Metabolic effects of high-carbohydrate, high-fiber diets for insulin-dependent diabetic individuals.

The metabolic effects of high-carbohydrate (70%), high-fiber (70 g) (HCHF) and low-carbohydrate (39%), low-fiber (10 g) (LCLF) diets were examined for 10 subjects with insulin-dependent diabetes mellitus (IDDM). After a 1-wk control period subjects on a metabolic ward were randomly allocated to HCHF or LCLF diets for 4 wk. After a 6-wk washout period subjects re-entered the metabolic ward for 4 wk on the alternate diet. Artificial-pancreas studies were performed on each diet for measurement of insulin requirements. Compared with the LCLF diet, the HCHF diet reduced basal insulin requirements (P less than 0.025), increased carbohydrate disposed of per unit insulin (P less than 0.0008), and lowered total (P less than 0.0004) and high-density-lipoprotein cholesterol (P less than 0.0013). Glycemic control and other lipid fractions did not differ significantly. These results suggest that in IDDM patients, HCHF diets enhance peripheral glucose disposal, decrease basal insulin requirements, and lower total cholesterol without altering glycemic control or triglycerides.     

Metabolic consequences of the alpha-glucosidase inhibitor BAY-M-1099 given to nondiabetic and diabetic rats fed a high-carbohydrate diet

The effect of a new alpha-glucosidase inhibitor BAY-M-1099 on postprandial glucose levels in nondiabetic and diabetic rats after sucrose loading was studied. Evaluation was also made of the metabolic consequences of the addition of BAY-M-1099 to a high-carbohydrate diet consisting of equal quantities of wheat starch and sucrose (Diet A). This drug significantly reduced (p less than 0.05) postprandial glucose levels in nondiabetic and diabetic rats after sucrose loading. BAY-M-1099 led to a significant reduction in urinary glucose loss (177.8 +/- 54.2 vs 98.9 +/- 35.6 mmol/L) and in postprandial plasma glucose levels in diabetic rats fed diet A. Addition of BAY-M-1099 to the diet of nondiabetic rats significantly (p less than 0.05) decreased the postprandial plasma glucose level at 45, 90, 180, and 225 min after a meal test. Addition of BAY-M-1099 to a diet containing starch plus sucrose led to reduced glycosuria and serum glucose levels and may have potential benefit in the management of diabetes mellitus.     

Adherence to high-carbohydrate, high-fiber diets: long-term studies of non-obese diabetic men

High-carbohydrate, high-fiber (HCF) diets provide short-term benefits for selected individuals with diabetes. Long-term effects of HCF diets, however, have not previously been documented. The effectiveness and acceptability of HCF diets for 14 men with diabetes followed for 4 years as outpatients were assessed. Hospital HCF diets with 70% of energy as carbohydrate and 65 gm plant fiber daily lowered insulin doses, serum cholesterol, and triglycerides. Home HCF diets with 55% to 60% carbohydrate and 50 gm plant fiber daily sustained improvements throughout the observed period of up to 86 months. Of the 11 patients for whom diet adherence was evaluated, 9 had good to excellent adherence, 1 had fair adherence, and 1 had poor adherence.     

Reduction of risk factors for atherosclerosis in diabetic patients treated with a high-fiber diet

A protective effect of dietary fiber against atherosclerosis could be mediated through the influence of fiber on risk factors such as hyperlipidemia and hyperglycemia. To clarify this matter 14 diabetic patients (6 insulin-dependent and 8 noninsulin-dependent) were submitted, in metabolic ward conditions, to three weight maintaining diets for 10 days each: Diet A (carbohydrates 53%, lipids 30%, proteins 17%, fiber 20 g); Diet B, identical to diet A except for its fiber content (54 g); Diet C, lower in fiber and carbohydrates (carbohydrates 42%, lipids 37%, proteins 21%, fiber 20 g). The three diets were similar in their $\text{P}\text{S}$ ratio and were composed only of natural foodstuffs. The 2-hr postprandial blood glucose concentration and the daily blood glucose were significantly lower during the high-fiber diet than during either diet A or C as were total and low-density lipoprotein (LDL) cholesterol. Very low-density lipoprotein triglyceride (VLDL-TG) was significantly lower during the high-fiber diet in comparison with diet A, but then did not change during diet C. The hypolipidemic effect of a fiber-rich diet was then evaluated in hyperlipidemic patients (type II) with diabetes (n = 5) and without diabetes (n = 6). LDL cholesterol was significantly reduced by the high-fiber diet in both groups. However, in diabetic patients LDL reduction was significantly higher than in nondiabetic patients (P < 0.01). In conclusion, a high-fiber diet with lipid composition similar to southern Italian diets, composed only of natural foodstuffs, is able to reduce blood glucose and blood lipids in diabetic patients, over and above the effects of low saturated fat and low cholesterol intake. Moreover, it significantly reduces LDL-cholesterol in patients with type II hyperlipidemia and therefore can be utilized for prevention of atherosclerosis in the general population.     

Effect of low-fat, high-carbohydrate, high-fiber diet on fecal bile acids and neutral sterols

The effect of a diet low in total fat and high in complex carbohydrates on the excretion of bile acids and neutral sterols and on serum lipids was studied in women, 46-47 years old, who were consuming a mixed Western diet. Participants kept an initial 3-day food record while consuming their normal diet (pre-diet period). During the dietary intervention period (experimental diet) which lasted for 26 days, all volunteers consumed a low-calorie, low-fat (less than 10% of total calories), high-fiber (37 g/day, high-carbohydrate diet. At the 1-year follow-up, the participants completed another 3-day food record, which indicates that these volunteers maintained their caloric and fat intake at levels slightly higher than the experimental diet, but lower than the pre-diet period. Individual 24-hr fecal samples for 2 days and blood samples were collected from the volunteers during each dietary period. Fecal samples were analyzed for neutral sterols and bile acids, and blood samples were analyzed to ascertain cholesterol and triglyceride levels. There were no significant differences in the excretion of neutral sterols between the dietary periods. Fecal secondary bile acids were significantly lower during the experimental and follow-up diet periods compared with the pre-test diet period. Serum cholesterol levels were significantly lower during the experimental and follow-up diet periods than during the pre-test diet period. These results suggest that switching from a high-fat, low-fiber diet to a low-fat, high-fiber diet can reduce the excretion of bile acids which are thought to be involved in the promotion of colon cancer.     

Metabolic differences in response to a high-fat vs. a high-carbohydrate diet

Energy expenditure was measured in a group of 7 subjects who received two isocaloric isonitrogenous diets for a period of 9-21 days with a 4-10-day break between diets. Diet 1 was a high-fat diet ( 83.5 +/- 3.6% of total energy). Diet 2 was a high carbohydrate diet ( 83.1 +/- 3.7% of total energy). Resting and postprandial resting metabolic rate were measured by open circuit indirect calorimetry 2-4 times during each metabolic period. Total energy expenditure (TEE) was measured by the doubly labeled water method over an 8-13-day period. The respiratory quotient was measured 2-4 hours after a meal during each metabolic period for the calculation of total energy expenditure by the doubly labeled water method. Levels of total T3 (TT3), T3 uptake, free thyroid index and T4 were measured at the end of each metabolic period. No significant changes in resting metabolic rate (RMR) were apparent on the two diets (1567 +/- 426 kcal/d high-fat diet and 1503 +/- 412 kcal/d high-carbohydrate diet n=7, p<0.15). Total energy expenditure measured in 5 subjects was significantly higher during the high-carbohydrate phase of the diet (2443 +/- 422 vs. 2078 +/- 482 kcal/d p<0.05). Activity estimated from TEE/RMR was greater on the high-carbohydrate diet but only approached statistical significance (p<0.06). Total T3 was significantly lower and free thyroid index and T3 uptake were significantly higher at the end of the high fat diet in comparison to the high-carbohydrate diet. These data suggest that individual tolerance to a high-fat diet varies considerably and may significantly lower TEE by changing levels of physical activity. The explanation for changes in thyroid hor. mone levels independent of changes in metabolic rate remains unclear.     

Characteristics that enhance adherence to high-carbohydrate/high-fiber diets by persons with diabetes

This study sought to characterize 40 clients with diabetes, 19 of whom adhered to a high-carbohydrate/fiber diet and 21 of whom did not, in accordance with the adherence pattern. There would seem to be distinct differences in the characteristics of adherers and non-adherers. Dietary adherence was found to be independent for sex, age, occupation, marital status, ethnicity, and education. However, comparison of the groups' health and dietary perceptions showed that non-adherers, as opposed to adherers, were not concerned about reaching their ideal body weight; needed to be motivated to exercise by family or friends; did not perceive diabetes as a threat to their health; were not satisfied with their knowledge about diabetes; were not content with their nutrient status but believed they were consuming adequate amounts of carbohydrate; and believed that they did not need to change their intake of fruit, vegetables, and bread--liking/disliking of these foods being the most important barrier to dietary change. Such patients, identified in screening for potential dietary non-adherence, may benefit from the use of educational strategies different from those used with patients who are more oriented toward health.     

Personalized diet management can optimize compliance to a high-fiber, high-water diet in children with refractory functional constipation

Diet modification to increase water and fiber consumption is considered an important component in the management of constipation. This prospective randomized study aimed to evaluate the compliance of 86 children with refractory functional constipation (mean age 4.4 years, range 1 to 11 years)-to a high-fiber, high-water diet following either physician's dietary advice (PI group) (n=42) or physician's dietary advice plus personalized diet management by a registered dietitian (DM group) (n=44). Dietary intake was assessed by a 24-hour dietary recall at baseline and 1 month later. The changes in water and fiber consumption were used as compliance criteria. DM group had comparable anthropometric measurements; sex distribution; and baseline intakes of energy, macronutrient, water, and dietary fiber compared with the PI group. Comparison of nutrient intakes between the two visits within each group showed a significant increase in fiber consumption in both groups that was more pronounced in the DM group. Water, energy, and carbohydrate consumption increased significantly only in the DM group. Multivariate regression analysis revealed that the intervention group was the only significant independent predictor for the change in fiber and water consumption after controlling for age, sex, and weight-for-age z score. Children receiving personalized diet management for refractory functional constipation achieved better compliance in increasing fiber and water consumption.     

Serum lipid response to dietary cholesterol in subjects fed a low-fat, high-fiber diet

To determine whether hyperresponse to dietary cholesterol occurs in individuals consuming a low-fat diet, a study was performed on 58 subjects whose plasma cholesterol had changed by greater than or equal to 5% when intakes of two and seven eggs per week were compared in a previous study. Here, the effect of eating nine, zero, and nine eggs per week was studied over 3 consecutive months. Plasma total, LDL, and HDL cholesterol did not differ significantly. There was no correlation between individuals' lipoprotein changes in this and the previous study. Consistent hyperresponse to moderate cholesterol intake is not apparent in people eating a low-fat, high-fiber diet. Reduction in dietary cholesterol below 400 mg/d produces no further substantial cholesterol lowering.     

Short-term effects of a very-low-protein diet supplemented with ketoacids in nondialyzed chronic kidney disease patients

OBJECTIVE: To evaluate the effects on the nutritional and metabolic parameters of a very-low-protein diet supplemented with ketoacids (VLPD+KA) in comparison with a conventional low-protein diet (LPD) in chronic kidney disease (CKD) patients. DESIGN: Prospective, randomized, controlled clinical study. SETTING: Outpatient Clinic of the Nephrology Division of Federal University of Sao Paulo, Brazil. SUBJECTS: The study involved 24 patients with advanced CKD (creatinine clearance <25 ml/min) that were randomly assigned to either a VLPD+KA (VLPD+KA group, 12 patients) or to a conventional LPD with 0.6 g/kg/day (LPD group, 12 patients). The patients were followed for 4 months. RESULTS: Nutritional status was adequately maintained with both diets for the studied period. Protein intake and serum urea nitrogen decreased significantly only in the VLPD+KA group (from 0.68+/-0.17 to 0.43+/-0.12 g/kg/day, P<0.05; from 61.4+/-12.8 to 43.6+/-14.9 mg/dl, P<0.001; respectively). Ionized calcium did not change in the VLPD+KA group but tended to decrease in the LPD group. Serum phosphorus tended to decrease in the VLPD+KA group probably as a result of a significant reduction in dietary phosphorus (529+/-109 to 373+/-125 mg/day, P<0.05) associated to the phosphorus-binding effect of the ketoacids. No change in these parameters was found in the LPD group. Serum parathormone increased significantly only in the LPD group (from 241+/-138 to 494+/-390 pg/ml, P<0.01). The change in PTH concentration was negatively correlated with changes in ionized calcium concentration (r=-0.75, P=0.02) and positively correlated with changes in serum phosphorus (r=0.71, P=0.03) only in the LPD group. CONCLUSION: This study indicates that a VLPD+KA can maintain the nutritional status of the patients similarly to a conventional LPD. Besides, an improvement in calcium and phosphorus metabolism and a reduction in serum urea nitrogen were attained only with the VLPD+KA. Thus, VLPD+KA can constitute another efficient therapeutic alternative in the treatment of CKD patients.     

Evaluation of a high-fiber diet in hyperlipidemia: a review

Epidemiologic studies of cardiovascular mortality rates in different countries have suggested that dietary fiber may play a protective role. Within a similar population, a large intake of fiber is associated with a lower relative risk of death from coronary heart disease. Dietary fiber may be separated into at least two types: insoluble, which includes cellulose, hemicellulose, and lignin; and soluble, including pectin and gums. Laxative effects appear to predominate with insoluble fibers such as wheat bran, with little change in plasma lipid levels in most studies. Pectin, guar gum, and oat bran (soluble fibers) have been reported to have hypocholesterolemic effects in both animals and man, with the effect being proportional to the degree of cholesterol elevation. Other gums, specifically those from locust bean and karaya, have a similar effect, with the decrease in total cholesterol due primarily to a decrease in the low-density lipoprotein cholesterol fraction. While some studies have shown continued improvement over a period of months, this has not been uniformly found. Both normal and elevated triglyceride levels appear to be more resistant to change with dietary fiber. An increase of dietary carbohydrate as a source of fiber may be associated with an increase in triglyceride levels. Fiber may, however, offer some protection against an increase in cholesterol and triglyceride levels in subjects fed diets containing large amounts of sucrose. Although rats fed oat bran, guar gum, or pectin had lower levels of hepatic and blood triglycerides, humans with hypercholesterolemia fed oat bran or guar showed no effect on their triglycerides.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intervention with a low-fat, high-carbohydrate diet does not influence the timing of menopause

BACKGROUND: Later age at menopause is associated with a greater risk of breast cancer. Dietary factors may at least partially influence breast cancer risk through an effect on the age at menopause. OBJECTIVE: We studied the effect of a low-fat, high-carbohydrate (LFHC) dietary intervention on the timing of menopause in women with greater risk of breast cancer. DESIGN: The study population included participants from an LFHC dietary intervention trial for the prevention of breast cancer in women with extensive mammographic density, a strong risk factor for breast cancer. Women who were premenopausal at baseline (n = 2611) were followed for an average of 7 y for menopause. Survival analysis was used to compare the time to menopause between the LFHC and control groups and to assess other factors associated with age at menopause. RESULTS: The LFHC intervention did not affect the time to natural menopause overall (P = 0.72 for log-rank test comparing study groups; n = 699 events). An observed interaction between study group and baseline body mass index (BMI; P = 0.01) indicated that the intervention group experienced earlier menopause than did the control group when BMI was low and that a higher BMI was associated with later menopause in the intervention group only. Greater parity, weight, and education were associated with later menopause, and greater age at first birth and baseline smoking were associated with earlier menopause. CONCLUSIONS: Overall, the LFHC dietary intervention did not influence the timing of menopause. Factors associated with age at menopause in this population were consistent with those reported in other populations.     

Feasibility of a low-fat/high-fiber diet intervention with soy supplementation in prostate cancer patients after prostatectomy

OBJECTIVES: To evaluate the feasibility and long-term compliance with a low-fat diet supplemented with soy protein in men at increased risk for recurrence after radical prostatectomy. DESIGN: Randomized, control study.Setting:Academic center in USA. SUBJECT: Forty men who had undergone radical prostatectomy and were at increased risk for recurrence. INTERVENTION: Low-fat (15% fat), high-fiber (18 g/1000 kcal) diet supplemented with 40 g soy protein isolate (n=26) was compared to USDA recommended diet (n=14). RESULTS: Over 4 years, subjects in the intervention group but not in the control group made and sustained significant changes in their diet as measured by the dietary assessment instruments and urinary isoflavone excretion. In the intervention group, dietary fat intake was reduced from 33.46+/-1.27% energy/day to 21.04+/-1.74% (P<0.05), fiber intake increased from 14.6+/-1.06 to 21.05+/-2.29 g/day. The insulin growth factor-1 (IGF-1) level was decreased from 260.4+/-8.6 ng/ml at baseline to 220.5+/-7.9 ng/ml at 6 months (P<0.05) in the intervention group with no significant change in the control group. An ex vivo assay demonstrated inhibition of LNCaP cell growth (-20.0+/-7.7%, P<0.05) by sera from patients in the intervention group after 6 months of dietary change compared to baseline. CONCLUSION: These data suggest that long-term low-fat dietary interventions as part of prospective randomized trials in prostate cancer survivors are feasible, and lead to reductions in circulating hormones or other growth factors stimulating prostate cancer growth ex vivo.