Effect of the glycemic index of carbohydrates on day-long (10 h) profiles of plasma glucose, insulin, cholecystokinin and ghrelin

Background: Low glycemic index (GI) carbohydrates have been linked to increased satiety. The drive to eat may be mediated by postprandial changes in glucose, insulin and gut peptides.
Objective: To investigate the effect of a low and a high GI diet on day-long (10 h) blood concentrations of glucose, insulin, cholecystokinin (CCK) and ghrelin (GHR).
Design: Subjects (n¼12) consumed a high and a low GI diet in a randomized, crossover design, consisting of four meals that were matched for macronutrients and fibre, and differed only in carbohydrate quality (GI). Blood was sampled every 30–60 min and assayed for glucose, insulin, CCK and GHR.
Results: The high GI diet resulted in significantly higher glucose and insulin mean incremental areas under the curve (IAUC, P¼0.027 and P¼0.001 respectively). CCK concentration was 59% higher during the first 7 h of the low GI diet (394±95 pmol/l min) vs the high GI diet (163±38 pmol/l min, P¼0.046), but there was no difference over 10 h (P¼0.224). GHR concentration was inversely correlated with insulin concentration (Pearson correlation 0.48, P¼0.007), but did not differ significantly between the low and high GI diets.
Conclusions: Mixed meals of lower GI are associated with lower day-long concentrations of glucose and insulin, and higher CCK after breakfast, morning tea and lunch. This metabolic profile could mediate differences in satiety and hunger seen in some, but not all, studies.

Glycemic index and glycogen

INTRODUCTION : Fatigue in sports is often associated with depletion of muscle glycogen storage. Obesity is considered to be a major barrier against physical activity in sports. In order to bring the glycogen storage to a satisfactory level sports persons tend to increase consumption carbohydrates, preferred consumption of high glycemic index (HGI) than low glycemic index (LGI) diets. But HGI foods may promote postprandial carbohydrate oxidation at the expense of fat oxidation and increase body fat gain. LGI diets that produce a low and slow glycemic response may enhance higher glycogen storage instead of fat deposition.

METHODOLOGY : To test this hypothesis, 30 male Wistar rats after weaning were given either a high glycemic index (HGI) or low glycemic index (LGI) diet for until their age of 12 weeks. Then the subjects were scarified and their plasma, serum, and muscle samples were collected. RESULTS-The study revealed that HGI diets fed rats had higher plasma cholesterol and Leptin (LGI Leptin 1.34 +/- 0.13ng/ml, HGI Leptin 2.12 +/- .20ng/ml) concentrations. It also found the liver and muscle glycogen storage in LGI diets showed higher level (LGI-liver 108 +/-3.0 mg/100g, LGI-muscle 22.6+/- 2.3g/100g) than that of HGI (HGI-liver 96 +/- 2.0mg/100g, HGI-muscle 18+/- 1.5g/100g) diets.

CONCLUSION : the long term feeding of LGI carbohydrate encourages more glycogen storage while HGI increases fat deposition. Consumption of LGI diets has an advantage over HGI diets of higher physical activity while elevating glycogen storage and reducing chances of obesity.

Pre-exercise carbohydrate ingestion : effect of the glycemic index on endurance exercise performance

Purpose: This study aimed to examine the effect of glycemic index of pre-exercise carbohydrate (CHO) ingestion on exercise metabolism and performance.

Methods: Eight endurance trained men ingested a high glycemic index (HGI), low glycemic index (LGI), or a placebo (CON) meal 45 min before exercise and then cycled for 50 min at 67% V·O_2max. Subjects subsequently performed a 15-min self-paced performance ride in which total work (kJ) was recorded.

Results: Plasma glucose concentrations were higher (P < 0.01) after ingestion in HGI compared with LGI and CON (7.53 ± 0.64 vs 5.55 ± 0.21 and 4.65 ± 0.14 mmol·L^-1 for HGI, LGI, and CON, respectively, 30 min postprandial; mean ± SE) but declined at the onset of exercise and were lower (P < 0.01) compared with LGI and CON (4.03 ± 0.31 vs 4.64 ± 0.24 and 5.09 ± 0.16 mmol·L^-1 for HGI, LGI, and CON respectively; mean ± SE) at 10 min of exercise. Plasma glucose remained depressed (P < 0.01) until 30 min into exercise in HGI compared with other trials. Plasma insulin concentrations were higher (P < 0.01) following ingestion during rest and exercise in HGI compared with LGI and CON. Plasma FFA concentrations were lower (P < 0.05) following ingestion in HGI and LGI compared with CON and higher (P < 0.05) in LGI compared with HGI at the start and end of exercise. RER and CHO oxidation was higher (P < 0.01) in HGI compared with LGI and CON during submaximal exercise. There were no differences in work output during the performance cycle.


Conclusions: These data indicate that pre-exercise CHO feedings with varying glycemic indexes do not affect exercise performance following short term submaximal exercise despite alterations in metabolism.

Effects of ingesting low glycemic index carbohydrate food for the sahur meal on subjective, metabolic and physiological responses, and endurance performance in Ramadan fasted men

To investigate the effect of low glycemic index (LGI) carbohydrate meal on subjective, metabolic and physiological responses, and endurance performance in the Ramadan fasted state.

The effect of rice variety and parboiling on in vivo glycemic response

Improved and traditional rice varieties grown in Sri Lanka namely, Bg 300, Bg 352, Bg 358, Bg 406, LD 356, Rathkaral, Wedaheenati and Heendikwel were studied for their in vivo glycemic response. Proximate compositions and amylose content of rice were determined according to standard methods and available carbohydrate content was calculated using the difference method. The in vivo glycemic response of selected improved and traditional rice varieties was assessed by determining the glycemic index (GI) using ten healthy subjects. Further, the effect of parboiling of rice on glycemic response was also assessed. The crude protein content was higher in parboiled rice as compared to nonparboiled rice. According to the amylose content, rice varieties studied were classified as intermediate and high amylose rice. The amylose content of Bg 406 was the lowest (20.18% ±0.17) while Rathkaral showed the highest (29%±0.07). The Glycemic index of rice varieties studied ranged from 57±1 to 73± 2. The Wedaheenati variety exhibited the lowest GI while Bg 406 exhibited the highest GI value. Unparboiled Bg 406, LD 356 and parboiled Bg 406 were classified as high GI foods while the rest of the rice varieties studied were categorized as intermediate GI foods. Parboiled rice brought about a reduction in glycemic response in healthy subjects. The maximum reduction of 10% in glycemic index upon parboiling was observed with Bg 352. The traditional rice produced significantly lower (p<0.05) postprandial glycemic effect than did the improved rice. By their low post-prandial glycemic response they could be potentially useful in low GI diets.

The 'caffeine-sweetness' effect; potential reduction of energy in caffeinated sugar-sweetened soft drinks

Background – Excessive consumption of sugar sweetened beverages (SSB) is a contributing factor in the occurrence of overweight and obesity. The high energy intake, low satiation, high glycemic index, and intense marketing are all thought to contribute to their over consumption. In addition, the role of the mildly-addictive chemical caffeine in SSB has been questioned (Griffiths and Vernotica, 2000, Keast and Riddell, 2007). We have previously shown that low concentrations of caffeine may decrease sweetness of sugars and thereby result in excess energy in SSB formulations (Ebbeling et al., 2006).
Objective – Without noticeably affecting flavour, to determine potential energy reduction when decreasing sucrose concentration from caffeinated and de-caffeinated SSB.
Design – Human psychophysical taste evaluations in water, sucrose and model SSB. Triangle forced-choice ascending method of limits was used to determine caffeine taste threshold in water and sucrose (n= 62). Directional paired comparison tests to determine 1/ the influence of caffeine on sweetness of sucrose (n= 23), and 2/ the nonperceivable difference when decreasing the sucrose and caffeine concentrations in a model SSB (n= 30).
Outcomes – Caffeine, at sub-threshold concentrations in common SSB (0.67mM) can be perceived in sucrose solutions because it significantly inhibits sweetness (p<0.001), the ‘caffeine sweetness effect’. Presumably coremoval of caffeine and sucrose could be achieved without affecting the sweetness of the SSB. Removing caffeine from the model SSB allowed an energy reduction of 137.4 KJ per 500 ml serving (12.6% sucrose reduction) without noticeably affecting flavour for 80% of the population. The energy reduction possible without co-removal of caffeine was a more modest 32 KJ per 500 ml serving (3.5% sucrose reduction).
Conclusion – Sub-threshold concentrations of caffeine suppress sweetness resulting in higher concentrations of sugars in SSB. Excessive consumption of SSB is linked to the obesity epidemic, and we suggest the removal of caffeine and subsequent removal of 137.4 KJ energy will have long term public health benefits.

The effect of type of cereal on the glycaemic response of two traditional Sri Lankan food items

Pittu and roti are two traditional food items consumed by Sri Lankan people mostly for breakfast or dinner. Rice (Oryza sativa L.) and kurakkan (Eleucine coracana L.) are two types of cereal that can be used to prepare them. The determination of blood glucose elevating effect (glycaemic response) of pittu and roti prepared from rice flour and kurakkan flour was the objective of this study. Proximate composition of Bg 403 rice flour and kurakkan flour was determined and the available carbohydrate content of the two types of cereal was calculated. Pittu and roti were prepared from each flour, following traditional methods and given to eight young healthy adult volunteers. Each subject was given a weighed portion of pittu or roti equivalent to 50 g available carbohydrate as the test food. As the standard food 50 g glucose was given orally. After a 12 hrs overnight fast on the assigned day each subject was given either the standard food or the test food and blood glucose was measured in capillary blood at fasting (0), 15, 30, 45, 60, 90 and 120 min after the consumption of food. The incremental area under the glycaemic response curve (IAUC) for each test food was expressed as a percentage of IAUC of the standard food taken by the same subject and the average value of subjects was taken as the glycemic index (GI) for the test food. Proximate analysis revealed that percentage moisture, crude fat, crude fibre, crude protein and minerals of rice flour and kurakkan flour were 13.0, 1.7, 0.42, 10.3, 0.88 and 13.2, 1.9, 4.4, 8.7 and 2.8, respectively. Accordingly the available carbohydrate percentage of rice flour and kurakkan flour were 73.7 and 69.0, respectively. The GI of pittu and roti, prepared using Bg 403 rice flour were 52 and 64 and that of kurakkan flour were 71 and 80 respectively. Based on the GI, it can be suggested that pittu is better for health than roti, while rice flour is better than kurakkan flour to prepare these. The basis of recommending kurkkan flour based products for diabetic people has to be re-examined in the light of these findings.

The role of reducing intakes of saturated fat in the prevention of cardiovascular disease : where does the evidence stand in 2010?

Current dietary recommendations advise reducing the intake of saturated fatty acids (SFAs) to reduce coronary heart disease (CHD) risk, but recent findings question the role of SFAs. This expert panel reviewed the evidence and reached the following conclusions: the evidence from epidemiologic, clinical, and mechanistic studies is consistent in finding that the risk of CHD is reduced when SFAs are replaced with polyunsaturated fatty acids (PUFAs). In populations who consume a Western diet, the replacement of 1% of energy from SFAs with PUFAs lowers LDL cholesterol and is likely to produce a reduction in CHD incidence of >2–3%. No clear benefit of substituting carbohydrates for SFAs has been shown, although there might be a benefit if the carbohydrate is unrefined and has a low glycemic index. Insufficient evidence exists to judge the effect on CHD risk of replacing SFAs with MUFAs. No clear association between SFA intake relative to refined carbohydrates and the risk of insulin resistance and diabetes has been shown. The effect of diet on a single biomarker is insufficient evidence to assess CHD risk. The combination of multiple biomarkers and the use of clinical endpoints could help substantiate the effects on CHD. Furthermore, the effect of particular foods on CHD cannot be predicted solely by their content of total SFAs because individual SFAs may have different cardiovascular effects and major SFA food sources contain other constituents that could influence CHD risk. Research is needed to clarify the role of SFAs compared with specific forms of carbohydrates in CHD risk and to compare specific foods with appropriate alternatives.

Relationship between body mass index and the use of healthcare services in Australia

Objective: To examine the relationship between body mass index (BMI) and the use of medical and preventive health services. Research Methods and Procedures: This study involved secondary analysis of weighted data from the Australian 1995 National Health Survey. The study was a population survey designed to obtain national benchmark information about a range of health-related issues. Data were available from 17,033 men and 17,174 women, 20 years or age. BMI, based on self-reported weight and height, was analyzed in relation to the use of medical services and preventive health services. Results: A positive relationship was found between BMI and medical service use, such as medication use, visits to hospital accident and emergency departments (for women only); doctor visits, visits to a hospital outpatient clinics; and visits to other health professionals (for women only). A negative relationship was found in women between BMI and preventive health services. Underweight women were found to be significantly less likely to have Papanicolaou smear tests, breast examinations, and mammograms. Discussion: This research shows that people who fall outside the healthy weight range are more likely to use a range of medical services. Given that the BMI of industrialized populations appears to be increasing, this has important ramifications for health service planning and reinforces the need for obesity prevention strategies at a population level.

Foods prepared outside the home: association with selected nutrients and body mass index in adult Australians

Objective: To determine the proportion of energy from foods prepared outside the home (FPOH) and the relationships with energy and nutrient intakes and body mass index (BMI).

Design: A nutrition survey of a representative sample of the Australian population aged 18 years and over (n = 10 863). Measure used was a 24-hour dietary recall. Underreporters (energy intake/estimated basal metabolic rate (EI/BMR) <0.9) were excluded from analysis. Daily energy and selected nutrient intakes were calculated using a 1996 nutrient composition database for all foods/beverages during the 24-hour period.

Results: On average FPOH contributed a significant 13% to total energy intake. About a third of the sample had consumed FPOH in the last 24 hours and on average this group consumed a third of their total energy as FPOH. The relative contributions of fat (for men and women) and alcohol (for women) were significantly higher for those in the top tertile of FPOH consumers. The intakes of fibre and selected micronutrients (calcium, iron, zinc, folate and vitamin C) were significantly lower in this group. After adjustment for age and income no relationship between FPOH and BMI was observed.

Conclusions: FPOH make a significant contribution to the energy intake of a third of the Australian population. FPOH contribute to poor nutritional intakes. Altering the supply of FPOH may be an effective means of improving diets at a population level.

Developing a national index of subjective wellbeing: the Australian unity wellbeing index

The Australian Unity Wellbeing Index has been designed as a new barometer of Australians' satisfaction with their lives, and life in Australia. It is based on, and develops, the theoretical model of subjective wellbeing homeostasis. The Index comprises two sub-scales of Personal and National Wellbeing. Data were collected through a nationally representative sample of 2,000 people in April/May 2001.Factor analysis confirmed the integrity of the two sub-scales and, confirming empirical expectation, the average level of life satisfaction was 75.5 percent of the scale maximum score. Group comparisons revealed that all age groups maintained their Personal Index score within the normal range. In addition,people in country areas were more satisfied with their personal lives than city-dwellers,but less satisfied about the national situation, and people who had recently experienced a strong positive event evidenced arise in wellbeing, whereas those who had experienced a strong negative event evidenced wellbeing in the low-normal range. It is argued that these data generally support homeostatic theory. However, an unusual result was that females were more satisfied with their own lives than males. A tentative argument is advanced that this may represent a constitutional difference. It is concluded that the Australian Unity Wellbeing Index has potential as a valid, reliable and sensitive instrument to monitor national wellbeing.

Surface spatial index structure of high-dimensional space

This paper proposes a spatial index structure based on a new space-partitioning method. Previous research proposed various high dimensional index structures. However, when dimensionality becomes high, the effectiveness of the spatial index structure disappears. This problem is called the “curse of dimensionality”. This paper focuses on the fact that the volume of high dimensional space is mostly occupied by its surface and then proposes a new surface index structure. The utility of this new surface spatial index structure is illustrated through a series of experiments.

A grid-based index method for time warping distance

Recently DTW (dynamic time warping) has been recognized as the most robust distance function to measure the similarity between two time series, and this fact has spawned a flurry of research on this topic. Most indexing methods proposed for DTW are based on the R-tree structure. Because of high dimensionality and loose lower bounds for time warping distance, the pruning power of these tree structures are quite weak, resulting in inefficient search. In this paper, we propose a dimensionality reduction method motivated by observations about the inherent character of each time series. A very compact index file is constructed. By scanning the index file, we can get a very small candidate set, so that the number of page access is dramatically reduced. We demonstrate the effectiveness of our approach on real and synthetic datasets.

A new interlink decision making index for making multi-criteria decisions

In this paper a mechanism that is the brain child of the authors, has been proposed to overcome the potential manipulation of results as a direct consequence of the applied weightings. It is known as the Interlink Decision Making Index