Low-glycaemic diets and health: implications for obesity

Association between quality and quantity of carbohydrate intake with selected anthropometric indices among primary school girls in Kerman city, Iran: a cross-sectional study

BACKGROUND

The school-age is a crucial period of physical and cognitive growth, which requires an assessment of dietary intake and its influence on body weight and height. This study aims to determine the association between the quality and quantity of carbohydrate intake with selected anthropometric indices in primary school girls in Kerman City, Iran.

METHODS

This cross-sectional study was conducted on 330 primary school girls ages 6-12 years in Kerman. We used a validated and reliable dish-based 185-item food frequency questionnaire to evaluate people's food intake. We assessed the amount of carbohydrates in children's diets as the percentage of daily calories and grams per day. We used dietary fiber intake (grams/day), the glycemic load, the ratio of whole grain to total grain, and the ratio of solid carbohydrates to total carbohydrates to assess carbohydrate quality. Height, weight, and arm circumference were measured. We calculated body mass index (BMI) by dividing the weight in kilograms by the height in centimeters squared. We used the World Health Organization z-scores charts for girls 5 to 19 years old to assess z-scores for BMI-for-age (BAZ), height-for-age (HAZ), and weight-for-age (WAZ). Socioeconomic status and physical activity were assessed. We used ANOVA and ANCOVA statistical tests to assess the association between anthropometric indices and carbohydrate quantity and quality parameters.

RESULTS

Participants with the highest amount of carbohydrate intake had significantly higher anthropometric indices, including arm circumference, BMI-for-age z score (BAZ), and Height-for-age z score (HAZ) (p < 0.001, p < 0.001, and p = 0.009, respectively). With the increase in glycemic load (GL) and dietary fiber intake, anthropometric indices including arm circumference (GL: p < 0.001, Fiber: p < 0.001), BAZ (GL: p < 0.001, Fiber: P < 0.001), and HAZ (GL: P = 0.009, Fiber: p < 0.001) increased significantly.

CONCLUSIONS

We concluded that there was a positive association between the amount of carbohydrate intake and anthropometric indices (MUAC, BAZ, and HAZ). Also, with the increase in glycemic load and dietary fiber intake, the anthropometric indices including MUAC, BAZ, and HAZ increased.

How do carbohydrate quality indices influence on bone mass density in postmenopausal women? A case-control study

BACKGROUND

Carbohydrates are the primary energy source in Asian countries, including Iran. An emerging method can be used to measure the quality of carbohydrates, including the carbohydrate quality index (CQI), which includes a variety of components. Low-carbohydrate diet score (LCDS) has been proposed as a new method of scoring micronutrient intake that could provide a reasonable explanation for the link between diet and the risk of chronic diseases.

OBJECTIVE

This study aimed to investigate the relationship between CQI, LCDS, glycemic index (GI), glycemic load (GL), insulin load (IL), and insulin index (II) with bone mass density (BMD) in postmenopausal women.

METHOD

In this case-control study, 131 postmenopausal women with osteoporosis/osteopenia and 131 healthy postmenopausal women aged 45-65 participated. The dual-energy X-ray absorptiometry (DEXA) method measured the BMD of the lumbar vertebrae and femoral neck. A validated semi-quantitative food frequency questionnaire was used to assess dietary intake. Logistic regression were used to evaluate the relation between GI, GL, II, IL, CQI, and LCDS with BMD.

RESULTS

Diets with higher GI increased the risk of osteopenia and osteoporosis, but LCDS and CQI decreased the risk of osteopenia and osteoporosis.

CONCLUSION

These findings suggest that a higher intake of fruits and vegetables and receiving various dietary vitamins, minerals, and antioxidant compounds may be a useful way to prevent osteopenia in Iranian women.

Low glycaemic index and glycaemic load diets in adults with excess weight: Systematic review and meta-analysis of randomised clinical trials

BACKGROUND

To compare the effects of low and high glycaemic index/glycaemic load (GI/GL) diets on body weight in adults with excess weight.

METHODS

We searched for randomised controlled trials comparing low GI/GL vs. high GI/GL diets from Medline (via PubMed), Embase, Scopus and Web of Science. The variables of interest were anthropometric measurements, fasting glucose and fasting insulin levels and lipid profile, and 10 studies were included in the meta-analysis.

RESULTS

The sample size ranged from 19 to 203 participants. Low GI/GL is not superior to high GI/GL diets on body weight reduction in adults with excess weight (body mass index [BMI] ≥ 25 kg m^-2 ). However, low GI/GL diets show greater body weight reductions in adults with BMI ≥ 30 kg m^-2 (-0.93 kg; 95% confidence interval [CI] = -1.73 to -0.12; p = 0.045). Compared with high GI/GL diets, low GI/GL diets may also help reduce fasting glucose (-1.97 mg dl^-1 ; 95% CI = -3.76 to 0.19; p = 0.030) and fasting insulin (-0.55 µU ml^-1 ; 95% CI = -0.95 to -0.15; p = 0.007). No differences in fat mass, fat-free mass, waist circumference and lipid profile were observed between low GI/GL and high GI/GL diets. The risk of bias for body weight was classified as 'low risk' (25% of the studies) and 'some concerns' for all domains of RoB 2 tool in most studies.

CONCLUSIONS

When compared with high GI/GL diets, low GI/GL diets appear to more effectively reduce fasting glucose and insulin and promote greater body weight reduction in adults with obesity (BMI ≥ 30 kg m^-2 ).

T. Clark C, Shab-Bidar S. Association between carbohydrate quality index and general and central obesity in adults: A population-based study in Iran

Introduction: To determine whether dietary carbohydrates quality index (CQI), glycemic index, and glycemic load is associated with general and abdominal obesity.

Methods: 850 participants, 20 to 59 years old, were enrolled in a cross-sectional study from five Tehran districts through health houses. The 168 items in the semi--quantitative food frequency questionnaire were used to assess dietary intake. The CQI was calculated by using the following four components: glycemic index, total fiber, solid carbohydrate to total carbohydrate ratio, and whole grains: total grains ratio.

Results: After adjusting for confounding factors, the chance of obesity in men (OR=0.38, 95% CI 0.15to 0.95; P =0.04) measured by waist circumference (WC) was significantly lower in the fourth quintile of CQI in comparison with the first quintile. In addition, OR for obesity in men (OR=2.53, 95% CI0.52 to 1.37; P =0.04) was significantly 2.5 times higher among those in the fourth quintile of glycemic index compared with those in the lowest quintile. There was no significant association between dietary carbohydrates with general obesity in men and women.

Conclusion: In summary, dietary CQI is significantly inversely related to central obesity in men,according to this study. Additionally, adherence to a diet with a higher glycemic index in men is positively associated with central obesity.

Effect of four viscous soluble dietary fibers on the physicochemical, structural properties, and in vitro digestibility of rice starch: A comparison study

The effect of carboxymethyl cellulose (CMC), high-methoxyl pectin (HMP), konjac glucomannan (KGM), and xanthan gum (XG) on the physicochemical, structural properties, and digestibility of rice starch were investigated and compared. The four viscous soluble dietary fibers (VSDFs) increased the viscosity, storage modulus and loss modulus while decreased the pasting temperature and gelatinization enthalpy. Moreover, XG produced the lowest peak viscosity and dynamic modulus compared with the other VSDFs. Furthermore, the degree of short-range ordered structure of starch with KGM increased from 0.8448 to 0.8716; and the relative crystallinity of starch with XG increased by 12%. An ordered and reunited network structure was observed in SEM. In addition, VSDF inhibited the digestibility of rice starch and significantly increased the resistant starch content. This study compared the effect of four VSDFs on the physicochemical, structural and digestion properties of rice starch to fully understand and develop their application to starchy foods.

Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance

Obesity has become one of the most important public health problems worldwide, which suggests the need for evidence-based dietary strategies for weight loss and its maintenance. Weight management depends upon complex factors such as amount of food eaten, type of food eaten, and timing of meals. In this review, we identified evidence-based dietary strategies for weight management based on these three components. An energy deficit is the most important factor in weight loss. A low-calorie diet with a low fat or carbohydrate content has been recommended; however, in some cases, a very-low-calorie diet is required for a short period. Some macronutrient composition-based diets, such as the ketogenic diet or high-protein diet, could be considered in some cases, although the potential risks and long-term effectiveness remain unknown. Meal timing is also an important factor in weight management, and higher-calorie breakfasts in combination with overnight fasting may help to prevent obesity. Our review indicated that there is no single best strategy for weight management. Hence, strategies for weight loss and its maintenance should be individualized, and healthcare providers must choose the best strategy based on patient preferences.

Nature and Cognitive Perception of 4 Different Breakfast Meals Influence Satiety-Related Sensations and Postprandial Metabolic Responses but Have Little Effect on Food Choices and Intake Later in the Day in a Randomized Crossover Trial in Healthy Men

Background

Regular breakfast consumption is associated with better health status and healthier food intake throughout the day, but this association is a complex interaction of several factors.

Objective

This study aimed to investigate the effect of nutritional and cognitive-perceived characteristics of breakfast on metabolic and behavioral variables related to food intake.

Methods

The study was a randomized, crossover, controlled trial, with 4 experimental conditions consisting of 3 iso-energetic breakfasts and 1 energy-free control meal. Breakfasts had similar nutritional profiles but differed for glycemic index (GI), glycemic load (GL), and perceived healthiness, satiety, palatability, or energy content. Fifteen healthy normal-weight men [means ± SDs; age: 24 ± 2 y; body mass index (BMI; kg/m2) 23.4 ± 1.6] underwent each experimental condition in random order during 4 different weeks, separated by ≥1-wk washout. On the third day of each intervention week, postprandial blood variables (with insulin as primary outcome), satiety ratings, and food intake during an ad libitum lunch consumed 4 h after breakfast (secondary outcomes) were measured for each experimental condition.

Results

A main effect of time, treatment, and time × treatment was found for postprandial insulin, glucose, and nonesterified fatty acids (P < 0.001 for all) after having the 3 iso-energetic breakfasts or the energy-free control one. Postprandial satiety was similar for the 3 energy-containing breakfasts, but higher when compared with the energy-free control (P < 0.001). No difference in energy intake was observed for the ad libitum lunch, whereas prolonged breakfast skipping was compensated by an increase (around +10%) in the average energy intake during the rest of the day, resulting in no differences in the total daily energy intake among the 4 conditions.

Conclusions

Although other advantages might exist for breakfasts based on low-GI/low-GL foods, our findings support the hypothesis that minor differences in nutritional and perceived characteristics of breakfast are of limited importance regarding medium-term energy intake in healthy men. This trial was registered at clinicaltrials.gov as BRNN-014 NCT02516956.

The nutritional property of endosperm starch and its contribution to the health benefits of whole grain foods

Purported health benefits of whole grain foods in lowering risk of obesity, type 2 diabetes, cardiovascular disease, and cancer are supported by epidemiological studies and scientific researches. Bioactive components including dietary fibers, phytochemicals, and various micronutrients present in the bran and germ are commonly considered as the basis for such benefits. Endosperm starch, as the major constituent of whole grains providing glucose to the body, has been less investigated regarding its nutritional property and contribution to the value of whole grain foods. Nutritional quality of starch is associated with its rate of digestion and glucose absorption. In whole grain foods, starch digestion and glucose delivery may vary depending on the form in which the food is delivered, some with starch being rapidly and others slowly digested. Furthermore, there are other inherent factors in whole grain products, such as phenolic compounds and dietary fibers, that may moderate glycemic profiles. A good understanding of the nutritional properties of whole grain starch is important to the development of food processing technologies to maximize their health benefits.

Effect of carbohydrate and protein solutions consumed during a moderate-intensity exercise on post-exercise appetite

This study aimed to investigate whether co-ingestion of carbohydrate and protein during exercise affect the post-exercise ad libitum food intake. Twelve healthy active male participants (mean±SD, age: 20±1; height: 176±6cm; weight: 63.6±5.3kg; VO_2peak: 51.2±7.1ml/kg/min) completed three main experimental trials in a randomized cross-over design. In each trial, the participants completed 1h of ergometer cycling at 60% VO_2peak, followed by 2h recovery. The participants were required to consume one of three solutions every 15min during exercise: distilled water (DW), carbohydrate-electrolyte solution (CE), and carbohydrate-electrolyte-protein solution (CEP). The energy was matched between the two latter solutions. The CHO-to-protein ratio in CEP was 2:1. At the end of recovery period, participants were provided with pizza lunch ad libitum, and the amount consumed was recorded. Several subjective feelings, appetite scores and blood glucose were determined during the experimental trials. No differences were found in either the amount of consumed pizza (DW vs. CE vs. CEP: 607±128 vs. 592±119 vs. 599±125g, P=0.845) or the appetite score before pizza was consumed (DW vs. CE vs. CEP: 14±9 vs. 12±14 vs. 14±10, P=0.357) among the three trials. The blood glucose concentrations during exercise were higher in the CE and CEP trials than in the DW trial. In conclusion, different solutions consumed during a 1h moderate-intensity exercise in the present study did not affect post-exercise appetite.

Eating habits and presence of cardiovascular risks in children

INTRODUCTION

The changes in the eating habits associated with physical inactivity are directly related to the increase in the prevalence of obesity and associated diseases such as diabetes mellitus (DM), metabolic syndrome and cardiovascular diseases.

OBJECTIVE

The aim of this study was to investigate the relationship between the frequency of consumption of some food groups (snacks, fruits, vegetables and candies), physical exercise, nutritional classification and biochemical profile in children.

METHODS

After the approval of the Ethics Committee, we studied 882 schoolchildren ranging between 6 and 10 years of age. Biochemical and anthropometric evaluations were performed and questionnaires were used in order to check the eating habits and physical activity.

RESULTS

Our results showed that we may relate the consumption of snacks, fruits, vegetables or candies with modifications in the glycemia, triglycerides, total cholesterol, HDL-c, and LDL-c but we did not observe association with the nutritional classification. It is noteworthy to say that almost 50% of the studied children were overweight or obese and many presented alterations in the lipid and glucose levels.

CONCLUSION

Our results also show that many children have abnormal levels of lipids and glycemia and a great number of them are classified as overweight or obese. In this context, we can say that urgent approaches are needed to be carried out by a multidisciplinary team in order to improve the diet and reduces the risk factors in this population of children and prevent secondary diseases in adolescence and adulthood.

Gut feedback mechanisms and food intake: a physiological approach to slow carbohydrate bioavailability

Glycemic carbohydrates in foods are an important macronutrient providing the biological fuel of glucose for a variety of physiological processes. A classification of glycemic carbohydrates into rapidly digestible carbohydrate (RDC) and slowly digestible carbohydrate (SDC) has been used to specify their nutritional quality related to glucose homeostasis that is essential to normal functioning of the brain and critical to life. Although there have been many studies and reviews on slowly digestible starch (SDS) and SDC, the mechanisms of their slow digestion and absorption were mostly investigated from the material side without considering the physiological processes of their in vivo digestion, absorption, and most importantly interactions with other food components and the gastrointestinal tract. In this article, the physiological processes modulating the bioavailability of carbohydrates, specifically the rate and extent of their digestion and absorption as well as the related locations, in a whole food context, will be discussed by focusing on the activities of the gastrointestinal tract including glycolytic enzymes and glucose release, sugar sensing, gut hormones, and neurohormonal negative feedback mechanisms. It is hoped that a deep understanding of these physiological processes will facilitate the development of innovative dietary approaches to achieve desired carbohydrate or glucose bioavailability for improved health.

Slowly digestible starch--a review

The link between carbohydrate intake and health is becoming increasingly important for consumers, particularly in the areas of glycemic index (GI) and extended energy-releasing starches. From a physiological point of view, slowly digestible starch (SDS) delivers a slow and sustained release of blood glucose along with the benefits resulting from low glycemic and insulinemic response. SDS has been implicated in several health problems, including diabetes, obesity, and cardiovascular diseases (metabolic syndromes). It may also have commercial potential as a novel functional ingredient in a variety of fields, such as nutrition, medicine, and agriculture. The present review assesses this form of digestion by analyzing methods to prepare and evaluate SDS, and factors affecting its transformation, its health benefits, and its applications.

Effect of Glycemic Index of Breakfast on Energy Intake at Subsequent Meal among Healthy People: A Meta-Analysis

Meals with low glycemic index (GI) may suppress short-term appetite and reduce subsequent food intake compared with high-GI meals. However, no meta-analysis has been conducted to synthesize the evidence. This meta-analytic study was conducted to assess the effect of high- and low-GI breakfast on subsequent short-term food intake. Trials were identified through MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled trials, and manual searches of bibliographies until May 2015. Randomized controlled and cross-over trials comparing the effect of low- with high-GI breakfast on subsequent energy intake among healthy people were included. Nine studies consisting of 11 trials met the inclusion criteria. Only one trial was classified with high methodological quality. A total of 183 participants were involved in the trials. The meta-analytic results revealed no difference in breakfast GI (high-GI vs. low-GI) on subsequent short-term energy intake. In conclusion, it seems that breakfast GI has no effect on short-term energy intake among healthy people. However, high quality studies are still warranted to provide more concrete evidence.

Post-exercise appetite was affected by fructose content but not glycemic index of pre-exercise meals

The purpose of this study was to investigate whether both glycemic index (GI) and breakfast fructose content affect appetite during the postprandial period and recovery period after 1 hr of brisk walking. Ten healthy young men (age: 21.7 ± 1.5 y, body mass index: 20.9 ± 1.1 kg∙m(-2), VO2max: 53.7 ± 3.7 mL∙kg(-1)∙min(-1)) completed 1 hr of brisk walking at 46% VO2max 2 hr after eating one of three isocaloric breakfasts: a low-GI breakfast not including fructose content (LGI), a low-GI breakfast including fructose beverage (LGIF) and a high-GI breakfast (HGI). All breakfasts provided 1.0 g∙kg(-1) body weight carbohydrates, and the calculated GI values for the three breakfasts were 41, 39, and 72, respectively. In the LGIF and HGI trials, approximately 25% of participants' energy was derived from either fructose or glucose beverage. Appetite scores were measured every 30 min during the 2-hr postprandial period and 1-hr recovery period. During the postprandial period, the incremental areas under the blood response curve values of glucose and insulin were higher in the HGI trial, compared with those in the LGI and LGIF trials. At 30 and 60 min during the recovery period, the appetite scores were lower in the LGIF trial than those in the LGI and HGI trials. No differences were observed between the LGI and HGI trials. Breakfast fructose content, rather than GI, seems to affect appetite during the recovery period after 1 hr of brisk walking.

Glycemic index, glycemic load and glycemic response: An International Scientific Consensus Summit from the International Carbohydrate Quality Consortium (ICQC)

BACKGROUND AND AIMS

The positive and negative health effects of dietary carbohydrates are of interest to both researchers and consumers.

METHODS

International experts on carbohydrate research held a scientific summit in Stresa, Italy, in June 2013 to discuss controversies surrounding the utility of the glycemic index (GI), glycemic load (GL) and glycemic response (GR).

RESULTS

The outcome was a scientific consensus statement which recognized the importance of postprandial glycemia in overall health, and the GI as a valid and reproducible method of classifying carbohydrate foods for this purpose. There was consensus that diets low in GI and GL were relevant to the prevention and management of diabetes and coronary heart disease, and probably obesity. Moderate to weak associations were observed for selected cancers. The group affirmed that diets low in GI and GL should always be considered in the context of diets otherwise understood as healthy, complementing additional ways of characterizing carbohydrate foods, such as fiber and whole grain content. Diets of low GI and GL were considered particularly important in individuals with insulin resistance.

CONCLUSIONS

Given the high prevalence of diabetes and pre-diabetes worldwide and the consistency of the scientific evidence reviewed, the expert panel confirmed an urgent need to communicate information on GI and GL to the general public and health professionals, through channels such as national dietary guidelines, food composition tables and food labels.

Effect of a barley-vegetable soup on plasma carotenoids and biomarkers of cardiovascular disease

Functional foods that provide benefits beyond their traditional nutritional value have attracted much interest. Aim of the study was to evaluate the nutritional and the functional properties of a frozen ready-to-eat soup containing barley and pigmented vegetables. Both glycaemic index and the glyceamic load of ready-to-eat soup were evaluated in vivo. Moreover the bioavailability of carotenoids (lutein and beta-carotene) and the effect on lipid profile and lipid peroxidation were studied in 38 volunteers whose diet was supplemented for two weeks with a daily portion (250 g) of the ready-to-eat soup. Plasma levels of carotenoids (lutein and beta-carotene) and plasma total antioxidant capacity significantly increased after 2 weeks of treatment. Furthermore, we observed a decrease in the levels of lipids (total cholesterol and low density lipoprotein-cholesterol) and of markers of lipid peroxidation (oxidized low density lipoprotein and lipid hydroperoxides) in plasma of all subjects. The glyceamic index of the product was 36, therefore it could be considered a low glyceamic index food. An accurate selection of vegetable foods results in a palatable and healthy product that provides benefits on plasma lipids and lipid peroxidation (Protocol number 211525).

Modeling of cooked starch digestion process using recombinant human pancreatic α-amylase and maltase-glucoamylase for in vitro evaluation of α-glucosidase inhibitors

In human, digestion of cooked starch mainly involves breaking down of α-amylase to α-limit dextrins and small linear malto-oligosaccharides, which are in turn hydrolyzed to glucose by the gut mucosal maltase-glucoamylase (MGAM). Human pancreatic α-amylase (HPA), amino- and carboxyl-terminal portions of MGAM (ntMGAM and ctMGAM) catalyze the hydrolysis of α-D-(1,4) glycosidic linkages in starch, playing a crucial role in the production of glucose in the human lumen. Accordingly, these enzymes are effective drug targets for the treatments of type 2 diabetes and obesity. In this study, a Plackett-Burman based statistical screening procedure was adopted to determine the most critical factors affecting cooked starch digestion by the combination of HPA, ctMGAM and ntMGAM. Six factors were tested and experimental results showed that pH and temperature were the major influencing factors, with optimal pH and temperature at 6.0 and 50 °C, respectively. Surprisingly, ntMGAM had no significant contribution to the glucose production from starch digestion compared to the HPA and ctMGAM. The optimal proportion of HPA and ctMGAM in a starch digestion system was further determined by response surface methodology. Results showed a maximum starch digestion (88.05%) within 0.5 h when used HPA:ctMGAM=1:9 (U). The inhibitory effects of various inhibitors on the cooked starch digestion by HPA1/ctMGAM9 were evaluated by determining their half maximal inhibitory concentration (IC50) values. Acarviostatin II03 showed the highest inhibitory activity, with 67 times higher potency than acarbose. Moreover, acarviostatin II03 could significantly depress postprandial blood glucose levels in mice, better than that by acarbose. These findings suggest that our in vitro enzymatic system can simulate in vivo starch digestion process, and thus can be used to screen and evaluate α-glucosidase inhibitors.

Effect of a barley-vegetable soup on plasma carotenoids and biomarkers of cardiovascular disease

Functional foods that provide benefits beyond their traditional nutritional value have attracted much interest. Aim of the study was to evaluate the nutritional and the functional properties of a frozen ready-to-eat soup containing barley and pigmented vegetables. Both glycaemic index and the glyceamic load of ready-to-eat soup were evaluated in vivo. Moreover the bioavailability of carotenoids (lutein and beta-carotene) and the effect on lipid profile and lipid peroxidation were studied in 38 volunteers whose diet was supplemented for two weeks with a daily portion (250 g) of the ready-to-eat soup. Plasma levels of carotenoids (lutein and beta-carotene) and plasma total antioxidant capacity significantly increased after 2 weeks of treatment. Furthermore, we observed a decrease in the levels of lipids (total cholesterol and low density lipoprotein-cholesterol) and of markers of lipid peroxidation (oxidized low density lipoprotein and lipid hydroperoxides) in plasma of all subjects. The glyceamic index of the product was 36, therefore it could be considered a low glyceamic index food. An accurate selection of vegetable foods results in a palatable and healthy product that provides benefits on plasma lipids and lipid peroxidation (Protocol number 211525).

Prevalence and Related Risk Factors of Overweight and Obesity among the Adult Population in the Balearic Islands, a Mediterranean Region

OBJECTIVE

To assess the prevalence and risk factors of overweight (OW) and obesity (OB) by BMI and abdominal obesity (AO) by waist-to-height ratio, (WHtR) among the Balearic Islands' adult population.

METHODS

Cross-sectional nutritional survey carried out in the Balearic Islands (2009-2010). A random sample (n = 1,081) of young (18-35 years) and middle-aged adults (36-55 years) were interviewed and anthropometrically measured. OW (BMI 25.0-29.9 kg/m(2)) and OB (BMI ≥ 30 kg/m(2)) were defined according to WHO criteria. AO was defined as WHtR ≥ 0.5. Socio-economic and lifestyle determinants were considered.

RESULTS

The overall prevalence of OW/OB and AO was 29.4% (95% confidence interval (95% CI) 26.9-32.3%), 11.2% (95% CI 9.5-13.2%) and 33.1% (95% CI 30.4-36.0%), respectively. Men showed higher prevalence of OW (35.9%, 95% CI 31.6-40.5%) and AO (37.9%, 95% CI 33.6-42.5%) than women (OW 24.9%, 95% CI 21.7-28.4%; AO 29.7%, 95%CI 26.2-33.4%). Overall prevalence of OB was 11.8% (95% CI 9.1-15.1%) in men and 10.8% (95% CI 8.6-13.5%) in women. Age and no leisure-time physical activity (LTPA) were main risk factors associated with OW/OB and AO. Living with at least one child at home and to be married in men as well as to be unemployed, to be born in South America, and a low level of education in women were associated with AO.

CONCLUSIONS

Men showed higher prevalence of OW and AO than women. In both sexes, age is the main risk factor associated with OW/OB and AO; in men also the absence of LTPA plays a significant role.

Glycemic load, glycemic index, bread and incidence of overweight/obesity in a Mediterranean cohort: the SUN project

BACKGROUND

To evaluate prospectively the relationship between white, or whole grain bread, and glycemic index, or glycemic load from diet and weight change in a Mediterranean cohort.

METHODS

We followed-up 9 267 Spanish university graduates for a mean period of 5 years. Dietary habits at baseline were assessed using a semi-quantitative 136-item food-frequency questionnaire. Average yearly weight change was evaluated according to quintiles of baseline glycemic index, glycemic load, and categories of bread consumption. We also assessed the association between bread consumption, glycemic index, or glycemic load, and the incidence of overweight/obesity.

RESULTS

White bread and whole-grain bread were not associated with higher weight gain. No association between glycemic index, glycemic load and weight change was found.White bread consumption was directly associated with a higher risk of becoming overweight/obese (adjusted OR (≥2 portions/day) versus (≤1 portion/week): 1.40; 95% CI: 1.08-1.81; p for trend: 0.008). However, no statistically significant association was observed between whole-grain bread, glycemic index or glycemic load and overweight/obesity.

CONCLUSIONS

Consumption of white bread (≥2 portions/day) showed a significant direct association with the risk of becoming overweight/obese.

Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation, and other metabolic risk factors: a randomized controlled trial

BACKGROUND

Low-glycemic index (GI) diets have been proven to have beneficial effects in such chronic conditions as type 2 diabetes, ischemic heart disease, and some types of cancer, but the effect of low-GI diets on weight loss, satiety, and inflammation is still controversial.

OBJECTIVE

We assessed the efficacy of 2 moderate-carbohydrate diets and a low-fat diet with different GIs on weight loss and the modulation of satiety, inflammation, and other metabolic risk markers.

DESIGN

The GLYNDIET study is a 6-mo randomized, parallel, controlled clinical trial conducted in 122 overweight and obese adults. Participants were randomly assigned to one of the following 3 isocaloric energy-restricted diets for 6 mo: 1) a moderate-carbohydrate and high-GI diet (HGI), 2) a moderate-carbohydrate and low-GI diet (LGI), and 3) a low-fat and high-GI diet (LF).

RESULTS

At weeks 16 and 20 and the end of the intervention, changes in body mass index (BMI; in kg/m(2)) differed significantly between intervention groups. Reductions in BMI were greater in the LGI group than in the LF group, whereas in the HGI group, reductions in BMI did not differ significantly from those in the other 2 groups (LGI: -2.45 ± 0.27; HGI: -2.30 ± 0.27; LF: -1.43 ± 0.27; F = 4.616, P = 0.012; pairwise comparisons: LGI compared with HGI, P = 1.000; LGI compared with LF, P = 0.016; HGI compared with LF, P = 0.061). The decrease in fasting insulin, homeostatic model assessment of insulin resistance, and homeostatic model assessment of β cell function was also significantly greater in the LGI group than in the LF group (P < 0.05). Despite this tendency for a greater improvement with a low-GI diet, the 3 intervention groups were not observed to have different effects on hunger, satiety, lipid profiles, or other inflammatory and metabolic risk markers.

CONCLUSION

A low-GI and energy-restricted diet containing moderate amounts of carbohydrates may be more effective than a high-GI and low-fat diet at reducing body weight and controlling glucose and insulin metabolism. This trial was registered at Current Controlled Trials (www.controlled-trials.com) as ISRCTN54971867.

A review of the nutritional value of legumes and their effects on obesity and its related co-morbidities

Since the 1970s, the proportion of overweight and obese people in the United States has grown at an alarming rate. An awareness of the consequences of obesity on the health and well-being of individuals is evident in the plethora of strategic plans at the local and national levels, most of which have largely fallen short of their goals. If interventions continue to be unsuccessful, it is estimated that approximately three of four Americans will be overweight or obese by 2020. Prevention of excess weight gain can be accomplished with relatively small changes in lifestyle behaviours to control body weight. Small sustainable changes are perhaps better than efforts to achieve larger changes that cannot be sustained. Legumes can be a valuable food by which the needs of the undernourished or under-served populations could be met. They can be incorporated into meat products, such as sausages and burgers, to lower the energy density of these foods while providing important nutrients. Replacing energy-dense foods with legumes has been shown to have beneficial effects on the prevention and management of obesity and related disorders, such as cardiovascular disease, diabetes and the metabolic syndrome. This review explores the nutritional value and obesity-related health benefits of legume consumption while focusing on pulses.

Celiac disease and overweight in children: an update

The clinical presentation of celiac disease in children is very variable and differs with age. The prevalence of atypical presentations of celiac disease has increased over the past 2 decades. Several studies in adults and children with celiac disease indicate that obesity/overweight at disease onset is not unusual. In addition, there is a trend towards the development of overweight/obesity in celiac patients who strictly comply with a gluten-free diet. However, the pathogenesis and clinical implications of the coexistence of classic malabsorption (e.g., celiac disease) and overweight/obesity remain unclear. This review investigated the causes and main clinical factors associated with overweight/obesity at the diagnosis of celiac disease and clarified whether gluten withdrawal affects the current trends of the nutritional status of celiac disease patients.

The effect of low glycemic index diet on body weight status and blood pressure in overweight adolescent girls: a randomized clinical trial

Although several studies have assessed the influence of the glycemic index on body weight and blood pressure among adults, limited evidence exists for the pediatric age population. In the current study, we compared the effects of low glycemic index (LGI) diet to the healthy nutritional recommendation (HNR)-based diet on obesity and blood pressure among adolescent girls in pubertal ages. This 10-week parallel randomized clinical trial comprised of 50 overweight or obese and sexually mature girls less than 18 years of age years, who were randomly assigned to LGI or HNR-based diet. Macronutrient distribution was equivalently prescribed in both groups. Blood pressure, weight and waist circumference were measured at baseline and after intervention. Of the 50 participants, 41 subjects (include 82%) completed the study. The GI of the diet in the LGI group was 42.67 ± 0.067. A within-group analysis illustrated that in comparison to the baseline values, the body weight and body mass index (not waist circumference and blood pressure) decreased significantly after the intervention in both groups (P = 0.0001). The percent changes of the body weight status, waist circumference and blood pressure were compared between the two groups and the findings did not show any difference between the LGI diet consumers and those in the HNR group. In comparison to the HNR, LGI diet could not change the weight and blood pressure following a 10-week intervention. Further longitudinal studies with a long-term follow up should be conducted in this regard.

Dietary strategies to increase satiety

Obesity has a multifactorial etiology. Although obesity is widespread and associated with serious health hazards, its effective prevention and treatment have been challenging. Among the currently available treatment approaches, lifestyle modification to induce a negative energy balance holds a particularly larger appeal due to its wider reach and relative safety. However, long-term compliance with dietary modifications to reduce energy intake is not effective for the majority. The role of many individual nutrients, foods, and food groups in inducing satiety has been extensively studied. Based on this evidence, we have developed sample weight-loss meal plans that include multiple satiating foods, which may collectively augment the satiating properties of a meal. Compared to a typical American diet, these meal plans are considerably lower in energy density and probably more satiating. A diet that exploits the satiating properties of multiple foods may help increase long-term dietary compliance and consequentially enhance weight loss.

Nutritional and behavioral modification therapies of obesity: facts and fiction

Current practice guidelines for management of overweight and obesity recommend a tripartite treatment - lifestyle modification program of diet, exercise, and behavior therapy for all persons with a body mass index of at least 30 (and those with body mass index 25 plus two weight-related comorbidities). Behavior therapy provides the structure that facilitates meeting goals for energy intake and expenditure. Lately, there has been a shift in focus from behavior change to cognitive change because it improves long-term results of lifestyle modification programs. Weight loss diets based on the amounts of individual macronutrients (high-protein diets, low-fat diets and low-carbohydrate diets, etc.) in the diet are not more effective than 'classical' low-calorie and balanced diets. An exception has been detected only in short-term diets with a low glycemic load. Also, epidemiological studies show that there is an inversely proportional relationship between body weight and Mediterranean diet. Cognitive behavioral therapy based on the Mediterranean diet has proven to be effective in clinical practice with regard to weight loss, body fat distribution, biochemical parameters, blood pressure and simplicity of following the diet.

Reduced glycaemic and insulinaemic responses following trehalose and isomaltulose ingestion: implications for postprandial substrate use in impaired glucose-tolerant subjects

The impact of slowly digestible sugars in reducing the risk of developing obesity and related metabolic disorders remains unclear. We hypothesised that such carbohydrates (CHO), resulting in a lower glycaemic and insulinaemic response, may lead to greater postprandial fat oxidation rates in subjects with impaired glucose tolerance (IGT). The present study intends to compare the postprandial metabolic responses to the ingestion of glucose (GLUC) v. trehalose (TRE) and sucrose (SUC) v. isomaltulose (IMU). In a randomised, single-blind, cross-over design, ten overweight IGT subjects were studied four times, following ingestion of different CHO drinks either at breakfast or in combination with a mixed meal at lunch. Before and 3 h after CHO ingestion, energy expenditure, substrate utilisation and circulating metabolite concentrations were determined. Ingestion of CHO drinks with a meal resulted in an attenuated rise in GLUC (-33 %) and insulin (-14 %) concentrations following TRE when compared with GLUC and following IMU, an attenuation of 43 and 34 % when compared with SUC ingestion, respectively. Additionally, there was less inhibition of the rise in NEFA concentrations and less decline in postprandial fat oxidation (22 %) after IMU when compared with SUC, whereas TRE did not differ from GLUC. The attenuated rise in GLUC and insulin concentrations following IMU ingestion attenuated the postprandial inhibition of fat oxidation compared with SUC when co-ingested with a meal. This suggests that exchange of SUC in the diet for IMU may result in a more favourable metabolic response and may help to reduce the risks associated with obesity and type 2 diabetes.

Glycaemic index, appetite and body weight

Much interest has been focused on the relationship between glycaemic index and body-weight loss, some of which is fueled by popular media. However, there is a number of potential mechanisms that could be triggered by reducing the glycaemic index of the carbohydrate consumed in the diet. For example, the effect of foods on the gastrointestinal tract and the effect on blood glucose both could lead to potential appetite effects. Acute meal studies seem to point to an effect of glycaemic index on appetite regulation. However, the results of longer-term studies of weight loss are not as clear. In the present review a possible reason for this variation in outcome from the weight-loss studies will be discussed. The present review focuses on the possibility that the fermentable fibre content of the low-glycaemic-index diet may be important in weight-loss efficacy. A novel receptor that binds SCFA, the products of carbohydrate fermentation, has recently been described on the enteroendocrine L-cell in the colon. This cell releases a number of anorectic hormones and could offer an explanation of the appetite suppressant effects of fermentable carbohydrates. It could also explain the variability in the results of glycaemic-index weight-loss studies.

Consumption of dry beans, peas, and lentils could improve diet quality in the US population

The US Department of Agriculture's MyPyramid guidelines introduced a near doubling of the dietary recommendations for vegetables. These recommendations target specific subgroups of vegetables, including dry beans and peas. Dry beans and peas provide an array of nutrients and phytochemicals that have been shown to have beneficial health effects, yet consumption levels in the United States are quite low. Few studies have examined the influence of legume consumption on nutrient intakes. Therefore, the purpose of this study was to assess nutrient and food group intakes of dry bean and pea consumers compared to nonconsumers. Dietary intake data from the 1999-2002 National Health and Nutrition Examination Survey for adults aged > or =19 years was used. Results show that on any given day only 7.9% of adults are consuming dry beans and peas; Mexican Americans or other Hispanics are more likely to be consumers than nonconsumers. Consuming approximately (1/2) c dry beans or peas resulted in higher intakes of fiber, protein, folate, zinc, iron, and magnesium with lower intakes of saturated fat and total fat. These data support the specific recommendation for dry beans and peas as part of the overall vegetable recommendation. Increased consumption of dry beans and peas-economical and nutrient-rich foods-could improve the diet quality of Americans.

The influence of carbohydrate on cognitive performance: a critical evaluation from the perspective of glycaemic load

Links between nutrition and cognition are widely acknowledged. Within the context of short-term cognitive performance, carbohydrate has been the dietary component most commonly investigated. The majority of studies investigating the influence of carbohydrate on cognitive performance have employed oral glucose drink interventions followed by measures of performance on cognitive tests. More recently, studies have investigated the effect of different carbohydrates on cognitive performance rather than just pure glucose drinks. To date, studies have not been evaluated based on a standardised measure of glycaemic response, such as glycaemic load. The present review provides a critical evaluation of eight studies that have explored the relationships between food carbohydrate and cognitive performance and allow glycaemic load to be used as a basis for comparison. The key finding is that these provide insufficient evidence to support a consistent effect of glycaemic load on short-term cognitive performance. Future studies should employ consistent test methodologies and describe food interventions in more detail to facilitate meaningful comparisons and interpretations of results.

Glycemic load, glycemic index, and body mass index in Spanish adults

BACKGROUND

Studies on obesity and glycemic index (GI) or glycemic load (GL) have had inconsistent results, perhaps in part because of underreporting or to heterogeneous dietary patterns across food cultures.

OBJECTIVES

We examined associations between body mass index (BMI) and GI or GL in a Mediterranean population, accounting for underreporting. We also constructed dietary factors related to GI and GL to better understand food patterns related to these measures.

DESIGN

Cross-sectional data on 8195 Spanish adults aged 35-74 y were analyzed. A validated food-frequency questionnaire was used to estimate GI and GL, with glucose as the reference value. Reduced-rank regression was used to construct dietary patterns that explained variation in GI and GL. Multivariate linear regression was used to estimate associations between BMI and GI, GL, and their respective diet factors with and without adjusting for energy, which may lie on the causal pathway between glycemic quality and obesity. Effects of excluding underreporters (ratio of energy intake:basal metabolic rate < 1.20) were examined.

RESULTS

Food patterns underlying high GI differed substantially from those of high GL, with fruits, vegetables, and legumes related positively to GL but negatively to GI. After excluding underreporters, GL was negatively associated with BMI, adjusting for energy. GI was not associated with BMI in any model.

CONCLUSIONS

After adjusting for energy, GL was associated with reduced BMI in this Mediterranean population. Underreporting did not explain this inverse relation, which was observed among subjects with plausible intakes.

The effects of 6-week low glycemic load diet based on low glycemic index foods in overweight/obese children--pilot study

OBJECTIVE

To evaluate the effectiveness of a 6-week low Glycemic Load (GL) diet intervention based on low Glycemic Index (GI) foods on body weight, body composition, metabolic risk factors and satiety in overweight/obese pre-pubertal children.

METHODS

Following a pediatric examination 8 healthy, average age 11 year old, Caucasian, pre-pubertal overweight/obese (BMI = 24, 7 +/- 3.8 kg/m(2)) children participated in the study. The Low GL diet intervention was based on the replacement of at least 50% of the high GI foods with Low-GI foods. The children with one of their parents participated in weekly nutrition consultations. Body composition, fasting glucose, insulin, cholesterol and triglyceride were measured before and after the study. Dietary changes were made based on weekly 4-day food-diaries.

RESULTS

Despite no change in body weight, there was a significant (p < 0.05) reduction in % body fat (29.4 +/- 4.2 vs. 25.4 +/- 5.3), Waist-to-Hip Ratio (WHR 0.87 +/- 0.053 vs. 0.86 +/- 0.05), decrease in self-reported hunger level (4.37 +/- 0.74 vs. 1.75 +/- 0.75) and the total number of risk factors (28 vs. 15). There was a strong negative correlation between fasting glucose and insulin levels at baseline and in the magnitude of change after the study (r = -0.93 and r = -0.85 respectively; p < 0.01).

CONCLUSIONS

A 6 week study demonstrated the practicality and effectiveness of this Low GL dietary approach. Despite of the unchanged body weight, Low GL diet consultations positively modified body fat content and cardiovascular risk factors in overweight or obese children.

Polymorphisms of the TUB gene are associated with body composition and eating behavior in middle-aged women

Background

The TUB gene, encoding an evolutionary conserved protein, is highly expressed in the hypothalamus and might act as a transcription factor. Mutations in TUB cause late-onset obesity, insulin-resistance and neurosensory deficits in mice. An association of common variants in the TUB gene with body weight in humans has been reported.

Methods/Findings

The aim was to investigate the relationship of single nucleotide polymorphisms (SNPs) of the TUB gene (rs2272382, rs2272383 and rs1528133) with both anthropometry and self-reported macronutrient intake from a validated food frequency questionnaire. These associations were studied in a population-based, cross-sectional study of 1680 middle-aged Dutch women, using linear regression analysis. The minor allele C of the rs1528133 SNP was significantly associated with increased weight (+1.88 kg, P = 0.022) and BMI (+0.56 units, P = 0.05). Compared with non-carriers, both AG heterozygotes and AA homozygotes of the rs2272382 SNP derived less energy from fat (AG: −0.55±0.28%, P = 0.05, AA: −0.95±0.48%, P = 0.047). However, both genotypes were associated with an increased energy intake from carbohydrates (0.69±0.33%, P = 0.04 and 1.68±0.56%, P = 0.003, respectively), mainly because of a higher consumption of mono- and disaccharides. Both these SNPs, rs2272382 and rs1528133, were also associated with a higher glycemic load in the diet. The glycemic load was higher among those with AG and AA genotypes for the variant rs2272382 than among the wild types (+1.49 (95% CI: −0.27–3.24) and +3.89 (95% CI: 0.94–6.85) units, respectively). Carriers of the minor allele C of rs1528133 were associated with an increased glycemic load of 1.85 units compared with non-carriers.

Conclusions

Genetic variation of the TUB gene was associated with both body composition and macronutrient intake, suggesting that TUB might influence eating behavior.

Glycemic response and health--a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes

BACKGROUND

Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. The impact of glycemic response on markers of health remains to be elucidated.

OBJECTIVE

We assessed the evidence relating the glycemic impact of foods to measures relevant for health maintenance and management of disease.

DESIGN

This was a systematic review and synthesis of interventional evidence from literature reported on glycemic index and markers of health through the use of meta-analyses and meta-regression models.

RESULTS

Data from 45 relevant publications were found to January 2005. Lower glycemic index (GI) diets reduced both fasting blood glucose and glycated proteins independently of variance in available and unavailable carbohydrate intakes. Elevated unavailable carbohydrate added to improvements in both blood glucose and glycated protein control. These effects were greater in persons with poor fasting blood glucose control. No effects were seen on fasting insulin<100 pmol/L; above this, study numbers were few but consistent with prevention of hyperinsulinemia in some but not all overweight persons. Insulin sensitivity according to a variety of measurement methods was improved by lower GI, higher unavailable carbohydrate interventions in persons with type 2 diabetes, in overweight and obese persons, and in all studies combined. Fasting triacylglycerol in addition to body weight reduction related more to glycemic load than to GI. Glycemic load reduction by >17 g glucose equivalents/d was associated with reduced body weight.

CONCLUSIONS

Consumption of reduced glycemic response diets are followed by favorable changes in the health markers examined. The case for the use of such diets looks compelling. Unavailable carbohydrate intake is equally important.

Glycaemic response to foods: Impact on satiety and long-term weight regulation

Should future nutritional recommendations for the general population take into account the notion of glycaemic index (GI)? This question is all the more legitimate as the glycaemic response to foods seems to be a factor that affects satiety and could therefore affect food intake. The aim of this review was to evaluate whether altering the glycaemic response per se can modulate satiety and to assess the short-term and long-term consequences. A systematic review of human intervention studies was performed. Confounding factors that may influence both GI and satiety were taken into consideration when selecting the studies. Thirty-two studies were thus selected and analysed. There is evidence from the short-term studies (1 day) that low-glycaemic foods or meals have higher satietogenic effect than high-glycaemic foods or meals. This substantiates claims such as 'low-GI foods help one to feel fuller for longer than equivalent high-GI foods'. The mechanisms involved may be the specific effect of blood glucose levels on satiety (glucostatic theory) and other stimuli (e.g. peptides) involved in the control of appetite. In some studies, however it seems difficult to tease out the separate effect of the lowering of postprandial glycaemia per se and fibres. Because of the increasing number of confounding variables in the available long-term studies, it is not possible to conclude that low-glycaemic diets mediate a health benefit based on body weight regulation. The difficulty of demonstrating the long-term health benefit of a satietogenic food or diet may constitute an obstacle to the recognition of associated claims.

Luminal substrate "brake" on mucosal maltase-glucoamylase activity regulates total rate of starch digestion to glucose

BACKGROUND

Starches are the major source of dietary glucose in weaned children and adults. However, small intestine alpha-glucogenesis by starch digestion is poorly understood due to substrate structural and chemical complexity, as well as the multiplicity of participating enzymes. Our objective was dissection of luminal and mucosal alpha-glucosidase activities participating in digestion of the soluble starch product maltodextrin (MDx).

PATIENTS AND METHODS

Immunoprecipitated assays were performed on biopsy specimens and isolated enterocytes with MDx substrate.

RESULTS

Mucosal sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM) contributed 85% of total in vitro alpha-glucogenesis. Recombinant human pancreatic alpha-amylase alone contributed <15% of in vitro alpha-glucogenesis; however, alpha-amylase strongly amplified the mucosal alpha-glucogenic activities by preprocessing of starch to short glucose oligomer substrates. At low glucose oligomer concentrations, MGAM was 10 times more active than SI, but at higher concentrations it experienced substrate inhibition whereas SI was not affected. The in vitro results indicated that MGAM activity is inhibited by alpha-amylase digested starch product "brake" and contributes only 20% of mucosal alpha-glucogenic activity. SI contributes most of the alpha-glucogenic activity at higher oligomer substrate concentrations.

CONCLUSIONS

MGAM primes and SI activity sustains and constrains prandial alpha-glucogenesis from starch oligomers at approximately 5% of the uninhibited rate. This coupled mucosal mechanism may contribute to highly efficient glucogenesis from low-starch diets and play a role in meeting the high requirement for glucose during children's brain maturation. The brake could play a constraining role on rates of glucose production from higher-starch diets consumed by an older population at risk for degenerative metabolic disorders.

Relation of nutrients and hormones in polycystic ovary syndrome

BACKGROUND

Insulin resistance, infertility, and hirsutism, common characteristics of polycystic ovary syndrome (PCOS), improve with even modest weight loss. Optimal dietary treatment for PCOS is not known.

OBJECTIVE

We compared the effects of acute protein administration with those of glucose challenges on hormones related to obesity and insulin resistance (ie, cortisol and insulin), hirsutism [ie, dehydroepiandosterone (DHEA) and androstenedione], and hunger (ie, ghrelin).

DESIGN

Patients with PCOS (n = 28; aged 26 +/- 2 y) were tested with a 5-h oral-glucose-tolerance test (OGTT) and a euvolemic, euenergetic protein challenge.

RESULTS

Glucose ingestion caused larger fluctuations in blood glucose and more hyperinsulinemia than did protein (P < 0.01, overall treatment-by-time interaction). During the protein challenge, cortisol and DHEA declined over 5 h. During OGTT, cortisol and DHEA increased after the third hour and began to show significant divergence from protein from the fourth hour (P <or= 0.01). During OGTT, 18 patients who had a blood glucose nadir of <69 mg/dL had elevated cortisol (baseline: 10.4 +/- 0.4; nadir: 5.9 +/- 0.1; peak: 12.7 +/- 0.9 microg/dL) and DHEA (baseline: 15.6 +/- 1.3; nadir: 11.2 +/- 1.0; peak: 24.6 +/- 1.6 ng/mL) (P < 0.01), whereas the remaining 10 patients with a glucose nadir of 76 +/- 2 mg/dL had no increase in adrenal steroids. Both glucose and protein suppressed ghrelin (from 935 +/- 57 to 777 +/- 51 pg/mL and from 948 +/- 60 to 816 +/- 61 pg/mL, respectively). After glucose ingestion, ghrelin returned to baseline by 4 h and increased to 1094 +/- 135 pg/mL at 5 h. After the protein challenge, ghrelin remained below the baseline (872 +/- 60 pg/mL) even at 5 h. The overall treatment effect was highly significant (P < 0.0001).

CONCLUSIONS

Glucose ingestion caused significantly more hyperinsulinemia than did protein, and it stimulated cortisol and DHEA. Protein intake suppressed ghrelin significantly longer than did glucose, which suggested a prolonged satietogenic effect. These findings provide mechanistic support for increasing protein intake and restricting the simple sugar intake in a PCOS diet.

High-glycemic-index carbohydrate meals shorten sleep onset

BACKGROUND

Dietary carbohydrate intake has been shown to increase the plasma concentration of tryptophan, a precursor of serotonin and sleep-inducing agent.

OBJECTIVE

To investigate the role of carbohydrate in sleep induction, we explored the effect of glycemic index (GI) and meal time on sleep in healthy volunteers.

DESIGN

We compared the effect of high- and low-GI carbohydrate-based meals ingested 4 h before bedtime on sleep quality. We also evaluated the effect of the timing of high-GI meals (4 h compared with 1 h) on sleep quality. Twelve healthy men (aged 18-35 y) were administered standard, isocaloric (3212 kJ; 8% of energy as protein, 1.6% of energy as fat, and 90.4% of energy as carbohydrate) meals of either Mahatma (low GI = 50) or Jasmine (high GI = 109) rice 4 h before their usual bedtime. On another occasion, the high-GI meal was given 1 h before bedtime. The participants underwent a familiarization night followed by 3 test nights in random order 1 wk apart.

RESULTS

A significant (P = 0.009) reduction in the mean (+/-SD) sleep onset latency (SOL) was observed with a high-GI (9.0 +/- 6.2 min) compared with a low-GI (17.5 +/- 6.2 min) meal consumed 4 h before bedtime. The high-GI meal given 4 h before bedtime showed a significantly shortened SOL compared with the same meal given 1 h before bedtime (9.0 +/- 6.2 min compared with 14.6 +/- 9.9 min; P = 0.01). No effects on other sleep variables were observed.

CONCLUSIONS

We showed that a carbohydrate-based high-GI meal resulted in a significant shortening of SOL in healthy sleepers compared with a low-GI meal and was most effective when consumed 4 h before bedtime. The relevance of these findings to persons with sleep disturbance should be determined in future trials.

Metabolic markers in relation to nutrition and growth in healthy 4-y-old children in Sweden

BACKGROUND

The worldwide increase in overweight and obesity probably involves dietary factors, and early indicators of risk must be identified.

OBJECTIVE

We aimed to analyze metabolic markers in relation to dietary intake and anthropometry in healthy 4-y-old children.

DESIGN

A cross-sectional study of nutritional intake was performed in 95 children by use of 7-d food records. Fasting blood samples were analyzed for glucose, insulin, and lipids.

RESULTS

The study population was representative of Swedish children except that more parents than the average had a university education. The boys' mean energy intake was higher (6.6 +/- 0.75 MJ) than the girls' (5.7 +/- 0.79 MJ). Significant associations were found between the percentage of energy from carbohydrates and that from fat (r = -0.91) and sucrose (r = 0.59). High body mass index was associated with a low percentage of energy from fat (r = -0.32). Serum triacylglycerol, insulin, and the HOMA (homeostatic model assessment) index were higher in girls than in boys. In girls, HOMA beta-cell function was significantly negatively associated with fat intake and serum fasting insulin, and HOMA insulin resistance indexes were significantly associated with the increment in z scores for height and weight from birth to age 4 y. Compared with children with fasting insulin concentrations below the group mean + SD, the children with concentrations above that value were smaller as newborns and had larger increments in growth z scores from birth to age 4 y.

CONCLUSION

In healthy Swedish 4-y-olds from well-educated families, low fat intake was related to high body mass index. Upward weight and height percentile crossings were related to insulin resistance, especially in girls.

Association between dietary glycemic index, glycemic load, and body mass index in the Inter99 study: is underreporting a problem?

BACKGROUND

The few studies examining the potential associations between glycemic index (GI), glycemic load (GL), and body mass index (BMI) have provided no clear pictures. Underreporting of energy intake may be one explanation for this.

OBJECTIVE

We examined the associations between GI, GL, and BMI by focusing on the confounding factor of total energy intake and the effect of exclusion of low energy reporters (LERs).

DESIGN

This was a cross-sectional study of 6334 subjects aged 30-60 y. Dietary intake was estimated from a food-frequency questionnaire. GI and GL were estimated by using white bread as the reference food. Underreporting of energy intake was assessed as reported energy intake divided by basal metabolic rate (EI/BMR); LERs were defined as those having an EI/BMR < 1.14. Univariate and multiple linear regression models were used to test for associations between GI, GL, and BMI. The confounders were sex, age, smoking, physical activity, alcohol intake, and energy intake. All analyses were conducted on 1) the entire population and 2) a subsample excluding LERs.

RESULTS

In the univariate analyses of the entire population, GL was inversely associated with BMI. No association was observed for GI. After full adjustment (including energy intake), both GI and GL were positively associated with BMI. When LERs were excluded, GL was positively associated with BMI in all analyses, and GI was positively associated with BMI in the multiple analyses.

CONCLUSIONS

We showed a positive association between GI, GL, and BMI. Energy adjustment and the exclusion of LERs significantly affected the results of the analysis; thus, we stress the importance of energy adjustment.

Nutridynamics--studying the dynamics of food components in products and in the consumer

The concentrations and biological effects of nutrients, antinutrients and bioactive compounds, including microbes and their constituents, are affected by production and processing steps, the food matrix in which they reside, the way they are digested and metabolized in the human body, and whether or not and in what form they subsequently reach their target site. A new scientific concept, denoted here as 'nutridynamics', aims to unravel the dynamics of these processes by using a systematic approach to study how a food component is affected by the food matrix itself and what it does in the body. This holistic concept has potential synergy with the areas of food technology and nutrigenomics, and provides a link between food production and the mechanistic effects of bioactive ingredients.