1.6. Metabolomics in Dietary Interventions: Special Emphasis on the Effects of Grain Products and Fish on Lipidomic Profile

Public examination of a doctoral dissertation in the field of clinical nutrition

Doctoral candidate MHSc Maria Lankinen

Time and venue 1.6.2011 at 12 noon, Mediteknia Auditorium, Kuopio campus

Metabolic syndrome (MetS) increases markedly the risk for type 2 diabetes mellitus (T2DM), but in contrast to advanced T2DM, MetS and pre-stages of T2DM may be reversible conditions, if addressed early enough by lifestyle modifications. Based on epidemiological evidence, whole grain foods, fatty fish and polyphenol rich fruits and vegetables, including berries, may help prevent the development of T2DM and cardiovascular diseases (CVD), but evidence from clinical trials is not incontestable. Metabolomics and lipidomics allow characterization of the effects of diet in more detail than more conventional approaches in nutrition research and could therefore help elucidate the complex relationship between nutrition and metabolism.

The overall aim of this work was to study the effects of whole grain, low insulin response grain products and rye, fish, and bilberries in subjects at increased risk for MetS or CVD by applying metabolomics approaches, with specific emphasis on the characterization of molecular lipids by lipidomic approaches.

The intake of whole grain or rye over a period of 12 weeks did not change lipidomic profiles. In contrast, a diet rich in oat-wheat bread and potato in the same study increased proinflammatory lysophosphatidylcholines. Consumption of high-fiber rye bread over a period of 8 weeks increased specific plasma metabolites that might mediate positive effects of rye bread on satiety and weight maintenance. In another study, the consumption of fatty fish decreased ceramides and diacylglycerols which are potential mediators of lipid induced insulin resistance and inflammation. In a 12-week intervention study, diet rich in whole grain and low insulin response grain products, fatty fish and bilberries altered lipidomic profile especially increasing triacylglycerols with long chain (n-3) PUFA. Increases in EPA and DHA were associated with improved insulin secretion and glucose disposal.

In conclusion, this thesis indicated that metabolomics is a valuable tool for studying effects of dietary interventions at the molecular level. Dietary changes altered metabolic profiles, e.g. altering lipids related to peroxidation, inflammation and insulin signaling, which may further affect predisposition to T2DM and CVD in high-risk persons.

The doctoral dissertation of Master of Health Sciences Maria Lankinen, entitled Metabolomics in Dietary Interventions: Special Emphasis on the Effects of Grain Products and Fish on Lipidomic Profile will be examined at the Faculty of Health Sciences. The opponent in the public examination will be Docent Kirsi Pietiläinen of the Hospital District of Helsinki and Uusimaa, and the custos will be Docent Ursula Schwab of the University of Eastern Finland.

Photo available for download at http://www.uef.fi/uef/vaitoskuvat

Contact: Maria Lankinen, ptel. 0400-985 527, maria.lankinen@uef.fi

Publishing year: 2011

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