Bioavailability in Dogs: Why Some Nutrients Never Reach Your Dog

As pet parents, we all want to feed our dogs the best ingredients possible. That’s why we focus on what's listed on the label or the ingredients we use- how much protein is my dog getting? Are there enough minerals and vitamins and Omega? And more

 But did you know that even if a food contains high-quality nutrients, there's no guarantee your dog will absorb and use them? That's where bioavailability comes in.

Bioavailability isn't about how much nutrition is in the bowl. It's about how much of that nutrition actually reaches your dog's body and does its job.

 

Bioavailability vs Digestibility vs Bio-accessibility: They're Not the Same Thing

These terms are often used interchangeably in the canine nutrition industry, but they mean very different things.

• Digestibility is how much food gets broken down and doesn't show up in the stool.
• Bioaccessibility is how much of that nutrition gets released from the food into a form that could be absorbed.
• Bioavailability is how much is actually absorbed, transported, and used by the body. Bioavailability is an outcome of a whole system: the nutrient + the food matrix + processing + the dog’s gut physiology + the dog’s current state (age, gut health, disease, meds, microbiome).

 

Bioavailability Is More Than Just the Nutrient

When people think about nutrition, they often focus on the ingredient itself.

In reality, bioavailability depends on much more:

• The nutrient
• The food it's packaged in
• How the food was processed
• The dog's digestive system
• Age, health, medications, and microbiome

This is why two dogs eating the same food can have completely different outcomes. One may thrive with a shiny coat and good energy levels, while another may struggle with loose stools, poor coat quality, or nutrient deficiencies.

 

The “5 Gates” Model: What A Nutrient Must Pass to Become Dog Nutrition

Imagine nutrition as a package being delivered to your dog's cells. Just because the package was shipped doesn't mean it arrives at the right address. Before a nutrient can benefit your dog, it must pass through five key gates.

Gate 1: Release: Can the nutrient be liberated from the food?

If a nutrient is trapped, the body can’t use it.

• Minerals can be bound to plant compounds.
• Proteins can be tightly folded
• Fats can be trapped inside plant cell walls

How the food is ground, cooked, hydrated, and chewed decides whether enzymes can even reach the nutrient. If a nutrient isn’t absorbed and made bioavailable, it doesn’t matter how much is in the formula; it won’t benefit the body.

Gate 2: Survival: Does the nutrient stay usable after cooking, storage, and digestion?

Some nutrients are damaged before the dog ever eats them.

A common example:

High heat and extrusion cooking (in kibble) can degrade amino acids such as lysine.

The label may still show “protein,” but part of it is no longer usable.

This is why scientists talk about “available” nutrients, not just total nutrients. If it’s damaged, the body can’t use it even if it’s listed on the label.

Gate 3: Access: Does it reach the absorption zone in time?

Dogs have shorter digestive tracts and faster gut movement than humans. This means food has a limited window to be broken down and absorbed. For nutrition to work, the food must digest and release nutrients at a pace that matches a dog’s digestive speed, so those nutrients are available in the right part of the gut where absorption occurs.

If food digests too slowly, nutrients may reach the intestine after the absorption window has passed. If it breaks down poorly, nutrients may never be released in a usable form. In both cases, the food passes through the body with much of its nutrition left unused.

Gate 4: Transport: Can it cross into the body and survive processing by the liver?

After absorption, nutrients still face hurdles:

• Some are broken down by gut or liver enzymes
• Some compete with other nutrients
• Some need fat or bile to be carried properly

Absorbed doesn’t always mean delivered. A nutrient can enter the body but still fail to reach the tissues where it’s actually needed.

Gate 5: Utilisation: Can the body actually use it where it’s needed?

Even a perfectly absorbed nutrient can fail here.

Reasons include:

• Missing helper nutrients (cofactors)
• Inflammation or gut imbalance
• Excess nutrients blocking each other

If the body can’t use it, it doesn’t matter how much was eaten.

 

Two Things Most Pet Parents Aren't Told

1. Dogs Never Absorb 100% of What They Eat

Nutrition recommendations are designed with this in mind.

Manufacturers typically include more nutrients than the theoretical requirement because some loss is expected during digestion and absorption.

2. Processing Matters

Heat, storage conditions, and ingredient choices can all influence bioavailability.

Certain amino acids, particularly lysine, are vulnerable to processing damage. As a result, two foods with similar nutrient levels on paper may deliver very different amounts of usable nutrition.

This is one reason why a food can be technically "complete and balanced" while still performing differently in real-world feeding.

 

Mineral Bioavailability & Plant-based Ingredients

Minerals provide a good example of why bioavailability matters. Many plant ingredients contain phytates (phytic acid). These compounds can bind to minerals such as:

• Zinc
• Iron
• Magnesium
• Calcium

Once bound, those minerals become harder for the dog's digestive system to absorb. This means a food may contain adequate mineral levels on paper, yet the dog may absorb less than expected.

Research also shows that:

• The source of the mineral matters.
• Organic and inorganic forms may be absorbed differently.
• High-phytate diets can reduce mineral availability even when total mineral content appears sufficient.

Minerals need to be present in the right form and the right dietary context to be useful.

 

Key Takeaways

Bioavailability reminds us that nutrition is not just about what's in the food. It's about what the dog's body can actually absorb, transport, and use.

A food may look impressive on the label, yet deliver less usable nutrition than expected. It may contain nutrients in forms that are difficult to absorb, or provide levels that appear adequate but don't translate into real biological benefit.

When evaluating a food or supplement, the most important question isn't, how much nutrition is in this product? It is, how much of that nutrition can my dog actually use?