| 1. |
- Jenkins, David J A, et al.
(författare)
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Effect of wheat bran on glycemic control and risk factors for cardiovascular disease in type 2 diabetes.
- 2002
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Ingår i: Diabetes care. - 0149-5992. ; 25:9, s. 1522-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Cohort studies indicate that cereal fiber reduces the risk of diabetes and coronary heart disease (CHD). Therefore, we assessed the effect of wheat bran on glycemic control and CHD risk factors in type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 23 subjects with type 2 diabetes (16 men and 7 postmenopausal women) completed two 3-month phases of a randomized crossover study. In the test phase, bread and breakfast cereals were provided as products high in cereal fiber (19 g/day additional cereal fiber). In the control phase, supplements were low in fiber (4 g/day additional cereal fiber). RESULTS: Between the test and control treatments, no differences were seen in body weight, fasting blood glucose, HbA(1c), serum lipids, apolipoproteins, blood pressure, serum uric acid, clotting factors, homocysteine, C-reactive protein, magnesium, calcium, iron, or ferritin. LDL oxidation in the test phase was higher than that seen in the control phase (12.1 +/- 5.4%, P < 0.034). Of the subjects originally recruited, more dropped out of the study for health and food preference reasons from the control phase (16 subjects) than the test phase (11 subjects). CONCLUSIONS: High-fiber cereal foods did not improve conventional markers of glycemic control or risk factors for CHD in type 2 diabetes over 3 months. Possibly longer studies are required to demonstrate the benefits of cereal fiber. Alternatively, cereal fiber in the diet may be a marker for another component of whole grains that imparts health advantages or a healthy lifestyle.
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| 2. |
- Jenkins, David J A, et al.
(författare)
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Glycemic index: overview of implications in health and disease.
- 2002
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Ingår i: The American journal of clinical nutrition. - 0002-9165. ; 76:1
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Forskningsöversikt (refereegranskat)abstract
- The glycemic index concept is an extension of the fiber hypothesis, suggesting that fiber consumption reduces the rate of nutrient influx from the gut. The glycemic index has particular relevance to those chronic Western diseases associated with central obesity and insulin resistance. Early studies showed that starchy carbohydrate foods have very different effects on postprandial blood glucose and insulin responses in healthy and diabetic subjects, depending on the rate of digestion. A range of factors associated with food consumption was later shown to alter the rate of glucose absorption and subsequent glycemia and insulinemia. At this stage, systematic documentation of the differences that exist among carbohydrate foods was considered essential. The resulting glycemic index classification of foods provided a numeric physiologic classification of relevant carbohydrate foods in the prevention and treatment of diseases such as diabetes. Since then, low-glycemic-index diets have been shown to lower urinary C-peptide excretion in healthy subjects, improve glycemic control in diabetic subjects, and reduce serum lipids in hyperlipidemic subjects. Furthermore, consumption of low-glycemicindex diets has been associated with higher HDL-cholesterol concentrations and, in large cohort studies, with decreased risk of developing diabetes and cardiovascular disease. Case-control studies have also shown positive associations between dietary glycemic index and the risk of colon and breast cancers. Despite inconsistencies in the data, sufficient, positive findings have emerged to suggest that the dietary glycemic index is of potential importance in the treatment and prevention of chronic diseases.
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| 3. |
- Jenkins, D J, et al.
(författare)
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Dietary fibre, lente carbohydrates and the insulin-resistant diseases.
- 2000
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Ingår i: The British journal of nutrition. - 0007-1145. ; 83 Suppl 1
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Forskningsöversikt (refereegranskat)abstract
- Several epidemiological studies link consumption of fibre-rich foods to a reduced risk of type 2 diabetes and CHD. The 'fibre hypothesis' suggested that this was a direct effect of fibre. However, fibre-rich foods contain different types of fibre as well as other potentially beneficial compounds, and many foods naturally high in fibre have low glycaemic and insulinaemic indices, possibly due to food form. The question therefore emerges as to the effect of isolated fibre per se on insulin sensitivity, lipids and other risk factors associated with the metabolic syndrome. Many beneficial effects are seen with pharmacological doses of isolated viscous soluble fibre, including improved insulin sensitivity, decreased LDL-cholesterol levels and decreased clotting factors. Similar effects are seen with low glycaemic-index foods. In contrast, insoluble non-viscous cereal fibre is not seen to act directly on risk factors when taken in refined foods such as in milled flour. Since cereal fibre, the major type of fibre in western diets, does not directly act on the risk factors for the metabolic syndrome, the question remains as to possible mechanisms. Until now, fibre and the nature and processing of the starch and particle size have been seen as the main determinants of the metabolic response to starchy foods. However, fibre-rich foods also have an increased protein-to-carbohydrate ratio. Hence we suggest that the protective effect of fibre may also be due to increased vegetable protein content, which may act directly to reduce clotting factors and oxidized LDL-cholesterol levels.
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| 4. |
- Jenkins, D J, et al.
(författare)
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Viscous and nonviscous fibres, nonabsorbable and low glycaemic index carbohydrates, blood lipids and coronary heart disease.
- 2000
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Ingår i: Current opinion in lipidology. - 0957-9672. ; 11:1, s. 49-56
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Forskningsöversikt (refereegranskat)abstract
- Viscous fibres such as guar, glucomannans, pectins, oat betaglucan and psyllium continue to be seen as hypocholesterolaemic. Nevertheless, in large cohort studies, ironically it is the insoluble cereal fibre that has been demonstrated to relate negatively to cardiovascular disease and diabetes, despite an absence of effect on fasting lipids or postprandial glycaemia. In general, resistant or nonabsorbable starch is lipid neutral, whereas some nonabsorbable sugars or oligosaccharides may raise serum cholesterol, possibly through providing more acetate after colonic fermentation by colonic microflora. On the other hand, fructo-oligosaccharides appear to reduce serum triglycerides for reasons that are not entirely clear. Of possibly greater recent interest have been the carbohydrates that are not so much resistant to absorption, but rather are slowly absorbed. They possess some of the features of dietary fibre in providing a substrate for colonic bacterial fermentation. In the small intestine, however, they form lente or sustained release carbohydrate. In the form of low glycaemic index foods, lente carbohydrate consumption has been shown to relate to improved blood lipid profiles in hyperlipidaemic individuals and improved glycaemic control in diabetes. In larger cohort studies, low glycaemic index foods or low glycaemic load diets have been associated with higher HDL-cholesterol levels and reduced incidence of diabetes and cardiovascular disease.
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