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Dietary chromium, glucose tolerance, insulin and lipoproteins in non-insulin dependent diabetics. - AN0520

The mean daily intake of chromium from the diet is 30 µg, but a number of studies have demonstrated a significant improvement in glucose tolerance and beneficial changes in blood lipids in diabetic subjects given a daily supplement of 200 µg chromium. The important question is whether or not the observed effects are physiological or pharmacological, i.e. is chromium an essential nutrient, and if so, what are the dietary requirements? The two main objectives of this pilot project are (a) to investigate the response of non- insulin dependent diabetics (NIDD) to increased levels of dietary chromium with regard to glucose tolerance, plasma insulin and lipoproteins, and (b) to establish methods to investigate the effect of dietary sources of chromium on the metabolism of major substrates. Foods high in chromium will be identified and the chemical form examined by inductively coupled plasma spectrometry (ICP-MS). Twenty non-smoking NIDD s (10 female, 10 male) will be recruited and dietary assessments made to determine chromium intake (7-day duplicate diets). A standard glucose tolerance test will be performed and plasma insulin, chromium and lipoproteins and 24-h urinary chromium measured. The subjects will then be given foods containing high levels of chromium to consume daily for 8 weeks, the measurements repeated, and then returned to their habitual diet. Approximately 4 weeks later, the biochemical and dietary assessments will again be repeated. Several foods (e.g. yeast, mushrooms, barley) will be biosynthetically labelled with different stable isotopes of chromium and mixtures fed to one or two volunteers. Urine and faeces will be collected and the absorption and retention of chromium from each of the foods determined. This is a collaborative project with IFR (see AN0519) who will conduct the intervention study, i ncluding sample preparation and ethical approval.
These objectives cover the whole project (for completeness) but CSL are responsible only for those marked (*). 1 Recruit staff and familiarise them with the project by 31/10/95 2 *Select foods rich in chromium and develop speciation methods by 31/10/95. 3 *Train staff in all biochemical/analytical techniques by 31/3/96 4 Prepare ethical submissions by 31/10/95 5 Plan biosynthesis labelling of foods by 31/10/95 6 Prepare foods for intervention by 31/12/95 7 Recruit volunteers, plan time-tabling for GTTs etc by 1/1/96 8 *Perform intervention study 30/6/96 9 *Prepare proposal for extension to project (if applicable) by 31/8/96. 10 *Feed labelled foods to volunteers by 31/8/96 11 *Prepare final report and publications by 30/9/96
Time-Scale and Cost
From: 1995

To: 1996

Cost: £63,025
Contractor / Funded Organisations
Central Science Laboratory