amino acid A compound with both an amino (-NH2) and a carboxylic acid (-COOH) group attached to the α-carbon. Proteins are composed of amino acids.
atherosclerosis The accumulation of fatty deposits in blood vessels, leading to reduction of the size of the blood vessels. Atherosclerosis in the coronary arteries is the commonest cause of ischaemic heart attacks.
basal metabolic rate (BMR) The energy expenditure by the body at complete rest, but not asleep, in the post-prandial (i.e. after eating) state.
body mass index (BMI) The ratio of body weight/height2 (kg/m2). A person with a BMI over 25 is considered to be overweight, and over 30 to be obese.
carbohydrate Compounds of carbon, hydrogen, and oxygen in the ratio CnH2nOn The dietary carbohydrates are sugars, starches, and non-starch polysaccharides.
catabolism Metabolic reactions resulting in the breakdown of complex molecules to simpler products, commonly oxidation to carbon dioxide and water, linked to the phosphorylation of ADP to ATP.
enzyme A protein that acts as a catalyst in a metabolic reaction.
international units (iu) Before vitamins and other substances were purified, their potency was expressed in arbitrary, but standardized, units of biological activity. Now this measurement is obsolete, but vitamins A, D, and E are still sometimes quoted in iu.
lipid A general term including fats and oils (triacylglycerols), phospholipids, and steroids.
lower reference nutrient intake (LRNI) An intake of a nutrient below which it is unlikely that physiological needs will be met or metabolic integrity be maintained.
metabolic fuel Those dietary components which are oxidized as a source of metabolic energy fats, carbohydrates, proteins, and alcohol.
metabolism The processes of interconversion of chemical compounds in the body.
organic Chemically, all compounds of carbon, other than simple
carbonate and bicarbonate salts, are called ‘organic’, since they were originally discovered in living matter. Also used to describe foods grown under specified conditions without the use of fertilizers, pesticides, etc.
physical activity ratio (PAR) Energy expenditure in a given activity, expressed as a ratio of the basal metabolic rate.
physical activity level (PAL) Energy expenditure, averaged over 24 hours, expressed as a ratio of the basal metabolic rate. The sum of the physical activity ratio x time spent for each activity during the day.
RDA Recommended daily (or dietary) allowance (or amount) of a nutrient. An intake of the nutrient two standard deviations above the observed mean requirement, and hence greater than the requirements of 97.5 per cent of the population.
RNI Reference nutrient intake, a term introduced in the 1992 UK Tables of Dietary Reference Values. An intake of the nutrient two standard deviations above the observed mean requirement, and hence greater than the requirements of 97.5 per cent of the population.
saturated An organic compound in which all carbon atoms are joined by single bonds, as opposed to unsaturated compounds with carbon—carbon double bonds. A saturated compound contains the maximum possible proportion of hydrogen.
standard deviation A statistical measure of the scatter of results around the average or mean value.
unsaturated An organic compound containing one or more carbon–carbon double bonds, and therefore less than the possible maximum proportion of hydrogen.