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Concept: Glycemic index

702

We propose that highly processed foods share pharmacokinetic properties (e.g. concentrated dose, rapid rate of absorption) with drugs of abuse, due to the addition of fat and/or refined carbohydrates and the rapid rate the refined carbohydrates are absorbed into the system, indicated by glycemic load (GL). The current study provides preliminary evidence for the foods and food attributes implicated in addictive-like eating.

Concepts: Nutrition, Food, Drug addiction, Addiction, Pharmacokinetics, Carbohydrate, Glycemic index, Glycemic load

178

Despite a considerable amount of data available on the relationship between dietary glycemic index (GI) or load (GL) and cardiovascular disease (CVD) risk factors, in aggregate, the area remains unsettled. The aim of the present review was to summarize the effect of diets differing in GI/GL on CVD risk factors, by examining randomized controlled-feeding trials that provided all food and beverages to adult participants. The studies included a low and high GI/GL diet phase for a minimum of four weeks duration, and reported at least one outcome related to CVD risk; glucose homeostasis, lipid profile or inflammatory status. Ten publications representing five trials were identified. The low GI/GL compared to the high GI/GL diet unexpectedly resulted in significantly higher fasting glucose concentrations in two of the trials, and a lower area under the curve for glucose and insulin in one of the two studies during an oral glucose tolerance test. Response of plasma total, low density lipoprotein and high density lipoprotein cholesterol concentrations was conflicting in two of the studies for which data were available. There was either weak or no effect on inflammatory markers. The results of the five randomized controlled trials satisfying the inclusion criteria suggest inconsistent effects of the GI/GL value of the diet on CVD risk factors.

Concepts: Nutrition, Atherosclerosis, Diabetes mellitus, Cardiovascular disease, Low-density lipoprotein, Blood sugar, Insulin resistance, Glycemic index

150

 What is the association between potato consumption before pregnancy and the risk of gestational diabetes mellitus (GDM)?

Concepts: Pregnancy, Diabetes mellitus, Diabetes, Obstetrics, Gestational diabetes, American Diabetes Association, Glycemic index

49

It is now well established that protein supplementation after resistance exercise promotes increased muscle protein synthesis, which ultimately results in greater net muscle accretion, relative to exercise alone or exercise with supplementary carbohydrate ingestion. However, it is not known whether combining carbohydrate with protein produces a greater anabolic response than protein alone. Recent recommendations have been made that the composition of the ideal supplement post-exercise would be a combination of a protein source with a high glycemic index carbohydrate. This is based on the hypothesis that insulin promotes protein synthesis, thus maximising insulin secretion will maximally potentiate this action. However, it is still controversial as to whether raising insulin level, within the physiological range, has any effect to further stimulate muscle protein synthesis. The present commentary will review the evidence underpinning the recommendation to consume carbohydrates in addition to a protein supplementation after resistance exercise for the specific purpose of increasing muscle mass. The paucity of data will be discussed, thus our conclusions are that further studies are necessary prior to any conclusions that enable evidence-based recommendations to be made.

Concepts: Metabolism, Nutrition, Insulin, Glucose, Muscle, Glycogen, Carbohydrate, Glycemic index

45

Purpose Observational studies have reported increased colon cancer recurrence and mortality in patients with states of hyperinsulinemia, including type 2 diabetes, obesity, sedentary lifestyle, and high glycemic load diet. Nut intake has been associated with a lower risk of type 2 diabetes, metabolic syndrome, and insulin resistance. However, the effect of nut intake on colon cancer recurrence and survival is not known. Patients and Methods We conducted a prospective, observational study of 826 eligible patients with stage III colon cancer who reported dietary intake on food frequency questionnaires while enrolled onto a randomized adjuvant chemotherapy trial. Using Cox proportional hazards regression, we assessed associations of nut intake with cancer recurrence and mortality. Results After a median follow-up of 6.5 years, compared with patients who abstained from nuts, individuals who consumed two or more servings of nuts per week experienced an adjusted hazard ratio (HR) for disease-free survival of 0.58 (95% CI, 0.37 to 0.92; Ptrend= .03) and an HR for overall survival of 0.43 (95% CI, 0.25 to 0.74; Ptrend= .01). In subgroup analysis, the apparent benefit was confined to tree nut intake (HR for disease-free survival, 0.54; 95% CI, 0.34 to 0.85; Ptrend= .04; and HR for overall survival, 0.47; 95% CI, 0.27 to 0.82; Ptrend= .04). The association of total nut intake with improved outcomes was maintained across other known or suspected risk factors for cancer recurrence and mortality. Conclusion Diets with a higher consumption of nuts may be associated with a significantly reduced incidence of cancer recurrence and death in patients with stage III colon cancer.

Concepts: Nutrition, Hypertension, Insulin, Diabetes mellitus, Obesity, Insulin resistance, Metabolic syndrome, Glycemic index

43

Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance.

Concepts: Protein, Metabolism, Nutrition, Enzyme, Glucose, Glycogen, Carbohydrate, Glycemic index

37

The consumption of sweetened beverages, refined foods, and pastries has been shown to be associated with an increased risk of depression in longitudinal studies. However, any influence that refined carbohydrates has on mood could be commensurate with their proportion in the overall diet; studies are therefore needed that measure overall intakes of carbohydrate and sugar, glycemic index (GI), and glycemic load.

Concepts: Nutrition, Food, Carbohydrate, Sugar, Glycemic index, Potato, Glycemic load, Insulin index

36

Qualitative aspects of diet influence eating behavior, but the physiologic mechanisms for these calorie-independent effects remain speculative.

Concepts: Psychology, Nutrition, Diet, Dieting, Glycemic index, Diabetic diet, Glycemic load, Carnivore

34

Factors linked to glucose metabolism are involved in the etiology of several cancers. High glycemic index (GI) or high glycemic load (GL) diets, which chronically raise postprandial blood glucose, may increase cancer risk by affecting insulin-like growth factor. We prospectively investigated cancer risk and dietary GI/GL in the EPIC-Italy cohort. After a median 14.9 years, 5112 incident cancers and 2460 deaths were identified among 45,148 recruited adults. High GI was associated with increased risk of colon and bladder cancer. High GL was associated with: increased risk of colon cancer; increased risk of diabetes-related cancers; and decreased risk of rectal cancer. High intake of carbohydrate from high GI foods was significantly associated with increased risk of colon and diabetes-related cancers, but decreased risk of stomach cancer; whereas high intake of carbohydrates from low GI foods was associated with reduced colon cancer risk. In a Mediterranean population with high and varied carbohydrate intake, carbohydrates that strongly raise postprandial blood glucose may increase colon and bladder cancer risk, while the quantity of carbohydrate consumed may be involved in diabetes-related cancers. Further studies are needed to confirm the opposing effects of high dietary GL on risks of colon and rectal cancers.

Concepts: Immune system, Cancer, Nutrition, Colorectal cancer, Carbohydrate, Sugar, Glycemic index, Glycemic load

30

AIMS: Diabetes rates are especially high in China. Risk of Type 2 diabetes increases with high intakes of white rice, a staple food of Chinese people. Ethnic differences in postprandial glycaemia have been reported. We compared glycaemic responses to glucose and five rice varieties in people of European and Chinese ethnicity and examined possible determinants of ethnic differences in postprandial glycaemia. METHODS: Self-identified Chinese (n = 32) and European (n = 31) healthy volunteers attended on eight occasions for studies following ingestion of glucose and jasmine, basmati, brown, Doongara(®) and parboiled rice. In addition to measuring glycaemic response, we investigated physical activity levels, extent of chewing of rice and salivary α-amylase activity to determine whether these measures explained any differences in postprandial glycaemia. RESULTS: Glycaemic response, measured by incremental area under the glucose curve, was over 60% greater for the five rice varieties (P < 0.001) and 39% greater for glucose (P < 0.004) amongst Chinese compared with Europeans. The calculated glycaemic index was approximately 20% greater for rice varieties other than basmati (P = 0.01 to 0.05). Ethnicity [adjusted risk ratio 1.4 (1.2-1.8) P < 0.001] and rice variety were the only important determinants of incremental area under the glucose curve. CONCLUSIONS: Glycaemic responses following ingestion of glucose and several rice varieties are appreciably greater in Chinese compared with Europeans, suggesting the need to review recommendations regarding dietary carbohydrate amongst rice-eating populations at high risk of diabetes. © 2012 The Authors. Diabetic Medicine © 2012 Diabetes UK.

Concepts: Nutrition, Diabetes mellitus, Starch, Han Chinese, Glycemic index, Rice, Parboiled rice, Varieties of rice