Adequate nutrition is one of our basic needs for survival. The lifestyle many of us have chosen in these busy years often prevent us from receiving the necessary foods to provide the appropriate nutrients for optimal bodily function. A good start in promoting good nutrition is to understand what our body needs from in the foods we eat. Most people are educated about the food guide pyramid. However many people are unaware of how the nutrients we need each day work within the body.

There are 6 categories of nutrients essential for good health

These are:
· Carbohydrates
· Lipids (fats)
· Proteins
These are our major nutrients

The other 3 nutrients are:
· Vitamins
· Minerals
· Water (this is considered a nutrient as it accounts for 60% of food volume we digest each day, however it will not be discussed in this article).


Most of the carbohydrates we digest are from plants, with the exception of milk (lactose). The purest form of carbohydrate is sugar, honey, sugar-beats, and milk. The more complex form of carbohydrates are found in legumes, grains, and root vegetables. Carbohydrates are broken down easily in the body and converted to glucose by the liver before entering circulation. Glucose is used as the body's immediate source of energy.

Cellulose is another form of carbohydrate, however it is inactive in the body, instead providing roughage (fibre) to increase the bulk of our bowel movements. Cellulose also helps to reduce the incidence of bowel disease.

The RDI (Recommended Daily Intake) is still unknown, however around 100g per day is thought to be the minimal amount needed to maintain adequate blood sugar levels. If there is excess in carbohydrates that the body does not use for energy, then it is converted to fat and stored in the body (as fat).
For RDI - see nutritional values on food products.

Lipids (fats)

There are various kinds of lipids, all of which play a role in maintaining the body's health. They are a concentrated energy source for skeletal muscles, and are drawn upon mostly when levels of carbohydrate stores are low. Lipids are essential for the body to absorb fat-soluble vitamins (vitamins A, D, E, K). Lipids also play an important role in the CNS (Central Nervous System). Fats are also essential to cushion the body's organs, such as the kidneys and the eyeballs.

The RDI should be less than 30% of the body's total calorie intake. Most of us have been educated about "good fats" and "bad fats." Saturated fats (bad fats) should be less than 10% of our calorie intake = to one egg yolk. They are found mostly in animal and coconut products. Unsaturated fats (good fats) are contained in seeds, nuts, and vegetable oils, and should be the bulk of our fat intake (due to saturated fats potentially increasing the incidence of cardiac disease).


Proteins are extremely important in making up the structural materials in the body (e.g. Keratin of the skin, elastin of connective tissue, and collagen). Proteins help to regulate normal hormonal function of the body, and are sometimes drawn upon for energy. The supply of amino acids (which are the building blocks for proteins) are essential to produce proteins. If one amino acid is missing the specific protein for that chain of amino acids cannot be made.

The RDI for proteins are based on 0.8g per kg of your body weight.
E.g.- 56g for a 70kg male
- 48g for a 58 kg woman
Proteins are found in nuts, seeds, grains, and vegetables. Most people consume more than their RDI due to the high accessibility of protein in foods. To calculate you RDI check on the back of products containing nutritional information.


Vita means Life. Unlike the nutrients previously discussed, vitamins are not an energy source for the body. However they are crucial in helping the body to utilise carbohydrates, fats, and proteins. Without vitamins, eating these three previously discussed nutrients would be useless.

Most vitamins cannot be made in the body; therefore are absorbed through the digestion of food. One exception is vitamin D, which is produced in the skin from contact with sunlight through a complex chemical reaction. Some dairy companies are now adding vitamin D to their products to help in the absorption of calcium (which is a mineral).

Vitamins are either fat or water-soluble. Water-soluble vitamins, such as C, and B complex, need water to be absorbed in the stomach. They are only stored in the body for a short time and are excreted in the urine. Therefore it is important for these vitamins to be consumed regularly.

Fat-soluble vitamins (A, D, K, and E) bind to lipids (fats) and are absorbed along with their digestive products. These vitamins are stored easily in the body, which means you are less likely to become deficient in them. A well rounded, healthy diet should provide the body with an adequate supply of its essential vitamins.


Minerals actually make up 4% of body weight. There are seven basic minerals that the body requires in order for it to stay healthy. These are calcium, chloride, phosphorus, Magnesium, potassium, sulphur, and sodium (these are called macro-minerals). Macro-minerals are minerals in which the body needs more than 100mg daily. There are also what are called micro-minerals in which the body needs less than 100mg per day (iron is one for example). Often the most common deficiency in minerals is in calcium or iron, if you suspect you are deficient in either of these (normally due to a poor diet) a simple blood test from your GP can detect whether your levels are healthy. If you are deficient, dietary supplements can be provided.

Minerals like vitamins have no value in calories; rather they work to promote healthy hormonal and protein function, along with aiding the body to maintain a stable fluid balance. Again, like vitamins, a well rounded, healthy diet should provide the body with an adequate supply of its essential minerals.

The information supplied in this article is not about how you can magically lose weight. I have provided this information to supply you with an understanding about basic nutrition and why it is needed for good health. I hope you have learnt some new things about the crucial role nutrients have in our bodies to keep us running at an optimal level!

- Louise Ganey (RN)


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