Combined effects of endurance training and dietary unsaturated fatty acids on physical performance, fat oxidation and insulin sensitivity

Endurance training improves exercise performance and insulin sensitivity, and these effects may be in part mediated by an enhanced fat oxidation. Since n-3 and n-9 unsaturated fatty acids may also increase fat oxidation, we hypothesised that a diet enriched in these fatty acids may enhance the effects of endurance training on exercise performance, insulin sensitivity and fat oxidation. To assess this hypothesis, sixteen normal-weight sedentary male subjects were randomly assigned to an isoenergetic diet enriched with fish and olive oils (unsaturated fatty acid group (UFA): 52% carbohydrates, 34% fat (12% SFA, 12% MUFA, 5% PUFA), 14% protein), or a control diet (control group (CON): 62% carbohydrates, 24% fat (12% SFA, 6% MUFA, 2% PUFA), 14% protein) and underwent a 10d gradual endurance training protocol. Exercise performance was evaluated by measuring VO2max and the time to exhaustion during a cycling exercise at 80% VO2max; glucose homeostasis was assessed after ingestion of a test meal. Fat oxidation was assessed by indirect calorimetry at rest and during an exercise at 50% VO2max. Training significantly increased time to exhaustion, but not VO2max, and lowered incremental insulin area under the curve after the test meal, indicating improved insulin sensitivity. Those effects were, however, of similar magnitude in UFA and CON. Fat oxidation tended to increase in UFA, but not in CON. This difference was, however, not significant. It is concluded that a diet enriched with fish- and olive oil does not substantially enhance the effects of a short-term endurance training protocol in healthy young subject

Prevalence, awareness and control of diabetes in the Seychelles and relationship with excess body weight

BACKGROUND: The evidence for a "diabesity" epidemic is accumulating worldwide but population-based data are still scarce in the African region. We assessed the prevalence, awareness and control of diabetes (DM) in the Seychelles, a rapidly developing country in the African region. We also examined the relationship between body mass index, fasting serum insulin and DM. METHODS: Examination survey in a sample representative of the entire population aged 25-64 of the Seychelles, attended by 1255 persons (participation rate of 80.2%). An oral glucose tolerance test (OGTT) was performed in individuals with fasting blood glucose between 5.6 and 6.9 mmol/l. Diabetes mellitus (DM), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were defined along criteria of the ADA. Prevalence estimates were standardized for age. RESULTS: The prevalence of DM was 11.5% and 54% of persons with DM were aware of having DM. Less than a quarter of all diabetic persons under treatment were well controlled for glycemia (HbA1c), blood pressure or LDL-cholesterol. The prevalence of IGT and IFG were respectively 10.4% and 24.2%. The prevalence of excess weight (BMI > or = 25 kg/m2) and obesity (BMI > or = 30 kg/m2) was respectively 60.1% and 25.0%. Half of all DM cases in the population could be attributed to excess weight. CONCLUSION: We found a high prevalence of DM and pre-diabetes in a rapidly developing country in the African region. The strong association between overweight and DM emphasizes the importance of weight control measures to reduce the incidence of DM in the population. High rates of diabetic persons not aware of having DM in the population and insufficient cardiometabolic control among persons treated for DM stress the need for intensifying health care for diabetes

A high-fructose diet impairs basal and stress-mediated lipid metabolism in healthy male subjects

The effects of a 7d high-fructose diet (HFrD) or control diet on lipid metabolism were studied in a group of six healthy lean males. Plasma NEFA and β-hydroxybutyrate concentrations, net lipid oxidation (indirect calorimetry) and exogenous lipid oxidation (13CO2 production) were monitored in basal conditions, after lipid loading (olive oil labelled with [13C]triolein) and during a standardised mental stress. Lactate clearance and the metabolic effects of an exogenous lactate infusion were also monitored. The HFrD lowered plasma concentrations of NEFA and β-hydroxybutyrate as well as lipid oxidation in both basal and after lipid-loading conditions. In addition, the HFrD blunted the increase in plasma NEFA and exogenous lipid oxidation during mental stress. The HFrD also increased basal lactate concentrations by 31·8%, and lactate production by 53·8%, while lactate clearance remained unchanged. Lactate infusion lowered plasma NEFA with the control diet, and net lipid oxidation with both the HFrD and control diet. These results indicate that a 7d HFrD markedly inhibits lipolysis and lipid oxidation. The HFrD also increases lactate production, and the ensuing increased lactate utilisation may contribute to suppress lipid oxidatio

Effects of a short-term overfeeding with fructose or glucose in healthy young males

Consumption of simple carbohydrates has markedly increased over the past decades, and may be involved in the increased prevalence in metabolic diseases. Whether an increased intake of fructose is specifically related to a dysregulation of glucose and lipid metabolism remains controversial. We therefore compared the effects of hypercaloric diets enriched with fructose (HFrD) or glucose (HGlcD) in healthy men. Eleven subjects were studied in a randomised order after 7d of the following diets: (1) weight maintenance, control diet; (2) HFrD (3·5g fructose/kg fat-free mass (ffm) per d, +35% energy intake); (3) HGlcD (3·5g glucose/kg ffm per d, +35% energy intake). Fasting hepatic glucose output (HGO) was measured with 6,6-2H2-glucose. Intrahepatocellular lipids (IHCL) and intramyocellular lipids (IMCL) were measured by 1H magnetic resonance spectroscopy. Both fructose and glucose increased fasting VLDL-TAG (HFrD: +59%, P<0·05; HGlcD: +31%, P=0·11) and IHCL (HFrD: +52%, P<0·05; HGlcD: +58%, P=0·06). HGO increased after both diets (HFrD: +5%, P<0·05; HGlcD: +5%, P=0·05). No change was observed in fasting glycaemia, insulin and alanine aminotransferase concentrations. IMCL increased significantly only after the HGlcD (HFrD: +24%, NS; HGlcD: +59%, P<0·05). IHCL and VLDL-TAG were not different between hypercaloric HFrD and HGlcD, but were increased compared to values observed with a weight maintenance diet. However, glucose led to a higher increase in IMCL than fructos

Blunting the response to endotoxin in healthy subjects: effects of various doses of intravenous fish oil

Objective: To test the dose response effect of infused fish oil (FO) rich in n-3 PUFAs on the inflammatory response to endotoxin (LPS) and on membrane incorporation of fatty acids in healthy subjects. Design: Prospective, sequential investigation comparing three different FO doses. Subjects: Three groups of male subjects aged 26.8±3.2years (BMI 22.5±2.1). Intervention: One of three FO doses (Omegaven®10%) as a slow infusion before LPS: 0.5g/kg 1day before LPS, 0.2g/kg 1day before, or 0.2g/kg 2h before. Measurements and results: Temperature, hemodynamic variables, indirect calorimetry and blood samples (TNF-α, stress hormones) were collected. After LPS temperature, ACTH and TNF-α concentrations increased in the three groups: the responses were significantly blunted (p<0.0001) compared with the control group of the Pluess et al. trial. Cortisol was unchanged. Lowest plasma ACTH, TNF-α and temperature AUC values were observed after a single 0.2g/kg dose of FO. EPA incorporation into platelet membranes was dose-dependent. Conclusions: Having previously shown that the response to LPS was reproducible, this study shows that three FO doses blunted it to various degrees. The 0.2g/kg perfusion immediately before LPS was the most efficient in blunting the responses, suggesting LPS capture in addition to the systemic and membrane effect

Divergent fifteen-year trends in traditional and cardiometabolic risk factors of cardiovascular diseases in the Seychelles

OBJECTIVE: Few studies have assessed secular changes in the levels of cardiovascular risk factors (CV-RF) in populations of low or middle income countries. The systematic collection of a broad set of both traditional and metabolic CV-RF in 1989 and 2004 in the population of the Seychelles islands provides a unique opportunity to examine trends at a fairly early stage of the "diabesity" era in a country in the African region. METHODS: Two examination surveys were conducted in independent random samples of the population aged 25-64 years in 1989 and 2004, attended by respectively 1081 and 1255 participants (participation rates &gt;80%). All results are age-standardized to the WHO standard population. RESULTS: In 2004 vs. 1989, the levels of the main traditional CV-RF have either decreased, e.g. smoking (17% vs. 30%, p &lt; 0.001), mean blood pressure (127.8/84.8 vs. 130.0/83.4 mmHg, p &lt; 0.05), or only moderately increased, e.g. median LDL-cholesterol (3.58 vs. 3.36 mmol/l, p &lt; 0. 01). In contrast, marked detrimental trends were found for obesity (37% vs. 21%, p &lt; 0.001) and several cardiometabolic CVD-RF, e.g. mean HDL-cholesterol (1.36 vs. 1.40 mmol/l, p &lt; 0.05), median triglycerides (0.80 vs. 0.78 mmol/l, p &lt; 0.01), mean blood glucose (5.89 vs. 5.22 mmol/l, p &lt; 0.001), median insulin (11.6 vs. 8.3 micromol/l, p &lt; 0.001), median HOMA-IR (2.9 vs. 1.8, p &lt; 0.001) and diabetes (9.4% vs. 6.2%, p &lt; 0.001). At age 40-64, the prevalence of elevated total cardiovascular risk tended to decrease (e.g. WHO-ISH risk score &gt; or =10; 11% vs. 13%, ns), whereas the prevalence of the metabolic syndrome (which integrates several cardiometabolic CVD-RF) nearly doubled (36% vs. 20%, p &lt; 0.001). Data on physical activity and on intake of alcohol, fruit and vegetables are also provided. Awareness and treatment rates improved substantially for hypertension and diabetes, but control rates improved for the former only. Median levels of the cardiometabolic CVD-RF increased between 1989 and 2004 within all BMI strata, suggesting that the worsening levels of cardiometabolic CVD-RF in the population were not only related to increasing BMI levels in the interval. CONCLUSION: The levels of several traditional CVD-RF improved over time, while marked detrimental trends were observed for obesity, diabetes and several cardiometabolic factors. Thus, in this population, the rapid health transition was characterized by substantial changes in the patterns of CVD-RF. More generally, this analysis suggests the importance of surveillance systems to identify risk factor trends and the need for preventive strategies to promote healthy lifestyles and nutrition

Misconceptions about fructose-containing sugars and their role in the obesity epidemic

A causal role of fructose intake in the aetiology of the global obesity epidemic has been proposed in recent years. This proposition, however, rests on controversial interpretations of two distinct lines of research. On one hand, in mechanistic intervention studies, detrimental metabolic effects have been observed after excessive isolated fructose intakes in animals and human subjects. On the other hand, food disappearance data indicate that fructose consumption from added sugars has increased over the past decades and paralleled the increase in obesity. Both lines of research are presently insufficient to demonstrate a causal role of fructose in metabolic diseases, however. Most mechanistic intervention studies were performed on subjects fed large amounts of pure fructose, while fructose is ordinarily ingested together with glucose. The use of food disappearance data does not accurately reflect food consumption, and hence cannot be used as evidence of a causal link between fructose intake and obesity. Based on a thorough review of the literature, we demonstrate that fructose, as commonly consumed in mixed carbohydrate sources, does not exert specific metabolic effects that can account for an increase in body weight. Consequently, public health recommendations and policies aiming at reducing fructose consumption only, without additional diet and lifestyle targets, would be disputable and impractical. Although the available evidence indicates that the consumption of sugar-sweetened beverages is associated with body-weight gain, and it may be that fructose is among the main constituents of these beverages, energy overconsumption is much more important to consider in terms of the obesity epidemi

Effects of endotoxin on lactate metabolism in humans.

ABSTRACT: INTRODUCTION: Hyperlactatemia represents one prominent component of the metabolic response to sepsis. In critically ill patients, hyperlactatemia is related to the severity of the underlying condition. Both an increased production and a decreased utilization and clearance might be involved in this process, but their relative contribution remains unknown. The present study aimed at assessing systemic and muscle lactate production and systemic lactate clearance in healthy human volunteers, using intravenous endotoxin (LPS) challenge. METHODS: Fourteen healthy male volunteers were enrolled in 2 consecutive studies (n = 6 in trial 1 and n = 8 in trial 2). Each subject took part in one of two investigation days (LPS-day with endotoxin injection and placebo-day with saline injection) separated by one week at least and in a random order. In trial 1, their muscle lactate metabolism was monitored using microdialysis. In trial 2, their systemic lactate metabolism was monitored by means of a constant infusion of exogenous lactate. Energy metabolism was monitored by indirect calorimetry and glucose kinetics was measured with 6,6-H2 glucose. RESULTS: In both trials, LPS increased energy expenditure (p = 0.011), lipid oxidation (p&lt;0.0001), and plasma lactate concentration (p = 0.016). In trial 1, lactate concentration in the muscle microdialysate was higher than in blood, indicating lactate production by muscles. This was, however, similar with and without LPS. In trial 2, calculated systemic lactate production increased after LPS (p = 0.031), while lactate clearance remained unchanged. CONCLUSIONS: LPS administration increases lactatemia by increasing lactate production rather than by decreasing lactate clearance. Muscle is, however, unlikely to be a major contributor to this increase in lactate production. TRIAL REGISTRATION: ClinicalTrials.gov NCT01647997

Effect of bicarbonate and lactate buffer on glucose and lactate metabolism during hemodiafiltration in patients with multiple organ failure

Objective: To compare the effects of sodium bicarbonate and lactate for continuous veno-venous hemodiafiltration (CVVHDF) in critically ill patients. Design and settings: Prospective crossed-over controlled trial in the surgical and medical ICUs of a university hospital. Patients: Eight patients with multiple organ dysfunction syndrome (MODS) requiring CVVHDF. Intervention: Each patient received the two buffers in a randomized sequence over two consecutive days. Measurements and results: The following variables were determined: acid-base parameters, lactate production and utilization (13C lactate infusion), glucose turnover (6,62H2-glucose), gas exchange (indirect calorimetry). No side effect was observed during lactate administration. Baseline arterial acid-base variables were equal with the two buffers. Arterial lactate (2.9 versus 1.5mmol/l), glycemia (+18%) and glucose turnover (+23%) were higher in the lactate period. Bicarbonate and glucose losses in CVVHDF were substantial, but not lactate elimination. Infusing 13C lactate increased plasma lactate levels equally with the two buffers. Lactate clearance (7.8±0.8 vs 7.5±0.8ml/kg per min in the bicarbonate and lactate periods) and endogenous production rates (14.0±2.6 vs 13.6±2.6mmol/kg per min) were similar. 13C lactate was used as a metabolic substrate, as shown by 13CO2 excretion. Glycemia and metabolic rate increased significantly and similarly during the two periods during lactate infusion. Conclusion: Lactate was rapidly cleared from the blood of critically ill patients without acute liver failure requiring CVVHDF, being transformed into glucose or oxidized. Lactate did not exert undesirable effects, except moderate hyperglycemia, and achieved comparable effects on acid-base balance to bicarbonat