Sri Lankan rice mixed meals: effect on glycaemic index and contribution to daily dietary fibre requirement.

INTRODUCTION: The glycaemic index (GI) concept ranks starchy foods according to the blood glucose responses following ingestion. When considering commonly consumed Sri Lankan meals, only a few can be categorised as low GI. However, a significant negative correlation between the GI of Sri Lankan meals and fibre content has been observed indicating the potential to reduce the GI of meals by incorporating naturally occurring sources of fibre. Thus, the objective of this study was to study the effect of increased edible quantities of fibre on the GI of rice meals consumed in Sri Lanka. METHODS: Meal 1 consisted of rice with several meal accompaniments (lentil curry, boiled egg, coconut gravy and Centella asiatica (gotukola) leaves salad). Meal 2 contained similar constituents as meal 1 and a Lasia spinosa (kohila) rhizome salad. The composition of meal 3 was similar to meal 2 but contained Trichosanthes cucumerina (snake gourd) salad instead of Lasia spinosa salad. Meal 3 contained similar fibre contents as meal 1 and similar meal size as meal 2. The glycaemic indices of the three meals were determined with healthy individuals (n=10, age=20-30 yrs, BMI=24 +/- 3 kg/m2) using bread as the standard. RESULTS: Meals 1 and 3 contained total dietary fibre (TDF) contents of 15.2g. Meal 2 contained 16.3g TDF. The GI values of the three meals were 63 +/- 5, 57 +/- 5, 61 +/- 5 respectively and were not significantly different from one another (p>0.05). The GI of the rice mixed meal 2 was reduced by 9% when total edible dietary fibre content of the actual meal was increased by 7.2%. CONCLUSION: The study results show that the GI of rice mixed meals may be reduced by including naturally occurring sources of fibre with starchy staples while fulfilling daily dietary fibre requirement of an adult at low cost.

Nutritional assessment of a jackfruit (Artocarpus heterophyllus) meal.

OBJECTIVES: The mature jackfruit (Artocarpus heterophyllus) is consumed in Sri Lanka either as a main meal or a meal accompaniment. However, there is no scientific data on the nutrient compositions of cooked jackfruit meals. Thus, the objective of the study was to carry out a nutritional assessment of a composite jackfruit breakfast meal comprising seeds and flesh. DESIGN: A jackfruit meal comprising of flesh (80% available carbohydrate) and seeds (20% available carbohydrate) was included in the study. The study was carried out in a random cross over design. Setting University of Sri Jayewardenepura. Study participants Healthy individuals (n=10, age: 20-30 yrs). MEASUREMENTS: The macronutrient contents, rapidly and slowly available glucose (SAG) contents, water solubility index of the jackfruit meal were determined according to standard methods. The GI of the meal was calculated according to FAO/WHO guidelines. RESULTS: The moisture content of the boiled jackfruit flesh was high (82% FW). Jack seeds contained 4.7% protein (FW), 11.1% total dietary fibre (FW) and 8% resistant starch (FW). Jackfruit meal elicited a GI of 75. The Glycaemic Load (GL) of the normal serving size of the meal is medium. The slowly available glucose (SAG) percentage of jackfruit meal (30%) was twice that of the standard. The boiled jackfruit flesh contained disintegrated starch granules while seeds contained intact swollen and disintegrated granules. CONCLUSIONS: The jackfruit seeds are a good source of starch (22%) and dietary fibre. The meal is categorized as a low GI meal. The low GI could be dueto the collective contributions from dietary fibre, slowly available glucose and un-gelatinised (intact) starch granules in the seeds.

Chemical compositions and glycemic responses to banana varieties.

Chemical compositions and glycemic indices of four varieties of banana (Musa spp.) (kolikuttu-Silk AAB, embul-Mysore AAB, anamalu-Gros Michel AAA, seeni kesel-Pisang Awak ABB) were determined. Silk, Gros Michel, Pisang Awak and Mysore contained the highest percentages of starch (14%), sucrose (38%), free glucose (29%) and fructose (58%) as a percentage of the total available carbohydrate content respectively. Total dietary fiber contents of four varieties ranged from 2.7 to 5.3%. Glycemic indices of Silk, Mysore, Gros Michel and Pisang Awak were 61 ± 5, 61 ± 6, 67 ± 7, 69 ± 9 and can be categorized as low against white bread as the standard. A single banana of the four varieties elicited a low glycemic load. Thus, consumption of a banana from any of these varieties can be recommended as a snack for healthy or diabetic patients who are under dietary management or pharmacological drugs to regulate blood glucose responses in between meals.

Do Sri Lankan meals help decrease blood glucose response?

OBJECTIVE: The prevalence of diabetes mellitus (DM) has rapidly increased in Asian countries including Sri Lanka during the past decade. Scientific data on postprandial glycaemic influence of common meals is essential when formulating diets. Objectives of this study were to analyse glycaemic indices (GI) of five common meals and effects of macronutrients, sources of carbohydrates, and physicochemical properties of starch on observed GI values. DESIGN: The meals analysed were; 1 - red rice (AT 353) meal, 2 - red rice mixed meal, 3 - stringhopper (wheat flour) meal, 4 - stringhopper (rice flour) meal, 5 - manioc (Manihot esculenta) meal. SETTING: University of Sri Jayewardenepura. SUBJECTS: Healthy individuals (n=10; age: 20-30 years). MEASUREMENTS: GI of each meal was calculated according to FAO/WHO guidelines by taking the ratio of incremental area under blood glucose curve (IAUC) of test and the standard. RESULTS: GI of meals 1-5 were 99 +/- 10, 60 +/- 5, 104 +/- 7, 102 +/- 11 and 120 +/- 9 respectively. The glycaemic response to rice mixed meal was significantly lower (p<0.05) than the others. The total dietary fibre content showed a significant negative correlation (p=0.044) with the GI value while the protein showed a non-significant negative relationship (p>0.05). Red rice had a combination of intact, swollen and disintegrated starch granules while string hoppers and manioc showed only the latter two types. CONCLUSION: The rice mixed meal has the lowest glycaemic index. Presence of dietary fibre and a legume reduces the glycaemic response. Cooking may change the glycaemic response of certain food.

Glycaemic indices of three Sri Lankan wheat bread varieties and a bread-lentil meal.

The glycaemic index (GI) concept ranks individual foods and mixed meals according to the blood glucose response. Low-GI foods with a slow and prolonged glycaemic response are beneficial for diabetic people, and several advantages have been suggested also for non-diabetic individuals. The recent investigations imply an increasing prevalence of diabetes mellitus in Sri Lanka. Thus, the present study was designed primarily to determine the glycaemic indices of some bread varieties in Sri Lanka as bread has become a staple diet among most of the urban people. A second objective was to observe the effects of macronutrients and physicochemical properties of starch on GI. Glycaemic responses were estimated according to FAO/WHO guidelines and both glucose and white bread were used as standards. Non-diabetic individuals aged 22-30 years (n=10) participated in the study. The test meals included white sliced bread, wholemeal bread, ordinary white bread and a mixed meal of wholemeal bread with lentil curry. The GI values (+/-standard error of the mean) of the meals were 77+/-6, 77+/-6, 80+/-4, 61+/-6, respectively (with glucose as the standard). The GI values of the bread varieties or the meal did not differ significantly (P >0.05). However, the meal can be categorized as a medium-GI food while the other bread varieties belong to the high-GI food group. A significant negative correlation was obtained with protein (P=0.042) and fat (P=0.039) contents of the food items and GI. Although the GI values of the foods are not significantly different, the inclusion of lentils caused the GI to decrease from a high-GI category to a medium-GI category. According to the present study, a ratio of 1.36 can be used to interconvert the GI values obtained with the two standards.

Deletion screening of Sri Lankan Duchenne muscular dystrophy patients using the polymerase chain reaction.

Duchenne muscular dystrophy (DMD) is an X-chromosome-linked myopathy caused by a defect in the DMD gene. Intragenic deletions appear to be the most common gene defect leading to DMD, and the deletion frequency has been estimated to be 66%. Results of this study using a group of 24 DMD patients of Sri Lankan origin employing the technique of multiplex DNA amplification using the polymerase chain reaction indicated a deletion frequency of 62.5%. Eighty per cent of these deletions were localized in a region of the DMD gene regarded as a 'hot spot' for DMD deletions. Our results are in agreement with the results of other studies carried out on Caucasian populations.

A linkage study of the locus for X-linked Charcot-Marie-Tooth disease.

A large family with Charcot-Marie-Tooth disease, showing a probable X-linked incomplete dominant inheritance, was studied by linkage analysis. Results, obtained by the use of X chromosome specific DNA probes of known regional location, suggest that the disease locus is linked to the DXYS1 locus (z = 2.59 at theta = 0.00) and to the DXS14 locus and, places the disease locus between the DXYS1 locus and the DXS14 locus, near the centromere of the X chromosome. Together with the published data, a distance of 13 cM (z = 6.95) was assessed between the disease locus and the DXYS1 locus.

Extra-pancreatic effects of Momordica charantia in rats.

The extra pancreatic effects of the oral hypoglycaemic plant Momordica charantia have been investigated in rats. It was found that the fruit juice of this plant caused an increased glucose uptake by tissues in vitro without concomitant increase of tissue respiration. Oral treatment with the juice prior to a glucose load was found to increase the glycogen content of liver and muscle while it had no effect on the triglyceride content of adipose tissue. Pretreatment of fasted rats with M. charantia fruit juice had no significant effect on the gluconeogenic capacity of kidney slices. Similar results were obtained with kidney slices pre-incubated with M. charantia fruit juice.

Effect of Momordica charantia on the glucose tolerance in maturity onset diabetes.

Investigations were carried out to evaluate the effect of Momordica charantia on the glucose tolerance of maturity onset diabetic patients. The fruit juice of M. charantia was found to significantly improve the glucose tolerance of 73% of the patients investigated while the other 27% failed to respond.

Oral hypoglycaemic activity of some medicinal plants of Sri Lanka.

Investigations were carried out to evaluate the oral hypoglycaemic activity of some Sri Lankan medicinal plants. Approximately 40 plants available locally are reputed to have oral hypoglycaemic activity. Of these, the mostly widely used are (a) Salacia reticulata (Celastraceae) (b) Aegle marmelos (Rutaceae) and (c) Momordica charantia (Cucurbitaceae). Aqueous decoctions of these plants were investigated for their ability to lower the fasting blood glucose level and improve the glucose tolerance in laboratory animals. The results indicate that the aqueous decoctions of all three plants possess significant hypoglycaemic effect. The magnitude of this effect showed time related variation with the three plants. The highest oral hypoglycaemic activity and the maximum improvement of the oral glucose tolerance were associated with the extract of Momordica charantia while the least but significant effects were shown by Salacia reticulata.

The insulin-releasing activity of the tropical plant momordica charantia.

An aqueous extract from the unripe fruits of the tropical plant Momordica charantia was found to be a potent stimulator of insulin release from beta-cell-rich pancreatic islets isolated from obese-hyperglycemic mice. The stimulation of insulin release was partially reversible. It differed from that of D-glucose and other commonly employed insulin secretagogues in not being suppressed by L-epinephrine and in even being potentiated by the removal of Ca2+. This anomalous behaviour was not associated with general effects on the metabolism of the beta-cells as indicated by an unaltered oxidation of D-glucose. Studies of 45Ca fluxes suggest that the insulin-releasing action is the result of perturbations of membrane functions. In support for the idea of direct effects on membrane lipids, the action of the extract was found to mimic that of saponin in inhibiting the Ca2+/H+ exchange mediated by the ionophore A23187 in isolated chromaffin granules and release Ca2+ from preloaded liposomes.