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Status: 22.10.2018 05:41:21

Image Clinical Nutrition

Department of Clinical Nutrition (KLE)

Projects

Summary

To improve dietary strategies and recommendations, our department examines the effects of specific food constituents and dietary patterns on metabolic regulatory mechanisms. We compared diets rich in plant versus animal protein in older patients with type 2 diabetes and observed similar, highly significant improvements in glucose metabolism and the levels of lipids, uric acid, and CRP, an inflammation marker. Despite differences in amino acid composition, the positive effects of the diets did not differ significantly.

We recently analyzed the metabolic effects of the gut hormone gastric inhibitory polypeptide (GIP) on the central nervous system, which promotes obesity and fatty liver. We observed that the effects of GIP are mediated by hypothalamic programming of energy metabolism in muscle by altering the methylation of regulatory regions of genes, which are involved in mitochondrial biogenesis and fat oxidation. The study Nutrigenomic Analysis in Twins (NUGAT) showed that responses to dietary changes are also regulated by genes. A high-fat diet in carriers of a gene variant of the angiotensin-converting enzyme (ACE) caused extensive increases in serum ACE and in blood pressure.

Fibers have been shown to be highly efficient in the prevention of type 2 diabetes, as well as other diseases such as dementia or infections. We studied whether an increased intake of non-soluble oat fibers may improve blood sugar regulation and reduce the incidence of diabetes in people with a high diabetes risk, a pre-diabetes. The Optimal Fibre Trial (OptiFiT) included around 200 participants who were randomized into groups which received either a placebo or 15 grams of oat fiber per day in a flavored drink. The trial duration was 2 years and included metabolism and oral glucose tolerance tests every 6 months. The fiber intake indeed reduced diabetes risk by 45 percent and improved markers of glucose metabolism, which was more pronounced in women than in men. Based on this data, we suggest an increased intake of non-soluble and low fermentable cereal fibers which have the advantage of causing little gastrointestinal discomfort and bloating due to the lack of fermentation. We support an enrichment of fibers in nutrients, because natural cereal products have a maximal fiber content of slightly more than 10%. However, it must be said that an adequate intake of fibers also means a high consumption of carbohydrates which in many cases would exceed daily requirements.

Humans, along with most living organisms, display extensive circadian rhythms of metabolism. The active phase is characterized by an increase in metabolic and energy-consuming processes which decrease again with the inactive phase in humans in the evening. We investigated whether the type of nutrient consumed in the morning or in the evening is important for this circadian regulation. To this end, study participants consumed either primarily carbohydrates in the morning and fats in the evening or, after a crossover, vice-versa, namely fats in the morning and carbohydrates in the evening. This indeed demonstrated that the carbohydrate efficiency is much higher in the morning than in the evening: this was reflected by an approximately 3-fold greater and longer increase in blood sugar in the evening as compared to the morning in response to the same meal. This led to increased total blood sugar levels, particularly in people with a pre-diabetes and an impaired fasting glucose and glucose tolerance, which also represents a further step towards the manifestation of diabetes. A reduction in carbohydrate intake in the evening should therefore be helpful and should improve metabolism in people with metabolic syndrome, obesity, high blood pressure, and lipid disturbances.

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