Fish Oil Protects Wild Type and Uncoupling Protein 1-Deficient Mice from Obesity and Glucose Intolerance by Increasing Energy Expenditure.

SCOPE: The mechanisms and involvement of uncoupling protein 1 (UCP1) in the protection from obesity and insulin resistance induced by intake of a high-fat diet rich in omega-3 (n-3) fatty acids are investigated. METHODS AND RESULTS: C57BL/6J mice are fed either a low-fat (control group) or one of two isocaloric high-fat diets containing either lard (HFD) or fish oil (HFN3) as fat source and evaluated for body weight, adiposity, energy expenditure, glucose homeostasis, and inguinal white and interscapular brown adipose tissue (iWAT and iBAT, respectively) gene expression, lipidome, and mitochondrial bioenergetics. HFN3 intake protected from obesity, glucose and insulin intolerances, and hyperinsulinemia. This is associated with increased energy expenditure, iWAT UCP1 expression, and incorporation of n-3 eicosapentaenoic and docosahexaenoic fatty acids in iWAT and iBAT triacylglycerol. Importantly, HFN3 is equally effective in reducing body weight gain, adiposity, and glucose intolerance and increasing energy expenditure in wild-type and UCP1-deficient mice without recruiting other thermogenic processes in iWAT and iBAT, such as mitochondrial uncoupling and SERCA-mediated calcium and creatine-driven substrate cyclings. CONCLUSION: Intake of a high-fat diet rich in omega-3 fatty acids protects both wild-type and UCP1-deficient mice from obesity and insulin resistance by increasing energy expenditure through unknown mechanisms.

Development of a brief, reliable and valid diet assessment tool for impaired glucose tolerance and diabetes: the UK Diabetes and Diet Questionnaire.

OBJECTIVE: Dietary advice is fundamental in the prevention and management of type 2 diabetes (T2DM). Advice is improved by individual assessment but existing methods are time-consuming and require expertise. We developed a twenty-five-item questionnaire, the UK Diabetes and Diet Questionnaire (UKDDQ), for quick assessment of an individual's diet. The present study examined the UKDDQ's repeatability and relative validity compared with 4 d food diaries. DESIGN: The UKDDQ was completed twice with a median 3 d gap (interquartile range=1-7 d) between tests. A 4 d food diary was completed after the second UKDDQ. Diaries were analysed and food groups were mapped on to the UKDDQ. Absolute agreement between total scores was examined using intra-class correlation (ICC). Agreement for individual items was tested with Cohen's weighted kappa (κ w). SETTING: South West of England. SUBJECTS: Adults (n 177, 50·3 % women) with, or at high risk for, T2DM; mean age 55·8 (sd 8·6) years, mean BMI 34·4 (sd 7·3) kg/m2; participants were 91 % White British. RESULTS: The UKDDQ showed excellent repeatability (ICC=0·90 (0·82, 0·94)). For individual items, κ w ranged from 0·43 ('savoury pastries') to 0·87 ('vegetables'). Total scores from the UKDDQ and food diaries compared well (ICC=0·54 (0·27, 0·70)). Agreement for individual items varied and was good for 'alcohol' (κ w=0·71) and 'breakfast cereals' (κ w=0·70), with no agreement for 'vegetables' (κ w=0·08) or 'savoury pastries' (κ w=0·09). CONCLUSIONS: The UKDDQ is a new British dietary questionnaire with excellent repeatability. Comparisons with food diaries found agreements similar to those for international dietary questionnaires currently in use. It targets foods and habits important in diabetes prevention and management.

Assessment of the mechanisms exerting glucose-lowering effects of dried peas in glucose-intolerant rats.

The present study compared the effects of feeding uncooked pea fractions (embryo v. seed coat) on glucose homeostasis in glucose-intolerant rats and examined potential mechanisms influencing glucose homeostasis. Rats were made glucose intolerant by high-fat feeding, after which diets containing both high-fat and pea fractions were fed for 4 weeks. Rats fed diets containing uncooked pea seed coats low (non-coloured seed coat; NSC) or high (coloured seed coat; CSC) in proanthocyanidins but not embryos had improved oral glucose tolerance (P < 0·05). NSC also lowered fasting and glucose-stimulated insulin secretion (P < 0·05), decreased ß-cell mass by 50 % (P < 0·05) and lowered levels of malondialdehyde, a marker of oxidative stress. Furthermore, NSC decreased the mucosal thickness of the colon by 25 % (P < 0·05), which might affect fibre fermentation and other gut functions. Small but statistically significant (P < 0·05) effects consistent with enhanced glucose transport or metabolism were observed in the skeletal muscle of rats fed NSC or CSC, for example, increased levels of AMP-dependent kinase or akt. We conclude that pea seed coats are the fraction exerting beneficial effects on glucose tolerance. Most of the changes were small in amplitude, suggesting that additive effects on multiple tissues may be important. NSC content appeared to have the most beneficial effects in improving glucose homeostasis but our ability to detect the effect of flavonoids may have been limited by their low concentration in the diet.

Conference on "Multidisciplinary approaches to nutritional problems". Symposium on "Diabetes and health". Nutrition interventions for the prevention of type 2 diabetes.

Diabetes mellitus is escalating globally and it is predicted that 200 million individuals worldwide will have diabetes by 2010 and 300 million by 2025. However, there is compelling evidence from many studies that for subjects with impaired fasting glucose or impaired glucose tolerance the presentation of type 2 diabetes can be delayed by lifestyle modification. The aim of the present review is to present a summary of lifestyle modification interventions that have included a dietary component in their overall diabetes prevention programme. Medline, allied health literature and diabetes journals were searched for peer-reviewed literature using the terms 'diet*' and 'diabetes' and 'intervention'. Inclusion criteria were: peer-reviewed studies from 1975 to 2008; a sample of at least fifty subjects; a healthy eating and/or physical activity component; prevention of diabetes as a primary goal. Generally, the participants were in a high-risk category for the development of diabetes. Outcomes were evaluated at two points in time (pre- and post-intervention) in terms of knowledge, behaviour change and clinical improvement, which included weight, blood pressure, BMI, body fat, waist circumference, waist:hip ratio and physiological and/or biochemical measures. Findings indicate that the most successful interventions combine individual dietary counselling with an activity component. Further factors predicting success are weight loss achieved, duration and intensity of the intervention and dietary compliance.

Comparison of insulin sensitivity assessment indices with euglycemic-hyperinsulinemic clamp data after a dietary and exercise intervention in older adults.

Multiple indices to assess insulin sensitivity calculated from mathematical equations based on fasting blood parameters or oral glucose tolerance data have been developed. Although these indices have frequently been validated using euglycemic-hyperinsulinemic clamp data, the utility of each equation in measuring change in insulin sensitivity over time remains uncertain. We examined change in insulin sensitivity in response to a 12-week diet and exercise intervention in 31 older men and women with impaired glucose tolerance using a euglycemic-hyperinsulinemic clamp and 10 commonly used insulin sensitivity equations. Mean glucose disposal as calculated from clamp data was significantly higher after the intervention compared with baseline (5.92 +/- 0.38 vs 5.18 +/- 0.30 mg . kg fat free mass(-1) . min(-1), P = .013). In contrast, none of the examined indices indicated a significant change in insulin sensitivity over time (all P > .3). A limits of agreement approach to compare insulin sensitivity calculated from each equation with the measure of glucose disposal from the clamp indicated overall imperfect agreement between measures (agreement limits ranged from +/-2.48 to +/-4.23 mg . kg fat free mass(-1) . min(-1)) despite significant bivariate correlations between indices and clamp data. The wide variability in the 95% prediction limits of agreement among equations suggests that these equations vary substantially from a euglycemic-hyperinsulinemic clamp in their ability to assess insulin sensitivity. Despite the observed limited agreement using this statistical approach, changes in several calculated indices were significantly correlated with changes in clamp data, suggesting that these indices may have some utility in tracking improvements in insulin sensitivity. Further research is necessary to examine agreement between indices and clamp data in larger, more heterogeneous populations and in response to other interventions where the magnitude of change in insulin sensitivity may be larger.

A dietary exchange of common bread for tailored bread of low glycaemic index and rich in dietary fibre improved insulin economy in young women with impaired glucose tolerance.

OBJECTIVE: To study the possibility of improving blood lipids, glucose tolerance and insulin sensitivity in women with impaired glucose tolerance and a history of gestational diabetes by merely changing the glycaemic index (GI) and dietary fibre (DF) content of their bread. DESIGN: Randomized crossover study where test subjects were given either low GI/high DF or high GI/low DF bread products during two consecutive 3-week periods, separated by a 3-week washout period. An intravenous glucose tolerance test followed by a euglycaemic-hyperinsulinaemic clamp was performed on days 1 and 21 in both the high- and low-GI periods, to assess insulin secretion and insulin sensitivity. Blood samples were also collected on days 1 and 21 for analysis of fasting levels of glucose, insulin, HDL-cholesterol and triacylglycerols (TG). SETTING: Lund University, Sweden. SUBJECTS: Seven women with impaired glucose tolerance. RESULTS: The study shows that a modest dietary modification, confined to a lowering of the GI character and increasing cereal DF of the bread products, improved insulin economy as judged from the fact that all women lowered their insulin responses to the intravenous glucose challenge on average by 35% (0-60 min), in the absence of effect on glycaemia. No changes were found in fasting levels of glucose, insulin, HDL-cholesterol or TG. CONCLUSION: It is concluded that a combination of low GI and a high content of cereal DF has a beneficial effect on insulin economy in women at risk of developing type II diabetes. This is in accordance with epidemiological data, suggesting that a low dietary GI and/or increased intake of whole grain prevent against development of type II diabetes. SPONSORSHIP: Supported by grants from Cerealia Research Foundation.