Confused by all the terminology? This section explains what everything means.

• Absorption: in order for the body to use a vitamin or mineral, it first has to pass into the blood or lymphatic system from the intestine. This process is known as absorption.
  
  
• Amino acids: the building blocks of protein. Protein in our diet is digested to free the amino acids, they are then used to build other proteins in the body.
  
  
• Antioxidants: along with antioxidant systems, they work to neutralise the potentially damaging free radicals when they are in excess in our bodies. Beta-carotene (also able to be converted to vitamin A) and vitamins C and E are antioxidants.
  
  
• Cholesterol: may be ingested in foods such as egg yolk and offal, but most is made in the body. An essential component of every living cell wall. May be converted to vitamin D, and is transported around the body in blood.
  
  
• Deficiency: if a person is deficient in a vitamin or mineral, it means that they are so lacking in that particular nutrient that they have developed clinical symptoms of deficiency.
  
  
• Depletion: when a person's vitamin or mineral level is depleted, it means that it has been consumed, perhaps in inadequate amounts, or reduced due to factors such as smoking, pollution, lifestyle changes etc.
  
  
• Enzyme: a protein, usually in combination with a vitamin or trace mineral (for example zinc) that regulates the speed at which a chemical reaction occurs. We have many thousands of different enzymes working throughout our bodies.
  
  
• Essential fatty acids: fatty acids which cannot be made in the body and which must be supplied by food. The term is sometimes abbreviated to EFAs.
  
  
• Essential nutrients: those nutrients that our bodies cannot make or cannot make enough of to meet demand. Some amino acids and some polyunsaturated fatty acids are essential, meaning that they must be present, fully formed, in the diet.
  
  
• Fat: the term used to describe fats and oils in the diet. Fats are triglycerides which are made up from glycerol and fatty acids.
  
  
• Fat soluble vitamins: the chemical characteristics of fat soluble vitamins mean that they dissolve in fats and not in water, As a result, we can store them in our bodies for longer than we can store the water soluble vitamins. A, D, E and K are fat soluble vitamins.
  
  
• Fatty acids are the sub-units that, along with glycerol, form the basic unit of fat, the triglyceride. Fatty acids can be saturated, polyunsaturated or monounsaturated.
  
  
• Free radicals: unstable by-products of the chemical reactions taking place in our bodies. Exposure to environmental pollution increases the amount of free radicals that are made. In their effort to become stable in a cell, free radicals can cause knock-on effects that include damage to the cell membranes, proteins and DNA. If the damage is severe, cells can die. In healthy body tissues, antioxidant systems neutralise the effects of free radicals, ending the chain of events and preventing damage from occurring.
  
  
• Glycerol: the part of the fat unit, triglyceride, to which the fatty acids are attached.
  
  
• Lipids: the scientific term embracing fats (triglycerides) and other substances that have chemical characteristics similar to fats.
  
  
• Macro nutrients: sometimes used to describe protein, fat and carbohydrate.
  
  
• Membranes: these surround our cells and have important roles in regulating cell function. They are made from lipids, which contain fatty acids, and proteins. Membranes also occur inside cells, where they surround certain sub compartments.
  
  
• Metabolism: the term used to describe the sum of all the chemical reactions that allow our bodies to function, move and grow. The breakdown of foods and the use of released nutrients around the body involve key metabolic reactions.
  
  
• Micronutrients: vitamins, minerals and other nutrients which are only needed in small amounts.
  
  
• Minerals: non carbon based substances that are found in, for example, soil and rocks (carbon is the building block of all living things). Plants take up minerals from the soil and in turn, these get passed to the animals that eat the plants. We get the minerals that we need to maintain a healthy body from both plant and animal sources.
  
  
• Monounsaturated fatty acids: fatty acids that contain only one double bond (a type of chemical bond) in their structure. The term is sometimes abbreviated to MUFAs.
  
  
• Non-starch polysaccharides (NSP): a newer, more accurate term for dietary fibre. But as the two terms do not mean exactly the same thing, amounts of NSP and dietary fibre are not strictly interchangeable.
  
  
• Nutrients: the substances that we need in our diet for energy, growth and maintenance. The nutrient groups are proteins, fats, carbohydrates, minerals, and vitamins.
  
  
• Phytates: substances found in dietary fibre. Phytates can reduce the absorption of some minerals by the body.
  
  
• Polyunsaturated fatty acids: fatty acids that contain more than one double bond in their structure. The term is sometimes abbreviated to PUFAs.
  
  
• Protein: protein in the diet is built from amino acids. During digestion, it is broken down into its amino acids, which are then used throughout the body to build other proteins.
  
  
• RDA: an abbreviation for recommended daily amount (or allowance). This is the daily amount of vitamin or mineral that the average healthy person needs to prevent deficiency.
  
  
• %RDA: some nutritional information on food packets and ingredient lists on health supplement packs give information about %RDA. For example 200 milligram vitamin C tablets contain 333%RDA. This figure tell you how much of the nutrients RDA you get from, in the case of a food, an average serving, or from each dosage of the supplement. So if something is giving you 10%RDA of vitamin A, it is giving you one tenth of the average daily vitamin A requirement of a group of healthy people.
  
  Some supplements contain levels of vitamins and minerals above the RDA (for example, 200miligram vitamin C tablets). This is because, for some nutrients, intakes above the RDA are safe and may be associated with particular benefits.
  
  
• Saturated fatty acids: fatty acids that do not contain any double bonds (see polyunsaturated and monounsaturated fatty acids). The term is sometimes abbreviated to SAFAs.
  
  
• Simple carbohydrates: sugars, such as sucrose, glucose, fructose and lactose.
  
  
• Starch: stored by plants as an energy source. It is made up of glucose units.
  
  
• Tannin: a substance found in foodstuffs such as tea and wine. It reduces the absorption of some minerals in the diet.
  
  
• Tissue: an arrangement of specialised cells that perform a particular function. Examples are nervous tissue and muscle tissue.
  
  
• Trace elements: the minerals of which we need only very small amounts of in our diet. Examples include selenium and zinc.
  
  
• Trans fatty acids: unsaturated fatty acids with a particular chemical shape. Though they are found in some foods, they are not the usual form (which are called cis fatty acids) Trans fatty acids are made during food processing, in a process called hydrogenation. The effects of their altered chemical shape can make oils into semi-solids, and can also extend the shelf-life of foods containing them. Though they are unsaturated, trans fatty acids are thought to act like saturated fatty acids in the body.
  
  
• Triglyceride: a chemical name for fats. Each triglyceride is made up from glycerol which has three fatty acids attached to it.
  
  
• Vitamins: the complex substances that our bodies need in small amounts. We have to have vitamins in our diet - a balance is vital for good health. The word 'vitamin' comes from 'vitamine' - the Latin 'vita', which means life, and the scientific term 'amine', because vitamins were originally thought to be amines. When it became clear that they were not, the e was dropped.
  
  
• Water soluble vitamins : these are less commonly stored in our bodies. Their chemical character means that they dissolve in water rather than in fats. This group consists of the B vitamins and vitamin C.