Benders'dictionary of nutrition and food technology

254so unavailable to micro-organisms) by the addition of glycerol,sorbitol, salt or certain organic acids, so preventing the growthof micro-organisms.international units (IU) Used as a measure of the potency orbiological activity of substances such as vitamins and hormones,before chemical measurement was possible. Still sometimes used(3.33IU vitamin a = 1µg; 40 IU vitamin d = 1µg; 1 IU vitamine = 1mg).intervention study Comparison of an outcome (e.g. morbidity ormortality) between two groups of people deliberately subjectedto different dietary, drug or other regimes.intestinal flora Bacteria and other micro-organisms that are normallypresent in the gastrointestinal tract.intestinal juice Also called succus entericus. Digestive juicesecreted by the intestinal glands lining the small intestine. Itcontains a variety of enzymes, including enteropeptidase, theenzyme that converts trypsinogen to active trypsin, aminopeptidase,nucleases and nucleotidases.See also gastrointestinal tract.intestine The gastrointestinal tract; the small intestine(duodenum, jejunum and ileum) where the greater part ofdigestion and absorption take place, and the largeintestine.intolerance (to foods) See adverse reactions to foods.intravenous nutrition See parenteral nutrition.intrinsic factor A protein secreted in the gastric juice by the parietal(oxyntic) cells of the gastric mucosa; essential for the absorptionof vitamin b 12 ; impaired secretion results in perniciousanaemia.See also achlorhydria; dump suppression test; schillingtest.intron A region of dna within a gene that does not containinformation coding for the protein and is spliced out during thepost-transcriptional modification of mRNA.See also exon.intussusception Telescoping or invagination of one part of thebowel into another.inulin Soluble undigested polymer of fructose found in rootvegetables, especially Jerusalem artichoke. Included with nonstarchpolysaccharides (dietary fibre). Also called dahlin andalant starch. Filtered by the kidney and not reabsorbed, so usedclinically to measure glomerular filtration rate and kidneyfunction.inversion Applied to sucrose, meaning its hydrolysis to glucoseand fructose (see sugar, invert).