BackgroundIt is well known that the microbiota of high-fat (HF) diet-induced obese mice differs from that of lean mice, but to what extent, this difference reflects the obese state or the diet is unclear. To dissociate changes in the gut microbiota associated with high HF feeding from those associated with obesity, we took advantage of the different susceptibility of C57BL/6JBomTac (BL6) and 129S6/SvEvTac (Sv129) mice to diet-induced obesity and of their different responses to inhibition of cyclooxygenase (COX) activity, where inhibition of COX activity in BL6 mice prevents HF diet-induced obesity, but in Sv129 mice accentuates obesity.ResultsUsing HiSeq-based whole genome sequencing, we identified taxonomic and functional differences in the gut microbiota of the two mouse strains fed regular low-fat or HF diets with or without supplementation with the COX-inhibitor, indomethacin. HF feeding rather than obesity development led to distinct changes in the gut microbiota. We observed a robust increase in alpha diversity, gene count, abundance of genera known to be butyrate producers, and abundance of genes involved in butyrate production in Sv129 mice compared to BL6 mice fed either a LF or a HF diet. Conversely, the abundance of genes involved in propionate metabolism, associated with increased energy harvest, was higher in BL6 mice than Sv129 mice.ConclusionsThe changes in the composition of the gut microbiota were predominantly driven by high-fat feeding rather than reflecting the obese state of the mice. Differences in the abundance of butyrate and propionate producing bacteria in the gut may at least in part contribute to the observed differences in obesity propensity in Sv129 and BL6 mice.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-017-0258-6) contains supplementary material, which is available to authorized users.

BackgroundMarine resources including fatty fish are important sources of n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs), which are important for brain development. To our knowledge, this is the first randomized controlled trial (RCT) investigating the impact of fatty fish on cognition in preschool children. The purpose of the trial was to investigate whether an increased intake of fatty fish compared to meat improves cognitive function in children 4–6 years old.MethodsThe children (n = 232) in this two-armed RCT, Fish Intervention Studies-KIDS (FINS-KIDS) were recruited from 13 kindergartens in Bergen, Norway. They were randomly assigned to lunch meals with fatty fish (herring/mackerel) or meat (chicken/lamb/beef) three times a week for 16 weeks. The fish and meat were weighed before and after the meals to record the exact consumption (dietary compliance). The primary outcome was cognitive function measured by the Wechsler Preschool and Primary Scale of Intelligence, 3rd edition (WPPSI-III) and fine-motor coordination measured by the 9-Hole Peg Test (9-HPT) at pre- and post-intervention. Biological samples (blood, urine, hair), and questionnaires to the caregivers were included at both time points. Linear mixed effect models with a random intercept for kindergarten were used to analyze changes from pre- to post-intervention in the primary outcome variables.ResultsThere were 218 children included in the trial (105 in the fish, and 113 in the meat group). The children consumed a mean (standard deviation) of 2070 (978) g fish or 2675 (850) g meat from the study meals (p < 0.0001). The fish group had a significant increase of red blood cell n-3 LC-PUFAs. The intervention had no effect on the WPPSI-III scores (mean change total raw score; fish group 17.7, 95% confidence interval (CI) 14.8–20.7 vs meat group 17.8, 95% CI 15.0–20.6, p = 0.97) in the main analyses. In the sub-analyses, adjusting for dietary compliance, the fish group showed a higher improvement on total raw score (20.4, 95% CI 17.5–23.3) compared to the meat group (15.2, 95% CI 12.4–18.0, p = 0.0060); docosahexaenoic acid mediated this effect.ConclusionsThere was no beneficial effect of fatty fish compared to meat on cognitive functioning in the preschool children. When considering dietary compliance, we found a beneficial effect of fatty fish on cognitive scores.Trial registrationClinicalTrials.gov, NCT02331667 December 17, 2014.Electronic supplementary materialThe online version of this article (10.1186/s12916-018-1020-z) contains supplementary material, which is available to authorized users.

Iodine is a trace element required for the production of thyroid hormones, essential for metabolism, growth and brain development, particularly in the first trimester of pregnancy. Milk and lean fish are the main dietary sources of iodine in the Norwegian diet. Thus, the aim of the present study was to provide updated analysed values of iodine concentration in six fish species, 27 selected Norwegian iodine-rich dairy foods and Norwegian hen’s eggs. The iodine concentrations in the wild fish species varied between 18 μg/100 g (Atlantic halibut) and 1,210 μg/100 g (pollack). The iodine concentration of cow milk varied between 12 and 19 μg/100 g and the iodine concentration of the eggs varied between 23 and 43 μg/100 g. The results in this study deviate somewhat from the current iodine concentrations in the Norwegian Food Composition Table. This deviation may have a large impact on the assessment of the iodine intake. Hence, updated knowledge about the variation in iodine level of fish, milk, dairy products and hen’s egg are of great importance when estimating the iodine intake in the population. These data will contribute substantially to future estimations of dietary iodine intake and will be made available for the public Norwegian Food Composition Table.

index carbohydrates abrogate the antiobesity effect of fish oil in mice. Am J Physiol Endocrinol Metab 302: E1097-E1112, 2012. First published February 14, 2012 doi:10.1152/ajpendo.00524.2011Fish oil rich in n-3 polyunsaturated fatty acids is known to attenuate diet-induced obesity and adipose tissue inflammation in rodents. Here we aimed to investigate whether different carbohydrate sources modulated the antiobesity effects of fish oil. By feeding C57BL/6J mice isocaloric high-fat diets enriched with fish oil for 6 wk, we show that increasing amounts of sucrose in the diets dose-dependently increased energy efficiency and white adipose tissue (WAT) mass. Mice receiving fructose had about 50% less WAT mass than mice fed a high fish oil diet supplemented with either glucose or sucrose, indicating that the glucose moiety of sucrose was responsible for the obesity-promoting effect of sucrose. To investigate whether the obesogenic effect of sucrose and glucose was related to stimulation of insulin secretion, we combined fish oil with high and low glycemic index (GI) starches. Mice receiving the fish oil diet containing the low-GI starch had significantly less WAT than mice fed high-GI starch. Moreover, inhibition of insulin secretion by administration of nifedipine significantly reduced WAT mass in mice fed a high-fish oil diet in combination with sucrose. Our data show that the macronutrient composition of the diet modulates the effects of fish oil. Fish oil combined with sucrose, glucose, or high-GI starch promotes obesity, and the reported anti-inflammatory actions of fish oil are abrogated. In conclusion, our data indicate that glycemic control of insulin secretion modulates metabolic effects of fish oil by demonstrating that high-GI carbohydrates attenuate the antiobesity effects of fish oil. energy efficiency; glucose tolerance; insulin secretion; n-3 polyunsaturated fatty acids