Colostrum is sometimes described simply as “first milk,” but that description doesn’t tell the whole story.

Colostrum is the pre-milk substance produced by mammals immediately following birth. It provides the newborn with concentrated nutrition along with immune and growth factors during a critical period of early development.

Bovine colostrum, which comes from cows, contains many of these same naturally occurring components and can be consumed by humans as a nutritional supplement.

Understanding what is actually in colostrum helps explain why its source, collection time and processing can make such a difference.

What makes colostrum different from regular milk?

Colostrum is produced during the earliest stage of lactation. According to the Udderly Colostrum information guide, whole colostrum contains a combination of immune factors, growth factors and nutritional components.

These include:

• Immunoglobulins
• Bioactive peptides, including PRPs
• Lactoferrin
• Oligosaccharides
• Cytokines
• Growth factors
• Amino acids
• Vitamins and minerals
• Proteins
• Lipids and phospholipids

The guide also identifies additional components including lysozyme, lactoperoxidase, leukocytes and milk fat globule membrane.

That complex composition is an important distinction. Colostrum isn’t simply a source of protein or a single isolated ingredient.

What are immunoglobulins?

Immunoglobulins are antibodies, and they make up an important part of colostrum’s immune-factor profile.

Whole bovine colostrum contains five classes identified in the information guide:

IgG, IgA, IgM, IgE and IgD.

The guide identifies immunoglobulins as the most abundant immune factors found in colostrum. It describes different functions for the individual classes, including IgG’s interaction with toxins and microbes and IgM’s role in responding to bacteria.

IgG receives considerable attention when comparing colostrum products because of its abundance. But total IgG is only one aspect of colostrum quality.

The type of IgG, when the colostrum was collected and whether the product remains whole are also worth considering.

What are PRPs?

Another important group of compounds found in colostrum is bioactive peptides, including proline-rich polypeptides, commonly called PRPs.

PRPs are associated with immune regulation. The information guide describes them as helping regulate the thymus gland and supporting cytokine production.

That distinction is useful because immune health isn’t simply a question of making an immune response stronger. A functioning immune system also needs signaling and regulation.

What is lactoferrin?

Lactoferrin is another naturally occurring component of whole colostrum.

As its name suggests, lactoferrin interacts with iron. The information guide describes its ability to bind iron and thereby limit the iron available to bacteria for reproduction. It also notes lactoferrin’s relationship with cytokine activity and immune cells.

Lactoferrin is one example of why looking only at the IgG percentage on a colostrum label can provide an incomplete picture.

Colostrum contains a much broader collection of bioactive compounds.

What about the gut?

The gastrointestinal system is another important part of the colostrum story.

The information guide identifies oligosaccharides as compounds that may help support the gut barrier by promoting development of the mucosal lining.

It also describes oligosaccharides and glycoconjugates as substances capable of attracting and binding to pathogens, which can interfere with their ability to attach to mucous membranes.

This relationship between the digestive tract and immune system helps explain why gut support and immune support frequently appear together when discussing bovine colostrum.

For a closer look at this subject, see Colostrum for Gut Health: How It Supports the Gut Lining and Microbiome.

Does colostrum contain growth factors?

Yes. The information guide identifies several naturally occurring growth factors in colostrum, including:

• Epithelial growth factor (EGF)
• Insulin-like growth factors I and II (IGF-I and IGF-II)
• Fibroblast growth factor (FGF)
• Platelet-derived growth factor (PDGF)
• Transforming growth factors
• Growth hormone (GH)

The guide associates these compounds with cell and tissue growth and discusses IGF-1 and GH in connection with muscle and bone growth and repair.

This is one reason colostrum is of interest beyond immune health.

What nutrients are naturally present in colostrum?

Whole colostrum also provides more familiar nutritional components.

The information guide identifies vitamins A, B1, B2, B6, B12 and E, along with minerals including calcium, sodium, magnesium and zinc. It also describes colostrum as a source of essential and non-essential amino acids and essential fats.

Those fats deserve particular attention because they are one of the differences between whole and skimmed or fractionated colostrum.

Why does “first milking” matter?

Colostrum changes rapidly after a calf is born.

First-milking colostrum is the colostrum present in the udder when the calf is born. The Udderly Colostrum information guide identifies this first collection as providing the highest amounts of important bioactive components.

As subsequent milkings occur, the composition begins changing toward ordinary milk.

This makes the phrase first milking more than marketing terminology. It describes when the colostrum was collected and therefore provides information about its composition.

For a detailed look at the differences, see First-Milking Colostrum vs Regular Colostrum: What’s the Real Difference?

Why does whole colostrum matter?

Another distinction is whether a colostrum product is whole or has been skimmed or fractionated.

Whole colostrum retains its naturally occurring fats and lipids along with its proteins and other bioactive components.

The information guide notes that colostrum contains essential fats, including phospholipids, and describes their role in protecting colostral proteins and facilitating absorption in the gut.

This is why evaluating a colostrum supplement solely by its advertised IgG percentage can overlook other parts of its natural composition.

So, what are the potential benefits of bovine colostrum?

Based on the research summarized in the Udderly Colostrum information guide, the primary areas of interest include:

Immune support. Immunoglobulins, PRPs, lactoferrin, cytokines and other components are associated with different aspects of immune function.

Gut support. Oligosaccharides and immune factors are associated with the gastrointestinal environment and mucosal barrier.

Muscle and bone support. Whole colostrum naturally contains IGF-1 and IGF-2, which the guide discusses in connection with lean muscle mass and bone density.

The guide discusses additional areas of research as well. As with any nutritional supplement, however, it’s important to distinguish supportive nutritional research from claims that a product can prevent or treat disease.

What should you look for in a colostrum supplement?

Once you understand what colostrum is, comparing products becomes easier.

Rather than focusing on a single number on the label, consider asking:

• Is it first-milking colostrum?
• Is it whole or fractionated?
• Does it retain its naturally occurring lipids?
• Does it contain bioactive peptides such as PRPs?
• What does the manufacturer disclose about its IgG?
• How is it processed?
• Is the finished product independently tested?

These questions tell you considerably more about a product than the word “colostrum” alone.

The Udder Truth

Colostrum is a remarkably complex first food.

Whole bovine colostrum naturally contains immunoglobulins, PRPs, lactoferrin, oligosaccharides, growth factors, amino acids, vitamins, minerals, proteins and lipids. These components are why bovine colostrum has become the subject of research involving immune function, gut health and other aspects of wellness.

But “colostrum” isn’t necessarily enough information when choosing a supplement.

Collection timing, composition and processing matter.

Understanding those differences is the best place to start.