Food and nutrients

The nutritional value of food

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Most foodstuffs are composed of many different nutrients. These nutrients all have very defined roles and must all be provided in what we eat. Nutrients are chemical molecules principally made up of carbon, hydrogen, oxygen and nitrogen atoms. For example, water is comprised of hydrogen and oxygen, hence the chemical formula H2O.


Proteins are large molecules formed by a chain of amino acids. There are 20 amino acids. These 20 include 8 which are known as 'essential' amino acids as the body cannot produce them. They therefore have to be provided by what we eat.


Lipids consist of fatty acids. Like amino acids, there are 'essential' fatty acids. The body is unable to synthesise them, despite the fact that they are essential for brain development. We can distinguish between ‘saturated’ and ‘unsaturated’ fatty acids.

Unsaturated fatty acids are liquid at room temperature. They are found in vegetable oils. Saturated fatty acids are solid at room temperature. They are found in solid animal and vegetable fats such as butter and coconut oil.

Keywords > Unsaturated fatty acids: vegetable oils
Keywords > Saturated fatty acids: solid animal or vegetable fats


Like fats, carbohydrates are made up of carbon, hydrogen and oxygen. We distinguish between ‘simple’ and ‘complex’ carbohydrates.

Fructose and glucose are simple carbohydrates. Starch and fibre are complex carbohydrates – which means they are made up of several simple carbohydrates. The digestive system can split starch into simple carbohydrates, which can be absorbed. However, we are not able to digest fibre, so it regulates the intestines.

Keywords > Simple carbohydrates: fructose, glucose
Keywords > Complex carbohydrates: starch, dietary fibre



We call all these molecules macronutrients. However, to assimilate and use these macronutrients, the body needs what we call micronutrients.

Keywords > Macronutrients: proteins, fats, carbohydrates
Keywords > Micronutrients: vitamins, minerals

Vitamins and minerals are examples of micronutrients that are vital for the body to function correctly.


Vitamins are made up of a variety of elements. They are vital to us but only needed in small amounts. They are present in most unprocessed food, yet not every vitamin is available in every kind of food.

For example, vitamin C is primarily available in fruit and vegetables while vitamin B12 is only available in food coming from animals. By eating food from all of the food groups we are more likely to cover all of our vitamin requirements.

Keywords > Vitamin C: fruit and vegetables
Keywords > Vitamin B12: animal-based food 


Minerals are inorganic elements. Some are present in large quantities in the body. These are called macroelements. Others are only present as traces and so we call them oligo-elements or simply trace elements.

Calcium and potassium are examples of macroelements, whereas iron and fluoride are oligo-elements.

Keywords > Macroelements: calcium, potassium
Keywords > Oligo-elements: iron, fluoride

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