Effect of glycemic index on obesity control

OBJECTIVE

Evaluate the effect of glycemic index (GI) on biochemical parameters, food intake, energy metabolism, anthropometric measures and body composition in overweight subjects.

MATERIALS AND METHODS

Simple blind study, in which nineteen subjects were randomly assigned to consume in the laboratory two daily low GI (n = 10) or high GI (n = 9) meals, for forty-five consecutive days. Habitual food intake was assessed at baseline. Food intake, anthropometric measures and body composition were assessed at each 15 days. Energy metabolism and biochemical parameters were evaluated at baseline and the end of the study.

RESULTS

Low GI meals increased fat oxidation, and reduced waist circumference and HOMA-IR, while high GI meals increased daily dietary fiber and energy intake compared to baseline. There was a higher reduction on waist circumference and body fat, and a higher increase on postprandial fat oxidation in response to the LGI meals than after high GI meals. High GI meals increased fasting respiratory coefficient compared to baseline and low GI meals.

CONCLUSION

The results of the present study showed that the consumption of two daily low GI meals for forty-five consecutive days has a positive effect on obesity control, whereas, the consumption of high GI meals result has the opposite effect.

Glycaemic index and glycaemic load of three traditional Mexican dishes

The purpose of the present study was to assess the glycaemic index (GI) and glycaemic load (GL) of different mixed meals traditionally consumed in Mexico. GI was measured for three meals (Pozole, Molletes and Mole), using glucose as a reference in 12 college student subjects. Mole (p = 0.002), Molletes (p = 0.043) and Pozole (p = 0.016) showed a lower IAUC than glucose. However, there was not difference between meals. Higher GI and GL levels were observed than the estimated GI using as reference the International Table of Atkinson et al. (2008. Diabetes Care 31(12):2281-2283). Since food ingredients vary among Mexican regions, it is recommended to assess the GI and GL of mixed meals according to the cooking habits of each region.

Glycaemic response to barley porridge varying in dietary fibre content

The interest in barley as a food is increasing worldwide because of its high dietary fibre (DF) content and low glycaemic index (GI). DF in cereals may prove beneficial in improving blood glucose response in the long term. However, a dose-dependent effect of insoluble fibre on reducing postprandial blood glucose levels is yet to be proven. The objective of the present study was to determine the glycaemic response to two barley porridges prepared from whole barley grains varying in fibre content. In two separate non-blind randomised crossover trials, ten human subjects consumed barley porridge with 16 g/100 g and 10 g/100 g fibre content provided in different serving sizes (equivalent to 25 and 50 g available carbohydrate). The glycaemic response to both barley porridges was significantly lower than the reference glucose (P < 0·05). There was no significant difference between the glucose areas under the curve or GI for the two barley porridges. We concluded that irrespective of the difference in total fibre content or serving size of barley porridges, their GI values did not differ significantly.

Fructose ingestion: dose-dependent responses in health research

Many hypotheses of disease risk and prevention depend on inferences about the metabolic effects of fructose; however, there is inadequate attention to dose dependency. Fructose is proving to have bidirectional effects. At moderate or high doses, an effect on any one marker may be absent or even the opposite of that observed at very high or excessive doses; examples include fasting plasma triglyceride, insulin sensitivity, and the putative marker uric acid. Among markers, changes can be beneficial for some (e.g., glycated hemoglobin at moderate to high fructose intake) but adverse for others (e.g., plasma triglycerides at very high or excessive fructose intake). Evidence on body weight indicates no effect of moderate to high fructose intakes, but information is scarce for high or excessive intakes. The overall balance of such beneficial and adverse effects of fructose is difficult to assess but has important implications for the strength and direction of hypotheses about public health, the relevance of some animal studies, and the interpretation of both interventional and epidemiological studies. By focusing on the adverse effects of very high and excessive doses, we risk not noticing the potential benefits of moderate to higher doses, which might moderate the advent and progress of type-2 diabetes, cardiovascular disease, and might even contribute to longevity. A salutary rather than hyperbolic examination of the evidence base needs to be undertaken.

Not just a grain of rice: the quest for quality

A better understanding of the factors that contribute to the overall grain quality of rice (Oryza sativa) will lay the foundation for developing new breeding and selection strategies for combining high quality, with high yield. This is necessary to meet the growing global demand for high quality rice while offering producing countries additional opportunities for generating higher export revenues. Several recent developments in genetics, genomics, metabolomics and phenomics are enhancing our understanding of the pathways that determine several quality traits. New research strategies, as well as access to the draft of the rice genome, will not only advance our understanding of the molecular mechanisms that lead to quality rice but will also pave the way for efficient and targeted grain improvement.