Metabolic and Blood Pressure Effects of Consuming Two Kiwifruit Daily for 7 Weeks: A Randomised Controlled Trial

Background: Eating two kiwifruit before breakfast by equi-carbohydrate partial exchange of cereal has been associated with lower postprandial glucose and insulin, but it increases the intake of fruit sugar. We assessed the effects of kiwifruit ingestion at breakfast over 7 weeks on metabolic and physiologic factors. Method: Forty-three healthy Asian participants were randomised to ingest 500 mL of carbonated water (control) or 500 mL of carbonated water plus two kiwifruit (intervention), before breakfast. Three-day weighed diet records were taken before and at week 4 during the intervention. Overnight fasting blood samples were taken at baseline and week 7. Forty-two participants completed the study (n = 22 control, n = 20 intervention). Results: The kiwifruit group consumed more fructose, vitamin C, vitamin E, and carbohydrates as a percentage of energy compared with the control group (p < 0.01). There was no evidence of between-group changes in metabolic outcomes at the end of the intervention, with the following mean (95% confidence interval) differences in fasting blood samples: glucose 0.09 (−0.06, 0.24) mmol/L; insulin −1.6 (−3.5, 0.3) μU/mL; uric acid −13 (−30, 4) μmol/L; triglycerides −0.10 (−0.22, 0.03) mmol/L; and total cholesterol −0.05 (−0.24, 0.14) mmol/L. There was a −2.7 (−5.5, 0.0) mmHg difference in systolic blood pressure for the intervention group compared with the control group. Conclusion: Eating two kiwifruit as part of breakfast increased fruit consumption and intake of antioxidant nutrients without a change in fasting insulin. There was a difference in systolic blood pressure and no adverse fructose-associated increases in uric acid, triglycerides, or total cholesterol. This simple intervention may provide health benefits to other demographic groups.

How do we support walking prescriptions for type 2 diabetes management? Facilitators and barriers following a 3-month prescription

INTRODUCTION Prescribing physical activity is an inexpensive method to promote patients' long-term health, but determinants of adherence with physical activity prescriptions are seldom considered. AIM To identify facilitators and barriers experienced by adults with type 2 diabetes when prescribed regular walking. METHODS Participants were prescribed a regular walking routine that met current physical activity guidelines for type 2 diabetes management for a period of 3 months. Pre- and post-intervention questions considered participants' self-rated health and physical activity amount. Thematic analysis of recorded interviews held after the 3-month prescription identified barriers and facilitators to adherence for participants. RESULTS Twenty-eight adults (aged 60±9 years, body mass index 32.3±4.0kg/m2, HbA1c 59±16mmol/mol) participated in the 3-month intervention, providing 7 years of lived experience. Self-rated health (14%; 95% confidence interval (CI) 7-22%) and time spent walking (+11 min/day; 95% CI 4-18 min/day) increased following the prescription. Major themes motivating participants were: establishing a walking routine; the support of their family members; observing health benefits; and being monitored by a health professional. The greatest barriers were associated with walking in the evening and included feelings of insecurity in the dark or a preference for sedentary behaviour. DISCUSSION A prescription to walk increased time spent in physical activity and self-rated health in adults with type 2 diabetes. Health-care professionals can support walking prescriptions by promoting facilitators and reducing barriers to prescription adherence. Practical solutions to barriers include identifying alternative physical activity opportunities within the house or advice to develop support networks to provide company while walking.

Comparison of Self-Reported Speed of Eating with an Objective Measure of Eating Rate

Slow eating may be beneficial in reducing energy intake although there is limited research quantifying eating rate. Perceived speed of eating was self-reported by 78 adults using a standard question “On a scale of 1–5 (very slow–very fast), how fast do you believe you eat?” Timing the completion of meals on three occasions was used to assess objective eating rate. The mean (SD) speeds of eating by self-reported categories were 49 (13.7), 42 (12.2), and 35 (10.5) g/min for fast, medium, and slow eaters, respectively. Within each self-reported category, the range of timed speed of eating resulted in considerable overlap between self-identified ‘fast’, ‘medium’ and ‘slow’ eaters. There was 47.4% agreement (fair) between self-reported speed of eating and the objective measure of eating rate (κ = 0.219). Self-reported speed of eating was sufficient at a group level to detect a significant difference (10.9 g/min (95% CI: 2.7, 19.2 g/min, p = 0.009)) between fast and slow; and fast and medium eaters (6.0 g/min (0.5, 11.6 g/min p = 0.033)). The mean difference (95% CI) between slow and medium eaters was 4.9 (−3.4, 12.2) g/min (p = 0.250). At an individual level, self-report had poor sensitivity. Compared to objectively measured speed of eating, self-reported speed of eating was found to be an unreliable means of assessing an individual’s eating rate. There are no standard protocols for assessing speed of eating or eating rate. Establishing such protocols would enable the development of population reference ranges across various demographic groups that may be applicable for public health messages and in clinical management.

Cognitive Performance Following Ingestion of Glucose-Fructose Sweeteners That Impart Different Postprandial Glycaemic Responses: A Randomised Control Trial

We aimed to investigate the isolated effect of glycaemia on cognitive test performance by using beverages sweetened with two different glucose–fructose disaccharides, sucrose and isomaltulose. In a randomised crossover design, 70 healthy adults received a low-glycaemic-index (GI) isomaltulose and sucralose beverage (GI 32) and a high-GI sucrose beverage (GI 65) on two occasions that were separated by two weeks. Following beverage ingestion, declarative memory and immediate word recall were examined at 30, 80 and 130 min. At 140 min, executive function was tested. To confirm that the glycaemic response of the test beverages matched published GI estimates, a subsample (n = 12) of the cognitive testing population (n = 70) underwent glycaemic response testing on different test days. A significantly lower value of mean (95% CI) blood glucose concentration incremental area under the curve (iAUC) was found for isomaltulose, in comparison to the blood glucose concentration iAUC value for sucrose, the difference corresponding to −44 mmol/L∙min (−70, −18), p = 0.003. The mean (95% CI) difference in numbers of correct answers or words recalled between beverages at 30, 80 and 130 min were 0.1 (−0.2, 0.5), −0.3 (−0.8, 0.2) and 0.0 (−0.5, 0.5) for declarative memory, and −0.5 (−1.4, 0.3), 0.4 (−0.4, 1.3) and −0.4 (−1.1, 0.4) for immediate free word recall. At 140 min, the mean difference in the trail-making test between beverages was −0.3 sec (−6.9, 6.3). None of these differences were statistically or clinically significant. In summary, cognitive performance was unaffected by different glycaemic responses to beverages during the postprandial period of 140 min.

Vitamin B12 Status of Various Ethnic Groups Living in New Zealand: An Analysis of the Adult Nutrition Survey 2008/2009

Vitamin B12 deficiency leads to serious health problems, whilst sub-optimal status is associated with raised biochemical markers of disease risk. Identifying at-risk groups could benefit both individuals and public health. Dietary data were sourced from the New Zealand Adult Nutrition Survey 2008/2009, involving a nationally representative sample of 4721 participants. Ethnic groupings were by regional origin: Māori and Pacific Islands, New Zealand European, East and South-East Asian, and South Asian. Diets were assessed using 24-h recalls and from responses to a questionnaire. Blood samples were obtained from a subset (n = 3348). The mean (95% CI) vitamin B12 intake of the Māori and Pacific Islands group was 5.1 (4.7, 5.5) µg/day, New Zealand Europeans 4.1 (3.8, 4.3) µg/day, East and South-East Asians 4.5 (3.7, 5.3) µg/day, and South Asians 3.0 (2.5, 3.6) µg/day. Overall, 20.1% of the sample had vitamin B12 inadequacy (<221 pmol/L). South Asians had the lowest vitamin B12 concentration at 282 (251, 312) pmol/L, whilst Māori/Pacific and East/South-East Asians had the highest, at 426 (386, 466) and 425 (412, 437) pmol/L, respectively. The main dietary determinant of serum vitamin B12 concentration was whether or not people ate red meat, with a regression coefficient of 27.0 (95% CI: 6.6, 47.5). It would be helpful for health agencies to be aware of the potential for compromised vitamin B12 status in South Asian communities.

Effect of Cold Storage and Reheating of Parboiled Rice on Postprandial Glycaemic Response, Satiety, Palatability and Chewed Particle Size Distribution

Background: Globally, hot cooked refined rice is consumed in large quantities and is a major contributor to dietary glycaemic load. This study aimed to compare the glycaemic potency of hot- and cold-stored parboiled rice to widely available medium-grain white rice. Method: Twenty-eight healthy volunteers participated in a three-treatment experiment where postprandial blood glucose was measured over 120 min after consumption of 140 g of rice. The three rice samples were freshly cooked medium-grain white rice, freshly cooked parboiled rice, and parboiled rice stored overnight at 4 °C. All rice was served warm at 65 °C. Chewing time was recorded. Results: incremental area under the curve (iAUC) of the control rice, freshly cooked medium-grain white rice, was the highest: 1.7-fold higher (1.2, 2.6) than reheated parboiled rice (p < 0.001) and 1.5-fold higher (1.0, 2.2) than freshly cooked parboiled rice (p = 0.001). No significant difference in postprandial glycaemic response was observed between freshly cooked and reheated parboiled rice samples (p = 0.445). Chewing time for 10 g cold-stored parboiled rice was 6 s (25%) longer and was considered more palatable, visually appealing and better tasting than freshly cooked medium-grain (all p < 0.05). Conclusions: For regular consumers of rice, reheating cooked rice after cold storage would lower the dietary glycaemic load and, in the long term, may reduce the risk for type 2 and gestational diabetes. More trials are needed to identify the significance.

Calculating meal glycemic index by using measured and published food values compared with directly measured meal glycemic index

BACKGROUND

Glycemic index (GI) testing is normally based on individual foods, whereas GIs for meals or diets are based on a formula using a weighted sum of the constituents. The accuracy with which the formula can predict a meal or diet GI is questionable.

OBJECTIVE

Our objective was to compare the GI of meals, obtained by using the formula and by using both measured food GI and published values, with directly measured meal GIs.

DESIGN

The GIs of 7 foods were tested in 30 healthy people. The foods were combined into 3 meals, each of which provided 50 g available carbohydrate, including a staple (potato, rice, or spaghetti), vegetables, sauce, and pan-fried chicken.

RESULTS

The mean (95% CI) meal GIs determined from individual food GI values and by direct measurement were as follows: potato meal [predicted, 63 (56, 70); measured, 53 (46, 62)], rice meal [predicted, 51 (45, 56); measured, 38 (33, 45)], and spaghetti meal [predicted, 54 (49, 60); measured, 38 (33, 44)]. The predicted meal GIs were all higher than the measured GIs (P < 0.001). The extent of the overestimation depended on the particular food, ie, 12, 15, and 19 GI units (or 22%, 40%, and 50%) for the potato, rice, and spaghetti meals, respectively.

CONCLUSIONS

The formula overestimated the GI of the meals by between 22% and 50%. The use of published food values also overestimated the measured meal GIs. Investigators using the formula to calculate a meal or diet GI should be aware of limitations in the method. This trial is registered with the Australian and New Zealand Clinical Trials Registry as ACTRN12611000210976.