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At least 19 recordsLinked to original sources

Carbohydrates, dietary fiber, and incident type 2 diabetes in older women.

BACKGROUND: Dietary carbohydrates may influence the development of type 2 (non-insulin-dependent) diabetes, for example, through effects on blood glucose and insulin concentrations. OBJECTIVE: We examined the relations of baseline intake of carbohydrates, dietary fiber, dietary magnesium, and carbohydrate-rich foods and the glycemic index with incidence of diabetes. DESIGN: This was a prospective cohort study of 35988 older Iowa women initially free of diabetes. During 6 y of follow-up, 1141 incident cases of diabetes were reported. RESULTS: Total grain, whole-grain, total dietary fiber, cereal fiber, and dietary magnesium intakes showed strong inverse associations with incidence of diabetes after adjustment for potential nondietary confounding variables. Multivariate-adjusted relative risks of diabetes were 1.0, 0.99, 0.98, 0.92, and 0.79 (P for trend: 0.0089) across quintiles of whole-grain intake; 1.0, 1.09, 1.00, 0.94, and 0.78 (P for trend: 0.005) across quintiles of total dietary fiber intake; and 1.0, 0.81, 0.82, 0.81, and 0.67 (P for trend: 0.0003) across quintiles of dietary magnesium intake. Intakes of total carbohydrates, refined grains, fruit and vegetables, and soluble fiber and the glycemic index were unrelated to diabetes risk. CONCLUSION: These data support a protective role for grains (particularly whole grains), cereal fiber, and dietary magnesium in the development of diabetes in older women.

Aged↗

Metabolic responses to dietary carbohydrates: interactions of dietary and hereditary factors.

It has been demonstrated that the metabolic responses to ingested carbohydrate depend on the genetic make-up of the recipient; the type of the ingested carbohydrate molecule, and the amount and nature of protein, fat and the different trace elements in the diet. All of these elements affect the glucose tolerance, the insulin response, the number of insulin receptors and the blood lipids and the hepatic content and synthesis. The metabolic responses differ between and within species. Experiments with the selection and feeding of animals with different genetic susceptibility to the same carbohydrate intake may explain why individuals or groups with different sensitivity may develop high blood glucose and/or lipid levels, whereas other individuals will retain normal values on consuming the same amount of the carbohydrate. This also explains why, in the same community, only a certain percentage of the population will develop diabetes or carbohydrate-induced lipidemia while others will not.

Animals↗

Limited effect of refined carbohydrate dietary supplementation on colonization of the gastrointestinal tract of healthy subjects by Candida albicans.

BACKGROUND: Infections due to Candida albicans occur readily in situations in which ample glucose is available. In mice, dietary refined carbohydrate supplementation leads to higher rates of Candida growth in the gastrointestinal tract and favors mucosal invasion. OBJECTIVE: The modulating properties of dietary carbohydrate supplementation on colonization of the human gastrointestinal tract by C. albicans were evaluated. DESIGN: A 2-step study was conducted in 28 healthy volunteers. First, we determined the subjects' habitual uptake of refined carbohydrates and correlated these data with the C. albicans blastoconidia concentration in the mouth washes and feces of subjects with no intervention. Second, we compared C. albicans counts in the specimens before, during, and after a high-sugar diet. RESULTS: No correlation between C. albicans counts in the specimens and the habitual uptake of refined carbohydrates was observed. A high-sugar diet did not increase the frequency of C. albicans-positive samples, the number of subjects positive for C. albicans in the mouth washes, or the concentration of candidal blastoconidia in the samples of the 28 subjects. However, in selected subjects with elevated counts of oral C. albicans, we observed an increase in fecal C. albicans counts in response to the diet. CONCLUSIONS: The effect of adding a high amount of refined carbohydrates to the diet of healthy human subjects has a limited influence on Candida colonization. Follow-up studies should define whether selected patient groups might benefit from dietary restriction of refined carbohydrates.

Adolescent↗

Alterations in carbohydrate metabolism in response to short-term dietary carbohydrate restriction.

Dietary carbohydrate restriction (CR) presents a challenge to glucose homeostasis. Despite the popularity of CR diets, little is known regarding the metabolic effects of CR. The purpose of this study was to examine changes in whole body carbohydrate oxidation, glucose availability, endogenous glucose production, and peripheral glucose uptake after dietary CR, without the confounding influence of a negative energy balance. Postabsorptive rates of glucose appearance in plasma (R(a); i.e., endogenous glucose production) and disappearance from plasma (R(d); i.e., glucose uptake) were measured using isotope dilution methods after a conventional diet [60% carbohydrate (CHO), 30% fat, and 10% protein; kcals = 1.3 x resting energy expenditure (REE)] and after 2 days and 7 days of CR (5% CHO, 60% fat, and 35% protein; kcals = 1.3 x REE) in eight subjects (means +/- SE; 29 +/- 4 yr; BMI 24 +/- 1 kg/m(2)) during a 9-day hospital visit. Postabsorptive plasma glucose concentration was reduced (P = 0.01) after 2 days but returned to prediet levels the next day and remained at euglycemic levels throughout the diet (5.1 +/- 0.2, 4.3 +/- 0.3, and 4.8 +/- 0.4 mmol/l for prediet, 2 days and 7 days, respectively). Glucose R(a) and glucose R(d) were reduced to below prediet levels (9.8 +/- 0.6 micromol x kg(-1) x min(-1)) after 2 days of CR (7.9 +/- 0.3 micromol x kg(-1) x min(-1)) and remained suppressed after 7 days (8.3 +/- 0.4 micromol x kg(-1) x min(-1); both P < 0.001). A greater suppression in carbohydrate oxidation, compared with the reduction in glucose R(d), led to an increased (all P </= 0.05) rate of nonoxidative glucose disposal at 7 days (5.2 +/- 0.5 micromol x kg(-1) x min(-1)), compared with 2 days (2.7 +/- 0.5 micromol x kg(-1) x min(-1)) and prediet (1.6 +/- 0.8 micromol x kg(-1) x min(-1)). In response to eucaloric CR, a marked increase in nonoxidative glucose disposal may help maintain systemic glucose availability.

Adaptation, Physiological↗

Apolipoprotein A1 expression in young and aged rats is modulated by dietary carbohydrates.

To determine if dietary carbohydrates modulate apolipoprotein A1 (ApoA1) expression, plasma ApoA1 protein and hepatic ApoA1 mRNA levels were measured in young and aged rats maintained on a high-fructose (60% of diet weight consisting of fructose), or high-glucose (60% glucose) diet or fed regular rat chow for 10 days. Aged rats on regular chow had significantly higher plasma ApoA1 concentrations and hepatic ApoA1 mRNA than young rats maintained on this diet. Plasma ApoA1 and hepatic ApoA1 mRNA levels in young rats or aged rats maintained on the 60% fructose diet were significantly higher than in rats within the same age group maintained on regular rat chow (P < .01). Similar induction of ApoA1 protein and mRNA was found in rats maintained on the 60% glucose diet (P < .01). It is concluded that ApoA1 expression in rats is modulated by factors related to the nature of dietary carbohydrates rather than insulin resistance associated with high-fructose feeding.

Aging↗

Dietary carbohydrates and glucose metabolism in diabetic patients.

Dietary carbohydrates represent one of the major sources of energy for the human body. However, the main (if not the only) therapy for diabetes since ancient times has been based on reducing dietary carbohydrates drastically because of their effects on blood glucose levels. The introduction of insulin in the 1920s and then of oral hypoglycaemic drugs led to various studies evaluating the biochemical characteristics of carbohydrates and their effects on glucose metabolism in diabetic patients. This review considers the role of dietary carbohydrates in the diet of diabetic patients in the light of the most recent studies and provides a short summary of the biochemistry of carbohydrates and the physiology of carbohydrate digestion.

Blood Glucose↗

A new look at dietary carbohydrate: chemistry, physiology and health. Paris Carbohydrate Group.

The current view of dietary carbohydrates as simply providing us with energy is outdated. Because of their varied chemistry and physical form the rate and extent to which the different types are digested in and absorbed from the small intestine varies. This in turn leads to affects on satiety, blood glucose and insulin, protein glycosylation, lipids and bile acids. Some carbohydrates reach the colon where they are fermented and affect many aspects of large bowel function, colonocyte and hepatic metabolism. A new framework for classifying and measuring food carbohydrates is needed to allow a greater understanding of the role of individual species in health and to inform the public of their importance. A classification based primarily on molecular size (degree of polymerisation) into sugars, oligosaccharides and polysaccharides, is suggested, with sub-groups identified by the nature of the monosaccharides. Greater knowledge of the chemical and physical properties of carbohydrates allow a more precise relation with physiology and health to be drawn. The Carbohydrate Group met in Paris in December 1995 at the invitation of Gerard Pascal, Director of CNERNA. Financial support for the meeting was provided by CNERNA.

Carbohydrates↗

Energy metabolism in relation to physical activity in growing pigs as affected by type of dietary carbohydrate.

The effect of dietary carbohydrate source on physical activity in relation to metabolic rate in pigs was studied. Six groups of 12 pigs (50-kg, castrated males) were fed one of two diets: a starch diet or a non-starch polysaccharide (NSP) diet. Both diets had a similar calculated net energy content. The starch diet contained 13% tapioca, and the NSP diet contained 17% sugar beet pulp silage. Pigs were housed in groups and fed at approximately two times maintenance (approximately 900 kJ ME.kg-.75.d-1). Nitrogen and energy balances were measured per group during a 7-d experimental period, which was preceded by a 2-wk adaptation period. Heat production and physical activity were measured during successive discrete 9-min intervals. Metabolizability of gross energy was 79.4% and 78.2% for the starch-fed and NSP-fed pigs, respectively (P < .10). Activity differed between treatments. Activity-related heat production tended to be higher for the starch-fed pigs than for those fed the NSP diet (P < .10); 118 and 90 kJ.kg-.75.d-1, respectively. During the dark phase of the day (from 2000 to 0800) activity-related heat production was 8 kJ.kg-.75.d-1 higher for the starch fed pigs than for those fed the NSP diet (P > .1) whereas during the light phase, this difference was 48 kJ.kg-.75.d-1 (P < .10). Retained energy was similar for both treatments. These results show that dietary composition can change physical activity of pigs and thereby affect their energy utilization.

Animals↗

Crypt-villus site of glucose transporter induction by dietary carbohydrate in mouse intestine.

Intestinal brush-border glucose uptake rate is regulated by dietary carbohydrate level. However, this uptake response takes a day or more after a change in dietary carbohydrate level. Is this dietary signal perceived in the crypts, and is the glucose transporter activity of enterocytes irreversibly programmed there? If so, this time lag could reflect cell migration times along the crypt-villus axis, since glucose transport is not fully expressed until cells reach the midvillus. Alternatively, however, the time lag could arise from the induction process itself, if glucose transporter activity in mature villus enterocytes can be reversibly reprogrammed by dietary carbohydrate levels. Hence, we measured glucose-protectable phlorizin binding (as a measure of glucose transporter site density) in mouse enterocytes fractionated along the crypt-villus axis by the Weiser method, as a function of time after an abrupt switch in dietary carbohydrate level. For an increase or decrease in dietary carbohydrate, an increase or decrease in phlorizin binding site density first appeared in the crypts and marched over the course of several days to the villus tips. Hence, the signal for glucose transporter regulation is perceived in the crypts, and the observed lag in uptake is due largely to cell migration times.

Animals↗

Restriction of maternal dietary carbohydrate decreases fetal brain indoles and glycogen in rats.

In spite of evidence that dietary carbohydrate can increase brain tryptophan and 5-hydroxytryptamine in adult rats, the possible influence of maternal dietary carbohydrate on fetal brain indoles has received little attention. We studied the effect of graded levels (0, 4, 12 and 60%) of maternal dietary fructose or glucose fed throughout pregnancy on fetal brain glycogen and indoles. The diets were isoenergetic and met the NRC energy requirements for pregnant rats. The results demonstrated that low maternal dietary carbohydrate, with adequate energy intake, reduced fetal brain weight and concentrations of glycogen, tryptophan, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid. There were no significant differences between glucose and fructose feeding at any dietary carbohydrate level for any fetal brain measurements, showing that it was the level and not the type of dietary carbohydrate that was important. Significant correlations between fetal brain 5-hydroxytryptamine and brain glycogen, and between fetal brain 5-hydroxytryptamine and brain weight, suggested that lowered brain 5-hydroxytryptamine was only one symptom of disrupted brain development in fetuses of dams fed low levels of carbohydrate. The results show that dietary carbohydrate restriction during pregnancy can have adverse effects on fetal brain development, glycogen levels, and neurotransmitter synthesis even when maternal dietary protein and energy intake are adequate.

Animals↗

Seasonal variation in amount of unabsorbed dietary carbohydrate from the intestine after breakfast in Japanese subjects.

We previously showed that daytime dim-light exposure has a negative effect on the efficiency of dietary carbohydrate absorption in the evening, whereas evening-time dim-light exposure has a beneficial effect. These results suggest that seasonal changes in the environmental light may affect gastrointestinal activity, and that there might, therefore, be seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine. In order to prove this hypothesis, we measured the amount of dietary carbohydrate unabsorbed from the intestine after a breakfast in healthy female Japanese subjects during the four seasons of the year. We estimated the amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air. A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 12 subjects in Osaka and 14 subjects in Nagano, were studied in the winter (January to February), spring (April to May), summer (July to August), and autumn (October to November) of 2004. We found the following results: (1) In no season were there any significant differences between the two subgroups in the orocecal transit time of the breakfast and the lactosucrose solution. Nor were there any significant differences in the amount of unabsorbed dietary carbohydrate from the breakfast. (2) Using the pooled data of the total of 26 subjects, there was no significant seasonal variation in the orocecal transit time of the breakfast or the lactosucrose solution. (3) There was a significant seasonal variation in the amount of unabsorbed dietary carbohydrate from the breakfast. (4) The amount of unabsorbed dietary carbohydrate from the breakfast was largest in winter and smallest in autumn. Results in spring and in summer were similar and intermediate between those in winter and autumn. Post hoc multiple comparison tests showed that the amount of unabsorbed dietary carbohydrate in winter was significantly larger than in autumn. (5) In winter, the average ratio of the amount of unabsorbed dietary carbohydrate to the total amount of carbohydrate in the breakfast was about 12%; in autumn it was about 6%. These results clearly show that there is seasonal variation in the efficiency of intestinal dietary carbohydrate absorption among young female Japanese subjects.

Adult↗