Carbohydrate intake and biomarkers of glycemic control among US adults: the third National Health and Nutrition Examination Survey (NHANES III)

Orthodontic Treatment as a Protective Factor for Dental Caries Experience and Severity: A Population-Based Study

Objective

The aim of this study was to assess the effects of orthodontic treatment on the experience, prevalence, and severity of dental caries later in life in a representative sample of U.S. adults.

Methods

Using a population-based study design, data from 9,486 participants in the third National Health and Nutrition Survey (NHANES), including self-reported information on the history of orthodontic treatment and its timing, were obtained. Caries experience and prevalence was assessed using the decayed (DT) and filled (FT) teeth indices (i.e., DT > 0, FT > 0, and their aggregate DFT > 0). Severe dental caries experience and prevalence was defined as DT > 2, FT > 11, and DFT > 12. Unadjusted and adjusted logistic regression models that accounted for the complex sampling design were used to assess the association between orthodontic treatment and dental caries experience, prevalence, and severity. Statistical significance was set at a P value of less than 0.05.

Results

The history of orthodontic treatment was reported in 19.62% of the adults. Around 94% of participants had at least one decayed or filled tooth (DFT > 0), and 21.09% met the aggregate DFT criterion for severe caries (DFT > 12). After controlling for confounding variables, a reported history of orthodontic treatment was found to significantly decrease the odds of DT > 0, DT > 2, FT > 11, and DFT > 12 (odds ratios (OR) = 0.41, 0.36, 0.74, and 0.60, respectively).

Conclusion

A history of orthodontic treatment was a protective factor for untreated dental caries, in assessments of the severity and prevalence of dental caries experience.

Nutrition transition in 2 lowland Bolivian subsistence populations

Background

Traditional diets are often credited for the robust cardiometabolic health of subsistence populations. Yet, rural subsistence populations are undergoing nutrition transitions that have been linked to the increase in chronic noncommunicable diseases. Few studies have presented detailed dietary estimates in transitioning populations.

Objectives

We aimed to 1) characterize and compare dietary profiles of 2 neighboring subsistence populations in Bolivia who vary in market integration and 2) identify dietary factors contributing to low cardiovascular disease risk.

Design

We used a mixed longitudinal design to estimate nutrient intake via 24-h recall and dietary questionnaires among 1299 Tsimane (aged 30-91 y) and 229 Moseten (aged 30-84 y) men and women. We constructed population-level estimates of energy intake, dietary diversity, and nutrient shortfalls and analyzed dietary changes over time and space using multilevel models. Last, we compared Tsimane and Moseten dietary profiles with those of Americans (NHANES).

Results

The Tsimane diet was characterized by high energy (2422-2736 kcal/d), carbohydrate (376-423 g/d), and protein (119-139 g/d) intakes; low fat intake (40-46 g/d); and low dietary diversity relative to the average US diet. Most calories (64%) were derived from complex carbohydrates. Total energy and carbohydrate intake increased significantly during the 5-y study, particularly in villages near market towns. Tsimane consumption of food additives (lard, oil, sugar, salt) increased significantly [sugar (15.8 g ⋅ person-1 ⋅ d-1) and oil (4.9 mL ⋅ person-1 ⋅ d-1)] between 2010 and 2015. The more-acculturated Moseten consumed substantially more sugar (by 343%) and oil (by 535%) than the Tsimane.

Conclusions

A high-energy diet rich in complex carbohydrates is associated with low cardiovascular disease risk when coupled with a physically active lifestyle. A transition away from a high-fiber and low-fat, low-salt, and low-processed-sugar diet is a salient health risk for transitioning populations. Evidence of a nutrition transition in Bolivia parallels trends of increasing body fat and body mass index, which suggests that a low prevalence of cardiovascular disease may not persist.

Added sugars and periodontal disease in young adults: an analysis of NHANES III data

BACKGROUND

Added sugar consumption seems to trigger a hyperinflammatory state and may result in visceral adiposity, dyslipidemia, and insulin resistance. These conditions are risk factors for periodontal disease. However, the role of sugar intake in the cause of periodontal disease has not been adequately studied.

OBJECTIVE

We evaluated the association between the frequency of added sugar consumption and periodontal disease in young adults by using NHANES III data.

DESIGN

Data from 2437 young adults (aged 18-25 y) who participated in NHANES III (1988-1994) were analyzed. We estimated the frequency of added sugar consumption by using food-frequency questionnaire responses. We considered periodontal disease to be present in teeth with bleeding on probing and a probing depth ≥3 mm at one or more sites. We evaluated this outcome as a discrete variable in Poisson regression models and as a categorical variable in multinomial logistic regression models adjusted for sex, age, race-ethnicity, education, poverty-income ratio, tobacco exposure, previous diagnosis of diabetes, and body mass index.

RESULTS

A high consumption of added sugars was associated with a greater prevalence of periodontal disease in middle [prevalence ratio (PR): 1.39; 95% CI: 1.02, 1.89] and upper (PR: 1.42; 95% CI: 1.08, 1.85) tertiles of consumption in the adjusted Poisson regression model. The upper tertile of added sugar intake was associated with periodontal disease in ≥2 teeth (PR: 1.73; 95% CI: 1.19, 2.52) but not with periodontal disease in only one tooth (PR: 0.85; 95% CI: 0.54, 1.34) in the adjusted multinomial logistic regression model.

CONCLUSION

A high frequency of consumption of added sugars is associated with periodontal disease, independent of traditional risk factors, suggesting that this consumption pattern may contribute to the systemic inflammation observed in periodontal disease and associated noncommunicable diseases.

Species incompatibilities in the pig-to-macaque islet xenotransplant model affect transplant outcome: a comparison with allotransplantation

BACKGROUND

Porcine islet transplantation into diabetic non-human primates is considered most relevant in translational research supporting a clinical application. Most studies have focused on immunosuppressive protocols, while metabolic aspects have mainly been utilized in graft monitoring. We evaluated data from our group regarding human and non-human primate (NHP) allotransplantation and pig-to-NHP xenotransplantation to identify incompatibilities in metabolic factors and their consequences for transplant outcomes.

METHODS

Basic gluco-metabolic parameters (fasting blood glucose, C-peptide, and response to stimulation with arginine or glucose) were derived from literature (humans), 72 macaques, and 47 adult Landrace pigs. Islet preparations from 15 human deceased donors, 61 macaques, and 23 adult pigs were compared with respect to yield, fractional viability assessed by oxygen consumption normalized for DNA, and in vitro glucose-induced insulin release. Metabolic parameters at day 75 after a single islet transplantation in the liver were compared for 19 patients and 9 macaques receiving an allotransplant and 11 macaques receiving a porcine xenotransplant: recipients received chronic immunosuppression.

RESULTS

Pigs differ from NHPs and humans by a much lower C-peptide level (0.42 vs. 1.3 to 2.0 ng/ml, respectively) and a 2- to 7-fold lower C-peptide response to arginine stimulation. In contrast, NHPs have the highest metabolic demand as evidenced by a high C-peptide and high C-peptide response to arginine stimulation; values are about twice higher than in humans. For manufactured islet preparations, these differences are reflected by glucose-stimulated insulin release (the stimulation index for pigs is 1.5, for humans 3.8, and for macaques 7.7), but not by fractional viability, which was in the same range. The day 75 outcome after transplantation assessed by C-peptide was similar for allotransplanted humans and NHPs (80 to 90% good graft function) and lower in xenografted NHPs (36% good graft function); gluco-metabolic parameters were in accordance with graft function, albeit different between species because normoglycemia under exogenous insulin is maintained more aggressively in patients than in NHPs. In xenografted NHPs, the shift in glycemic control with respect to normal values, combined with low values of circulating porcine C-peptide, resembled more the normal condition in a pig than that in a macaque.

CONCLUSIONS

The substantially lower glucose-induced insulin response in adult porcine islet preparations as opposed to islets manufactured from humans or macaques combined with the much higher need for insulin in macaques than in humans creates an imbalance between the metabolic demand and the engrafted islet mass in the pig-to-NHP xenograft recipient. Engrafted islet mass is affected by dose, suggesting that a much higher dose level of islets is necessary in the xenogeneic setting than in human or NHP allotransplantation, and pig islets need to be given at a higher dose in macaques than the anticipated effective dose in humans. To cope with differences in metabolic demand and presumably also metabolic dynamics, a liberal regime in supportive exogenous insulin might be essential to achieve long-term survival. These intrinsic characteristics of the NHP model deserve consideration to optimally design experimental studies with the perspective of translational value of results.

Multifunctional food: medical evidence and methodological notes on substantiating health claims

In nutritional research, a specific issue is about understanding how to provide a clear and solid proof of the health effects of each functional food. The problems range from regulatory perspectives down to very basic methodological issues. In addition, when multi-functionality comes into play, then several additional problems are posed in terms of the methodological appropriateness of research done. In this review, a focus is provided on some methodological issues related to (i) the general concepts of 'proving' effects in a methodological perspective and (ii) the difficulties of specifically proving functional effects of food. A specific attention is dedicated on the characteristic problems which, from a methodological perspective, arise when multi-functionality is the matter of the proof.

A meat, processed meat, and French fries dietary pattern is associated with high allostatic load in Puerto Rican older adults

BACKGROUND

Consumption of certain dietary patterns, such as a Western diet, has been associated with unfavorable physiologic outcomes. Diet has been proposed as a contributor to allostatic load, a composite measure of physiological dysregulation.

OBJECTIVE

To determine the association of dietary patterns, defined by "meat and french fries," "traditional Puerto Rican foods" (rice, beans, and oils), or "sweets," with allostatic load, and with the 10 individual physiologic parameters that comprise it.

PARTICIPANTS

Baseline data collected from participants of the Boston Puerto Rican Health Study (n=1,117; aged 45 to 75 years) was used to run linear and logistic regression models, adjusting for age, sex, alcohol intake, smoking, medications, energy intake, and body mass index or physical activity.

RESULTS

Significant trends across increasing quintiles of the meat and french fries pattern were observed for higher allostatic load score (P=0.002), waist circumference (P=0.032), systolic blood pressure (P=0.008), and diastolic blood pressure (P<0.0001). Participants in the highest quintile of the meat and french fries pattern had significantly higher allostatic load score than those in the lowest quintile (mean 4.3±0.11 vs 3.9±0.12, P=0.030), and had higher odds of having high allostatic load (odds ratio [95% confidence interval]: 1.8 [1.2 to 2.9]), low dehydroepiandrosterone sulfate (odds ratio 1.9 [95% confidence interval: 1.2 to 3.1]), and high glycosylated hemoglobin (odds ratio 1.7 (95% confidence interval: 1.0 to 2.9]). The traditional pattern was not associated with allostatic load, whereas a significant association between the sweets pattern and allostatic load disappeared after restricting analysis to participants without diabetes.

CONCLUSIONS

A meat, processed meat, and french fries dietary pattern may contribute to the deregulation of multiple physiologic parameters in Puerto Rican adults. Efforts to limit consumption of this pattern may help prevent further cumulative physiological dysregulation in this high risk population.

Differential contribution of dietary fat and monosaccharide to metabolic syndrome in the common marmoset (Callithrix jacchus)

There is a critical need for animal models to study aspects type 2 diabetes (T2D) pathogenesis and prevention. While the rhesus macaque is such an established model, the common marmoset has added benefits including reduced zoonotic risks, shorter life span, and a predisposition to birth twins demonstrating chimerism. The marmoset as a model organism for the study of metabolic syndrome has not been fully evaluated. Marmosets fed high-fat or glucose-enriched diets were followed longitudinally to observe effects on morphometric and metabolic measures. Effects on pancreatic histomorphometry and vascular pathology were examined terminally. The glucose-enriched diet group developed an obese phenotype and a prolonged hyperglycemic state evidenced by a rapid and persistent increase in mean glycosylated hemoglobin (HgbA1c) observed as early as week 16. In contrast, marmosets fed a high-fat diet did not maintain an obese phenotype and demonstrated a delayed increase in HgbA1) that did not reach statistical significance until week 40. Consumption of either diet resulted in profound pancreatic islet hyperplasia suggesting a compensation for increased insulin requirements. Although the high-fat diet group developed atherosclerosis of increased severity, the presence of lesions correlated with glucose intolerance only in the glucose-enriched diet group. The altered timing of glucose dysregulation, differential contribution to obesity, and variation in vascular pathology suggests mechanisms of effect specific to dietary nutrient content. Feeding nutritionally modified diets to common marmosets recapitulates aspects of metabolic disease and represents a model that may prove instrumental to elucidating the contribution of nutrient excess to disease development.

Nutritional profiles in a public health perspective: a critical review

Nutritional profiling is defined as 'the science of categorizing foods according to their nutritional composition' and it is useful for food labelling and regulation of health claims. The evidence for the link between nutrients and health outcomes was reviewed. A reduced salt intake reduces blood pressure, but only a few randomized controlled trials have verified the effect of salt on overall and cardiovascular mortality. Evidence linking a reduced fat intake with cardiovascular mortality and obesity is generally non-significant. Studies that have examined the relationship between obesity and diet have produced contrasting results. A simulation exercise that demonstrated that the impact of a reduced salt and fat intake on overall mortality would be negligible in the European population was carried out. Consideration of the literature and the results of this simulation exercise suggest that the introduction of nutritional profiles in Europe would be expected to have a very limited impact on health outcomes.

Nutritional composition of the diets of South Asian, black African-Caribbean and white European children in the United Kingdom: the Child Heart and Health Study in England (CHASE)

In the UK, South Asian adults have increased risks of CHD, type 2 diabetes and central obesity. Black African-Caribbeans, in contrast, have increased risks of type 2 diabetes and general obesity but lower CHD risk. There is growing evidence that these risk differences emerge in early life and that nutritional factors may be important. We have therefore examined the variations in nutritional composition of the diets of South Asian, black African-Caribbean and white European children, using 24 h recalls of dietary intake collected during a cross-sectional survey of cardiovascular health in eighty-five primary schools in London, Birmingham and Leicester. In all, 2209 children aged 9-10 years took part, including 558 of South Asian, 560 of black African-Caribbean and 543 of white European ethnicity. Compared with white Europeans, South Asian children reported higher mean total energy intake; their intakes of total fat, polyunsaturated fat and protein (both absolute and as proportions of total energy intake) were higher and their intakes of carbohydrate as a proportion of energy (particularly sugars), vitamin C and D, Ca and haem Fe were lower. These differences were especially marked for Bangladeshi children. Black African-Caribbean children had lower intakes of total and saturated fat (both absolute and as proportions of energy intake), NSP, vitamin D and Ca. The lower total and saturated fat intakes were particularly marked among black African children. Appreciable ethnic differences exist in the nutritional composition of children's diets, which may contribute to future differences in chronic disease risk.

Small Rice Bowl-Based Meal Plan versus Food Exchange-Based Meal Plan for Weight, Glucose and Lipid Control in Obese Type 2 Diabetic Patients

Background

The Korean National Health and Nutrition Examination Surveys reported 65% of daily energy intake (EI) as carbohydrate (CHO) in the Korean population and main source of CHO was cooked rice. We used a standardized-small sized rice bowl for diet education and investigated its effectiveness on body weight, glucose and lipid, compared to the conventional food exchange system in type 2 diabetes obese women.

Methods

Type 2 diabetic women with body mass index ≥ 23 kg/m² were randomly assigned to small rice bowl-based meal plan (BM) and food exchange-based meal plan (ExM) group. Both groups were asked to reduce their EI by 500 kcal/day for 12 weeks. The macronutrient composition was instructed: 55 to 60% of EI as CHO, 15 to 20% as protein, and 20 to 25% as fat. BM group received only a simple instruction for application of the rice bowl. Nutrient intake was estimated with the 3-day dietary records.

Results

Finally, 44 subjects finished the study. The percent reduction of body weight was significant both BM group (-5.1 ± 2.6%) and ExM group (-4.8 ± 2.8%) after 12 weeks (P < 0.001) but there was no difference between the groups. There was no difference in the proportional change of CHO, protein and fat in EI between the groups. Additionally, the change of HbA1c and low density lipoprotein-cholesterol were not significantly different between the two groups.

Conclusion

The BM group was as effective as ExM for body weight and glucose control in type 2 diabetes obese women.

Dietary patterns and metabolic syndrome factors in a non-diabetic Italian population

Objective

To examine the relationship between dietary patterns and metabolic syndrome.

Design

Population-based cross-sectional study. The K-means clustering method was used to identify dietary patterns and logistic regression models were used to compare the adjusted prevalence rates of metabolic syndrome factors, stratifying by obesity status.

Setting

The 1992–3 Italian Bollate Eye Study, a population-based survey carried out in the town of Bollate (Milan), Italy.

Subjects

A total of 1052 non-diabetic Italian subjects, 527 men and 525 women, aged 42–74 years.

Results

Five dietary clusters were identified: common, animal products, starch, vegetal/fat and vitamin/fibre. After adjusting for potential confounders, the starch group showed the highest prevalence of metabolic syndrome (36 %) followed by the animal products group (30 %); the vitamin/fibre (20 %) and vegetal/fat groups (19 %) showed the lowest prevalence. The starch group had more dyslipidaemia (higher TAG and lower HDL cholesterol levels) and the animal products group had a higher prevalence of impaired fasting glucose. The vitamin/fibre group had the lowest prevalence of abdominal obesity. The beneficial effect of the vegetal/fat and vitamin/fibre dietary patterns seemed stronger among the obese.

Conclusions

Our results confirm the deleterious effect of a very-low-fat, high-carbohydrate diet and also of high intakes of animal products. The consumption of a diet high in vegetal fats or rich in fruits and vegetables is associated with a healthier metabolic profile. Reducing obesity is essential to prevent metabolic syndrome, but even among the obese dietary habits are important for preserving healthy lipid and glycaemic profiles.

Comparison of time course changes in blood glucose, insulin and lipids between high carbohydrate and high fat meals in healthy young women

Few studies have examined short term responses to the different contents of carbohydrate or fat in the meal, although long term effects of the high fat meal have been considered as compound risk factor for metabolic disorders. The aim of this study was to investigate the postprandial changes of plasma glucose, insulin and lipids upon intakes of high carbohydrate or high fat meal in young healthy women. Subjects were randomly assigned to either the high carbohydrate meal (HCM, 75% carbohydrate, n=13) or the high fat meal (HFM, 60% fat, n=12) groups. The meals were prepared as isocaloric typical Korean menu. Blood samples were obtained prior to and 30, 60, 90, 120, 180 and 240 minute after the meal. There were no significant differences on fasting blood parameters including glucose, insulin, lipids concentrations between the groups prior to the test. The HCM had higher blood glucose and insulin concentrations, reached the peak at 30 min and maintained for 240 min compared to the HFM (P<0.05). The HFM had higher plasma triglyceride (TG) and free fatty acid (FFA) concentrations, reached the peak at 120 min and maintained for 240 min compared to the HCM (P<0.05). It is concluded that macronutrients content in the meal may be an important determinant of postprandial substrate utilization in healthy women.

Determining the relationship between dietary carbohydrate intake and insulin resistance

Insulin resistance underlies type 2 diabetes, CVD and the metabolic syndrome, driven by changes in diet, lifestyle, energy over–consumption and obesity. Nutritional recommendations for insulin resistance remain an area of controversy, particularly the quantity and types of dietary carbohydrate. The present review gives an overview of insulin resistance, its relationship to impaired insulin secretion and the metabolic syndrome, research methodologies used to measure insulin action and the epidemiological and intervention studies on the relationship between dietary carbohydrate and insulin resistance. Epidemiological studies provide little evidence to suggest that total dietary carbohydrate predicts risk of type 2 diabetes, and high–carbohydrate, high–fibre diets with low–glycaemic index (GI) may even contribute to diabetes prevention. Despite inherent limitations associated with techniques used to measure insulin resistance and dietary assessment, most intervention studies reveal an increase in glucose tolerance or insulin sensitivity with high–carbohydrate, low–fat diets in non–diabetic and diabetic individuals. When energy is restricted the source or reduced content of carbohydrate does not appear to be as important as fat for body weight. Thus, low energy intake is key to weight loss and augmentation of insulin sensitivity. Given this, widespread adoption of popular low–carbohydrate high–fat diets highlights the necessity to evaluate dietary interventions regarding safety and metabolic effects. While current evidence supports FAO/WHO recommendations to maintain a high–carbohydrate diet with low–GI foods, the relationships between carbohydrate and insulin sensitivity remains an important research area. Emerging technologies should further enhance understanding of gene–diet interactions in insulin resistance, providing useful information for future nutrition policy decisions.

Association of diet-induced hyperinsulinemia with accelerated growth of prostate cancer (LNCaP) xenografts

BACKGROUND

Prior research suggested that energy balance and fat intake influence prostate cancer progression, but the influence of dietary carbohydrate on prostate cancer progression has not been well characterized. We hypothesized that hyperinsulinemia resulting from high intake of refined carbohydrates would lead to more rapid growth of tumors in the murine LNCaP xenograft model of prostate cancer.

METHODS

Athymic mice were injected subcutaneously with LNCaP human prostate cancer cells and, when tumors were palpable, were randomly assigned (n = 20 per group) to high carbohydrate-high fat or low carbohydrate-high fat diets. Body weight and tumor volume were measured weekly. After 9 weeks, serum levels of insulin and insulin-like growth factor 1 (IGF-1) were measured by enzyme immunoassay. AKT activation and the levels of the insulin receptor in tumor cells were determined by immunoblotting. The in vitro growth response of LNCaP cells to serum from mice in the two treatment groups was measured based on tetrazolium compound reduction. All statistical tests were two-sided.

RESULTS

After 9 weeks on the experimental diets, mice on the high carbohydrate-high fat diet were heavier (mean body weight of mice on the high carbohydrate-high fat diet = 34 g versus 29.1 g on the low carbohydrate-high fat diet, difference = 4.9 g, 95% CI = 3.8 to 6.0 g; P = .003), experienced increased tumor growth (mean tumor volume in mice on high carbohydrate-high fat diet = 1695 versus 980 mm3 on low carbohydrate-high fat diet, difference = 715 mm3, 95% CI = 608 to 822 mm3; P<.001), and experienced a statistically significant increase in serum insulin and IGF-1 levels. Tumors from mice on the high carbohydrate-high fat diet had higher levels of activated AKT and modestly higher insulin receptor levels than tumors from mice on the low carbohydrate-high fat diet. Serum from mice on the high carbohydrate-high fat diet was more mitogenic for LNCaP cells in vitro than serum from mice fed the low carbohydrate-high fat diet.

CONCLUSION

A diet high in refined carbohydrates is associated with increased tumor growth and with activation of signaling pathways distal to the insulin receptor in a murine model of prostate cancer.

Carbohydrate quantity and quality in relation to body mass index

The increased prevalence of overweight and obesity in the United States since approximately 1980 is temporally associated with an increase in carbohydrate intake, with no appreciable change in absolute intake of fat. Despite speculation that both carbohydrate quantity and quality have contributed significantly to excess weight gain, the relationship between carbohydrate intake and body mass index (BMI) is controversial. A review of relevant literature indicates that most epidemiologic studies show an inverse relationship between carbohydrate intake and BMI, even when controlling for potential confounders. These observational studies are supported by results from a number of dietary intervention studies wherein modest reductions in body weight were observed with an ad libitum, low-fat, high-carbohydrate diet without emphasis on energy restriction or weight loss. With few exceptions, high glycemic load is associated with lower BMI, even when adjusted for total energy intake. Data on the association between glycemic index and BMI are not as consistent, with more studies showing either no association or an inverse relationship, rather than a positive relationship. Whole-grain intake is generally inversely associated with BMI; refined grain intake is not. Because overall dietary quality tends to be higher for high-carbohydrate diets, a low-fat dietary strategy with emphasis on fiber-rich carbohydrates, particularly cereal fiber, may be beneficial for health and weight control.

Lack of findings for the association between obesity risk and usual sugar-sweetened beverage consumption in adults – A primary analysis of databases of CSFII-1989–1991, CSFII-1994–1998, NHANES III, and combined NHANES 1999–2002

The relationship between obesity risk and sugar-sweetened beverage (SSB) consumption was examined together with multiple lifestyle factors. Statistical analysis was performed using population dietary survey databases of USDA CSFII 1989-1991, CSFII 1994-1996, CDC NHANES III, and combined NHANES 1999-2002. Totally, 38,409 individuals, ages 20-74 years, with accompanying data of dietary intake, lifestyle factors, and anthropometrics were included in the descriptive statistics and risk analysis. Analytical results indicate that obesity risk was significantly and positively associated with gender, age, daily TV/screen watching hours and dietary fat content, and negatively associated with smoking habit, education and physical activity; obesity risk was not significantly associated with SSB consumption pattern, dietary saturated fat content and total calorie intake. No elevated BMI values or increased obesity rates were observed in populations frequently consuming SSB compared to populations infrequently consuming SSB. Additionally, one-day food consumption data was found to overestimate SSB usual intake by up to 38.9% compared to the data of multiple survey days.

CONCLUSION

multiple lifestyle factors and higher dietary fat intake were significantly associated with obesity risk. Populations who frequently consumed SSB, primarily HFCS sweetened beverages, did not have a higher obesity rate or increased obesity risk than that of populations which consumed SSB infrequently.

Comparison of 11 human insulin assays: implications for clinical investigation and research

BACKGROUND

The American Diabetes Association task force on standardization of insulin assays in 1996 showed wide variation in assay bias. Newer assays are specific for insulin, with several now available on automated immunoassay analyzers.

METHODS

In 2004, we compared 11 commercially available insulin assays by analyzing 150 serum samples (99 fasting/51 postprandial) from study participants with various degrees of glucose intolerance (exclusions being type 1 diabetes, insulin treatment, or presence of insulin antibodies). All assays were calibrated against International Reference Preparation 66/304. One assay was not specific for insulin and another was an RIA; 10 assays used enzyme/chemiluminescent labels. Bland-Altman difference plots were modified to use the mean insulin from all assays on the x-axis as a common comparator.

RESULTS

As in the 1996 study, insulin values from the different assays varied by a factor of 2, with the nonspecific assay ranking in the middle of the distribution. Spearman rank correlation coefficients, for ranking samples vs the mean, were 0.983-0.997. Both offsets and concentration-dependent differences were seen in the modified difference plots. Imprecision (mean CV) for automated assays (3%) was not significantly different from manual assays (5%). Similar values were obtained when one automated assay was run in laboratories in both the UK and the US. Results of 1 assay showed lower insulin concentrations in heparinized plasma than in serum.

CONCLUSIONS

Assay performance must be considered before comparing insulin results. The 2-fold variation in insulin results may be related to specificity, manufacturers' calibration procedures or conversion factors.

Cognitive performance is associated with macronutrient intake in healthy young and middle-aged adults

PRIMARY OBJECTIVE

The objective was to examine whether dietary intakes of macronutrients are associated with neuropsychological performance.

RESEARCH DESIGN AND METHOD

Study participants were 3960 adults aged 20-59 years, who completed three neuropsychological tests and a 24-hour dietary recall as a part of the Third National Health and Nutrition Examination Survey, 1988-1994. Poor performance was defined as the test score below gender-specific 15th percentile.

MAIN OUTCOMES AND RESULTS

While holding the energy percentages from different macronutrients, additional 100 kcal intake of energy was associated with a reduced odds of poor performance on serial digital learning test (OR = 0.98, 95% CI = 0.96, 0.99) and symbol digital substitution test (OR = 0.97, 95% CI = 0.96, 0.99). Compared with equivalent energy from carbohydrates, each 5% of energy from poly-unsaturated fatty acids (PUFA) or total fat was associated with a reduced OR of poor performance on simple reaction time test (PUFA: OR = 0.77, 95% CI = 0.63-0.95 and total fat: OR = 0.93, 95% CI = 0.87, 0.99). Poor global cognition was associated with an additional intake of 100 mg cholesterol (OR = 1.14, 95% CI = 1.05, 1.23). These associations were more salient in men.

CONCLUSION

Habitual intake of macronutrients is weakly but significantly associated with cognitive functioning. These relationships are more evident in men.

The role of nutrition therapy and dietitians in the management of the metabolic syndrome

Nutrition therapy interventions for the metabolic syndrome include weight reduction or maintenance, physical activity, whole grains and fiber, and type and amount of food fats. Interventions related to carbohydrate--amount and type--and alcohol are controversial. The role of the dietitian is to assist persons with the metabolic syndrome to make lifestyle changes that modify the factors that increase risk of diabetes and cardiovascular disease.

Low-carbohydrate-high-protein diet and long-term survival in a general population cohort

OBJECTIVE

We have evaluated the effects on mortality of habitual low carbohydrate-high-protein diets that are thought to contribute to weight control.

DESIGN

Cohort investigation.

SETTING

Adult Greek population. SUBJECTS METHODS: Follow-up was performed from 1993 to 2003 in the context of the Greek component of the European Prospective Investigation into Cancer and nutrition. Participants were 22 944 healthy adults, whose diet was assessed through a validated questionnaire. Participants were distributed by increasing deciles according to protein intake or carbohydrate intake, as well as by an additive score generated by increasing decile intake of protein and decreasing decile intake of carbohydrates. Proportional hazards regression was used to assess the relation between high protein, high carbohydrate and the low carbohydrate-high protein score on the one hand and mortality on the other.

RESULTS

During 113 230 persons years of follow-up, there were 455 deaths. In models with energy adjustment, higher intake of carbohydrates was associated with significant reduction of total mortality, whereas higher intake of protein was associated with nonsignificant increase of total mortality (per decile, mortality ratios 0.94 with 95% CI 0.89 -0.99, and 1.02 with 95% CI 0.98 -1.07 respectively). Even more predictive of higher mortality were high values of the additive low carbohydrate-high protein score (per 5 units, mortality ratio 1.22 with 95% CI 1.09 -to 1.36). Positive associations of this score were noted with respect to both cardiovascular and cancer mortality.

CONCLUSION

Prolonged consumption of diets low in carbohydrates and high in protein is associated with an increase in total mortality.

Dietary glycemic index and glycemic load, carbohydrate and fiber intake, and measures of insulin sensitivity, secretion, and adiposity in the Insulin Resistance Atherosclerosis Study

OBJECTIVE

We studied the association of digestible carbohydrates, fiber intake, glycemic index, and glycemic load with insulin sensitivity (S(I)), fasting insulin, acute insulin response (AIR), disposition index, BMI, and waist circumference.

RESEARCH DESIGN AND METHODS

Data on 979 adults with normal (67%) and impaired (33%) glucose tolerance from the Insulin Resistance Atherosclerosis Study (1992-1994) were analyzed. Usual dietary intake was assessed via a 114-item interviewer-administered food frequency questionnaire from which nutrient intakes were estimated. Published glycemic index values were assigned to food items and average dietary glycemic index and glycemic load calculated per subject. S(I) and AIR were determined by frequently sampled intravenous glucose tolerance test. Disposition index was calculated by multiplying S(I) with AIR. Multiple linear regression modeling was employed.

RESULTS

No association was observed between glycemic index and S(I), fasting insulin, AIR, disposition index, BMI, or waist circumference after adjustment for demographic characteristics or family history of diabetes, energy expenditure, and smoking. Associations observed for digestible carbohydrates and glycemic load, respectively, with S(I), insulin secretion, and adiposity (adjusted for demographics and main confounders) were entirely explained by energy intake. In contrast, fiber was associated positively with S(I) and disposition index and inversely with fasting insulin, BMI, and waist circumference but not with AIR.

CONCLUSION

Carbohydrates as reflected in glycemic index and glycemic load may not be related to measures of insulin sensitivity, insulin secretion, and adiposity. Fiber intake may not only have beneficial effects on insulin sensitivity and adiposity, but also on pancreatic functionality.

The optimal diet for women with polycystic ovary syndrome?

An optimal diet is one that not only prevents nutrient deficiencies by providing sufficient nutrients and energy for human growth and reproduction, but that also promotes health and longevity and reduces the risk of diet-related chronic diseases. The composition of the optimal diet for women with polycystic ovary syndrome (PCOS) is not yet known, but such a diet must not only assist short term with weight management, symptoms and fertility, but also specifically target the long-term risks of type 2 diabetes, CVD and certain cancers. With insulin resistance and compensatory hyperinsulinaemia now recognised as a key factor in the pathogenesis of PCOS, it has become clear that reducing insulin levels and improving insulin sensitivity are an essential part of management. Diet plays a significant role in the regulation of blood glucose and insulin levels, yet research into the dietary management of PCOS is lacking and most studies have focused on energy restriction rather than dietary composition per se. On the balance of evidence to date, a diet low in saturated fat and high in fibre from predominantly low-glycaemic-index-carbohydrate foods is recommended. Because PCOS carries significant metabolic risks, more research is clearly needed.

Atypically high insulin responses to some foods relate to sugars and satiety

Much research has focused on how the glycemic index (GI) of the diets of healthy people relates to long-term risk for coronary heart disease, stroke, and non-insulin dependent diabetes. Low-GI diets appear to produce some of their beneficial effects largely by moderating insulinemic responses to meals. Wolever and Bolognesi (1996) have derived a formula for predicting the insulinemic index (II) from the GI for starchy foods. Using data from Holt et al. (1995, 1997) on a wide variety of common foods, we have examined differences between the observed II and GI-based estimates of the II. These differences were found to correlate negatively with satiety index ratings and positively with contents of total sugars. We suggest that the aforementioned method of measuring and expressing the relation between the GI and the II may prove useful in exploring how various components and sensory properties of food may affect hunger and energy intake.

Nutrition in patients with Type 2 diabetes: are low-carbohydrate diets effective, safe or desirable?

Low-carbohydrate diets have been around for over 100 years. They have become very popular recently but the scientific basis for their use remains to be fully established. This article reviews the recent trials that have been published and also what is known about the effects of low-carbohydrate, high-protein diets on energy expenditure and body composition. Although many controversies remain, there is now mounting evidence that these diets can lead to effective weight loss and may thus be a useful intervention for patients who have, or are at risk of, diabetes. The practical aspects of using these diets as a short- to medium-term intervention are discussed.

Diet composition and the risk of type 2 diabetes: epidemiological and clinical evidence

In the last 10 years nutritional research on diabetes has improved dramatically in terms of both number of studies produced and quality of methodologies employed. Therefore, it is now possible to attempt to provide the evidence on which nutritional recommendations for the prevention of type 2 diabetes could be based. We therefore performed a literature search and, among the papers published in indexed journals, we selected relevant epidemiological (mostly prospective) and controlled intervention studies. Lifestyle factors that have, so far, been consistently associated with increased risk of type 2 diabetes are overweight and physical inactivity. However, recent evidence from epidemiological studies has shown that the risk of type 2 diabetes is also associated with diet composition, particularly with: (1) low fibre intake; (2) a high trans fatty acid intake and a low unsaturated:saturated fat intake ratio; (3) absence of or excess alcohol consumption. All these factors are extremely common in Western populations and therefore the potential impact of any intervention on them is large: indeed, >90 % of the general population has one or more of these risk factors. The ability to correct these behaviours in the population is estimated to reduce the incidence of diabetes by as much as 87 %. Recent intervention studies have shown that type 2 diabetes can be prevented by lifestyle changes aimed at body-weight reduction, increased physical activity and multiple changes in the composition of the diet. Within this context, the average amount of weight loss needed is not large, about 5 % initial weight, which is much less than the weight loss traditionally considered to be clinically significant for prevention of type 2 diabetes. In conclusion, new emphasis on prevention by multiple lifestyle modifications, including moderate changes in the composition of the habitual diet, might limit the dramatic increase in incidence of type 2 diabetes envisaged worldwide.

Diet but not aerobic exercise training reduces skeletal muscle TNF-alpha in overweight humans

AIMS/HYPOTHESIS

Our aim was to test the hypothesis that TNF-alpha protein levels in skeletal muscle are important in mediating the improvements in glucose homeostasis that are associated with diet and exercise regimens intended to reduce cardiovascular risk.

METHODS

We recruited 20 people with a body mass index of 32.1 +/- 1.2 kg/m2 (mean +/- SEM) and one other component of the metabolic syndrome. The average age was 51.2 +/- 8.1 years (mean +/- SD). Of the 20 subjects, 6 were men and 14 were women. All subjects completed an 8-week control period, followed by randomisation to 8 weeks of moderate cycling exercise (30 min, three times per week) or to a diet with the following characteristics: low in saturated fat, high in fibre, low glycaemic index, rich in complex carbohydrates.

RESULTS

Diet induced a small reduction in body mass index (3.0 +/- 0.7%, p<0.05), although weight loss was not intended. Exercise training increased maximum oxygen consumption by 12 +/- 6% (p<0.05). Both interventions reduced fasting plasma insulin levels by about 20%. Diet reduced skeletal muscle TNF-alpha protein by 54 +/- 10% (p<0.05), an effect that was independent (p=0.94 in covariate analysis) of the small concurrent weight loss (-2.8 +/- 0.7 kg). Levels of GLUT4 protein were unchanged in the diet group. In contrast, exercise training did not significantly change TNF-alpha protein expression, but GLUT4 protein expression increased by 105 +/- 37% (p<0.05).

CONCLUSIONS/INTERPRETATION

These data indicate that the metabolic benefits of a diet aimed at cardiovascular risk reduction are associated with a decrease in skeletal muscle TNF-alpha protein.