Macro + Micronutrients✨

Nutrition can feel like a big topic when you first start studying it.

From carbohydrates, fats, proteins, vitamins, minerals, fibre, water + suddenly it feels like there is a lot to remember.

But when you break it down, nutrients can be split into two main groups: macronutrients + micronutrients.

Both are essential, but they have different roles in the body.

Macronutrients are needed in larger amounts - they provide energy, structure + support for normal body function.

Micronutrients are needed in smaller amounts, but they are still really important for things like metabolism, growth, immunity, hormone function + overall health.

✨ What are macronutrients?

Macronutrients are nutrients the body needs in larger amounts.

The main macronutrients are:

• Carbohydrates
• Fibre
• Fat
• Protein
• Water

They help provide energy, support body tissues, aid digestion + keep normal body systems working properly.

Carbohydrates

Carbohydrates are made from carbon, hydrogen + oxygen.

They are mainly used as a source of energy + provide glucose for cells. They can also help form important compounds in the body, such as DNA + RNA.

Carbohydrates can be split into:

Monosaccharides — simple sugars, such as glucose
Disaccharides — two sugar units, such as lactose
Polysaccharides — complex carbohydrates, such as starch and cellulose

In dogs + cats, carbohydrate digestion involves enzymes such as amylase, which help break starch down into smaller sugars. These are eventually absorbed as monosaccharides in the small intestine.

A key thing to remember is that dogs + cats cannot digest cellulose.

Fibre

Fibre is a type of carbohydrate that resists enzymatic digestion.

This means it is not digested in the same way as other carbohydrates, but it still has important functions in the body.

Fibre can help:

• Increase intestinal bulk and water
• Support gut transit
• Maintain colon health
• Help regulate nutrient absorption
• Support weight control
• Manage some fibre-responsive diseases

There are two main types:

Soluble fibre — such as pectins, which can help regulate glucose + cholesterol
Insoluble fibre — such as cellulose, which helps support bowel movement

Fibre is especially important when thinking about gut health + faecal quality.

Fat

Fat is a concentrated source of energy and provides around 8.5 kcal/g.

It is made from triglycerides, which are formed from glycerol + three fatty acids.

Fat has several important roles, including:

• Energy storage
• Insulation
• Helping absorb fat-soluble vitamins
• Supporting hormone synthesis
• Improving palatability of food

Fat-soluble vitamins include A, D, E and K, so adequate fat is important for their absorption.

Essential fatty acids are also needed in the diet. These include linoleic acid + arachidonic acid.

Cats specifically require arachidonic acid in their diet. Signs that may suggest fatty acid deficiency can include poor coat condition, skin issues + impaired healing.

Protein

Protein is made from amino acids joined together by peptide bonds.

It is needed for growth, repair + normal body function.

Protein helps with:

• Tissue growth and repair
• Energy provision
• Hormone production
• Enzyme production
• Immune function
• Metabolism regulation

Some amino acids are essential, which means they must be obtained from the diet. Others are non-essential, meaning the body can synthesise them.

Protein quality is often linked to biological value, which refers to how much protein is retained + used by the body.

A good way to think about protein is that it is not just “muscle food” — it is needed throughout the body for repair, function + regulation.

Water

Water is often overlooked, but it is the most vital nutrient.

It makes up around 60–70% of body weight + is essential for normal body function.

Water helps:

• Maintain fluid balance
• Support temperature regulation
• Aid digestion
• Transport nutrients
• Lubricate joints and tissues
• Support biochemical reactions

Even small changes in hydration can affect how a patient feels and functions, which is why water intake, hydration status + fluid balance are so important in nursing care.

✨ What are micronutrients?

Micronutrients are needed in smaller amounts than macronutrients, but they are still essential.

The main micronutrients are:

• Minerals
• Vitamins

They do not provide energy in the same way as carbohydrates, fats + protein, but they are involved in lots of important body processes.

Minerals

Minerals can be split into macrominerals + trace minerals.

Macrominerals

These are needed in larger amounts.

Examples include:

• Calcium
• Phosphorus
• Sodium
• Chloride
• Potassium
• Magnesium

Trace minerals

These are needed in smaller amounts.

Examples include:

• Iron
• Copper
• Zinc
• Manganese
• Selenium
• Iodine

Minerals have lots of important functions, including:

• Bone and teeth structure
• Electrolyte balance
• Muscle function
• Nerve function
• Enzyme activity
• Hormone function
• Oxygen transport
• Immune support

Some simple examples include:

Calcium — bones, teeth, muscle contraction and clotting
Phosphorus — bone growth and energy metabolism
Magnesium — enzyme activity and muscle function
Potassium — nerve and muscle function
Sodium and chloride — fluid balance
Iron — oxygen transport via haemoglobin
Zinc — immune and skin health
Copper — connective tissue and pigmentation
Iodine — thyroid hormone production
Selenium — antioxidant function and immune health

Vitamins

Vitamins are organic compounds that are essential for metabolism, growth + health.

They can be split into fat-soluble + water-soluble vitamins.

Fat-soluble vitamins

These include:

Vitamin A — vision, skin and bone growth
Vitamin D — calcium absorption and bone health
Vitamin E — antioxidant function
Vitamin K — blood clotting

Because these vitamins are fat-soluble, they rely on fat for absorption.

Water-soluble vitamins

These include:

Vitamin C — antioxidant role, although it is not considered essential for dogs and cats
B vitamins — energy metabolism, nerve function and red blood cell function

There are also vitamin-like substances, such as:

Choline — cell membranes and neurotransmission
L-carnitine — fatty acid metabolism

✨ Why this matters in veterinary nursing 

Understanding nutrients is not just for exams.

It helps you understand why nutrition matters in real patients.

For example:

• A patient with poor wound healing may need nutritional support
• A cat with poor coat condition may need diet history considered
• A patient with diarrhoea may benefit from fibre discussion
• A hospitalised patient not eating may quickly need escalation
• A patient on a restricted diet may need careful monitoring

Nutrition links into recovery, immunity, wound healing, gut health, energy balance + long-term wellbeing.

As nurses, we are often the ones noticing appetite changes, monitoring food intake, discussing feeding with clients and flagging when a patient is not eating well.

✨Key takeaways

• Macronutrients are needed in larger amounts
• Micronutrients are needed in smaller amounts but are still essential
• Carbohydrates provide glucose and energy
• Fibre supports gut health and bowel movement
• Fat provides concentrated energy and helps absorb fat-soluble vitamins
• Protein supports growth, repair, enzymes, hormones and immunity
• Water is the most vital nutrient
• Minerals and vitamins support many body functions
• Nutrition is an important part of patient recovery and nursing care

✨ Want to learn nutrition in a simpler way? ✨

If you’re studying veterinary nutrition and want everything broken down into clear, student-friendly sections, my Nutrition + Feeding Guide goes through the key topics in a simple, visual way.

It’s designed to help student veterinary nurses understand the basics without feeling overwhelmed — perfect for revision, placement support or building confidence with nutrition topics.

You can find the guide here:
https://thatvetnurselife.co.uk/products/nutrition-feeding-a5-guide-for-student-veterinary-nurses

 

Thank you, Jade x