- Absorption
- The movement of nutrients and other food constituents from the gut into the blood.
- Acid-base balance
- The appropriate acidity of the blood and tissues. Abnormal acid-base balance may indicate a change in respiratory or metabolic status.
- Adduct (see DNA adduct)
- Adenocarcinoma
- Cancer of glandular epithelial cells.
- Adenosine triphosphate (ATP)
- The principal molecule used for storage and transfer of energy in metabolic processes.
- Adipose tissue
- Body fat. Tissue comprising mainly cells (adipocytes) containing triglyceride. It acts as an energy reserve, provides insulation and protection, and secretes metabolically active hormones.
- Adiposity rebound
- The age at which body mass index (BMI) increases after reaching a nadir at around 4–6 years of age. Earlier age of adiposity rebound has been linked to later development of obesity.
- Adjustment
- A statistical tool for taking into account the effect of known confounders (see reference 3.1).
- Adrenarche
- The period, typically between age 6 and 10 years, characterised by an increase in secretion of androgens from the adrenal cortex. Aerobic metabolism The normal process of producing ATP as a source of energy using oxygen. Aflatoxins Naturally-occurring mycotoxins that are produced by many species of Aspergillus, afungus, most notably Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and carcinogenic to animals, including humans (see reference 4.1.4).
- Age-adjusted incidence
- The number of events in a population, usually expressed per 100,000 people, over a defined period of time, adjusted for the varying proportion of people in each age group between populations and over time. It allows for comparisons between countries with different age structures (see reference 7.1.1).
- Alpha-linolenic acid
- An essential n-3 polyunsaturated fatty acid (C18:3 n3).
- Amenorrhoea
- The absence of menstruation.
- Amino acid
- An organic compound containing an amino group and a carreferenceylic acid group. The basic building blocks of proteins such as enzymes.
- Anaerobic metabolism
- The process of producing ATP as a source of energy without oxygen, resulting in lactic acid accumulation.
- Androgen
- Any masculinising sex hormone, such as testosterone.
- Angiogenesis
- The process of generating new blood vessels.
- Antioxidants
- Any substance that inhibits oxidation or traps or quenches reactive oxygen species generated during metabolism. Anthropometric measures Measures of body dimensions. ATP (see adenosine triphosphate)Basal energy expenditure (see basal metabolic rate)
- Basal metabolic rate (BMR)
- The amount of energy required to maintain the essential body functions in resting and fasting conditions, expressed as megajoules, kilojoules, or kilocalories per minute, hour, or day.
- Begg’s test
- A statistical test for small study effects such as publication bias.
- Beta-glucans
- Non-starch polysaccharides composed of glucose subunits linked in such a way as to render them indigestible by pancreatic amylase. A major component of the cell wall polysaccharides of oats (see non-starch polysaccharides and dietary fibre).
- Bias
- In epidemiology, deviation of an observed result from the true value in a particular direction (systematic error) due to factors pertaining to the observer or to study design or analysis. See also selection bias.
- Bile
- A greenish-yellow fluid secreted by the liver and stored in the gallbladder. Bile plays an important role in the intestinal absorption of fats. Bile contains cholesterol, bile salts, and waste products such as bilirubin.
- Biliary tract
- The biliary tract includes the bile ducts within the liver, the common bile duct, which connects the liver and gallbladder to the small intestine, and the cystic duct, which connects the gallbladder to the common bile duct.
- Bioavailability
- The degree to which a nutrient (or other substance) can be absorbed and used by the body.
- BMI (see body mass index)
- BMR (see basal metabolic rate)
- Body mass index (BMI)
- Body weight expressed in kilograms divided by the square of height expressed in metres (BMI = kg/m2). It provides an indirect measure of body fatness. Also called Quetelet’s Index.
- Caffeine
- An alkaloid found in coffee, tea, kola nuts, chocolate, and other foods that acts as a stimulant and a diuretic.
- Cancer survivor
- Any person who has received a diagnosis of cancer
- Cantonese-style salted fish
- Fish that has been treated with varying amounts of salt and dried in natural conditions outdoors. It is characterised by treatment with less salt than typically used and is also subject to fermentation duringthe drying process due to relatively high outdoor temperature and moisture levels (see reference 4.3.5).
- Carcinogen
- Any substance or agent capable of causing cancer.
- Carcinoma
- Malignant tumour derived from epithelial cells, usually with the ability to spread into the surrounding tissue (invasion) and produce secondary tumours (metastases).
- Carcinoma in situ
- The first stage of carcinoma in which the malignant tumour has not spread beyond the epithelium.
- Cardiovascular disease
- A group of diseases that involve the heart and/or blood vessels (arteries and veins). While the term technically refers to any disease that affects the cardiovascular system, it is usually used to refer to those related to atherosclerosis.
- Case-control study
- An epidemiological study in which the participants are chosen based on their disease or condition (cases) or lack of it (controls) to test whether past or recent history of an exposure such as smoking, genetic profile, alcohol consumption, or dietary intake is associated with the risk of disease (see reference 3.4).
- CE
- Common Era — the period of measured time beginning with the year one on the Gregorian calendar. The notations CE and BCE (Before Common Era) are alternative notations for AD and BC, respectively.
- Cell cycle
- The sequence of stages that a cell passes through between one cell division and the next.
- Cell signalling
- Mechanisms whereby cells send messages to, or respond to external stimuli from, other cells.
- Cerebrovascular disease
- A group of diseases of the brain due to damage to the blood vessels, in which an area of the brain is transiently or permanently affected by ischaemia or bleeding.
- Cholesterol
- The principal sterol in animal tissues, synthesised in the body; an essential component of cell membranes and the precursor of the steroid hormones and vitamin D.
- Chromatin
- Mass of genetic material in the nucleus of a cell, composed of DNA and proteins that condense to form chromosomes.
- Chronic disease
- A disease that develops or persists over a long period of time. Includes noncommunicable diseases such as cancer, cardiovascular disease, and diabetes, and some infectious diseases such as tuberculosis.
- CI (see confidence interval)
- Coeliac disease
- Intolerance to the gliadin fraction of the protein gluten from wheat, rye, and barley. The villi of the small intestine atrophy and nutrient absorption from food is poor. Stools are often bulky and contain a large amount of unabsorbed fat.
- Cohort study
- A study of a (usually large) group of people whose characteristics are recorded at recruitment (and sometimes later), followed up for a period of time during which outcomes of interest are noted. Differences inthe frequency of outcomes (such as disease) within the cohort are calculated in relation to different levels of exposure to factors of interest, for example smoking, alcohol consumption, diet, and exercise. Differencesin the likelihood of a particular outcome are presented as the relative risk comparing one level of exposure to another (see reference 3.4).
- Compliance
- The extent to which people such as study participants follow an allocated treatment programme.
- Computed tomography (CT)
- A form of X-ray that produces cross-sectional or other images of the body.
- Confidence interval (CI)
- A measure of the uncertainty in an estimate, usually reported as 95% confidence interval (CI), which is the range of values within which there is a 95% chance that the true value lies. For example the effect of smoking on the relative risk of lung cancer in one study may be expressed as 10 (95% CI 5–15). This means that in this particular analysis, the estimate of the relative risk was calculated as 10, and that there is a 95% chance that the true value lies between 5 and 15.
- Confounder
- A variable, within a specific epidemiological study, that is associated with an exposure, is also a risk factor for the disease, and is not in the causal pathway from the exposure to the disease. If not adjusted for, this factor may distort the apparent exposure–disease relationship. An example is that smoking is related both to coffee drinking and to risk of lung cancer and thus, unless accounted for (controlled) in studies, might make coffee drinking appear falsely as a possible cause of lung cancer (see reference 3.1).
- Confounding factor (see confounder)
- Confounding variable (see confounder)
- Cretinism
- Underactivity of the thyroid gland (hypothyroidism) in infancy, resulting in poor growth, severe mental retardation, and deafness.
- CT (see computed tomography)
- Curing
- Various preservation and flavouring processes, especially of meat or fish, by the addition of a combination of salt, sugar, and either nitrate or nitrite. Curing processes often involve smoking. The addition of saltpetre (sodium nitrate) gives a pinkish colour to meat. Bacteria convert the nitrates in cured meats to nitrites and nitrosamines, which are potentially carcinogenic to humans (see reference 4.3.2).
- Cytotoxic
- Poisonous to living cells.
- Deoxyribonucleic acid (DNA)
- The double-stranded, helical molecular chain found within the nucleus of each cell that carries the genetic information.
- DEXA (see dual energy X-ray absorptiometry)
- Diabetes mellitus
- A metabolic disorder involving impairedmetabolism of glucose due either to failure ofsecretion of the hormone insulin (type 1diabetes) or to impaired responses of tissues toinsulin (type 2 diabetes), which results incomplications including kidney failure,blindness, and increased risk ofcardiovascular disease.
- Dietary fibre
- Constituents of plant cell walls that are notdigested in the small intestine. Severalmethods of analysis are used, which identifydifferent components. The many constituentsthat are variously included in the definitionshave different chemical and physiologicalfeatures that are not easily defined under asingle term. The different analytical methodsdo not generally characterise the physiologicalimpact of foods or diets. Non-starchpolysaccharides are a consistent feature andare fermented by colonic bacteria to produceenergy and short chain fatty acids includingbutyrate. The term dietary fibre is increasinglyseen as a concept describing a particular aspectof some dietary patterns (see reference 4.1.2).
- Dietary supplement
- A substance, often in tablet or capsule form,which is consumed in addition to the usualdiet. Dietary supplements typically refer tovitamins or minerals, thoughphytochemicals or other substances may beincluded.
- Differentiation
- The process of development of cells to take onthe structural and functional characteristicsspecific to a particular tissue. Also, the degreeto which tumour cells have the structure orfunction of the organ from which the tumourarose. Tumours can be described as well,moderately, or poorly differentiated: welldifferentiatedtumours appear similar to thecells of the organ in which they arose; poorlydifferentiated tumours do not. The degree ofdifferentiation is often of prognosticsignificance.
- Disaccharide
- A carbohydrate composed of twomonosaccharides.
- Diverticular disease
- The presence of pouch-like hernias(diverticula) through the muscle layer of thecolon, associated with a low intake of dietaryfibre and high intestinal pressure due tostraining. Faecal matter may be trapped inthese diverticula, causing them to becomeinflamed, causing pain and diarrhoea(diverticulitis).
- DNA (see deoxyribonucleic acid)
- DNA adducts
- DNA adducts are compounds formed by thereaction of a chemical with DNA, which maydamage the DNA. If repaired, some adductscan be excreted and measured in the urine as amarker of DNA damage. If not repaired, DNAmay function abnormally and may thereforebe a stage in carcinogenesis.
- Docosahexaenoic acid (DHA)
- A long-chain n-3 polyunsaturated fatty acid (C22:6 n3).
- Dose response
- A term derived from pharmacology thatdescribes the degree to which an effectchanges with the level of an exposure, forinstance the intake of a drug or food (see reference3.2).
- Double bond
- A covalent bond between two carbon atomseach with one hydrogen atom, for instance infatty acids.
- Dual energy X-ray absorptiometry (DEXA)
- A means of measuring the density of differentbody tissues such as bone or fat, using two Xraybeams with differing energy levels.
- Dyslipidaemia
- Any disorder of lipoprotein metabolismresulting in abnormal plasma concentrationsor forms of lipoprotein, such as high total orlow-density lipoprotein (LDL) cholesterolor triglyceride, and low high-densitylipoprotein (HDL) cholesterol concentrations.
- Dysplasia
- Abnormal development of the cells of a tissue.
- Ecological study
- A study in which differences in patterns of exposure, for instance in consumption of a particular nutrient or food, are compared at aggregate level, with populations (rather than individuals) as the unit of analysis (see reference 3.4).
- Egger’s test
- A statistical test for small study effects such as publication bias.
- Eicosapentaenoic acid (EPA)
- A long-chain n-3 polyunsaturated fatty acid(C20:5 n3).
- Effect modifier/effect modification Effect modification (or effect-measure modification) occurs when a measure of effectfor an exposure changes over levels of another variable (the modifier) (see reference 3.6).
GLOSSARY
Terms here are defined in the context of this Site. Some terms may have other meanings in other contexts.
Emulsifier
A substance that promotes the formation of astable mixture, or emulsion, of two substancesthat do not normally mix well (for example oiland water).
Endocrine
Referring to organs or glands that secretehormones into the blood.
Energy
Energy, measured as calories or joules, isrequired for all metabolic processes. Fats,carbohydrates, proteins, and alcohol fromfoods and drinks release energy when they aremetabolised in the body.
Energy adjustment
The use of statistical methods to ‘adjust’intakes of a dietary factor under study for total energy intake (see reference 3.7).
Energy balance
The state in which the total energy absorbed from foods and drinks equals total energy expended. Also the degree to which intake exceeds expenditure (positive energy balance)or expenditure exceeds intake (negative energy balance).
Enzyme
A protein that acts as a catalyst in living organisms, promoting chemical reactions andregulating the rate at which they proceed.
Epidemic
A widespread or rapidly spreading disease that affects many individuals in a population at thesame time, markedly in excess of the number normally expected.
Epigenetic
Relating to the control of gene expression through mechanisms that do not depend onchanges in the nucleotide sequence of DNA,for example through methylation of DNA oracetylation of histone.
Epithelial (see epithelium)
Epithelial-mesenchymal transition (EMT)
A disorder of cell differentiation where cellsassume a mesenchymal rather than anepithelial phenotype. Cancer cells may have phenotypic similarities to EMT.
Epithelium
The layer of cells covering internal andexternal surfaces of the body, including theskin and mucous membranes lining body cavities such as the lung, gut, and urinary tract.
Essential amino acid
An amino acid that is required for normal cellular structure and metabolic function but which humans cannot synthesise and so mustobtain from food.
Evidence
Information that helps to determine whethera proposal or belief is true or valid, or false orinvalid.
Exercise
A type of physical activity, often deliberatesuch as sport, which improves fitness or health.
Exposure
A factor to which an individual may beexposed to varying degrees, such as intake ofa food, level or type of physical activity, oraspect of body composition.
Extracellular fluid
All body fluid not contained within cells.Includes the fluid in blood vessels (plasma) and between cells (interstitial fluid).
Factor analysis
A statistical technique used to examine thestructure underlying the interactions betweenseveral variables.
Fat-free mass
The mass of all body tissue excluding the lipidcomponents.
Fatty acid
A carreferenceylic acid with a carbon chain ofvarying length, which may be either saturated(no double bonds) or unsaturated (one ormore double bonds). Three fatty acid sattached to a glycerol backbone make up atriglyceride, the usual form of fat in foods and adipose tissue.
Fermentation
The anaerobic metabolic breakdown ofmolecules such as glucose. Fermentation yieldsenergy in the form of lactate, acetate,ethanol, or other simple product.Fetal programming (see programming)
Food systems
The interconnected agricultural, ecological,economic, social, cultural, and technologicalsystems involved in food production,distribution, and consumption.
Forest plot
A simple visual representation of the amountof variation between the results of theindividual studies in a meta-analysis. Theirconstruction begins with plotting the observed exposure effect of each individualstudy, which is represented as the centre of a square. Horizontal lines run through this toshow the 95% confidence interval. Different sized squares may be plotted for each of theindividual studies, the size of the referenceincreasing with the size of the study and theweight that it takes in the analysis. The overallsummary estimate of effect and its confidenceinterval can also be added to the bottom ofthis plot, if appropriate, and this isrepresented as a diamond. The centre of thediamond is the pooled summary estimate andthe horizontal tips are the confidence intervals(see reference 3.3).
Fortification
The deliberate addition of nutrients to foodsor drinks as a means of increasing the level ofintake in a population (see reference 4.10.1).
Functional food
Any food, similar in appearance toconventional food, claiming to have specific physiological effects that benefit healthand/or reduce the risk of disease. Products aresometimes sold in medicinal forms (see reference4.10.2).
Gene expression
The active production of the RNA and proteinthat are coded for by a particular gene. In any cell, not all genes are expressed (seeepigenetic).
Genetic modification
The manipulation of a living organism’sgenetic material by eliminating, modifying, oradding copies of specific genes, often fromother organisms. Also known as ‘geneticengineering’.
Germ cell (see germ line)
Germ line
Eggs and sperm and the cells that develop intothem, through which genetic information ispassed from generation to generation.
Genotype
The genetic makeup of a cell or organism.
GH (see growth hormone)
Gleason score
A quantitative measure of the degree ofdifferentiation of prostate cancers. HighGleason scores, representing aggressivedisease, are associated with poor prognoses.Whitemore and Jewett scales are used toassess prostate cancer stage.
Glycaemic index
A system for ranking foods containingcarbohydrates according to the effect of astandard amount on blood glucose levels.Foods that raise the blood sugar the mosthave the highest glycaemic index (see reference4.1.3).
Glycaemic load
The glycaemic index of a food multiplied bythe number of grams of carbohydrate in theserving of food (see reference 4.1.3).
Glycerol
A three-carbon molecule that forms thebackbone of triglyceride in fats (see fattyacid).
Goitre
Enlargement of the thyroid gland, seen as aswelling in the neck; may be hypothyroid, withlow production of thyroid hormone,euthyroid (normal levels), or hyperthyroid(excessive production). Deficiency of iodine isone cause.
Gross domestic product
The total market value of all the goods andservices produced within a nation in a givenyear.
Growth hormone (GH)
Also known as somatotropin, a hormonesecreted by the pituitary gland that stimulatessecretion of growth factors from the liver andso also protein synthesis and growth of thelong bones in the legs and arms. It alsopromotes the breakdown and use of fattyacids, rather than glucose, as an energysource.
Haem
The part of the organic molecule haemoglobinin red blood cells containing iron to whichoxygen binds for transport around the body.
Herbicide
A pesticide used to kill or control the growthof unwanted plants. Selective herbicides killcertain targets while leaving a desired croprelatively unharmed. Non-selective herbicideskill every plant with which they come intocontact.
Heterocyclic amines
A family of compounds formed from proteinand sugars in meat, chicken, and fish cookedat very high temperatures by grilling (broiling)or frying that have potential carcinogeniceffects (see reference 4.3.4).
Heterogeneity
A measure of difference between the resultsof different studies addressing a similarquestion. In meta-analysis, the degree ofheterogeneity may be calculated statisticallyusing the I2 test.
High fructose corn syrup (HFCS)
A form of corn syrup that has undergoneenzymatic processing in order to increase itsfructose content. Used to sweeten soft drinks,juices, ice cream, and many other processedfoods, especially in the USA (see reference 4.6.1).
High-income countries
Countries with a gross average annualnational product of more than an agreedfigure per head (in 2006 this was more than$US 10 726). This term is less judgemental andmore descriptive than ‘economicallydeveloped’ countries.
Homeostasis
The maintenance of biological conditions in astable state.
Hormone
A substance secreted by specialised cells thataffects the structure and/or function of othercells or tissues in another part of the body.
Hydrogenation
The process by which unsaturated fatty acidsin vegetable oils are made more saturated bythe addition of hydrogen. This makes liquidoils more solid at room temperature and moreresistant to oxidation, for instance in themanufacture of margarines. Incompletehydrogenation can lead to the formation oftrans-fatty acids (see reference 4.5.1).
Hyperkeratosis
Excessive thickening of the outer horny layerof the skin, affecting the palms and soles.
Hyperplasia
An increase in the number of cells in a tissue.
Hypertension
High blood pressure; a risk factor forcardiovascular and kidney disease.
Hypoxia
Abnormally low levels of oxygen in blood ortissues.
IARC
International Agency for Research on Cancer(www.iarc.fr).
IGF binding proteins
Proteins that bind to insulin-like growthfactors (which are implicated in the cancerprocess, see Chapter 2) in the bloodstream.
Immune response
The production of antibodies or specialisedcells in response to foreign proteins or othersubstances.
Incidence rates
The number of new cases of a conditionappearing during a specified period of timeexpressed relative to the size of thepopulation, for example 60 new cases ofbreast cancer per 100 000 women per year.
Inflammation
The immunologic response of tissues to injuryor infection. Inflammation is characterised byaccumulation of white blood cells thatproduce several bioactive chemicals, causingredness, pain, and swelling.
Inflammatory bowel disease
A term used to describe Crohn’s disease andulcerative colitis: both are characterised bychronic inflammation of the gut.
Insulin
A protein hormone secreted by the pancreasthat promotes the uptake and utilisation ofglucose, particularly in the liver and muscles.Inadequate secretion of, or tissue response to,insulin leads to diabetes mellitus.
Intrinsic sugars
Sugars naturally integrated into the cellularstructure of foods, for example those presentin unprocessed fruits and vegetables.
Intra-abdominal fat
Also known as visceral fat. Fat stored withinthe abdomen surrounding the internal organs(see adipose tissue).
In utero
In the uterus; refers to events that occurbefore birth.
Invasive cancer
Tumours that spread into surrounding healthytissue.
Iron-deficiency anaemia
A low blood concentration of haemoglobindue to a deficiency of iron, due either tounusually high demands or low intake orimpaired absorption.
Irradiation
Exposure to ionising radiation. Foodirradiation is used to disinfest, sterilise, orpreserve food.
Jewett scale (see Whitemore and Jewett scales)
K-ras
One of a class of genes (proto-oncogenes)which when mutated can malfunction tobecome an oncogene, promoting thetransformation of normal cells into cancer cells(see reference 2.2).
Lactation
The production and secretion of milk by themammary glands.
Lacto-ovo-vegetarian diet
A vegetarian diet characterised by theinclusion of eggs and dairy products, but noother animal products.
Latency
The period of time between the onset of adisease process and its detection or clinicalappearance.
Lean body mass
The mass of those parts of the body that arenot adipose tissue. Lean body mass includessome lipid and is not synonymous with fatfreemass.
Lesion
A general term for any abnormality of cells ortissues, including those due to cancerouschange.
Linoleic acid
An essential n-6 polyunsaturated fatty acid(C18:2 n6).
Lipids
Naturally occurring organic molecules that areinsoluble in water, including triglycerides;fatty acids; phospholipids; lipoproteins;carotenoids; cholesterol, which is aprecursor of steroid hormones and vitaminD; and the other fat-soluble vitamins A, E, andK. Lipids are an essential component of cellmembranes and many metabolic processes.
Low-density lipoprotein (LDL) cholesterol
A class of lipoproteins that is the major carrierof cholesterol in the blood in humans. A highblood LDL cholesterol concentration is a causeof coronary artery disease.
Low-income countries
Countries with a gross average annualnational product of less than an agreedfigure per head (in 2006 this was $US 875).This term is less judgemental and moredescriptive than ‘economically developing’countries.
Lymphocyte
Several types of white blood cell, part of theimmune system, found in the blood and lymphglands.
Macronutrient
Those nutrient components of the diet thatprovide energy: carbohydrate, fat, andprotein; ethanol also provides energy but isnot a nutrient.
Magnetic resonance imaging (MRI)
A technique that produces images of parts ofthe body using analysis of the behaviour ofwater molecules within body tissues whenplaced in a strong magnetic field.
Malignant
A tumour with the capacity to spread tosurrounding tissue or to other sites in thebody.
Melanoma
Malignant tumour of the skin derived fromthe pigment-producing cells (melanocytes).Membrane potentialThe difference in electrical charge across thecell membrane.
Menarche
The beginning of menstruation (see referencees 6.1and 6.2).
MET (see metabolic equivalent)
Meta-analysis
The process of using statistical methods tocombine the results of different studies.
Metabolic equivalent (MET)
One MET equals the resting metabolic rate,measured as the rate of oxygen consumption,which is approximately 3.5 millilitres of oxygenper kilogram body weight per minute.Equivalent to physical activity ratio (see reference5.1).
Metabolic syndrome
A common cluster of a variety of several riskfactors for cardiovascular disease includinginsulin resistance, abdominal obesity, highblood pressure, and abnormal blood lipids.
Metastasis
The spread of malignant cancer cells todistant locations around the body from theoriginal site.
Micronutrients
Vitamins and minerals present in foods andrequired in the diet for normal body functionin small quantities, conventionally of less than1 g/day (see reference 4.2.3).
Migrant study
A study of people who migrate from onecountry to other countries with differentenvironments and cultural backgrounds. Theexperience, such as mortality or diseaseincidence, of the migrant group is comparedwith that of people in their current country ofresidence and in their country of origin.
Mineral
An inorganic compound in food required bythe body for normal function, such as calcium,magnesium, and iron.
Monosaccharide
Simple sugar consisting of a single sugarmolecule, such as glucose, fructose, andgalactose. They form the basis ofdisaccharides such as sucrose, and ofoligosaccharides, starch, and non-starchpolysaccharides.
MRI (see magnetic resonance imaging)
Mucosal
Relating to mucous membranes.
Mutagens
Chemical compounds or physical agentscapable of inducing genetic mutations.
Mycotoxins
Toxins produced by fungi (moulds), especiallyAspergillus flavus under tropical conditionsand Penicillium and Fusarium species undertemperate conditions (see reference 4.1.4).
Neoplasm
A benign or malignant tumour.
Nested case-control study
A case-control study in which cases andcontrols are drawn from the population of acohort study; often used for studies ofprospectively collected information orbiological samples.
Neurotransmitter
A chemical secreted by one nerve cell thatstimulates a response in a neighbouring nervecell.
Night blindness
A condition in which a person has impairedvision in the dark, characteristic of vitamin Adeficiency.
Nitrate
A salt containing the nitrate ion, whichcontains nitrogen and oxygen in proportion1:3 (NO3). Derived from decomposing organicmaterial such as manure, plants, and humanwaste, and a component of chemical fertilisers(see reference 4.3.2).
Nitrite
A salt containing the nitrite ion, whichcontains nitrogen and oxygen in proportion1:2 (NO2). Sodium nitrite is added to manyprocessed meats. Nitrites are also formed inthe body from nitrates in plant foods that areeaten. When consumed, nitrites can lead tothe generation of N-nitroso compounds,some of which are known carcinogens (seereference 4.3.2).
Nitrosamines
A group of chemicals formed by the reactionof nitrites with amines; some nitrosaminesare carcinogens (see reference 4.3.2).N-nitroso compound (see nitrosamines)
Non-caloric sweetener
A food additive that replicates the sweetnessof sugar but with negligible food energy (seereference 4.6.2).
Non-exercise activity thermogenesis (NEAT)
The energy used in non-conscious orspontaneous physical activity, such asfidgeting and posture maintenance.
Non-milk extrinsic sugars
Sugars not present within the cellularstructure of foods, apart from those in milk ormilk products. For example those added tofoods or in juices, syrups, or honey.
Non-starch polysaccharide
A carbohydrate comprising at least 10 simplesugar molecules; a major component of plantcell walls and the principal analytic fractioncharacterising dietary fibre (see reference 4.1.2).
Nucleic acid
The four building blocks of DNA – guanine,thymine, cytosine, and adenine.
Nutrient
A substance present in food and required bythe body for maintenance of normal structureand function, and for growth anddevelopment. Nutrients includemacronutrients (fat, protein, andcarbohydrate), which provide energy as wellas performing metabolic and structuralfunctions, and micronutrients (vitamins andminerals), which do not provide energy butare necessary for normal metabolic function.
Obesity
Excess body fat to a degree that increases therisk of various diseases. Conventionallydefined as a BMI of 30 kg/m2 or more.Different cut-off points have been proposedfor specific populations.
Odds ratio
A measure of the risk of an outcome such ascancer, associated with an exposure ofinterest, used in case-control studies;approximately equivalent to the relative risk.
Oligosaccharide
A compound comprising between 2 and 10simple sugar molecules (monosaccharides).
Oncogene
A gene whose protein product contributes tothe transformation of normal cells into cancercells. Oncogenes result from the mutation ofnormal genes called proto-oncogenes (see reference2.2).
Organic compounds
Any member of a large class of chemicalcompounds whose molecules contain carbon(and other elements), with exception ofcarbides, carbonates, and carbon oxides. Mostoccur naturally only in the bodies andproducts of living organisms.
Organic farming
Agricultural production system without orwith only limited use of pesticides, syntheticfertilisers, growth regulators, and livestockfeed additives (see reference 4.9.2).
Osteomalacia
A disease due to vitamin D deficiencycharacterised by inadequate bonemineralisation, pain, and increased bonefragility.
Osteoporosis
Loss of the tissues of bone (bone cells, mineral,and protein) to an extent that increases therisk of fracture.
Oxidative damage
Damage to cells or structures in cells caused byoxidation, either by chemicals or by radiation.Some oxidants are generated in the normalcourse of metabolism. Oxidation of DNA isone cause of mutation.p53A protein central to regulation of cell growth.Mutations of the p53 gene are importantcauses of cancer (see oncogene and reference 2.2).
Pasteurisation
Partial sterilisation of foods at atemperature that destroys microorganismssuch as bacteria, viruses, moulds, yeast, andprotozoa without major changes in thechemistry of the food.
Pathogenesis
The origin and development of disease. Themechanisms by which causal factors increasethe risk of disease.
Pedometer
An instrument that records the number ofsteps taken.
Peer review
The scrutiny of scientific papers by one ormore suitably qualified scientists.
Pentosan
A polysaccharide composed of pentosesugars (with a ring comprising 5 carbonatoms), for example arabans or xylans.
Phenotype
The characteristics displayed by an organism;this depends on both the genotype andenvironmental factors.
Phosphorylation
Addition of phosphate groups to hydroxylgroups on proteins, catalysed by a proteinkinase with ATP as phosphate donor. A keyprocess in cell signalling and energytransfer.
Physical activity
Any movement using skeletal muscles.
Physical activity level (PAL)
Energy expenditure per day as a multiple ofbasal metabolic rate (BMR) (see reference 5.2).
Physical activity ratio (PAR)
The energy cost of an activity per minutedivided by the energy cost of basalmetabolic rate per minute. Thus, the energycost of sitting at rest is about 1.2; for walkingat a normal pace, 4; and for jogging, 7.
Phytochemicals
Compounds found in plants not required fornormal structure or function, which maymodify physiological functions and influencehealth (see reference 4.2.1).
Point estimate
An estimate that is reported as a single value.The precision of a point estimate is indicatedby the width of the confidence interval thatsurrounds it.
Point mutation
Mutation of a single DNA base in a gene oftenleading to a single peptide change in aprotein, which can influence its function.
Polycyclic aromatic hydrocarbons
A family of chemical compounds, includingseveral known carcinogens, formed byincomplete combustion of organic substancessuch as wood, coal, diesel, fat, or tobacco (seereference 4.3.4).
Polymorphisms
Common variations (more than 1 per cent ofthe population) in the DNA sequence of agene.
Polyphenol
Any of a group of chemical substances foundin plants that have more than one phenolgroup per molecule; includes tannins, lignins,and flavonoids.
Polysaccharide
A polymer composed of multiple subunits ofmonosaccharides (simple sugars) linkedtogether.
Polyunsaturated fatty acids
Fatty acids containing two or more doublebonds.
Pooled analysis (see pooling)
Pooling
In epidemiology, a type of study whereoriginal individual-level data from two ormore original studies are obtained, combined,and re-analysed.Positive energy balance (see energybalance)
Prebiotic
Dietary carbohydrate that reaches the colon,where it promotes growth of beneficialbacterial flora (see reference 4.10.2).
Precursor
A chemical compound from which anothercompound is formed.
Processed meat
Meat (usually red meat) preserved bysmoking, curing, or salting, or by theaddition of preservatives. Definitions varybetween countries and studies as to whatprecisely is included (see reference 4.3.1).
Programming
The process whereby events happening duringfetal life (fetal programming), such as growthrestriction, or in infancy can permanentlyaffect the structure and function of particularorgans, and so also metabolic processes.Combined with other factors, this can in turnalter the response to environmentalexposures and so susceptibility to disease.
Promoter region
The region of DNA in a gene which initiatesthe transcription of DNA to RNA when theenzyme RNA polymerase binds to it.
Prostaglandins
A range of hormones derived from essentialfatty acids. Among many other processes,they influence blood pressure andinflammation.
Publication bias
A bias in the overall balance of evidence inthe published literature due to selectivepublication. Not all studies carried out arepublished, and those that are may differ fromthose that are not. Publication bias can betested for with either Begg’s or Egger’stests.
Randomised controlled trial (RCT)
A study in which a comparison is madebetween one intervention (often a treatmentor prevention strategy) and another (control).Sometimes the control group receives aninactive agent (a placebo). Groups arerandomised to one intervention or the other,so that any difference in outcome between thetwo groups can be ascribed with confidence tothe intervention. Neither investigators norsubjects usually know to which condition theyhave been randomised; this is called ‘doubleblinding’(see reference 3.4).
RCT (see randomised controlled trial)
Reactive oxygen species
Oxygen-containing radical or reactive ion thatoxidises DNA (removes electrons); can behydroxyl radical (OH-), hydrogen peroxide(H2O2) or superoxide radical (O2-).
Red meat
Meat from domesticated cattle, pigs, sheep,and goats; not poultry and fish or meat fromwild animals.
Refined sugars
Sugars obtained by purification from plantswhich contain it, principally sugar cane orbeet.
Relative risk (RR)
The ratio of the rate of disease or deathamong people exposed to a factor, comparedto the rate among the unexposed, usually usedin cohort studies (see odds ratio).
Resting metabolic rate
Metabolic rate in a fasting subject sittingquietly (also see basal metabolic rate).
Reverse causation
The situation when an abnormal level of anexposure is caused by the cancer or itstreatment, rather than the other way round.For example if cancer causes weight loss, thenthe finding that low BMI is associated withincreased risk may reflect weight loss due tocancer rather than low weight causing cancer.
Ribonucleic acid (RNA)
The molecule created by RNA polymerase fromDNA (transcription) which carries the geneticmessage to ribosomes (translation), whereproteins are made.
Rickets
Malformation of the bones in growingchildren due to deficiency of vitamin D. Inadults the equivalent is osteomalacia.
RNA (see ribonucleic acid)
Salt iodisation
The practice of fortifying salt with iodide as ameans of ensuring adequate iodine intake.
Satiation
The development of fullness during eatingthat limits the size of a meal consumed (seesatiety).
Satiety
The suppression of appetite after eating thatinhibits the starting of eating (see satiation).Saturated fatty acidsFatty acids that do not contain any doublebonds.
Selection bias
Bias arising from the procedures used to selectstudy participants and from factors influencingparticipation.
Single bond
A covalent bond between two carbon atoms,each with two hydrogen atoms, for instance insaturated fatty acids.
Single nucleotide polymorphism (SNP)
DNA sequence variation where a singlenucleotide in the DNA is altered. SNPs accountfor 90% of all human genetic variation (seepolymorphism and point mutation).SLR (see systematic literature review)
Smoking (foods)
Smoking is the process of curing, cooking, orseasoning food by exposing it for long periodsof time to the smoke from a wood fire. ‘Hotsmoking’ is a process that can be used to fullycook raw meats or fish, while ‘cold smoking’ isan hours- or days-long process that is generallyused to preserve or flavour foods (usuallymeats or fish, but sometimes cheeses,vegetables, fruits).
SNP (see single nucleotide polymorphism)
Socioeconomic status
A combined product of social and economicstatus reflecting education level, personalwealth, class, and associated factors.
Solvent
Substances (usually liquid) capable ofdissolving or dispersing one or more othersubstances.Spontaneous physical activity (see nonexerciseactivity thermogenesis)
Squamous cell carcinoma
A malignant cancer derived from squamousepithelial cells.
Stabiliser
One of a number of food additives, such asagar or pectin (used in jam, for example), thatgive foods a firmer texture. While they are nottrue emulsifiers, they help to stabiliseemulsions.
Statistical significance
The probability that any observed result mightnot have occurred by chance. In mostepidemiologic work, a study result whoseprobability is less than 5% (p < 0.05) isconsidered sufficiently unlikely to haveoccurred by chance to justify the designation‘statistically significant’ (see confidenceinterval).
Stem cell
A cell that can self-renew or give rise to alineage of more differentiated cells.
Sterilisation
The destruction of bacteria or othermicroorganisms by heat, radiation, orchemical means.
Steroid hormone
One of several hormones derived fromcholesterol and having a central effect ongrowth and metabolism.Supplement (see dietary supplement)
Systematic literature review (SLR)
A means of compiling and assessing publishedevidence that addresses a scientific questionwith a predefined protocol and transparentmethods (see reference 3.5).
Testosterone
An androgenic steroid hormone and the principal male sex hormone.
Thermodynamics
The branch of physics concerned with the study of energy and its conversion between different forms.
Thermogenesis
The process of heat production. In adults, arising from the metabolic processes during the digestion and assimilation of food and during shivering.
Tocotrienol
A form of vitamin E.
Total energy expenditure
The energy expended in a 24-hour period by an individual or a group of individuals. It reflects the average amount of energy spent in a typical day, but may not be the exact amount of energy spent each and every day.
Transcription
Synthesis of RNA from DNA by the enzyme RNA polymerase.
Transition cultures
Countries in the process of changing from one predominant social/cultural structure to another, for instance moving from lowerincome to higher-income status with the accompanying changes that this implies.
Translation
The process by which RNA carries the genetic message from DNA to generate proteins in the ribosome.
Tumour suppressor gene
A gene whose protein product inhibits tumour formation (see also oncogene and reference 2.2).
UICC
International Union Against Cancer (www.uicc.org).
Ulcerative colitis
A disease causing chronic inflammation of the large intestine (colon). Together with another disease of inflammation of the intestines called Crohn’s disease, referred to as inflammatory bowel disease.
Underwater weighing
A method for estimating the proportions of body fat and lean mass. By comparing weight underwater with weight on land, and taking account of the different densities of fat and lean tissue, the proportions of fat and lean can be calculated.
UVA/UVB
Ultraviolet light of different wavelengths. UVA has relatively long wave lengths, UVB relatively short.
Visceral fat (see intra-abdominal fat)
Waist to hip circumference ratio (WHR)
A measure of body shape indicating fat distribution.
Weight cycling
Repeated abnormal losses and regains of weight, often the result of repeated diet regimes.
Whitemore and Jewett scales
A scale used to describe the stage of prostate cancer.
WHO
World Health Organization (www.who.int).
Wholegrain
Cereal grain that retains the bran and germ as well as the endosperm, in contrast to refined grains that retain only the endosperm. All components of the grain are retained in their usual proportions, though the term‘wholegrain’ may apply to products that include other constituents, so that the complete product comprises less than 100% wholegrain (see reference 4.1.1).
WHR (see waist to hip circumference ratio)
