Andrew O. Wheatley

Food processing methods influence the glycaemic indices of some commonly eaten West Indian carbohydrate-rich foods.

Glycaemic index (GI) values for fourteen commonly eaten carbohydrate-rich foods processed by various methods were determined using ten healthy subjects. The foods studied were round leaf yellow yam (Dioscorea cayenensis), negro and lucea yams (Dioscorea rotundata), white and sweet yams (Dioscorea alata), sweet potato (Solanum tuberosum), Irish potato (Ipomoea batatas), coco yam (Xanthosoma spp.), dasheen (Colocasia esculenta), pumpkin (Cucurbita moschata), breadfruit (Artocarpus altilis), green banana (Musa sapientum), and green and ripe plantain (Musa paradisiaca). The foods were processed by boiling, frying, baking and roasting where applicable. Pure glucose was used as the standard with a GI value of 100. The results revealed marked differences in GI among the different foods studied ranging from 35 (se 3) to 94 (se 8). The area under the glucose response curve and GI value of some of the roasted and baked foods were significantly higher than foods boiled or fried (P<0.05). The results indicate that foods processed by roasting or baking may result in higher GI. Conversely, boiling of foods may contribute to a lower GI diet.

Relationship between Processing Method and the Glycemic Indices of Ten Sweet Potato (Ipomoea batatas) Cultivars Commonly Consumed in Jamaica.

This study investigated the effect of different traditional cooking methods on glycemic index (GI) and glycemic response of ten Sweet potato (Ipomoea batatas) cultivars commonly eaten in Jamaica. Matured tubers were cooked by roasting, baking, frying, or boiling then immediately consumed by the ten nondiabetic test subjects (5 males and 5 females; mean age of 27 ± 2 years). The GI varied between 41 ± 5–93 ± 5 for the tubers studied. Samples prepared by boiling had the lowest GI (41 ± 5–50 ± 3), while those processed by baking (82 ± 3–94 ± 3) and roasting (79 ± 4–93 ± 2) had the highest GI values. The study indicates that the glycemic index of Jamaican sweet potatoes varies significantly with the method of preparation and to a lesser extent on intravarietal differences. Consumption of boiled sweet potatoes could minimize postprandial blood glucose spikes and therefore, may prove to be more efficacious in the management of type 2 diabetes mellitus.

Citrus peel polymethoxylated flavones extract modulates liver and heart function parameters in diet induced hypercholesterolemic rats

The primary aim of this study was to investigate the effects of Ortanique peel polymethoxylated flavones extract (PMF(ort)) on organ function parameters in the serum of hypercholesterolemic and normal rats. Thirty Sprague-Dawley rats were fed high cholesterol diets supplemented with 1.5% PMF(ort) and niacin respectively for 49days. Hypercholesterolemic rats fed PMF(ort) had significant reductions in the activities of aspartate aminotransferase and alkaline phosphatase (69.12±3.34 and 87.22±8.42U/L respectively) compared to the untreated hypercholesterolemic group (118.61±4.85 and 132.62±10.62U/L respectively, p<0.05). Supplementation of the diet with niacin or PMF(ort) resulted in no significant differences in the serum levels of creatinine or urea in any of the groups. Total bilirubin was highest in the untreated hypercholesterolemic group. Supplementation of the diets of hypercholesterolemic rats with PMF(ort) resulted in significant reductions in the activities of serum creatine kinase and lactate dehydrogenase (119.3±25.3; 222.5±50.3U/L, p<0.05) respectively relative to the untreated hypercholesterolemic group (257.2±48.3; 648.8±103U/L, p<0.05). The results would suggest that PMF(ort) modulates hypercholesterolemia-associated organ injury in rats. PMF(ort) could therefore be a suitable candidate for prophylactic and therapeutic treatment of hypercholesterolemia-associated organ injury.

DEVELOPMENT OF SALT ADAPTATION IN IN VITRO GREATER YAM (DIOSCOREA ALATA) PLANTLETS

SummaryThe development of plants capable of growing under saline conditions is one approach at utilizing saline soils that are otherwise arable. This study was designed to develop salt-tolerant yam (Dioscorea alata) plantlets, using tissue culture techniques. Salt-tolerant yam (Dioscorea alata cv. Sweet yam) plantlets were produced in vitro through repeated culturing and selection on saline media. Two hundred plantlets were subcultured on normal multiplication media (Murashige and Skoog basal media with 30 gl−1 sucrose and 0.44 μM benzylaminopurine). A further 400 plantlets were equally subcultured on multiplication media supplemented with 100 or 200 mM NaCl. Plantlets that proliferated on medium with 100 mM saline conditions were repeatedly subcultured on saline media. Growth of plantlets and root formation were assessed along with some biochemical parameters such as invertase (EC 3.2.1.26), peroxidase (EC 1.11.1.7), and polyphenol oxidase (EC 1.10.3.1) activities. No growth was observed for plantlets transferred to the highly saline media of 200 mM NaCl and the explants did not survive beyond 6 wk. Control plantlets exhibited 100% rooting within 3 wk compared to 5 wk for plantlets on 100 mM NaCl. Development of new nodes and leaves were observed for plantlets on 100 mM NaCl, although at an initially slower rate than the control plantlets. The enzyme activity profiles obtained for plantlets on 100 mM NaCl reflected the biochemical adjustments of the plantlets to cope with the saline conditions. This was further substantiated by the detection of two reproducible bands of sizes 1 and 0.35 kb from reverse transcription polymerase chain reaction (RT-PCR) studies of salt-tolerant yam plantlets. These results can be translated into efforts aimed at maximizing the use of saline soils.

The interplay between yam (Dioscorea sp.) starch botanical source, micromeritics and functionality in paracetamol granules for reconstitution

A comparative investigation of the interplay between starch botanical source, micromeritics and their functionality in formulated paediatric paracetamol granules for reconstitution was conducted using starches extracted from five local yam (Dioscorea spp.) species. Significant differences were observed in the physicochemical properties of the different starches studied (p<0.05). The observed differences in paracetamol dissolution correlated well with the physicochemical properties of the starches. Granules formulated with Chinese yam and Bitter yam starches showed the fastest rate of paracetamol dissolution with T(80) of 2.2 and 2.6 min, respectively, at 2.5%w/w, and 3.75 and 4.00 min, respectively, at 10% w/w binder concentrations. Those formulated with Round leaf yellow yam starch had the slowest dissolution rate with T(80) of 4.5 and 8.75 min, respectively, at 2.5% and 10% binder concentrations. The results generally indicate a significant dependence of the rate of paracetamol dissolution from granules on starch surface tension, viscosity, swelling power and water binding capacity, particle size distribution, specific surface and porosity. These, in turn, were found to be starch botanic source-dependent suggesting careful consideration of botanic source when substituting one starch product for another in granule formulation.

An Investigation of the Antioxidant Capacity in Extracts from Moringa oleifera Plants Grown in Jamaica

Moringa oleifera trees grow well in Jamaica and their parts are popularly used locally for various purposes and ailments. Antioxidant activities in Moringa oleifera samples from different parts of the world have different ranges. This study was initiated to determine the antioxidant activity of Moringa oleifera grown in Jamaica. Dried and milled Moringa oleifera leaves were extracted with ethanol/water (4:1) followed by a series of liquid–liquid extractions. The antioxidant capacities of all fractions were tested using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. IC50 values (the amount of antioxidant needed to reduce 50% of DPPH) were then determined and values for the extracts ranged from 177 to 4458 μg/mL. Extracts prepared using polar solvents had significantly higher antioxidant capacities than others and may have clinical applications in any disease characterized by a chronic state of oxidative stress, such as sickle cell anemia. Further work will involve the assessment of these extracts in a sickle cell model of oxidative stress.

Relationship between the physicochemical properties of starches and the glycemic indices of some Jamaican yams (Dioscorea spp.)

Starch granules from round leaf yellow yam (RY), Lucea yam (LY), white yam (WY), and Chinese yam (CY) grown in Jamaica were isolated and the relationship between starch amylose content, crystallinity, microscopic properties, in vitro digestibility, and the glycemic index (GI) of the tubers was investigated. The results indicate that RY had the highest amylose content (265.30 +/- 0.09 g/kg starch) while CY the lowest (111.44 +/- 0.03 g/kg starch). A corresponding variation in starch digestibility and GI was also observed, as CY which had the highest in vitro digestibility had the highest GI (21.27 +/- 0.01 and 97.42 +/- 0.62%, respectively), while RY, LY, and WY starches with low digestibility had lowest GI. Differences in the crystalline pattern of the different starches were observed, where RY, LY, and WY displayed the type B crystalline pattern while CY had the intermediate crystallite (type C).

Plasma Cocaine Metabolite and Liver CYP450 3A4 Isoenzyme Levels as Indicators of Cocaine Dependence in Rats Treated with Nutritional Supplements

The effects that chronic cocaine administration CCA have on craving, cocaine metabolite concentrations and cytochrome P450 3A4 isoenzyme CYP450 3A4 activities in Sprague-Dawley rats following the administration of Salako Nutritional Supplements SNS were examined. Five groups of fifty rats were used to assess the effect of the SNS following CCA. Craving was analyzed for each rat using a Conditioned Place Preference protocol. Blood samples were obtained at regular intervals and used to measure cocaine plasma metabolite levels. CYP450 3A4 activity was determined in the liver. Administration of the SNS reduced craving of cocaine significantly, upon discontinuing cocaine in the rats. Blood plasma analysis showing higher benzoylecgonine equilibrium and the CYP450 3A4 levels demonstrated that the SNS possibly aided in the removal of the stored metabolites indicative of increased metabolism of cocaine, enhanced by the Supplements. Results indicate that the SNS formulation reduces craving caused by CCA by increasing the liver CYP450 3A4 activity, resulting in better plasma clearance.

High Fiber Caribbean Diets with Low-Intermediate GI Improve Glycemic Control, Cardiovascular and Inflammatory Indicators in Overweight Persons with Type 2 Diabetes: A Randomized Control Study

This study focused on the effect of consumption of indigenous Caribbean foods with low and intermediate glycemic index (GI) high fiber contents on glycated haemoglobin (A 1c), insulin, fasting blood glucose, homocysteine (tHCY), high sensitivity C-reactive protein (hs-CRP), homeostasis model assessment of Insulin Resistance (HOMA-IR) and lipoprotein profile levels in overweight persons with type 2 diabetes. The methodology followed a randomized controlled parallel design, which compared two dietary treatment modalities in adult Jamaicans who were overweight and diagnosed with type 2 diabetes (mean age 42.5 ± 2.0 years, 55% females, mean A1c 9.30 ± 0.56%) over six months. The intervention group (n=32) underlined the consumption of low-intermediate-GI foods, whereas the control group (n = 33) were not so advised and consumed a high-GI diet. Attempts were made to ensure that both groups were isocaloric with 45-50% of energy from carbohydrates. Consumption of low-intermediate GI foods resulted in significant reductions (p<0.005) in A 1C compared to participants who consumed high GI foods (-0.84 ± 0.26 vs. -0.35 ± 0.04%), hs-CRP (-0.52 ± 0.17 vs. -0.17 ± 0.31 mg/dL) and tHCY (-1.32 ± 0.39 vs. -0.59 ± 0.38 µmol/L). Insulin sensitivity, HDL-C and triglycerides significantly improved in participants who consumed the low-intermediate-GI diet. The data strengthen the metabolic benefits of meal plans that emphasize the consumption of low and intermediate GI high fiber foods, particularly, indigenous Caribbean complex starchy foods.

Glycemic Index of Some Traditional Fruits in Jamaica

Background: Fruits and vegetables, for their complex carbohydrates, dietary fiber and micronutrients, should form an essential part of every diet. In order to give good dietary advice to diabetic patients, it is necessary to know the glycemic index of foods commonly consumed locally. The objective of this study was to determine the glycemic index (GI) and glycemic load (GL) of commonly available and consumed June plum (Spondias dulcis), Otaheite apple (Syzygium malaccense), Pineapple (Ananas comosus), and Cucumber (Cucumis sativus) in Jamaica. Methods: Ten (10) healthy Jamaican subjects (5 males, 5 females) with mean age 30 ± 2 years and mean BMI 25 ± 1 kg/m2 were recruited to the study. Using a non-blind, crossover design trial, the subjects consumed 50 (or 25) grams of available carbohydrate portions of glucose (standard food) and test foods after an overnight fast. Their serum glucose levels were then determined at 0, 15, 30, 45, 60, 90 and 120 minutes after the consumption of each test food. Glucose was tested on three separate occasions, and the test foods once. The GI value was calculated geometrically by expressing the incremental area under the blood glucose curve (IAUC) for the test foods as a percentage of each subjects average IAUC for the standard food. Results: The results indicated that the IAUC for Pineapple (96 ± 15) and Otaheite apple (122 ± 29) were significantly higher (p < 0.05) than that of June plum (23 ± 6) and Cucumber (40 ± 14). Similarly the GI of Pineapple (80 ± 20) and Otaheite apple (64 ± 15) were significantly higher than June plum (13 ± 5) and Cucumber (21 ± 6). Conclusion: June plum, Cucumber, were shown to have low glycemic index values, whereas Otaheite apple was intermediate and Pineapple high.