ABSTRACT
Potatoes, especially mashed potatoes, are known to result in high glycaemic and insulinaemic responses. However, in most meals, potatoes are accompanied by other foods. The objective of the present study was to investigate how glycaemic and insulinaemic responses to a mashed potato meal changed when a high-fat food (rapeseed oil), a high-protein food (chicken breast) and/or salad were added to the meal. Healthy subjects (n 11) ingested the test meals once and the reference food (glucose solution) twice in a random order at 1-week intervals. Capillary blood samples were then drawn for 2 h, and glucose and insulin were analysed. The 2 h glycaemic responses to six mashed potato-containing meals varied more than twofold. The glycaemic index (GI) of pure mashed potato was 108, whereas combined with chicken breast, rapeseed oil and salad, it was only 54. The latter GI also differed considerably from its predicted value of 103, which was based on the individual GI of the components of the meal. The insulinaemic indices of the mashed potato-based meals varied between 94 and 148. Chicken breast in the meal increased the insulinaemic response, and rapeseed oil diminished it. However, the insulinaemic response to mashed potato with chicken breast and rapeseed oil was lower than that to mashed potato alone. In conclusion, the protein, fat and salad contents of a meal exert considerable influence on the glycaemic and insulinaemic responses to mashed potatoes. Furthermore, the estimation of the GI of a mixed meal by calculation is imprecise.
Subject(s)
Blood Glucose/metabolism , Dietary Carbohydrates/metabolism , Dietary Fats/pharmacology , Dietary Proteins/pharmacology , Glycemic Index/drug effects , Insulin/blood , Solanum tuberosum , Adult , Animals , Chickens , Diet , Energy Metabolism/drug effects , Fatty Acids, Monounsaturated , Female , Humans , Male , Meat , Middle Aged , Plant Oils/pharmacology , Plant Tubers , Plants , Rapeseed Oil , Reference Values , Vegetables , Young AdultABSTRACT
BACKGROUND: Methodologic choices affect measures of the glycemic index (GI). The effects on GI values of blood sampling site, reference food type, and the number of repeat tests have been insufficiently determined. OBJECTIVE: The objective was to study the effect of methodologic choices on GI values. Comparisons were made between venous and capillary blood sampling and between glucose and white bread as the reference food. The number of tests needed for the reference food was assessed. Rye bread, oatmeal porridge, and instant mashed potato were used as the test foods. DESIGN: Twelve healthy volunteers were served each test food once and both reference foods 3 times at 1-wk intervals in a random order after they had fasted overnight. Capillary and venous blood samples were drawn at intervals for 3 h after each study meal. RESULTS: GIs and their CVs based on capillary samples were lower than those based on venous samples. Two tests of glucose solution as the reference provided stable capillary GIs for the test foods. The capillary GIs did not differ significantly when white bread was used as the reference 1, 2, or 3 times, but the variation was lower when tests were performed 2 and 3 times. Capillary GIs with white bread as the reference were 1.3 times as high as those with glucose as the reference. The capillary GIs of rye bread, oatmeal porridge, and mashed potato were 77, 74, and 80, respectively, with glucose as the reference. CONCLUSIONS: Capillary blood sampling should be used in the measurement of GI, and reference tests with glucose or white bread should be performed at least twice.
Subject(s)
Blood Glucose/metabolism , Dietary Carbohydrates/metabolism , Glycemic Index , Insulin/blood , Adult , Area Under Curve , Avena , Capillaries , Cross-Over Studies , Female , Glycemic Index/physiology , Humans , Male , Middle Aged , Reference Values , Secale , Solanum tuberosum , VeinsABSTRACT
OBJECTIVE: To assess whether lifestyle counselling is effective in non-pharmacological treatment of hypertension in primary health care. DESIGN: Open randomized controlled trial. SETTING: Ten municipal primary health care centres in eastern Finland. PATIENTS: Seven hundred and fifteen subjects aged 25-74 years with systolic blood pressure 140-179 mmHg and/or diastolic blood pressure 90-109 mmHg or antihypertensive drug treatment. INTERVENTIONS: Systematic health counselling given by local public health nurses for 2 years. MAIN OUTCOME MEASURES: Blood pressure, lipids and lifestyle data were collected annually. RESULTS: Among participants with no antihypertensive drug treatment, the net reductions after 1 year both in systolic blood pressure [-2.6 mmHg; 95% confidence interval (CI), -4.7 to -0.5 mmHg] and in diastolic blood pressure (-2.7 mmHg; 95% CI, -4.0 to -1.4 mmHg) were significant in favour of the intervention group. This difference in blood pressure change was maintained during the second year. In participants with antihypertensive drug treatment, no significant difference in blood pressure reduction was seen between the groups during the study. CONCLUSIONS: A relatively modest, but systematic counselling in primary health care can, at least among untreated hypertensive subjects, produce reductions in blood pressure levels that are modest for the individual, but very important from the public health point of view.
