Biomedical subjects

Kaisa S Poutanen

Publications and source records attributed to Kaisa S Poutanen.

6 recordsLinked to original sources

PubMed2006

Interaction between cholesterol and glucose metabolism during dietary carbohydrate modification in subjects with the metabolic syndrome.

BACKGROUND: Carbohydrate modification based on rye bread and pasta enhances early insulin secretion in subjects with the metabolic syndrome. OBJECTIVE: Because the actions of insulin and cholesterol metabolism are interrelated, the question is raised of whether it is possible to alter cholesterol metabolism by means of dietary carbohydrate modification. DESIGN: We investigated the 12-wk effects of dietary carbohydrate modification on cholesterol synthesis and absorption by measuring the ratios of surrogate markers of precursor (cholestenol, desmosterol, and lathosterol) and absorption (cholestanol and plant sterols) sterols to cholesterol and their association to glucose metabolism in 74 subjects with the metabolic syndrome. The subjects were randomly assigned to diets with rye bread and pasta (RPa) or oat, wheat bread, and potato (OWPo) as the main carbohydrate source (34% and 37% of energy intake, respectively). RESULTS: During the study, serum cholesterol concentrations remained unchanged. Cholesterol synthesis was lower (6-10% for cholestenol and lathosterol; P < 0.05) and absorption higher (9%; P < 0.05 for sitosterol) with the OWPo diet than at baseline. With the RPa diet, cholesterol absorption was lower and synthesis higher than with the OWPo diet. The increment in the glucose area under the curve with the RPa diet was positively related to baseline cholesterol synthesis (eg, lathosterol; r = 0.480, P < 0.05) and negatively to absorption (for cholestanol; r = -0.520, P < 0.05). In the combined group, the changes in the cholestanol ratio and the insulinogenic index were interrelated (r = -0.464, P < 0.001). CONCLUSIONS: Carbohydrate modifications had dissimilar effects on cholesterol metabolism. Consumption of RPa, as compared with OWPo, may be clinically more favorable because it seems to inhibit the absorption of cholesterol, a factor crucial in the development of arterial atherosclerosis.

Adult↗

PubMed2005

Suitability of a batch in vitro fermentation model using human faecal microbiota for prediction of conversion of flaxseed lignans to enterolactone with reference to an in vivo rat model.

BACKGROUND: In vitro fermentation models have been used widely for studies of shortchain fatty acid (SCFA) formation from carbohydrates, whereas the suitability of these methods for enterolactone (ENL) formation has received less attention. AIM: The aim was to study the suitability of an in vitro fermentation model for prediction of bioconversion of lignans to ENL, to compare the approach with that of an in vivo rat model and to study the SCFA formation in both models. METHODS: Predigested samples of rye bran (R), flaxseed meal (F) alone, or in combination with rye bran (R&F) and a faecal control were incubated in an in vitro fermentation model using human faecal microbiota. In the in vivo experiment rats consumed a non-fibre control diet (C) or diets supplemented either with rye bran (R), flaxseed meal (F) alone, or with their combination (R&F) for four weeks. Enterodiol (END), ENL and SCFA concentrations were measured from in vitro faecal fermentation samples and from the intestinal contents of rats. Plasma ENL concentrations from rats were also measured. RESULTS: The highest ENL production was found in vitro with the F supplement (areas under curve: 740 +/- 4, 7,500 +/- 400, 2,600 +/- 500 and 1,520 +/- 70 nmol x h for the R, F, R&F supplements and faecal control, respectively). In vivo, the concentration of ENL in caecal digesta from flaxseed meal was significantly (P < 0.05) enhanced by the presence of rye bran (medians 261, 407 and 24 nmol/g in the F, R&F and C groups, respectively). No correlation was found between the models regarding ENL production, possibly due to different responses to the presence of rye bran matrix, differences in microbiota or application of a batch in the in vitro fermentation model. Rye bran supplementation enhanced butyrate production both in vitro and in vivo. CONCLUSION: In vitro fermentation and the in vivo rat models responded differently to the presence of rye bran and no correlation with regard to the ENL formation from flaxseed lignans was observed.

4-Butyrolactone↗

PubMed2005

Dietary carbohydrate modification enhances insulin secretion in persons with the metabolic syndrome.

BACKGROUND: The metabolic syndrome markedly increases the risk of type 2 diabetes and cardiovascular disease, but the influence of dietary modification on insulin and glucose metabolism independent of weight loss is still poorly understood. OBJECTIVE: Our aim was to test whether carbohydrate dietary modifications improve insulin sensitivity and secretion and glucose tolerance in overweight or obese persons with the metabolic syndrome, even in the absence of weight loss. DESIGN: We assessed the effect of carbohydrate modification on insulin and glucose metabolism in 72 overweight or obese men and women with the metabolic syndrome, as determined according to the National Cholesterol Education Program criteria. The subjects were randomly assigned to 12-wk diets in which either rye bread and pasta or oat and wheat bread and potato were the main carbohydrate sources (34% and 37% of energy intake, respectively). RESULTS: Body weight did not significantly change in either group during the trial. No significant difference was observed in the changes in fasting glucose and insulin concentrations or in glucose and insulin areas under the curve between the groups during a 2-h oral-glucose-tolerance test. The insulinogenic index (an index of early insulin secretion) increased more in the rye bread and pasta group than in the oat and wheat bread and potato group (33.2% compared with 5.5%; P = 0.026). In the combined groups, an enhanced insulinogenic index was associated with improved glucose tolerance, whereas weight gain worsened glucose tolerance. Moreover, even modest weight gains abolished the relative improvement in the insulinogenic index in the rye bread and pasta group compared with the oat and wheat bread and potato group (P for the interaction between weight change and group = 0.019). CONCLUSIONS: Rye bread and pasta-based carbohydrate modification enhances early insulin secretion in persons with the metabolic syndrome, which may lower the risk of deteriorating glucose tolerance and development of type 2 diabetes.

Adult↗

PubMed2003

High-fiber rye bread and insulin secretion and sensitivity in healthy postmenopausal women.

BACKGROUND: Fiber and whole-cereal intakes may protect against hyperinsulinemia and the risk of type 2 diabetes. OBJECTIVE: The aim was to study whether the long-term use of high-fiber rye bread and white-wheat bread modifies glucose and insulin metabolism in healthy postmenopausal women. DESIGN: The study was a randomized crossover trial consisting of 8-wk test and 8-wk washout periods. The subjects were 20 postmenopausal women [macro x +/- SD age: 59 +/- 6.0 y; body mass index (in kg/m(2)): 27.5 +/- 2.9; baseline fasting serum cholesterol: 6.5 +/- 0.8 mmol/L], of whom 3 had impaired glucose tolerance as determined by a 2-h oral-glucose-tolerance test. The test breads were high-fiber rye and white-wheat breads, planned to make up > or =20% of energy. Fasting blood samples were collected for the measurement of plasma glucose and insulin at the beginning and at the end of both bread periods. The frequently sampled intravenous-glucose-tolerance test was performed at the run-in and at the end of both bread periods. The acute insulin response, insulin sensitivity, and glucose effectiveness were calculated. RESULTS: The rye bread made up 23.4 +/- 4.3% and wheat bread 26.7 +/- 8.2% of total energy intake. Compared with that during the run-in period, the acute insulin response increased significantly more during the rye bread period (9.9 +/- 24.2%) than during the wheat bread period (2.8 +/- 36.3%; P = 0.047). Other measured variables did not change significantly during the study. CONCLUSIONS: Modification of carbohydrate intake by high-fiber rye bread did not alter insulin sensitivity in postmenopausal, hypercholesterolemic women. High-fiber rye bread appears to enhance insulin secretion, possibly indicating improvement of b cell function.

Area Under Curve↗

PubMed2003

Structural differences between rye and wheat breads but not total fiber content may explain the lower postprandial insulin response to rye bread.

BACKGROUND: Rye bread has a beneficial effect on the postprandial insulin response in healthy subjects. The role of rye fiber in insulin and glucose metabolism is not known. OBJECTIVE: The aim of the study was to determine the effect of the content of rye fiber in rye breads on postprandial insulin and glucose responses. DESIGN: Nineteen healthy postmenopausal women aged 61 +/- 1 y, with a body mass index (in kg/m(2)) of 26.0 +/- 0.6, and with normal glucose tolerance participated in the study. The test products were refined wheat bread (control), endosperm rye bread, traditional rye bread, and high-fiber rye bread; each bread provided 50 g available carbohydrate and was served with breakfast. Plasma glucose, insulin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1, and serum C-peptide were measured in fasting and 8 postprandial blood samples. In vitro starch hydrolysis and the microscopic structure of the breads were also determined. RESULTS: Postprandial insulin, glucose-dependent insulinotropic polypeptide, and C-peptide responses to the rye breads were significantly lower than the response to the control; no significant differences in insulin and C-peptide responses to the rye breads were found. Glucose and glucagon-like peptide 1 responses to the rye breads were not significantly different from those to the control, except at 150 and 180 min. In vitro starch hydrolysis was slower in all rye breads than in the control, and the structure of continuous matrix and starch granules differed between the rye and control breads. CONCLUSION: Total fiber content does not explain the lower postprandial insulin response to rye bread than to wheat bread, but structural differences between rye and wheat breads might.

Blood Glucose↗

PubMed2002

Postprandial glucose, insulin, and incretin responses to grain products in healthy subjects.

BACKGROUND: Various botanical and structural characteristics of starchy food modify the postprandial glucose and insulin responses in humans. OBJECTIVE: We investigated what factors in grain products affect human glucose and insulin responses and elucidated the mediating mechanisms. DESIGN: Ten men and 10 women [mean age: 28 +/- 1 y; mean body mass index (in kg/m(2)): 22.9 +/- 0.7] with normal glucose tolerance were recruited. The test products were whole-kernel rye bread, whole-meal rye bread containing oat beta-glucan concentrate, dark durum wheat pasta, and wheat bread made from white wheat flour. Paracetamol, a marker of the rate of gastric emptying, was added to the breads during baking. Each product provided 50 g available carbohydrate and was served in random order with breakfast (except for the beta-glucan rye bread, which was served at the last visit). Fasting and 8 postprandial blood samples were collected at intervals of 15-30 min for 3 h to determine plasma glucose, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), serum insulin, and paracetamol concentrations. The in vitro starch hydrolysis, the structural characteristics (by light microscopy), and the molecular weight of beta-glucan in the test products were analyzed. RESULTS: Glucose responses and the rate of gastric emptying after consumption of the 2 rye breads and pasta did not differ from those after consumption of white wheat bread. However, insulin, GIP, and GLP-1 responses, except for GLP-1 responses to the rye bread containing oat beta-glucan concentrate, were lower after the consumption of rye breads and pasta than after consumption of white wheat bread. CONCLUSIONS: Postprandial insulin responses to grain products are determined by the form of food and botanical structure rather than by the amount of fiber or the type of cereal in the food. These effects may be mediated through GIP and GLP-1.

Acetaminophen↗