Raw milk versus UHT milk: Impact on gut health and growth.

Raw vs. UHT Milk: Which is Best for Your Gut and Growth?

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Mira Elwood in Health & Wellness December 2025 • 4 min read.

"A calf study reveals how different milk processing temperatures impact nutrient absorption, gut health, and overall growth performance."


Milk is widely recognized as a nutritional powerhouse, packed with essential proteins and bioactive compounds. To extend its shelf life, the dairy industry employs various heat treatments, primarily pasteurization and ultra-high temperature (UHT) processing. While these processes ensure safety and longevity, questions remain about their impact on milk's nutritional value and digestibility.

Many assume that the benefits of raw milk remain unchanged after pasteurization or UHT treatments. However, research suggests that heat processing can alter milk's composition, potentially affecting its digestibility and interaction with the gut microbiota. For instance, UHT treatment leads to the formation of Amadori products, which reduce the availability of lysine, an essential amino acid.

A recent study investigated the effects of different milk processing temperatures on growth performance, nitrogen retention, and gut health. By using young dairy calves as a model, researchers were able to assess how raw, pasteurized, and UHT milk impact these critical factors. This article will delve into the findings, providing insights into the potential trade-offs between milk processing and nutritional benefits.

UHT Milk: Compromised Growth and Increased Nitrogen Excretion

Raw milk versus UHT milk: Impact on gut health and growth.

The study, conducted using Holstein male calves, compared the effects of raw milk (RM), pasteurized milk (PAST), and UHT milk (UHT) on several key health indicators. Calves were carefully monitored for growth, nutrient digestion, and changes in their gut microbiota and inflammatory status. The results revealed some notable differences between the milk types.

One of the most striking findings was the significantly lower growth rate in calves fed UHT milk compared to those fed raw milk. While milk consumption was slightly reduced in the UHT group, the difference in growth was more pronounced than could be explained by intake alone. This suggests that UHT processing may affect nutrient utilization beyond simply reducing consumption.

  • Furosine Content: UHT milk contained approximately 33 times more furosine, an Amadori product, compared to raw and pasteurized milk. Furosine reduces the availability of lysine.
  • Nitrogen Excretion: Calves consuming UHT milk excreted significantly more nitrogen in their urine, indicating a less efficient use of protein.
  • Lactobacillus Levels: The quantification of Lactobacillus was lower in calves consuming PAST or UHT milk compared to raw milk.
  • Gram-Negative Bacteria: Gram-negative bacteria were more prevalent in UHT-fed calves than in pasteurized-fed calves.
These findings suggest that UHT treatment may hinder the nutritional value of milk by compromising growth and increasing nitrogen excretion in young calves. The alterations in gut bacteria populations and inflammatory status further underscore the potential downsides of high-temperature milk processing.

Rethinking Milk Processing: Balancing Safety and Nutrition

The study's conclusions highlight the need to carefully consider the trade-offs between milk processing methods and nutritional quality. While UHT treatment offers the advantage of extended shelf life, it may come at the cost of reduced growth potential, altered gut microbiota, and increased nitrogen excretion.

Raw milk, on the other hand, appears to offer superior nutritional benefits in terms of growth performance and gut health. However, it's essential to acknowledge the safety concerns associated with raw milk consumption, as it may contain harmful bacteria.

Future research should focus on identifying processing methods that minimize the negative impacts on milk's nutritional value while ensuring safety. Exploring alternative technologies and optimizing existing processes could help strike a better balance between extending shelf life and preserving the health benefits of milk.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1017/s0022029917000401, Alternate LINK

Title: Influence Of Milk Processing Temperature On Growth Performance, Nitrogen Retention, And Hindgut'S Inflammatory Status And Bacterial Populations In A Calf Model

Subject: Animal Science and Zoology

Journal: Journal of Dairy Research

Publisher: Cambridge University Press (CUP)

Authors: Alex Bach, Anna Aris, Maria Vidal, Francesc Fàbregas, Marta Terré

Published: 2017-08-01

Everything You Need To Know

1

How does UHT milk affect growth compared to raw milk, according to the calf study?

The study indicated that calves fed UHT milk exhibited a notably lower growth rate compared to those fed raw milk. While UHT milk consumption was slightly reduced, the disparity in growth was more significant than intake alone could explain, suggesting UHT processing may affect nutrient utilization.

2

Why does consuming UHT milk lead to increased nitrogen excretion?

The study found that calves consuming UHT milk excreted significantly more nitrogen in their urine. This suggests a less efficient utilization of protein in UHT milk compared to raw or pasteurized milk, indicating that UHT processing might compromise the protein quality or digestibility.

3

What is furosine, and why is its presence in UHT milk a concern?

Furosine is an Amadori product formed during UHT processing, and it was found in significantly higher concentrations in UHT milk compared to raw and pasteurized milk. Elevated levels of furosine reduce the availability of lysine, an essential amino acid necessary for growth and development.

4

How do pasteurization and UHT processing impact the levels of beneficial bacteria like Lactobacillus in the gut?

The research revealed that Lactobacillus levels were lower in calves consuming pasteurized or UHT milk compared to raw milk. Furthermore, gram-negative bacteria were more prevalent in UHT-fed calves than in pasteurized-fed calves, indicating that high-temperature processing affects the gut microbiota composition, potentially impacting gut health.

5

What are the broader implications of the calf study on milk processing, balancing safety with nutritional value?

The study underscores the need to balance milk processing methods with nutritional quality. While UHT treatment extends shelf life, it may come at the expense of reduced growth potential, altered gut microbiota, and increased nitrogen excretion. Further research is needed to optimize processing techniques that minimize nutritional losses while ensuring safety and longevity.

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