Project

Back to overview

Effects of carbohydrate containing diets on lipid metabolism & fatty acid oxidation in healthy young men - a randomized, double-blinded study

English title Effects of carbohydrate containing diets on lipid metabolism & fatty acid oxidation in healthy young men - a randomized, double-blinded study
Applicant Spinas Giatgen A.
Number 144204
Funding scheme Project funding
Research institution Klinik für Endokrinologie, Diabetologie und Klinische Ernährung Universitätsspital Zürich
Institution of higher education University of Zurich - ZH
Main discipline Clinical Endocrinology
Start/End 01.01.2013 - 31.12.2015
Approved amount 483'000.00
Show all

Keywords (5)

obesity; softdrinks; lipogenesis; fructose; stabile tracers

Lay Summary (English)

Lead
Lay summary

Effects of Carbohydrate Containing Diets on Lipid Metabolism & Fatty AcidOxidation in Healthy Young Men – a Randomized, Double-Blinded Study.

 

There is a worldwide discussion about the potentially harmful effects soft drinks. Soft drinks contain large amounts of fructose, which affects lipid metabolism adversely and increase the risk for diabetes (type 2) and cardiovascular diseases.

 

In our study we investigate the effects of soft drinks on the metabolism of healthy men. There are diverse natural sugars e. g. glucose, fructose or sucrose. These sugars differ in their structure and in their sweetening power. They are absorbed by the body and broken down differently. Over the last decades, the consumption of fructose increased, which is attributed to the spread of fruit sugar-sweetened soft drinks. Epidemiological studies have shown a link between soft drink consumption and the development of various diseases. Why fructose compared to other sugars causes much more significant changes in fat metabolism is not fully understood and will be investigated in our study.

 

Volunteers will drink daily for eight weeks either fructose, glucose, sucrose or aspartame-sweetened beverages, or continue their usual diet. During this time, various metabolic studies are carried out in which the lipogenesis, lipolysis, and lipid oxidation is studied. The investigations will reveal differences in the fatty acid formation and energy production from fatty acids.

 

The results of the study will improve the understanding of the sugar and fat metabolism. A solid understanding of the relationship between soft drink consumption and the development of metabolic disorders is of great importance to our society. It will help to raise people’s awareness of the health risks of soft drinks and thereby contribute to prevention.

 

This study is carried out at the University Hospital of Zurich, Division of Endocrinology, Diabetes and Clinical Nutrition under the direction of Prof. Dr. Kaspar Berneis in collaboration with Prof. Luc Tappy the University of Lausanne. The study will be conducted with 120 subjects, and will begin in fall 2012 and end in summer 2015.

 

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
University Lausanne, Prof. Luc Tappy, Département de Physiologie Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media „Die bittere Wahrheit des Fruchtzuckers“ Sonntagszeitung German-speaking Switzerland 2015
Media relations: print media, online media „Die Wahrheit über Fruktose“ Zeitschrift Sprechstunde Dr. Stutz German-speaking Switzerland 2015
Media relations: print media, online media „Fruktose contra Glukose“ Neue Zürcher Zeitung German-speaking Switzerland 2015
Media relations: print media, online media „Nur zwei Süssmittel sind gut“ Gesundheitstipp German-speaking Switzerland 2015
Media relations: radio, television „Säfte und Smoothies“ Puls-Beitrag Schweizer Fernsehen German-speaking Switzerland 2015
Media relations: print media, online media „Schädliche Süsse“ Apotheken-Umschau, Deutschland International 2015

Associated projects

Number Title Start Funding scheme
119706 Effects of dietary fructose on glucose and lipid metabolism in healthy human subjects 01.06.2008 Project funding
119706 Effects of dietary fructose on glucose and lipid metabolism in healthy human subjects 01.06.2008 Project funding

Abstract

Introduction: Sugar-sweetened beverages (SSB) are the most commonly consumed caloric beverages in many western countries. In our recent SNF supported project, we could show that low to moderate amounts of sugars, such as fructose, glucose or sucrose result in impaired glucose homeostasis and dyslipidaemia. There was a striking difference between fructose and glucose containing beverages in respect to the lipid metabolism. Particularly soft drinks sweetened with fructose led to a reduction of LDL particle size and therefore to a more atherogenic lipoprotein profile. Additionally, changes in acylcarnitine profiles suggest reduced beta-oxidation rates after fructose containing diets compared to glucose.Now, we aim to dissect differences in the metabolic pathways of fructose and glucose, but also metabolic adaptations during fructose and glucose diets in a follow up study using stable isotope tracers.Methods: 120 healthy male adults will be included in this study. They will be randomized to one of five dietary interventions provided as “soft” drinks three times daily for 7 weeks. These SBB will contain either 26.6 g of fructose, 26.6 g of glucose, 26.6 g of sucrose or 133 mg aspartame, served three times per day. In addition a control group will be included with no change in dietary habits. Three day food records will be used to measure total fructose and glucose intake at baseline and the following visits 1-5.75 g oral glucose tolerance testing will be performed at baseline and visit 5 in the fasted state. Each visit will last for 11 hours. During 10 hours several experiments using stable isotope tracers will be performed (visit 2: 13C acetate infusion in the fasting state, together with D5-glycerol, visit 3: ingestion of an additional drink in the morning one hour before infusion of 13 C acetate, together with D5-glycerol, visit 4 infusion of 13 C palmitate and D2 glycerol in the fasting state), in the morning of visit 1, 13 C fructose will be given perorally. During all visits several tests (indirect calorimetry, sampling of breath for 13C enrichment of CO2) and blood analysis (measurement of 13C enrichment of ß-hydroxybutyrate, palmitate in VLDL particles and non-esterfied fatty acids (NEFA), glucose, deuterium enrichment of glycerol, measurement of total cholesterol HDL-C, triglycerides, free fatty acids, acylcarnitines and plasma fatty acid profiles) will be performed.Additional analyses include blood pressure and waist circumference measurements. Plasma lipids, adiponectin and resistin will be measured by standard methods and LDL size will be measured by gradient gel electrophoresis. Body composition will be measured by bioelectrical impedance analysis at baseline and after one and two week. Hypothesis: Consumption of SSBs increases postprandial lipogenesis. However, fructose sweetened beverages increase postprandial lipogenesis significantly more than glucose sweetened ones. Increased lipogenesis after fructose consumption could be due to the abundance of substrates for fatty acid synthesis (e.g. Acetyl-CoA) and increased triglyceride synthesis. In addition, an enhanced and extended activity of regulatory proteins (SREBP-1 and ChREBP, e.g.) that induce the expression of ACC (Acetyl CoA Carboxylase) may enhance de novo lipogenesis after fructose consumption. The increase may not only be postprandial but also sustained in the fasting state. We expect an increased fatty acid synthesis measured as increased incorporation of 13C after 13C acetate infusion into palmitate, TGs and VLDLs in subjects on fructose diet compared to glucose, aspartame and control.In the fasting state, triglyceride levels will be increased in the blood of subjects on fructose diet due to a state of “lipid overflow”. We expect to measure an increased total lipid turnover indicated by an decreased rate of appearance of D-glycerol after infusion in subjects on fructose diet compared to glucose and control.Fluxes through beta-oxidation of fatty acids may be limited after consumption of fructose containing SSB compared to glucose or control, due to downregulation of beta-oxidation enzymes via PPARa, e.g., and feedback mechanisms of product overflow (e.g. Acetyl-CoA). Based on our previous results from acylcarnitine analysis, this effect is assumed to persist in the fasting state.We expect decreased concentrations of 13 CO2 in breath samples of subjects on fructose diet compared to glucose and control after infusion of U13 palmitate due to decreased lipid oxidation.SSB sweetened with aspartame may slightly decrease lipolysis. However based on the literature, it is well possible that there will be no significant difference when compared to the control group.
-