Chitosan improves insulin sensitivity as determined by the euglycemic-hyperinsulinemic clamp technique in obese subjects

In accordance with obesity is associated with insulin resistance and dyslipidemia and chitosan decrease weight and lipids, but its effect on insulin sensitivity is unknown. Our hypothesis for the research was that chitosan improves insulin sensitivity estimated with the euglycemic-hyperinsulinemic clamp technique in obesity. We undertook this study with the objective to determine the effect of chitosan on insulin sensitivity using the euglycemic-hyperinsulinemic clamp technique in obese patients during a 3-month period. A randomized, double-blind clinical trial was carried out in 12 obese adults without diabetes mellitus. During a 3-month period, 6 patients received chitosan (750 mg, 3 times per day) 30 minutes before meals, and the other 6 subjects received placebo. Serum glucose, total cholesterol, high-density lipoprotein cholesterol, and triglycerides (TG) were measured. Insulin sensitivity was estimated with the euglycemic-hyperinsulinemic clamp technique before and after the intervention. Insulin sensitivity increased significantly with the administration of chitosan (2.4 ± 1.4 vs 3.6 ± 1.4 mg kg⁻¹ min⁻¹; P = .043). In addition, there was a decrease in weight (90.7 ± 14.2 vs 84.7 ± 13.7 kg; P = .027), body mass index (34.3 ± 2.7 vs 31.6 ± 2.2 kg/m²; P = .028), waist circumference (106 ± 12 vs 99 ± 9 cm; P = .028) and TG (2.4 ± 0.9 vs 1.6 ± 0.9 mmol/L; P = .028) in the chitosan group. In conclusion, 3-month administration of chitosan increased insulin sensitivity in obese patients and demonstrated a decrease in weight, body mass index, waist circumference, and TG.     

Chia seed does not promote weight loss or alter disease risk factors in overweight adults

The objective of this study was to assess the effectiveness of chia seed (Salvia hispanica L) in promoting weight loss and altering disease risk factors in overweight adults. The hypothesis was that the high dietary fiber and α-linolenic (ALA) contents of chia seed would induce a small but significant decrease in body weight and fat and improve disease risk factors. Subjects were randomized to chia seed (CS) and placebo (P) groups, and under single-blinded procedures, ingested 25 g CS or P supplements mixed in 0.25 L water twice daily before the first and last meal for 12 weeks. Ninety nondiseased, overweight/obese men and women between the ages of 20 and 70 years were recruited into the study, with 76 subjects (n = 39 CS, n = 37 P) completing all phases of the study. Pre- and poststudy measures included body mass and composition (dual energy x-ray absorptiometry), inflammation markers from fasting blood samples (C-reactive protein, interleukin 6, monocyte chemoattractant protein 1, and tumor necrosis factor α), oxidative stress markers (trolox equivalent antioxidant capacity and plasma nitrite), blood pressure, and a serum lipid profile. Plasma ALA increased 24.4% compared to a 2.8% decrease in CS and P, respectively (interaction effect, P = .012). No group differences were measured for changes in plasma eicosapentaenoic acid and docosahexaenoic acid (interaction effects, P = .420 and .980, respectively). Pre-to-post measures of body composition, inflammation, oxidative stress, blood pressure, and lipoproteins did not differ between CS and P for both sexes. In conclusion, ingestion of 50 g/d CS vs P for 12 weeks by overweight/obese men and women had no influence on body mass or composition, or various disease risk factor measures.     

Waist circumference is positively correlated with markers of inflammation and negatively with adiponectin in women with metabolic syndrome

The purpose of this study was to correlate biomarkers of metabolic syndrome (MetS), with markers of inflammation and macronutrient intake in 89 women (25-72 years) with MetS. We hypothesized that waist circumference (WC) would have the stronger correlations with inflammatory parameters and would correlate with carbohydrate intake. Values for WC (108.7 ± 11.1 cm) and plasma triglycerides (202.7 ± 52.1 mg/dL) were elevated, whereas plasma glucose levels varied from 66 to 179 mg/dL, with 42% of women having insulin resistance. Plasma levels of interleukin 6 (0.2-15.9 mg/L), tumor necrosis factor α (1.47-12.3 mg/L), and high-sensitivity C-reactive protein (0.06-3.08 mg/dL) varied widely, with most women being above values considered normal. Subjects had high intake of total sugar (92.3 ± 56.4 g/d), high glycemic index (59.8 ± 6.5), and glycemic load (127.2 ± 56.1), whereas dietary fiber (17.1 ± 9.1 g/d) was below recommended intake. Waist circumference was positively correlated with insulin (r = 0.275, P < .01) and with the inflammatory markers interleukin 6 (r = 0.307, P < .01) and tumor necrosis factor α (r = 0.228, P < .05) and negatively correlated with plasma adiponectin (r = −0.309, P < .0001). In addition, WC was positively correlated with total carbohydrate, added sugar, and glycemic load (P < .05) but not with fat or protein. These results are consistent with central obesity being a key marker of the inflammatory state, and they also suggest that carbohydrates, particularly those that are digested rapidly, contribute to increased risk of central obesity and development of MetS.     

Young overweight and obese women with lower circulating osteocalcin concentrations exhibit higher insulin resistance and concentrations of C-reactive protein

The role of the skeleton in the regulation of energy metabolism in humans is not clear. This study investigates the hypothesis that biomarkers of bone turnover are associated with indices of glucose homeostasis and systemic inflammation in young adults. A cross-sectional study investigating the relationships between biomarkers of bone turnover (serum total and uncarboxylated osteocalcin, bone-specific alkaline phosphatase, C-telopeptide of type I collagen, urinary N-telopeptide of type I collagen) and glucose metabolism (fasting plasma glucose [FPG], insulin, insulin resistance [homeostatic model assessment of insulin resistance]), systemic inflammation (high-sensitivity C-reactive protein [hsCRP] and interleukin-6), adipokines (leptin and adiponectin), and body composition was conducted in 268 young, nondiabetic overweight and obese adults aged 20 to 40 years (116 men, 152 women; body mass index, 27.5-32.5 kg/m²). Data on diet, physical activity, serum 25-hydroxyvitamin D, and parathyroid hormone were also collected. In women, there was a stepwise increase in lean body mass (P < .05) and a decrease in serum hsCRP (P < .001) across tertiles of total osteocalcin. Multiple linear regression analysis showed significant inverse associations between total osteocalcin and FPG (β = −0.350; P = .016; 95% confidence interval [CI], −0.35 to −0.04), insulin (β = −0.455; P = .002; 95% CI, −1.9 to −0.46), and homeostatic model assessment of insulin resistance (β = −0.508; P = .001; 95% CI, −10.93 to −3.17) in women with total osteocalcin concentrations below the group median. Men in the lowest tertile of uncarboxylated osteocalcin had twice the concentration of hsCRP than did other men (P = .05). In this sample, women with less lean body mass had lower circulating total osteocalcin concentrations and exhibited higher FPG, insulin resistance, and hsCRP compared with their similarly sized counterparts, suggesting that associations between osteocalcin and systemic inflammation, glucose homeostasis, and insulin resistance may be influenced by differences in sex and body composition.     

The influence of diet and/or exercise and parental compliance on health-related quality of life in obese children

Recent findings of a direct association of obesity and impaired health-related quality of life (HRQOL) in children suggest a need for early weight-management interventions that address psychosocial issues and lifestyle. Our aim was to compare the effects of exercise, diet, or diet + exercise on HRQOL in obese children. We hypothesized that HRQOL will improve as a result of the weight-loss intervention and will be correlated with the amount of weight loss achieved by each of the intervention groups. A total of 162 children aged 6 to 11 years with a body mass index (BMI) exceeding the 95th percentile were randomly allocated to a 12-week regimens of diet, exercise, or diet + exercise. Weight, height, and percent fat mass were measured, and parents completed the Pediatric Quality of Life Inventory (PedsQL) 4.0 at baseline and at the end of the intervention. The reductions in BMI were significantly greater in the diet and diet + exercise groups than in the exercise group. Pediatric Quality of Life Inventory scores improved significantly, with no differences among the groups. A greater reduction in BMI occurred in children whose parents completed the PedsQL at baseline (n = 105) than in children whose parents did not (n = 15) (−1.8 ± 1.3 vs −1.0 ± 1.5; P = .048) and in children whose parents completed the PedsQL at the end of the intervention (n = 73) than in children whose parents did not (n = 47) (−2.0 ± 1.3 vs −1.3 ± 1.3; P = .013). Weight-management programs that promote a healthy eating and physical activity can serve as an effective tool to improve the low HRQOL of obese children. Parental compliance is an important factor and may be assessed by the parents' cooperativeness in completing questionnaires.     

High intake of fruits and vegetables predicts weight loss in Brazilian overweight adults

To determine whether changes in dietary intakes predict weight loss, we studied 80 overweight adults who attended a nutritional counseling program during 6 months of follow-up at a primary health care center in Brazil. Habitual diet was assessed using a validated food frequency questionnaire at baseline and after 6 months. The mean age (±SD) of the participants was 46.5 ± 9.5 years, and their mean body mass index was 29 ± 3 kg/m² at baseline. After 6 months, the differences in body weight and fruit/vegetable intake were −1.4 ± 3 kg and ±109 ± 320 g daily, respectively. Using multiple linear regression models adjusted for age, sex, changes in walking time, and total energy intake, the increased intake of dietary fiber from fruits/vegetables was associated with a greater weight loss (β1 [95% confidence interval (CI)] = −0.180 [−0.269, −0.091]) after 6 months of follow-up. Similar results were observed for increased intake of vegetables (β1 [95% CI] = −0.00497 [−0.008, −0.002]) and fruits (β1 [95% CI] = −0.00290 [−0.005, −0.001]) as predictors of weight loss. The increase of 100 g/d of vegetables and fruits represented a body weight loss of 500 and 300 g after 6 months, respectively (P < .05). Our findings support the relevance of increased intakes of fruits and vegetables that may help avoid weight gain in overweight adults.     

Fructose consumption during pregnancy and lactation induces fatty liver and glucose intolerance in rats

Nutritional insults during pregnancy and lactation are health risks for mother and offspring. Both fructose (FR) and low-protein (LP) diets are linked to hepatic steatosis and insulin resistance in nonpregnant animals. We hypothesized that dietary FR or LP intake during pregnancy may exacerbate the already compromised glucose homeostasis to induce gestational diabetes and fatty liver. Therefore, we investigated and compared the effects of LP or FR intake on hepatic steatosis and insulin resistance in unmated controls (CTs) and pregnant and lactating rats. Sprague-Dawley rats were fed a CT, or a 63% FR, or an 8% LP diet. Glucose tolerance test at day 17 of the study revealed greater (P < .05) blood glucose at 10 (75.6 mg/dL vs 64.0 ± 4.8 mg/dL) minutes and 20 (72.4 mg/dL vs 58.6 ± 4.0 mg/dL) minutes after glucose dose and greater area under the curve (4302.3 mg?dL^− 1? min^− 1 vs 3763.4 ± 263.6 mg?dL^− 1? min^− 1) for FR-fed dams compared with CT-fed dams. The rats were euthanized at 21 days postpartum. Both the FR- and LP-fed dams had enlarged (P < .05) livers (9.3%, 7.1% body weight vs 4.8% ± 0.2% body weight) and elevated (P < .05) liver triacylglycerol (216.0, 130.0 mg/g vs 19.9 ± 12.6 mg/g liver weight) compared with CT-fed dams. Fructose induced fatty liver and glucose intolerance in pregnant and lactating rats, but not unmated CT rats. The data demonstrate a unique physiological status response to diet resulting in the development of gestational diabetes coupled with hepatic steatosis in FR-fed dams, which is more severe than an LP diet.     

Effect of Flaxseed Intervention on Inflammatory Marker C-Reactive Protein: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Functional food-flaxseed and its derivatives (flaxseed oil or lignans) are beneficial for human health, possibly because of their anti-inflammatory effects. C-reactive protein (CRP), a sensitive marker of inflammation was chosen to evaluate the anti-inflammatory effects of flaxseed. We searched randomized controlled trials from PubMed and the Cochrane Library in October 2015 and conducted a meta-analysis to evaluate the effectiveness of flaxseed and its derivatives on CRP. The mean differences (net change) in CRP (mg/L) concentrations were pooled with a random- or a fixed-effects model depending on the results of heterogeneity tests. Overall, flaxseed interventions had no effects on reduction of CRP (p = 0.428). The null effects were consistent in the subgroup analysis with multiple studies and population characteristics. Significant heterogeneity was observed in most of the analyses. Meta-regression identified baseline body mass index (BMI) as a significant source of heterogeneity (P-interaction = 0.032), with a significant reduction in CRP of 0.83 mg/L (95% confidence interval −1.34 to −0.31; p = 0.002) among subjects with a BMI of ≥30 kg/m². In conclusion, our meta-analysis did not find sufficient evidence that flaxseed and its derivatives have a beneficial effect on reducing circulating CRP. However, they may significantly reduce CRP in obese populations.     

Associations between obesity and serum lipid-soluble micronutrients among premenopausal women

Elucidating potential pathways that micronutrients may reduce/promote chronic disease may contribute to our understanding of the underlying etiology of disease and their utility as markers of risk. In the current study, we examined associations of serum lipid-soluble micronutrients with body mass index (BMI). We hypothesized that obesity may differentially influence serum micronutrient levels, thereby affecting risk for chronic disease incidence and mortality. Baseline serum samples from 180 premenopausal women from a nutritional trial were analyzed for leptin, C-reactive protein, 25-hydroxyvitamin D, carotenoids, and tocopherols. Participants were stratified into normal-weight (18.5-24.9), overweight (25-29.9), and obese (≥30) subgroups by BMI (in kilograms per square meter). Differences in serum biomarkers among BMI subgroups were adjusted for Asian ethnicity and smoking status. As expected, obese individuals had significantly higher serum levels of leptin and C-reactive protein (Ps < .05) compared with normal-weight women. γ-Tocopherol levels were significantly higher in obese individuals (P < .05), whereas α-tocopherol levels did not differ among BMI subgroups. Serum levels of 25-hydroxyvitamin D and carotenoids (except lycopene) were significantly lower in obese than in normal-weight women (Ps < .05). The associations between BMI and carotenoids were independent of dietary intake. The obesity-associated reduction for total provitamin A carotenoids (45%) was approximately 3-fold greater than that observed for non–provitamin A carotenoids (16%). Our results indicate potential influences of obesity on serum levels of lipid-soluble micronutrients and suggest that metabolism of provitamin A carotenoids may contribute to the differences observed.     

Mild weight loss reduces inflammatory cytokines,leukocyte count,and oxidative stress in overweight and moderately obese participants treated for 3 years with dietary modification

Obesity-induced oxidative stress and inflammation are involved in the pathogenesis of cardiovascular disease. We investigated whether diet-induced, long-term, mild weight loss improved proinflammatory cytokine levels, leukocyte count, and oxidative stress. Overweight/obese participants (25 ≤ body mass index < 34 kg/m², N = 122, 30-59 years) joined a 3-year-long clinical intervention involving daily 100-kcal calorie deficits. Successful weight loss was defined as a reduction in initial body weight equal to 2 kg after the clinical intervention period. Body weight in the successful mild weight loss group (SWL, n = 50) changed 5.4% (−4.16 ± 0.31 kg) compared to 0.05 ± 0.14 kg in the unsuccessful weight loss group (n = 49). After 3 years, SWL participants exhibited significantly reduced insulin, triglycerides, total and low-density lipoprotein cholesterol, free fatty acids, and leukocyte count (P = .030). Furthermore, in the SWL group, serum interleukin (IL)-1β, IL-6, and urinary 8-epi-prostaglandin (PG)F_2α were significantly reduced (45%, 30%, and 14%, respectively). In contrast, the unsuccessful weight loss group exhibited significant increases in percentage of body fat, waist circumference, oxidized low-density lipoprotein, and tumor necrosis factor–α, as well as a significant decrease in high-density lipoprotein cholesterol. After adjusting for baseline values, the 2 groups demonstrated significantly different percentage of body fat, waist circumference, leukocyte count (P = .018), insulin, IL-6 (P = .031), IL-1β (P < .001), and tumor necrosis factor–α (P < .001), as well as urinary 8-epi-PGF_2α (P = .036). A positive correlation existed between IL-1β and urinary 8-epi-PGF_2α (r = 0.435, P < .001) and between changes in IL-6 and urinary 8-epi-PGF_2α (r = 0.393, P < .001). Long-term mild weight loss reduces inflammatory cytokine levels, leukocyte counts, and oxidative stress and may reverse the elevated oxidative stress induced by inflammatory mediators in the overweight and obese.     

Low-energy cranberry juice decreases lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome

Cranberries, high in polyphenols, have been associated with several cardiovascular health benefits, although limited clinical trials have been reported to validate these findings. We tested the hypothesis that commercially available low-energy cranberry juice (Ocean Spray Cranberries, Inc, Lakeville-Middleboro, Mass) will decrease surrogate risk factors of cardiovascular disease, such as lipid oxidation, inflammation, and dyslipidemia, in subjects with metabolic syndrome. In a randomized, double-blind, placebo-controlled trial, participants identified with metabolic syndrome (n = 15-16/group) were assigned to 1 of 2 groups: cranberry juice (480 mL/day) or placebo (480 mL/day) for 8 weeks. Anthropometrics, blood pressure measurements, dietary analyses, and fasting blood draws were conducted at screen and 8 weeks of the study. Cranberry juice significantly increased plasma antioxidant capacity (1.5 ± 0.6 to 2.2 ± 0.4 μmol/L [means ± SD], P < .05) and decreased oxidized low-density lipoprotein and malondialdehyde (120.4 ± 31.0 to 80.4 ± 34.6 U/L and 3.4 ± 1.1 to 1.7 ± 0.7 μmol/L, respectively [means ± SD], P < .05) at 8 weeks vs placebo. However, cranberry juice consumption caused no significant improvements in blood pressure, glucose and lipid profiles, C-reactive protein, and interleukin-6. No changes in these parameters were noted in the placebo group. In conclusion, low-energy cranberry juice (2 cups/day) significantly reduces lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome.     

Increased interleukin-10 but unchanged insulin sensitivity after 4 weeks of (1, 3)(1, 6)-β-glycan consumption in overweight humans

Obesity-induced insulin resistance has been suggested to be a systemic inflammatory condition with activation of the innate immune system. Animal studies indicate that certain dietary fibers such as (1,3)(1,6)-β-d-glycans (BDG) have potent effects on immune activity such as increasing the antiinflammatory cytokine interleukin-10 (IL-10) and reducing the secretion of inflammatory factors. Therefore, we hypothesized that BDG consumption improves inflammatory markers and insulin sensitivity in overweight and obese subjects with moderately increased levels of C-reactive protein, indicating subclinical inflammation. We screened 180 overweight and obese subjects for moderately increased C-reactive protein levels on 2 or more occasions, in the absence of any signs of acute infection. Twelve of the subjects met all inclusion criteria and were investigated in a randomized, double-blind, placebo-controlled, crossover design for 2 × 4 weeks (washout ≥4 weeks). Subjects ingested capsules containing 3 × 0.5 g of highly purified BDG or 3 × 0.5 g of placebo (waxy maize starch) daily. Maintenance of the normal diet of the participants and the correct intake of the capsules were monitored, using 6 × 3-day food recording and counting of the provided capsules. Predefined outcome measures were BDG-induced changes in pro and antiinflammatory markers in circulating blood and gene expression in adipose tissue and peripheral insulin sensitivity expressed as M value. The BDG consumption for 4 weeks significantly increased both circulating levels and adipose tissue messenger RNA (mRNA) expression of the antiinflammatory cytokine IL-10 in overweight and obese humans. Insulin sensitivity as well as circulating levels and mRNA expression of proinflammatory cytokines were unaffected by BDG treatment. Increased IL-10 after BDG consumption might be a contributing factor to the known beneficial effects of dietary fiber intake.     

Increases in cycling performance in response to caffeine ingestion are repeatable

The primary aim of this study was to determine the repeatability of caffeine's ergogenic effects on cycling performance. It was hypothesized that improvements in performance would be similar when caffeine was ingested on 2 separate days. Nine endurance-trained men and women (mean age and maximal oxygen uptake, 27.4 ± 5.9 years and 57.5 ± 3.9 mL kg⁻¹ min⁻¹) initially completed 2 familiarization trials. During 3 subsequent sessions separated by at least 48 hours, the subjects completed a 10-km cycling time trial preceded by ingestion of a drink containing caffeine (5 mg/kg) or placebo. Treatments were ingested using a randomized, single-blind, crossover design, and the subjects were deceived as to the specific content of all drinks. During exercise, heart rate, rating of perceived exertion, and time were recorded every 1.6 km. Repeated-measures analysis of variance was used to compare the differences in variables across distance and treatment. In both caffeine trials, caffeine increased (P = .02) cycling performance by 1.6% and 1.9% vs placebo (16.98 ± 0.96 and 16.92 ± 0.97 minutes with caffeine vs 17.25 ± 0.96 minutes in placebo), and 7 of 9 subjects revealed improved performance. The mean performance improvement in the caffeine trials was similar (P = .35; −0.27 and −0.32 minutes, respectively) across days. Heart rate during exercise was higher (P < .001) with caffeine vs placebo, although the rating of perceived exertion was similar (P = .65). Data reveal that caffeine's ergogenic effects on cycling performance are repeatable across days, yet some individuals did not exhibit improved performance with caffeine.     

Dietary selenium intake is negatively associated with serum sialic acid and metabolic syndrome features in healthy young adults

Low-grade and chronic inflammation related to excessive body weight can increase the risk for type 2 diabetes and cardiovascular disease, whereas the intake of antioxidant nutrients appears to produce anti-inflammatory effects. The purpose of this observational study was to assess the potential relationships between serum SA levels, metabolic syndrome features, and dietary selenium intake to test the hypothesis that this antioxidant micronutrient may also have anti-inflammatory properties in healthy young adults. Forty-three healthy participants with a mean age of 18.0 ± 0.93 years and a mean body mass index of 22.2 ± 2.7 kg/m² were enrolled. Anthropometric, body composition, and blood pressure determinations were measured as well as serum lipid profile, glucose, insulin, and SA concentrations. Nutritional intake was estimated by a computerized, validated semiquantitative food frequency questionnaire. The findings included a positive correlation between SA and triacylglycerol levels (r = 0.317, P = .038) and a trend to significance with the homeostatic model assessment of insulin resistance index (r = 0.297, P = .053). Moreover, subjects with higher dietary selenium intake showed statistically lower SA levels compared with subjects with lower dietary selenium intake (1.8 ± 0.4 vs 2.1 ± 0.4 mmol/L, P = .037), while dietary selenium negatively correlated with SA (r = −0.331, P = .030) and triacylglycerol levels (r = −0.312, P = .041). It can be concluded that a relationship of SA, an inflammatory marker, with metabolic syndrome features such as lipid profile impairment and insulin resistance has been envisaged. In addition, we report (apparently for the first time) a negative association between SA and selenium intake, a recognized antioxidant trace element, in healthy young subjects, reinforcing the view of selenium as a potential anti-inflammatory nutrient.     

Hydrolyzed guar gum decreases postprandial blood glucose and glucose absorption in the rat small intestine

We hypothesized that infusing partially hydrolyzed guar gum (PHGG) into the duodenum would reduce increases in postprandial plasma glucose by decreasing the rate of glucose diffusion from the small intestine luminal digesta of the rat. The postprandial plasma glucose and apparent glucose disappearance from the small intestine were measured after infusing artificial digesta containing 0 (control), 3.0, or 6.0 g/L PHGG into the duodenum via a cannula under anesthesia in experiments 1 and 2. The diffusion of glucose in the artificial digesta was estimated using dialysis tubing, filled with the same artificial digesta, soaked in a buffer in experiment 3. In experiment 1, the plasma glucose concentration was lower in the digesta containing 3.0 and 6.0 g/L PHGG than in the control digesta at 120 minutes (P < .05). The plasma insulin concentration was lower for the digesta containing 6.0 g/L PHGG than for the control digesta at 60 minutes (P < .05) and lower for the digesta containing 6.0 g/L PHGG than for that containing 3.0 g/L PHGG at 120 minutes (P < .05).The area under the curve of plasma glucose and insulin (experiment 1), apparent disappearance of glucose in the lumen of the small intestine (experiment 2), and net disappearance of glucose in the dialysis tube depended negatively on the viscosity of the artificial digesta (P < .05, .05, .001, and .05), which was increased by adding PHGG. Therefore, PHGG can decrease the postprandial blood glucose by lowering the rate of absorption from the small intestine in the rat by reducing the diffusion of glucose in the lumen.     

Low-dose fish oil supplementation increases serum adiponectin without affecting inflammatory markers in overweight subjects

Obesity is associated with an increased risk of cardiovascular disease, whereas long-chain n-3 polyunsaturated fatty acids (PUFAs) from fish may have cardioprotective and anti-inflammatory effects. This study aimed to investigate the hypothesis that acute and short-term supplementation with a low dose of marine n-3 PUFA exerts an anti-inflammatory effect in overweight subjects. In a double-blind, placebo-controlled trial with 2 parallel groups, 50 overweight subjects were randomized to receive daily supplementation with 2 capsules containing either 2 g of fish oil (1.1 g marine n-3 PUFA) or 2 g of olive oil. Blood samples and adipose tissue biopsies were collected at baseline, after 1 day (acute effect), and after 6 weeks (short-term effect) of supplementation. No significant effects were seen after supplementation for 1 day, but after 6 weeks, subjects receiving fish oil had a significant increase in the n-3 PUFA content of granulocytes and adipose tissue (P < .01). Serum adiponectin levels were increased by 0.55 μg/mL (95% confidence interval, 0.02-1.08) in the fish oil group compared with the control group (P = .04) after 6 weeks of supplementation. Levels of interleukin 6 were inversely correlated to the marine n-3 PUFA content of granulocytes and adipose tissue at baseline (excluding α-linolenic acid). In conclusion, daily supplementation with 1.1 g of marine n-3 PUFA significantly increased serum adiponectin, but the effect was small, and no overall anti-inflammatory effect of the supplement could be demonstrated.     

Glucose and insulin do not decrease in a dose-dependent manner after increasing doses of mixed fibers that are consumed in muffins for breakfast

Conventional wisdom suggests that fiber consumption leads to lower postprandial glucose and insulin response. We hypothesized that increasing doses of mixed, viscous fiber would lower glucose and insulin levels in a dose-dependent manner. Healthy men (n = 10) and women (n = 10) with a body mass index of 24 ± 2 (mean ± SEM) participated in this double-blind, crossover study. On 4 separate visits, fasting subjects consumed an approximately 2093 kJ (500 calorie) muffin with 0, 4, 8, or 12 g of mixed fibers. Blood was drawn to measure glucose and insulin at regular intervals throughout a 3-hour test period. Area under the curve (AUC) glucose was significantly lower after 0 g of fiber than after 4, 8, or 12 g of fiber (arbitrary AUC units ± SEM: 25.3 ± 5.2 vs 44.6 ± 7.7, 49.7 ± 7.9, 51.5 ± 6.6, respectively; P < .006). Area under the curve glucose increased with increasing fiber doses (P for trend = .0003). Area under the curve insulin was higher after the 4-g dose than after the 0-, 8-, and 12-g doses (arbitrary AUC units ± SEM: 84.4 ± 8.0 vs 60.1 ± 6.5, 69.4 ± 8.7, 69.7 ± 8.5, respectively; P < .05); it did not change in a dose-dependent manner. Area under the curve glucose and AUC insulin did not correlate with each other. Glucose and insulin did not decrease in a dose-dependent manner after 0, 4, 8, and 12 g of mixed fibers were consumed in muffins for breakfast. The lack of differences was largely based on the individual variation in glucose response. Caution should be used when making general claims about the expected impact of fiber on glucose and insulin levels.     

Increases in peptide Y-Y levels following oat β-glucan ingestion are dose-dependent in overweight adults

Peptide Y-Y (PYY) is an anorexigenic hormone implicated in appetite control, and β-glucan is a fiber known to affect appetite. We hypothesized that plasma PYY levels would increase in overweight human adults consuming increasing doses of β-glucan. The objective was to test whether the effect could be seen with β-glucan delivered through extruded cereals containing a high β-glucan oat bran with demonstrated high molecular weight and solubility. Fourteen subjects consumed a control meal and 3 cereals of varying β-glucan concentration (between 2.2 and 5.5 g), and blood samples were collected over 4 hours. Analysis of raw PYY data showed a trend toward significant increases over 4 hours. An increasing dose of β-glucan resulted in higher levels of plasma PYY, with significant differences between groups from 2 to 4 hours post test-meal. Data for the area under the curve analysis also approached significance, with post hoc analysis showing a difference (P = .039) between the control and the highest dose of β-glucan (5.5 g). The PYY levels at 4 hours were significantly different between the control and high-dose meal test (P = .036). There was a significant dose response, with a positive correlation between the grams of β-glucan and PYY area under the curve (r² = 0.994, P = .003). The optimal dose of β-glucan appears to lie between 4 and 6 g, with the effects on PYY mediated by viscosity and concentration. Meal-test studies examining a range of hormones should measure hormones over a minimum of 4 hours and record meal intake for even longer time frames.     

Higher amounts of body fat are associated with inadequate intakes of calcium and vitamin D in African American women

Calcium and vitamin D are associated with obesity. We hypothesized that African American women with higher calcium and vitamin D intakes would have lower body fat compared with women with lower calcium and vitamin D intakes. This cross-sectional study included 100 premenopausal African American women aged 18 to 40 years with a spectrum of body mass indices (17.3-46.7 kg/m²). Dietary information was obtained using 24-h recalls. Total body fat was determined by dual-energy x-ray absorptiometry and reported as percentage body fat (%BF). Subjects' data were divided into 2 groups (n = 50 per group) based on the median quartile of %BF, and differences were determined using independent t tests. Women with at least 37.9%BF had mean calcium (mg per day ± SD) and vitamin D intakes (µg per day ± SD) of 528.6 ± 146.0 and 3.8 ± .9, respectively. In comparison, women with lower %BF (<37.9%) had higher (P < .001) calcium and vitamin D intakes of 911.5 ± 208.3 and 5.0 ± 0.8, respectively. Partial correlation coefficients (controlling for the confounding variables of fat, carbohydrate, and protein intakes) indicated significant (P < 0.001) inverse associations between calcium intake and %BF (r = −.666), and vitamin D and %BF (r = −.460) in the 100 women. In conclusion, women with lower intakes of calcium and vitamin D were more likely to exhibit excessive adiposity compared with women with higher intakes.     

An acute intake of a walnut-enriched meal improves postprandial adiponectin response in healthy young adults

A deficit in adiponectin plays an important causal role in insulin resistance and metabolic syndrome. We hypothesized that as seen during the fasting state, the intake of a walnut-enriched meal increased postprandial adiponectin. Twenty-one healthy white men followed a 4-week baseline diet and then consumed 3 fat-loaded meals that included 1 g fat/kg body weight (65% fat) according to a randomized crossover design: olive oil–enriched meal (22% saturated fatty acids [SFA], 38% monounsaturated fatty acids [MUFA], 4% polyunsaturated fatty acids [PUFA]), butter-enriched meal (35% SFA, 22% MUFA, 4% PUFA), and walnut-enriched meal (20% SFA, 24% MUFA, 16% PUFA, and 4% α-linolenic acid). Leptin, resistin, adiponectin, and free fatty acids were determined at 0, 3, 6, and 8.5 hours after the fat load. After the walnut-enriched meal, plasma adiponectin concentrations were higher at 3 and 6 hours (P = .011, P = .046, respectively) compared with the butter-enriched meal and higher at 6 hours compared with the olive oil–enriched meal (P = .036). Free fatty acid levels decreased from baseline at 3 hours after the walnut-enriched meal (P = .001). No differences were observed between the 3 meals for leptin and resistin responses. Our data confirmed a beneficial profile in the postprandial response to walnuts, source of omega-3 PUFA with an increased postprandial adiponectin and lower postprandial free fatty acid responses. These findings suggest that the postprandial state is important for understanding the possible cardioprotective effects associated with omega-3 PUFA dietary fat.