A new seminal review in a special issue of the Journal of Dairy Science® highlights that the complex structure of dairy foods affects their metabolism beyond just their composition

Philadelphia, June 30, 2025 — How do we determine how healthy our food is? We know now that our nutrition shouldn’t just be measured in calories, or even in just macronutrients (the balance of fats, protein, and carbohydrates). An emerging body of research is instead demonstrating that the unique interplay between nutrients and components and how they connect to each other to form a holistic food matrix all play a role in the nutritional value that foods deliver. A new review article in a special issue of the Journal of Dairy Science, published by Elsevier, dedicated to the dairy matrix and human nutrition explores what the latest science has to say about the incredible structural complexity of dairy foods, as well as the impact of the dairy food matrix on nutrient digestion and absorption.

In her introduction to the special issue, editor Grace E. Lewis, PhD, of the University of Wisconsin–River Falls, explained, “The primary goal of this special issue in the Journal of Dairy Science, ‘Dairy Foods: A Matrix for Human Health and Precision Nutrition,’ is to provide a comprehensive and holistic outlook on dairy food nutrition, emphasizing the crucial role dairy food components play in human health from infancy to adulthood, including dairy food digestion, dairy food bioactives, the milk fat globule membrane, and infant formula.”

David W. Everett, PhD, principal investigator and international stakeholder relationship manager at the Riddet Institute (Palmerston North, New Zealand) and author of the review added, “Dairy science has shown that the structure of a dairy food product—whether on a macro-, micro-, or even molecular-scale—impacts its nutritional properties, or how it’s absorbed by and fuels the human body. I wanted to consolidate what we know now, from both lab and clinical trials, on how the unique structure of milk and dairy products impacts nutritional value, focusing on how the structure is broken down during digestion and how nutrients are absorbed.”

So, what do you find in milk and dairy products down at the micro- and molecular level? That depends on how small you go. Dr. Everett explained, “Milk contains an enormous number of components of different molecular sizes.”

On a colloidal scale—of the order of nanometers—the structures include casein micelles, which are a complex structure of thousands of casein protein molecules grouped together, as well as fat globules. At the molecular level, there are individual casein and whey proteins, lactose, milk fat triacylglycerides (also known as triglicerides), lipid components (both charged and neutral), calcium, and micronutrients.

Understanding how each of these components fits together into a holistic structure helps us understand how they interact and change during processing as milk becomes cheese, yogurt, ice cream, protein powder, and many more products, as well as how they change during digestion.

Dr. Everett clarified, “The way milk and dairy are processed during manufacturing significantly reshapes their microscopic structures, which, in turn, has a direct impact on how easily we digest them and absorb their nutrients.”

Common processes like heat treatment during pasteurization and mixing during homogenization affect the structure of milk and dairy products, making it easier for us to digest and absorb proteins and minerals. Ingredients are also added during processing that can significantly change a product’s final structure. For example, in cheesemaking, we use enzymes or acid to clot milk, creating different protein networks that influence how quickly the cheese is digested and the types of protein fragments released.

After processing, the next important change these products go through is human digestion, which happens in three phases: in the mouth, stomach, and, finally, the small and large intestines. “All of the particles dispersed in milk, such as casein micelles, fat globules, whey proteins, and colloidal calcium phosphate, have structures that make our ability to absorb nutrients most effective, especially for infants at a critical stage of development and growth.”

For example, once milk hits the stomach, the mix of acid and pepsin transforms liquid milk into a gel, which clots and slows down the rate of digestion, making the amino acids bioavailable at the most appropriate rate for the human body.

The structure of dairy products—and how that structure is changed during processing—has a distinct effect on how those products are digested and how they influence human health.

Dr. Everett elaborated, “Clinical studies show that, paradoxically, eating a whole dairy food product impacts health differently than consuming milk nutrients in other food items, or even as individual nutrients.”

Unraveling the mysteries of how food structures affect nutrition will require a fuller understanding of the milk’s structural chemistry and biochemistry under unique and complex digestive conditions. This presents an interesting path ahead for dairy foods research and will require additional breakthroughs, particularly in developing computer simulations and artificial models that can closely mimic human digestion.

Dr. Everett concluded, “Ultimately, as we work to better understand nutrition science, it’s important to not only consider food components but also develop an understanding of the emerging discipline of structural nutrition—how components interact with one another to form a network that behaves differently than individual elements on their own. This goes some way to explaining why different foods with the same nutritional profile have differing effects on human health.”