consumed

For most of human history, milk was consumed raw and close to where it was produced.

Families often kept cows or purchased milk from nearby farms, and it was typically consumed soon after milking.

Because the supply chain was short and local, milk did not need to travel long distances or remain stored for extended periods.

Why Pasteurization Became Common

In the late 1800s and early 1900s, cities began growing rapidly and the demand for milk increased.

Milk had to be transported farther distances to supply urban populations, often without refrigeration. Large urban dairy operations sometimes kept cows in crowded conditions, and sanitation standards were inconsistent.

Under these conditions, contamination became a serious problem in some milk supplies.

Pasteurization was introduced as a way to reduce these risks and make milk safer in large dairy distribution systems. Over time, it became the standard method used for most commercial milk production.

Raw Foods Always Carry Some Risk

Like many foods people eat raw, milk can contain bacteria if contamination occurs during milking, handling, or storage.

This is not unique to dairy. Many foods that are commonly eaten raw, including fruits, leafy greens, and vegetables, can also carry bacteria if contamination occurs before they reach the kitchen.

Outbreaks linked to raw produce occasionally occur for this reason. In practice, most people regularly consume a variety of raw foods.

The key factor for any raw food, including raw milk, is how it is produced, handled, and stored before it is consumed.

Does Raw Milk Contain More Nutrients?

Raw milk and pasteurized milk contain many of the same core nutrients, including protein, fat, calcium, and vitamins.

However, heat can reduce certain sensitive components in milk, including enzymes and some vitamin activity that can be beneficial for digestion and overall health.

Raw milk also retains its naturally occurring beneficial bacteria, which are largely removed during pasteurization.

Why Some People Can Drink Raw Milk but Not Regular Milk

Many people report feeling uncomfortable after drinking conventional milk but tolerate raw milk more easily.

Raw milk contains beneficial bacteria and enzymes that help break down parts of the milk during digestion. Processing steps like pasteurization and homogenization remove many of these natural components and alter the structure of milk.

Protein differences such as A1 versus A2 milk may also influence how people respond to dairy.

Together, these factors may help explain why some individuals tolerate raw dairy much better than highly processed milk.

Understanding the Differences

The discussion around raw milk and pasteurized milk often focuses only on safety. However, pasteurization also changes several natural characteristics of milk. Heating milk helps extend shelf life for large dairy supply chains, while also removing naturally occurring beneficial bacteria and enzymes found in fresh milk.

These differences may influence how some people digest dairy.

Understanding how milk is produced and processed allows people to make more informed decisions about the types of dairy that work best for them. For a broader breakdown of dairy choices, see the full dairy decision guide.