What is nutrition – and why does it matter?

It seems like every other week there’s a new diet to try, or new food or nutrient to avoid. So it’s no wonder we’re confused, with many of us throwing our hands up in frustration and eating what tastes good! But in our quest for the toned physique, have we forgotten about the most important thing of all – our health?

Eating isn’t just for fun or flavour (although a good diet will be both nutrient dense and delicious). We need to eat to obtain the fuel that we need to keep us alive and thriving. Here’s a crash course on everything that’s essential to you, and your health and wellbeing.

Introducing your ‘macro-nutrients’…

Protein is composed of amino acids, and is vital for optimal health. We need it for muscle synthesis and repair, for growth, hormone production, healing, as well as for immunity. It is also the most satiating of the macronutrients – meaning it helps you to feel fuller for longer. Complete proteins (contains all 22 amino acids) are found most abundantly in animal products (meat, eggs, and dairy), as well as the plants quinoa and soy. Foods such as nuts, seeds and legumes also provide protein but aren’t ‘complete’, so they must be eaten in combination with other foods. Protein deficiency can lead to muscle wasting, edema, hair loss, and susceptibility to infection.

Carbohydrates are made up of various forms of sugar molecules, and are so essential that our bodies can manufacture all the glucose it needs from our protein and fat intake – without the need to add carbs to our diets. Carbs serve one primary function: to provide energy. While they are the least satiating of the macronutrients, they also are the best source of fibre. Rich sources of carbs include potato, kumara and rice. However, highly refined or processed carbs (many breads, pastas and cereals) and added sugars are now being implicated in many chronic disease states such as diabetes, heart disease, stroke, and even Alzheimer’s and some cancers.

Fats are arguably the most controversial macronutrient in our diets, but are crucial for many bodily functions and processes. No food has only one type of fat in it – even butter is a mixture of saturated, monounsaturated, and polyunsaturated fats. Our two essential polyunsaturated fats are omega three and omega six. Omega three has many health benefits, including improved heart and brain health. Omega six is most commonly found in manufactured seed oils (such as canola or rice bran oil). However using seed oils for high-heat cooking can create harmful trans fats – which have been linked to cardiovascular disease and various cancers. Trans fats can also be found in many processed foods (identified in the ingredients list as ‘partially hydrogenated’ oils). A deficiency in fatty acids (and fat-soluble vitamins such as A, E, D and K) can lead to skin and cognitive problems, as well as vision problems.

Introducing your ‘micronutrients’ – your vitamins and minerals…

Although not an exhaustive list, below are some of the most commonly known vitamins and minerals, and what can happen when you don’t get enough of them.


Vitamin C is found in fruits and vegetables including citrus fruits, berries and dark leafy greens. It is a powerful anti-oxidant, and deficiency (scurvy) can cause reduced wound-healing rate, easy bruising, and nosebleeds.

Vitamin B12 is only found in animal products (meats, eggs, and dairy). It plays a key role in the normal functioning of the brain and nervous system, and in the formation of blood. Deficiency can cause severe and irreversible damage to the brain and nervous system.

Vitamin A is found in abundance in organ meats, milk and eggs, as well as leafy greens, orange and yellow vegetables, and tomatoes. Deficiency is rare in developed countries.


Iron comes in two forms – heme and nonheme. Heme iron is easily absorbed by the body and is found in animal sources such as red meats, chicken and fish. Nonheme iron is found in leafy greens, beans, and nuts. Deficiency can cause lethargy, weakness, and breathlessness.

Calcium can be obtained by eating dairy products, seaweed, some nuts, and small fish (such as sardines). Vitamin D is important for calcium absorption, and calcium deficiency can cause muscle spasms, weak and brittle bones, and memory loss.

Magnesium is found in dark leafy greens, nuts and seeds, avocados, and dark chocolate. Deficiency is very common, and can cause tremors, nausea, high blood pressure, and poor memory.

Selenium sources include brazil nuts, fish, and eggs. Deficiency has become an issue in New Zealand due to soils becoming depleted of this mineral, and can cause thyroid problems, a weakened immune system, and hair loss.

Iodine is found in iodized table salt, seaweed, shell-fish, and fish, and is needed for the production of thyroid hormone.

What you can do about your nutrition

As you can see, eating well is actually a very complex task with many moving parts. A balanced diet based on plant foods (such as vegetables and fruits), rich sources of protein (such as meats, eggs, dairy products, nuts and seeds, or legumes) and enough added healthy fats to feel full should see you right.

Our Commissions Administrator Jenna Osborne is also studying for her Graduate Diploma in Sport and Exercise with a focus on nutrition.

Disclaimer: The information published here should not be taken as medical or nutritional advice, or as an endorsement of the author. At Fidelity Life, we try hard to make the information we publish accurate and helpful to you, but we cannot guarantee its accuracy and we aren’t liable for any action you take as a result.