Effects of different proportions of carbohydrates, polysaccharides/monosaccharides, and different fibers on the metabolic control in diabetic rats

Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes

AIM

The aim of this study was to evaluate the efficacy of agar diet in combination with a conventional diet (traditional Japanese food) for obese patients with impaired glucose tolerance and type 2 diabetes.

METHODS

After a 4-week run-in period on their habitual diets, 76 patients were randomly assigned to have conventional diet or conventional diet with agar. Both groups were on these diets for 12 weeks. Body weight, body mass index (BMI), glycaemic control, blood pressure, insulin resistance, total body fat, fat distribution and lipids were assessed before and after the experimental period.

RESULTS

In both groups, after 12 weeks, mean body weight, BMI, fasting glucose levels, homeostasis model assessment-insulin resistance, and systolic and diastolic blood pressures had decreased significantly from their baseline values. HbA(1)c, visceral fat area, subcutaneous fat area, total body fat, insulin area under the curve after oral glucose tolerance test and total cholesterol decreased significantly in the agar-diet group. After 12 weeks, mean changes of body weight (-2.8 +/- 2.7 kg vs. -1.3 +/- 2.3 kg, p = 0.008), BMI values (-1.1 +/- 1.1 kg/m(2) vs. -0.5 +/- 0.9 kg/m(2), p = 0.009) and total cholesterol (-7.6 +/- 27.5 mg/dl vs. + 2.4 +/- 23.4 mg/dl, p = 0.036) were significantly greater in the agar-diet group than in the conventional diet group.

CONCLUSIONS

The agar diet resulted in marked weight loss due to the maintenance of reduced calorie intake and to an improvement in metabolic parameters.

Adverse effects of a high-glucose diet on body weight and plasma calcium and 1,25-dihydroxyvitamin D3 levels in calcium-deficient growing rats

We tested the hypothesis that dietary calcium would lead to greater impairment of body weight gain and calcium homeostasis if rats are fed a diet with a high glucose content compared with our standard diet in which the carbohydrate is supplied by whole wheat flour. Groups of female rats at 21 days of age were given either of two equivalent calcium-deficient diets with carbohydrate supplied either by glucose (LCaG) or by wheat flour (LCaW). Control rats were fed the wheat-flour diet containing 0.4% calcium. Since previous studies indicated divergent effects of glucose-based and flour-based diets on body weight in vitamin D-deficient rats, we designed a parallel study with vitamin D-deprived rats. Compared with rats fed the LCaW diet, the rats fed the LCaG diet had inferior body weight gain and more severe hypocalcemia (1-2 mg/ml lower) over a 40-day period, and no significant elevation of the plasma 1,25(OH)2D3 level at 61 days of age. Rats fed the LCaW diet maintained a 3-fold elevation of plasma 1,25(OH)2D3 relative to the level of control rats fed the 0.4% calcium diet. The dry weight and percent ash of tibias were similarly reduced in the two calcium-restricted groups compared to the control group. Among the vitamin D-deprived rats, those fed the glucose diet had poorer weight gain than those fed the wheat flour diet. However, both groups had similarly depressed serum calcium level, tibia ash content and 1,25(OH)2D3 level. Thus, a glucose diet combined with calcium restriction or vitamin D deprivation appears to accentuate the impairment of body weight gain and, when combined with calcium restriction, it also accentuates the impairment of calcium homeostasis and interferes with the adaptive increase in plasma 1,25(OH)2D3.