NUTRITION

Nutrition 

Nutrition is the intake of food, considered in relation to the body’s dietary needs. Good nutrition – an adequate, well balanced diet combined with regular physical activity – is a cornerstone of good health. Poor nutrition can lead to reduced immunity, increased susceptibility to disease, impaired physical and mental development, and reduced productivity.

The list of nutrients that people are known to require is, in the words of Marion Nestle, "almost certainly incomplete". As of 2014, nutrients are thought to be of two types: macro-nutrients which are needed in relatively large amounts, and micronutrients which are needed in smaller quantities. A type of carbohydrate, dietary fiber, i.e. non-digestible material such as cellulose, is required, for both mechanical and biochemical reasons, although the exact reasons remain unclear. Other micronutrients include antioxidants and phytochemicals, which are said to influence (or protect) some body systems. Their necessity is not as well established as in the case of, for instance, vitamins.

Nutrients and their functions

Carbohydrate

Carbohydrates can be divided into two broad categories: available carbohydrate and unavailable carbohydrate.

Available carbohydrate

Sugars and starch are categorised as available carbohydrate.

Sugars are present naturally in fruit, vegetables and milk and are also added to many processed foods such as confectionery, cakes and biscuits. 

Starch is found in foods such as bread, cereals and potatoes.

Both starch and sugars are digested in the body and converted to simple sugars (mainly glucose), which are then used by the body to provide energy.

Protein

Proteins are essential for growth and maintenance of body tissues and for the production of substances such as hormones and enzymes which help to control many functions within the body. If insufficient carbohydrate and fat are available in the diet, then protein may also be used to provide the body with energy.

Proteins are made from building blocks known as amino acids.

There are 20 different amino acids.

Some amino acids can be made in the body and others can only be supplied by the diet -these are known as the essential amino acids.

Some foods are better providers of these amino acids than others. Those which contain all the essential amino acids are known as “high biological value” foods e.g. milk and dairy foods, meat, eggs etc.

Those which contain fewer of the essential amino acids are known as “low biological value” foods e.g. cereals, beans, lentils and nuts.

However if a wide variety of foods are consumed in the correct proportions the different protein sources can work together to provide the ideal levels of the different amino acids.