Isotope Ratio Mass Spectrometer for Nutritional and Metabolic Studies

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To fully understand how nutrients in our diet are metabolised and promote health or risk of disease, we need to trace molecules such as sugars and fats around the body. The gold-standard method for this is by using stable isotope tracers. These are molecules that have been modified so that one or more of their atoms is replaced with a less common form of the atom (a stable isotope). These tracers are not radioactive; they are safe to give to humans, including children and pregnant women, and they have really shaped our understanding of nutrition and metabolism. For example, if a person ingests a meal containing a specific type of fat that has been labelled with a stable isotope tracer, we can follow the movement of this fat in and out of the blood over the course of time, and independently of other types of fat in the body. We do this by measuring the stable isotope tracer in a series of timed blood samples, using mass spectrometry.It is absolutely vital that we, and others, continue to use this technique to answer fundamental questions about how nutrition and physiology relate to human health, as outlined in the BBSRC's strategic plan. To this end, it is essential for us to update our old equipment (an isotope ratio mass-spectrometer, IRMS) with more reliable, next generation equipment. This will allow us to expand our analytical capability in the use of stable isotope tracer methodology at Surrey, and Nationwide. The more efficient software and hardware will allow us to operate the equipment in such a way as to maximise its use. This will involve widening access to the methodology, by increasing the available time on the machine, and by 'demystifying' the use of the technology through training and promotion. Our aim is train the next generation of undergraduate and postgraduate students, and visiting Fellows, in the use of stable isotope tracers. To help facilitate this aim, we have an industrial sponsor, LGC (The Laboratory of the Government Chemist), who will provide training on quality control procedures, and provide assurance that our measurements are of the highest standard.A major biological challenge of modern life is to understand how the Western diet impacts on human health. We are currently applying stable isotope tracers to address this challenge in three multi-centred studies funded by the BBSRC, one MRC-funded project and two BBSRC doctoral training partnership PhD projects that relate to the UK eating patterns. The first BBSRC study has been designed to better understand why some people's blood cholesterol is very sensitive to changes in the intake of dietary saturated fat, while others people's blood cholesterol shows little or no effect. We will be giving stable isotope labelled saturated fat to 'cholesterol responders' and 'non-responders' to trace the differences in metabolic pathways that might explain this variation in cholesterol response to saturated fat. In another BBSRC DRINC funded project, we will use potatoes that have the starch pre-labelled with an isotope label. This will help us to understand how chilling and reheating a mashed potato meal improves the body's handling of a particular type of starch in the potato. In a third BBSRC study, we will provide new evidence for the health effects of 'inter-esterified' fats that are being introduced by the food industry as substitutes for unhealthy, hydrogenated trans fats. An MRC funded project will examine the impact of the balance of food eaten in the morning and evening on metabolic and behavioural regulation during weight loss. This study will help to understand how energy balance can be modulated by altering meal timing. Finally, our BBSRC DTP students are measuring the intestinal handling of fructose in vivo and in a cell model, and investigating the regulation of enzymes that mediate the conversion of alpha linolenic acid in cooking oils, into long chain polyunsaturated fatty acids. Both of these studies would employ the use of a new IRMS.