Nutrients are components of food that help nourish the body and are essential for life and healthy functioning: i.e. they provide energy or serve as building materials. The nutrients are the macronutrients carbohydrates, fats and proteins; micronutrients – all the vitamins and minerals; water and fibre.

Macronutrients are all capable of providing energy, but have other crucial roles too. Carbohydrates provide energy for quick bursts or more sustained bouts and, to a degree, can help control our metabolic rate. Digestible carbohydrates are ultimately broken down into short chains or single units and absorbed into the bloodstream where the simple carbohydrate glucose is available as a readily available energy source. What’s not used is stored in the liver and the muscles. This energy store can be quickly mobilised to supply the body when called upon. The capacity for storing carbohydrate is limited and excess carbs are transformed and stored as adipose tissue (i.e. body fat).

Although frequently maligned, fat is in fact essential for life. Fat has a number of essential functions including providing warmth, cushioning for essential organs, providing structure to cells and as a storage form of energy. There are different types of fats and only some are essential. Due to modern poor diets, many of us are consuming too much of the wrong types of fat, and this, coupled with an excess of calories from fat and other macronutrients, is contributing to some of the major health problems.

Protein has a number of essential functions including providing structure in muscles, skin, hair and nails, as hormones regulating body functions, as enzymes for the digestion and metabolism of nutrients, the transport of oxygen and for the immune system. Also, in times of need protein can also be used for energy.

Micronutrients are elements or small molecules essential for life but are only required in very small quantities, i.e. dietary minerals and vitamins. There are a number of vitamins which we need for life; some are fat soluble and some water soluble. They perform a number of functions including energy transformation, the regulation of minerals, as antioxidants, in red blood cells, night vision, tissue healing, immune system, and more.

There are a number of minerals which we need for life including macrominerals like calcium, phosphorous and iron; electrolytes including sodium and potassium; and trace elements including vanadium, copper, manganese, iodine, selenium and a number of others. Deficiency in minerals can lead to bone wasting, heart problems, exhaustion, dehydration, anaemia and other conditions often specific to the mineral in question.

Although we don’t often think of it as such, water is actually a nutrient. It’s the most essential nutrient as we can’t go that long without it, otherwise we become dehydrated and die. There’s no specified amount of water recommended per day, but we do need more during hard activity and exercise: drink plenty of fluid every day.

Fibre is essentially a carbohydrate, but it’s all the carbohydrate which humans can’t digest. This doesn’t mean it has no use, far from it: fibre can help us digest food, regulate blood cholesterol levels and help keep us feeling full to stop binging on excess food.

So, very briefly, the above has explained what nutrients are. But that’s not the full story; there are also other constituents of food which we refer to as anutrients or phytonutrients. Although these are not required for life and do not exhibit any deficiency symptoms, they may have perpetrated health benefits. Examples of these include the flavonoids found in tea and red wine which may play a role as antioxidants in cancer prevention.

Read more about nutrients and how they contribute to specific meal plans devised by James Collier on http://www.mealplansite.com