Understanding Nutrients

When we talk about feeding dogs, we often talk about foods. Chicken, beef, eggs, sardines, vegetables, yoghurt, bone, liver and a long list of other ingredients. We may also talk about proteins, fats, vitamins and minerals, but these are often treated as though they are simply components we add to a diet to make it “complete”.

There is a much more useful way to think about nutrition.

Your dog does not actually need chicken, beef, carrots or blueberries. Your dog needs the nutrients those foods provide.

Food is the vehicle. Nutrients are the biologically useful substances the body extracts, transforms and uses.

Understanding that distinction is one of the foundations of understanding canine nutrition.

What is a nutrient?

A nutrient is a substance that the body requires for energy, growth, maintenance, repair or normal physiological function. Some nutrients must be obtained from the diet because the body cannot make enough of them itself. Others can be manufactured by the body from other substances, although dietary sources may still contribute to the overall nutrient supply.

Nutrients are broadly divided into macronutrients and micronutrients.

The macronutrients are protein, fat and carbohydrates. They are present in relatively large amounts in the diet and provide energy or the raw materials required to build and maintain the body.

Micronutrients include vitamins and minerals. They are required in much smaller quantities, but their small quantities should not be mistaken for minor importance. A nutrient needed in milligrams rather than grams can still be absolutely essential to life.

Water deserves its own category. It does not provide calories, but it is arguably the most immediately essential nutrient of all. Every physiological system depends upon adequate hydration.

These categories are useful, but they don't tell the whole story. Nutrients do not operate independently of one another. The body is an interconnected biological system, and nutrition is therefore an interconnected system too.

Protein is much more than “muscle”

Protein is often discussed as though its primary purpose is building muscle. In reality, protein is fundamental to almost every aspect of the body.

Dietary proteins are digested into amino acids and smaller peptides. These become the raw materials from which the body produces its own proteins, including enzymes, hormones, transport proteins, antibodies, receptors, structural proteins and the proteins that make up muscle and other tissues.

Dogs require particular amino acids in their diet. Some can be manufactured from other compounds, while others are considered essential because the body cannot synthesise sufficient quantities to meet its needs.

This is an important distinction.

The nutritional value of a protein isn't determined simply by how much protein a food contains. Its amino acid composition, digestibility and the amount actually available to the body all matter.

This is why looking at a single number such as “protein percentage” tells us relatively little about the nutritional quality of an entire diet.

Protein is also not simply a building material. When necessary, amino acids can be used as an energy source, and the body continually breaks down and rebuilds proteins as part of normal metabolism.

Fat is an active biological component

Fat has traditionally been viewed primarily as a concentrated source of energy. It certainly is that, but its role is considerably broader.

Dietary fats supply essential fatty acids, contribute to cell membranes, participate in signalling pathways and help with the absorption of fat-soluble vitamins. Fat also makes food more energy dense and can influence palatability.

The different fatty acids matter.

Omega-3 and omega-6 fatty acids, for example, are not interchangeable. They participate in different metabolic pathways and can influence inflammatory signalling, cell membrane composition and other physiological processes.

The body also needs particular fatty acids rather than simply “some fat”.

This is another reason that nutritional discussions based solely on percentages can become misleading. Two diets could contain the same total amount of fat while providing very different fatty acid profiles.

Carbohydrates are not simply “fillers”

Carbohydrates are often discussed in extremely polarised terms, particularly in online dog-nutrition conversations.

Biologically, carbohydrates are a diverse group of molecules with different functions. Starches can provide glucose, while different forms of fibre can influence gastrointestinal function, stool characteristics and the activity of the gut microbiome.

Dogs can obtain glucose from sources other than dietary carbohydrate, because their metabolism can produce glucose from compounds such as amino acids and glycerol. This does not mean that every carbohydrate-containing food is nutritionally useless, nor does it mean that dietary carbohydrate is an essential macronutrient in the same sense as certain amino acids and fatty acids.

The important question is what the particular carbohydrate is contributing to the diet.

A starchy food, a piece of fruit and a source of fermentable fibre are not nutritionally equivalent simply because they all contain carbohydrates.

Vitamins are small but powerful

Vitamins are organic compounds required in small quantities for normal physiological processes. They participate in an enormous variety of reactions involving metabolism, immunity, blood formation, vision, reproduction, antioxidant protection and tissue maintenance.

They are commonly divided into fat-soluble and water-soluble vitamins.

The fat-soluble vitamins A, D, E and K can be stored in the body. The water-soluble B vitamins and vitamin C behave differently, although the distinction is more complicated physiologically than simply saying that water-soluble vitamins are never stored.

Dogs can also manufacture some vitamins themselves. Vitamin C is a good example. Unlike humans, dogs can synthesise vitamin C endogenously under normal circumstances, so dietary vitamin C is not generally considered an essential nutrient for healthy dogs.

This illustrates an important principle in nutrition:

Just because a substance is beneficial to biological systems does not necessarily mean that it is an essential dietary nutrient.

Essentiality depends on whether the body can obtain sufficient amounts through its own metabolic processes or whether it must obtain that substance, or its precursor, from the diet.

Minerals are not just “supplements”

Minerals are inorganic elements rather than organic compounds. They include major minerals such as calcium, phosphorus, magnesium, sodium and potassium, as well as trace elements such as zinc, copper, iodine and selenium.

They have remarkably diverse functions.

Calcium and phosphorus are important components of the skeleton, but calcium is also involved in muscle contraction, nerve transmission and cellular signalling. Sodium and potassium contribute to fluid balance and the electrical activity of nerves and muscles. Iron is involved in oxygen transport. Zinc participates in numerous enzymatic and cellular processes. Iodine is required for thyroid hormone production.

The fact that some minerals are required in tiny amounts does not make them unimportant.

It also creates one of the great challenges of nutrition: the difference between too little and too much can sometimes be relatively small.

More is not necessarily better

One of the most important concepts in nutrition is that nutrients exist within ranges of requirement.

Deficiency can cause problems, but excessive intake can also cause problems. This is particularly relevant for nutrients that the body stores or that have narrow safety margins.

Vitamin D is an obvious example. Dogs require it, but excessive vitamin D can be toxic.

Calcium is another example. It is essential for normal bone development and numerous physiological functions, but simply adding more calcium to a diet does not make the diet healthier.

Nutrition is therefore not a matter of collecting as many beneficial substances as possible.

It is about providing appropriate amounts of the nutrients the body requires.

Nutrients interact

Perhaps the most important reason to stop thinking about nutrients as isolated ingredients is that they interact.

Calcium and phosphorus are closely connected in skeletal metabolism. Vitamin D influences calcium and phosphorus homeostasis. Copper and zinc interact at the level of absorption and metabolism. Fat influences the absorption of fat-soluble vitamins. The amount and type of fibre can influence the intestinal environment and the absorption or utilisation of other nutrients.

There are countless examples.

This means that nutritional adequacy cannot always be determined by looking at one nutrient in isolation.

A diet can contain a nutrient without that nutrient necessarily being fully available to the dog.

Which brings us to another important concept: bioavailability.

What is bioavailability?

Bioavailability refers, broadly, to the proportion of a nutrient that is absorbed and available for use by the body.

The amount present in a food and the amount the body can actually utilise are not necessarily identical.

The chemical form of a nutrient matters. So does the food matrix in which it is contained. Digestibility, processing, interactions with other nutrients and the dog's own physiology can all influence nutrient availability.

This is one reason nutrition is considerably more complicated than reading a list of ingredients.

An ingredient list tells you what went into a food.

It does not necessarily tell you everything about what the dog ultimately absorbs and uses.

Nutrients come packaged in foods

Whole foods don't generally provide isolated nutrients.

A piece of sardine provides protein, fat, fatty acids, minerals and other biologically active compounds. Liver provides protein along with exceptionally concentrated amounts of particular vitamins and minerals. Eggs provide protein, fat, fatty acids, vitamins and minerals. Vegetables provide varying combinations of fibre, vitamins, minerals and phytochemicals.

This is one of the fascinating things about food.

A food is not simply a collection of isolated nutrients.

The nutrients exist within a biological matrix, alongside countless other compounds.

That doesn't mean that whole foods are automatically nutritionally perfect. Nor does it mean that every food is appropriate in unlimited quantities. Some foods are particularly concentrated sources of particular nutrients, and excessive amounts can create imbalances.

It simply means that nutrition is more complex than reducing food to a list of individual numbers.

Balance is a moving target

We often use the word “balance” as though it describes a single perfect ratio that applies to every dog.

In reality, nutritional requirements vary.

A growing puppy does not have exactly the same nutritional requirements as an adult dog. Pregnancy and lactation create different demands. A highly active working dog has different energy requirements from a sedentary companion. Age, reproductive status, health and individual physiology can all influence nutritional needs.

Even energy requirements vary enormously between individual dogs of the same size.

This is why feeding a dog is not simply a matter of finding the one “perfect” food.

It is about providing the nutrients the individual needs in appropriate amounts over time.

Nutrition happens over time

This is particularly important when feeding fresh foods.

A single meal does not need to contain every nutrient your dog will ever require.

At the same time, “balance over time” should not become an excuse for routinely excluding important nutrients or feeding an extremely narrow diet. Some nutrients are required regularly, while others can be stored in the body to varying degrees.

The nutritional adequacy of a diet therefore needs to be considered as a whole rather than judged by one meal or one ingredient.

Variety can be valuable because different foods provide different nutrient profiles. Rotating appropriate sources of meat, organs, edible bone, fish, eggs, dairy and plant foods can broaden the range of nutrients and other biologically active compounds available within a diet.

But variety alone does not guarantee adequacy.

A varied diet can still be poorly formulated, just as a repetitive diet can potentially provide appropriate nutrition if it has been carefully formulated.

Variety is a tool, not a nutritional guarantee.

Start asking better questions

Once you begin thinking in terms of nutrients rather than simply foods, the questions you ask about your dog's diet change.

Instead of asking, “Is chicken good for dogs?” you might ask, “What nutrients does chicken contribute, and what nutrients does it provide less of?”

Instead of asking, “Are vegetables necessary?” you can ask, “What does this particular vegetable contribute to the diet?”

Instead of asking, “Does this supplement contain lots of vitamins?” you can ask, “Does my dog actually need additional amounts of these nutrients, and what happens if I provide too much?”

And instead of asking whether a food is “complete”, you can ask a much more useful question:

“What nutrients does this diet provide, in what amounts, and are those amounts appropriate for this particular dog?”

That is a much more scientific way of thinking about nutrition.

Food first, nutrition always

There is no single magic ingredient that creates a healthy dog.

Health emerges from a complex interaction between genetics, environment, lifestyle, disease status and nutrition. Food supplies the raw materials from which the body builds, repairs, regulates and fuels itself, but those raw materials need to be supplied in appropriate forms and amounts.

Understanding nutrients allows us to move beyond thinking of food as simply calories, ingredients or marketing categories.

We can start looking at what the food is actually doing inside the body.

Protein supplies amino acids. Fat supplies energy and essential fatty acids. Carbohydrates can provide energy and different forms of fibre. Vitamins and minerals participate in thousands of physiological processes. Water supports virtually every biological system. And all of these components interact.

That is nutrition.

Not a list of ingredients.

Not a label.

Not a single percentage.

And certainly not a single “superfood”.

It is the science of supplying the raw materials that allow a living body to function, adapt, repair and thrive.

Once you understand that, choosing foods becomes much more interesting.

You stop asking which food is “best” and start asking what each food contributes, what is missing, how nutrients interact, and how those pieces fit together to meet the needs of the individual dog.

And that is where genuine nutritional understanding begins.