C. Jeya K. Henry

Glycaemic index values for commercially available potatoes in Great Britain

The glycaemic response to eight potato varieties commercially available in Great Britain was compared against a glucose standard in a non-blind, randomised, repeated measure, crossover design trial. Seventeen healthy subjects (three males, fourteen females), mean age 32 (sd 13) years and mean BMI 22.3 (sd 3.6) kg/m2, were recruited to the study. Subjects were served portions of eight potato varieties and a standard food (glucose), on separate occasions, each containing 50 g carbohydrate. Capillary blood glucose was measured from finger-prick samples in fasted subjects (0 min) and at 15, 30, 45, 60, 90 and 120 min after the consumption of each test food. For each potato variety, the glycaemic index (GI) value was calculated geometrically by expressing the incremental area under the blood glucose curve (IAUC) as a percentage of each subjects average IAUC for the standard food. The eight potato varieties exhibited a wide range in GI values from 56 to 94. A trend was seen whereby potatoes with waxy textures produced medium GI values, whilst floury potatoes had high GI values. Considering the widespread consumption of potatoes in Great Britain (933-1086 g per person per week), this information could be used to help lower the overall GI and glycaemic load of the diets of the British population.

High-molecular-weight barley β-glucan in chapatis (unleavened Indian flatbread) lowers glycemic index.

Food products incorporated with soluble dietary fiber beta-glucan have shown varying effects on postprandial glycemia. The objective of the present study was to test the hypothesis that a food product fortified with barley beta-glucan and subjected to minimum processing and mild cooking might be effective in lowering glycemic response. In a randomized, single-blind, controlled crossover trial, 8 healthy human subjects (3 men, 5 women; aged 26-50 years; body mass index, <30 kg/m(2)) consumed unleavened Indian flatbreads called chapatis containing high-molecular-weight barley beta-glucan at doses of 0, 2, 4, 6, and 8 g on different occasions. Capillary blood samples were collected at 0, 15, 30, 45, 60, 90, and 120 minutes after consuming the chapatis. The incremental area under the glucose curve values for all the 5 different types of chapatis were significantly low (P < .001) compared with reference food glucose. The incremental area under the glucose curve of chapatis containing 4 and 8 g beta-glucan were significantly lower than control chapatis (P < .05). Postprandial blood glucose was significantly reduced at 45 minutes by chapatis containing 4 g (P < .05) and 8 g beta-glucan (P < .01) and at 60 minutes by chapatis with 8 g beta-glucan (P < .01). The glycemic index (GI) values of chapatis with 4 and 8 g beta-glucan were 43% to 47% lower (GI, 30 and 29, respectively) compared with chapatis without beta-glucan (GI, 54). We conclude that barley beta-glucan significantly reduces GI of chapatis, particularly at doses of 4 and 8 g per serving.

Glycaemic index and glycaemic load values of commercially available products in the UK

The objective of this paper is to provide glycaemic index (GI) and glycaemic load (GL) values for a variety of foods that are commercially available in the UK and to compare these with previously published values. Fasted subjects were given isoglucidic (50 or 25 g carbohydrate) servings of a glucose reference at least two to three times, and test foods once, on separate occasions. For each test food, tests were repeated in at least eight subjects. Capillary blood glucose was measured via finger-prick samples in fasting subjects (0 min) and at 15, 30, 45, 60, 90 and 120 min after the consumption of each test food. The GI of each test food was calculated geometrically by expressing the incremental area under the blood glucose response curve (IAUC) of each test food as a percentage of each subjects average IAUC for the reference food. GL was calculated as the product of the test foods GI and the amount of available carbohydrate in a reference serving size. The majority of GI values of foods tested in the current study compare well with previously published values. More importantly, our data set provides GI values of several foods previously untested and presents values for foods produced commercially in the UK.

How well do children aged 5-7 years recall food eaten at school lunch?

OBJECTIVE This study aimed to determine the accuracy with which children aged 5 to 7 years were able to report the food eaten at a school lunch. SUBJECTS/SETTING Two hundred and three children (103 boys, 100 girls) aged 5-7 years were recruited from three primary schools in Oxford. DESIGN Trained investigators made observational records of the school dinner and packed lunch intakes of four or five children per session. Children were interviewed within two hours of finishing the lunchtime meal and asked to provide a free recall of their meal. When the child had completed the recall, non-directive prompts were used to assess if the child was able to remember anything else. Foods recalled were classified as matches (recalled food agreed with observation), omissions (failed to report a food observed) or phantoms (recalled food was not observed). RESULTS The percentage of accurate recall was significantly higher (P<0.01) in children eating packed lunch (mean 70 +/- 29%) than in children consuming school dinners (mean 58 +/- 27% ). This difference may have been due to increased familiarity of foods in packed lunches. Leftovers were not readily reported in this age group. Prompts and cues enhanced recall by all children. CONCLUSIONS This study indicated that there was a wide range in the ability of children aged 5-7 years to recall intake from a packed lunch and/or school dinner. This dietary assessment method is unlikely to be suitable at an individual level. Investigators using dietary recall to estimate food intake in children aged 5-7 years need to be aware of the limitations of this method.

Glycemic response and glycemic index of semolina spaghetti enriched with barley β-glucan.

OBJECTIVE The postprandial glycemic response and glycemic index (GI) of spaghetti made with semolina and the addition of two β-glucan barley concentrates, Glucagel (GG) and Barley Balance (BB), was studied. METHODS For each type of β-glucan concentrate, six spaghetti samples containing increasing percentages (0%, 2%, 4%, 6%, 8%, and 10%) of β-glucan were made. Nine healthy subjects were recruited for measuring the glycemic response and GI. Subjects were served portions of the test foods (50 g of available carbohydrates) and a reference food (50 g of glucose) on separate occasions. Capillary blood glucose was measured up to 120 min after consuming the spaghetti. The total glycemic response was calculated geometrically as the incremental areas under the curve (IAUC) using the trapezoid rule. The GI was calculated geometrically by expressing the IAUC for the test food as a percentage of each subjects average IAUC for the glucose. RESULTS The IAUC for spaghetti with and without β-glucan was significantly less compared with glucose. The GG spaghetti had IAUC values similar to the spaghetti without β-glucan concentrate. The BB spaghetti showed IAUC values lower than that of the spaghetti without β-glucan. In particular, the spaghetti with 10% BB had an IAUC 52% lower (P ≤ 0.017) than the spaghetti with β-glucan. The GI values for spaghetti with GG were statistically similar to the control. The GI of BB spaghetti decreased with increasing BB concentrations. In particular, the GI of 10% BB spaghetti was 54% lower (P ≤0.02; GI = 29) than that of the control (GI = 64). CONCLUSION The BB concentrate significantly decreases the IAUC and GI of spaghetti at a dose of 10%. GI at the same concentrations does not.

The influence of adding fats of varying saturation on the glycaemic response of white bread.

The aim of this study was to examine the effect of three different fats of varying degrees of saturation on the glycaemic response of white bread. Standard white bread was served alone or with 30 g butter, 24.8 g olive oil or 24.8 g grape-seed oil. On separate occasions, 15 subjects consumed the four test foods and reference food (glucose) in 50 g available carbohydrate amounts. Capillary blood glucose was measured from finger-prick samples in fasted subjects (−5 and 0 min) and at 15, 30, 45, 60, 90 and 120 min after starting to eat. All fats lowered the glycaemic response of bread; however, no significant differences in glycaemic index were recorded between the types of fat used when ingested with bread. The results of the present study suggest that the glycaemic response of bread can be lowered using any type of fat; therefore, the use of unsaturated fat is recommended for its potential lipidaemic advantage.

Effects of long-term intervention with low-and high-glycaemic-index breakfasts on food intake in children aged 8-11 years

The aim of the present study was to investigate the effects of long-term intervention of low-glycaemic-index (GI) v. high-GI breakfasts on energy and macronutrient intakes in children aged 8-11 years. Preadolescent children were assigned to one of two groups in a random cross-over design. Each group was given low-GI and high-GI breakfasts on two non-consecutive days per week for 10 weeks per breakfast type. Each breakfast provided approximately 1273 kJ (300 kcal) and was closely matched for macronutrient and dietary fibre content. Subsequent food intake at an ad libitum buffet lunch was recorded and daily energy and macronutrient intakes were measured by 24 h recall and 3 d food diaries. There was a tendency towards a reduced energy intake at lunch following the low-GI breakfast compared with the high-GI breakfast, although the mean difference of 75 kJ (18 kcal) was not significant (P = 0.406). In particular, there was a trend towards a reduced energy intake in the low-GI arm compared with the high-GI arm among boys. In addition, data from the 3 d food diaries showed that there was a tendency towards a reduced energy intake during the low-GI compared with the high-GI study period. In conclusion, although the difference in energy intake following the low-GI and high-GI breakfasts was not statistically significant, the reduced energy intake following the low-GI breakfast is encouraging. Both dietary fibre and carbohydrate type may affect GI, thus their potential and relative modulating effect on appetite requires further investigation.

Oxidative stability and shelf-life evaluation of selected culinary oils.

Four out of eight ‘healthier’ oils—namely, almond oil, avocado oil, hazelnut oil and macadamia nut oil—studied were rich sources of monounsaturated fatty acids like olive oil. Grape seed oil, rice barn oil (marketed recently), toasted sesame oil and walnut oil contained high levels of essential fatty acids. The order of oxidative stability determined by Rancimat measuring of the induction period at four temperatures (90°C, 100°C, 110°C, and 120°C) was found to be macadamia oil > rice bran oil ≈ toasted sesame oil > avocado oil > almond oil > hazelnut oil > grape seed oil > walnut oil. High-level monounsaturated fatty acid oils gave a linear relationship between 100 times the reciprocal of the induction period against the total unsaturated fatty acid content obtained as%C18:2 + 0.08 x%C18:1 + 2.08 x%C18:3, while the polyunsaturated fatty acid oils gave an exponential relationship. In the case of rice bran and hazelnut oils, shelf-life prediction from the extrapolation of the Arrhenius plots and the Q10 factors was compared well with that of storage time given by the oil producers. In the cases of the other oils (with an exception of macadamia nut oil), the predicted shelf-lives were significantly lower than that of the storage times; especially, walnut oil (very prone to oxidation) gave 15–20 times lower shelf-life than the best-before storage life.

Postmastication digestion factors influence glycemic variability in humans.

The glycemic response (GR) to food is influenced by both intrinsic and extrinsic factors. A consistent observation in GR studies is the wide within- and between-individual variations. The authors hypothesize that between-individual variations in the GR, insulin response (IR) and gastric emptying occur even when food particle size is standardized. Volunteers were tested on 2 nonconsecutive days after an overnight fast in randomized order. On 1 day, the volunteers consumed large (>2000 μm) rice particles, and on the second day, small rice particles (500-1000 μm). Subsequently, gastric emptying using the sodium [(13)C] acetate breath test (for 240 minutes) and GR and IR (for 120 minutes) from finger-prick blood samples were measured. The incremental area under the curve (IAUC) for the GR for small particles varied 45% more compared with whole rice. The small particles elicited a significantly greater GR IAUC than the large particles. The standard deviations associated with the IR IAUC for the small particles was 140% greater than that of the large particles. The total IAUC for IR was also significantly greater for the small particles than the large particles. The between-individual variations associated with gastric emptying times were similar for both samples. The gastric emptying latency phase, lag, and half time were significantly shorter for the small particles. Ingesting small particles causes faster gastric emptying and produces greater glycemic and IRs. Between-individual variations in GR and IR can be observed even when all the food associated factors including ingested particle size (mastication) are controlled for in humans.

Use of natural food flavours to increase food and nutrient intakes in hospitalized elderly in Hong Kong.

The present study investigated the effect of natural food flavours on food and nutrient intake in hospitalized elderly patients in Hong Kong. Food intake was directly measured for breakfast, lunch and dinner over five consecutive days -- two control days and three experimental days. For the three experimental days, six natural food flavours, based on familiarity of use and wide acceptance to the patient population, were added to each standard lunch and dinner meal. Each food item provided to each patient was weighed before and after consumption. Fourteen elderly subjects (≥65 years; seven males) from Shatin Hospital in Hong Kong participated in the study. The use of natural food flavours in the hospitalized elderly promoted increased food and macronutrient intakes. Total food, energy and fat intakes on day 3 were significantly increased (P=0.037, P=0.008 and P=0.019, respectively). Although total energy and protein intakes were increased by 13-26% and 15-28%, respectively, nutrient intakes remained low compared with requirements. Findings from this pilot study suggest a role for natural food flavours in the elderly. Whether food and nutrient intakes would have shown an increase in the absence of any intervention could not be determined. Further work to investigate the long-term effect of natural food flavours on food and nutrient intakes in the elderly is required.