Impact of Vegetarian and the Nordic Diet on Glucose Metabolism: A Human Intervention Study

Background: Recent epidemiological studies indicate that the so-called ‘Nordic’ diet (rich in berries, fish and nuts) as well as a vegetarian diet improve serum glucose kinetics and, thus, reduce the risk of diabetes development compared to the ‘Western’ diet. Evidence for these effects from controlled human intervention studies is limited. Methods: One hundred and twenty overweight adults with at least 1 metabolic syndrome trait (60±7 y, BMI 31.1±3.5 kg/m2, WC men 109±9 cm, women 104±9 cm) were randomized into 3 groups, adhering to Nordic diet [ND], lacto-ovo vegetarian diet [VD], or habitual control diet [HD] for 6 weeks, based on a recipe list, which was adapted to individual energy expenditure (RMR measured by QuarkRMR device, multiplied by a factor of 1.5 for physical activity). At baseline and after 6 weeks, OGTT and mixed meal tolerance test [MMTT] (180 min; postprandial measurements at 7 time points [tp]) were performed. Statistical data analysis was conducted using linear mixed-effect models (group-specific comparison: visit*diet*tp interaction). Results: As expected no changes in body weight (p=0.083) and body composition (p=0.354) were detected. Within groups, fasting glucose (p=0.760) and insulin levels (p=0.066), HbA1c (p=0.979) and HOMA index (p=0.150) did not change after 6 weeks compared to baseline. Insulin sensitivity (Matsuda index p=0.498, OGIS p=0.478, insulinogenic index p=0.203) and ß-cell function (disposition index p=0.997) showed no intergroup variations. In the group comparison, no effect was found after OGTT and MMTT on AUC of glucose (p=0.869/p=0.824) and insulin (p=0.850/p=0.999). However, compared to controls, VD improved kidney values and ND improved blood lipids, liver and kidney values. Conclusion: Our medium-term isoenergetic intervention study did not confirm earlier results. Improvements in glucose kinetics as observed in epidemiologic studies are possibly due to a loss of body weight (hypoenergetic nutrition) independent of diet composition. Disclosure H. Huber: None. B. Stoffel-wagner: None. M. Coenen: None. L. Weinhold: None. M. Schmid: None. P. Stehle: None. M. Simon: None. Funding German Federal Ministry of Education and Research (01EA1809A)