Angela Giacco

EFFECT OF DIETARY FIBRE ON GLUCOSE CONTROL AND SERUM LIPOPROTEINS IN DIABETIC PATIENTS

To evaluate the effects of a fibre-rich diet on blood glucose and serum lipoproteins, eight diabetic patients, four on insulin and four on oral hypoglycaemic drugs, were put on three different diets, a different one for each consecutive 10-day period: diet A (carbohydrate 53%, fibre 16 g), diet B (carbohydrate 53%, fibre 54 g), and diet C (carbohydrate 42%, fibre 20 g). All diets had identical polyunsaturated/saturated fat ratios. Both 2 h post-prandial glucose and mean daily glucose levels were significantly lower after diet B than after either of the two other diets, as were total and LDL cholesterol levels. Total and VLDL triglyceride levels after diet B were significantly lower than those after diet A but almost identical to those after diet C. HDL cholesterol concentration was not affected by dietary fibre but was significantly increased by the low-carbohydrate diet. A high-fibre, normal-carbohydrate diet (the fibre coming exclusively from foodstuffs with a naturally high content of fibre) improves blood glucose control and decreases the concentration of atherogenic lipoproteins in diabetic patients. This effect is independent of the amount of available carbohydrates in the diet.

Effect of Digestible Carbohydrates on Glucose Control in Insulin-dependent Diabetic Patients

Recent studies have demonstrated that high-carbohydrate—high-fiber diets may improve the metabolic control in diabetes. To evaluate the influence of dietary carbohydrates separate from dietary fiber on blood glucose control, six insulin-dependent diabetic patients (IDD) were assigned in random order to two weight-maintaining diets for consecutive periods of 10 days. The diets differed in carbohydrate (41% in diet A and 60% in diet B) and fat content (41% and 20%, respectively) but were identical in calories, proteins, simple sugars, and fiber. After each dietary period blood glucose was continuously monitored for 24 h (Biostator GCIIS, Life Science Instruments, Miles Laboratories, Elkhart, Indiana). The M value was 48 ± 20 after diet A and 96 ± 27 after diet B (t = 3.83, P < 0.025); the mean daily blood glucose was 152 ± 5 mg/dl after diet A and 206 ± 11 mg/dl after diet B (t = 7.50, P < 0.001). Similarly, the blood glucose level for the 3-h period after each of the three main meals was lower after diet A than after diet B (analysis of variance: F = 5.2, P < 0.05). No significant difference in fasting serum cholesterol, triglycerides, or serum lipoprotein composition was observed between the two diets. In order to separate the influence of dietary carbohydrate and fat on postprandial blood glucose concentration, an additional test meal experiment was performed in eight insulin-dependent diabetic patients. In random order on consecutive days they were given two standard meals that were identical in carbohydrate and protein content and differed only in the amount of olive oil added to the meals (12 g versus 36 g) The average blood glucose increments calculated for the 3h after the meal were almost identical after the high-fat and the low-fat test meal. It is concluded that increasing the amount of dietary carbohydrate leads to the deteriorationof blood glucose control in ID

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 PS 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.

Extra-Virgin Olive Oil Reduces Glycemic Response to a High–Glycemic Index Meal in Patients With Type 1 Diabetes: A Randomized Controlled Trial

OBJECTIVE To evaluate whether fat quality, in the context of meals with high– (HGI) or low–glycemic index (LGI), influences postprandial blood glucose (PPG) response in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS According to a randomized crossover design, 13 patients with type 1 diabetes on insulin pump consumed two series (HGI or LGI) of meals with the same carbohydrate quantity while differing for amount and quality of fat: 1) low in fat (“low fat”), 2) high in saturated fat (butter), or 3) high in monounsaturated fat (extra-virgin olive oil) (EVOO). Premeal insulin doses were based on insulin–to–glycemic load ratios. Continuous glucose monitoring was performed and 6-h PPG evaluated. RESULTS PPG was significantly different between HGI and LGI meals (P = 0.005 for time × glycemic index interaction by repeated-measures analysis [RMA]), being significantly higher during the first 3 h after the HGI meals with a later tendency to an opposite pattern. In the context of HGI meals, PPG was significantly lower after EVOO than after low fat or butter (P < 0.0001 for time × meal interaction by RMA), with a marked difference in the 0- to 3-h glucose incremental area under the curve between EVOO (mean ± SD 198 ± 274 mmol/L × 180 min) and either low fat (416 ± 329) or butter (398 ± 355) (P < 0.05). No significant differences were observed in PPG between the three LGI meals. CONCLUSIONS Carbohydrate quality of a mixed meal influences shape and extent of PPG. Besides, using EVOO in a HGI meal attenuates the early postprandial glucose response observed when this meal is consumed with either low fat or butter. Therefore, an optimal prandial insulin administration would require considering, in addition to the quantity of carbohydrates, the quality of both carbohydrate and fat.

Evaluation of the hypocholesterolemic effect of vegetable proteins

The hypocholesterolemic effect of dietary vegetable proteins was studied by comparing egg-white protein and fava bean protein concentrate in one normal and seven hypercholesterolemic (six type II A, one II B) persons; five completed the crossover design. To maintain stable body weight, subjects were kept on an isocaloric diet (20% protein, 48% carbohydrate (CH), 32% fat, P/S = 2) for 1 month and then hospitalized for two consecutive 18-day periods while receiving an isocaloric diet of different composition (15% protein, 50% CH, 26% fat, P/S = 2). Women were provided 50 g and men 70 g daily of egg-white or fava bean protein concentrate during the two crossover periods. Hematocrit and fasting plasma or serum were analyzed every 3 days for glucose, insulin, uric acid, creatinine, total and low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) cholesterols, and for total and VLDL triglyceride. Dietary adequacy of both proteins was evaluated by measuring plasma concentration of prealbumin, transferrin, and retinol-binding globulin. Insulin and hematocrit did not show any change, nor did any other biochemical variables show significant differences when results were compared at the end of each crossover period. Compared with baseline, fasting plasma glucose significantly decreased on the fava bean diet. Serum total and LDL cholesterol decreased during both diets but were statistically significant only on the egg-white diet. Serum HDL cholesterol significantly decreased only on the fava bean diet. Serum total and VLDL triglyceride did not show any significant change. Labile plasma protein concentration was significantly reduced only on the fava bean diet. In conclusion, the fava bean diet did not show a significant effect on lowering serum total and LDL cholesterol. Such an effect was mild but significant on the egg-white diet, compared with baseline.

A nutritional intervention programme at a worksite canteen to promote a healthful lifestyle inspired by the traditional Mediterranean diet

Abstract This study investigates the effectiveness and long-term impact on the composition of the habitual diet of a nutritional intervention programme – undertaken through panels, totems, and table mats or handout leaflets – based on the promotion at a worksite canteen of healthy food-choices resembling the traditional Mediterranean diet. A significantly higher choice of dishes based on wholegrain cereals, legumes, white meat and fish, and a lower choice of dishes based on refined cereals, red and processed meat, eggs and cheese was observed at the end of the intervention and after six months and three years of follow-ups. A significantly better adherence to the nutritional recommendations for saturated-fat, cholesterol, sugars and fibre was observed. This study reveals that a nutritional intervention programme promoting the traditional Mediterranean diet and utilising a minimally intensive approach is feasible and effective to modify in a beneficial way the dietary habits of a working population and keep these changes in the long-term.

Adherence to the traditional Mediterranean diet in a population of South of Italy: factors involved and proposal of an educational field-based survey tool

Abstract We developed and validated a tool assessing the adherence to the Mediterranean diet based on current nutritional recommendations for health promotion (MEDI-Quest). Four-hundred-and-eleven clinically healthy subjects completed both the MEDI-Quest-score and the validated MedDietScore (MDS). A good accordance between MEDI-Quest and MDS was observed (R = 0.638), as well as for the percentage of individuals having similar scores with both methods for each food group. Regarding socio-cultural-factors, higher adherence was observed in people with older-age (OR = 1.030, p < .0001), more qualifier-employment (OR = 1.136, p < .005), higher-income (OR = 1.925, p < .0001), interest in reading-food-labels (OR = 2.057, p < .0001), and having frequent physical activity (OR = 1.608, p < .05). In conclusion, our findings show that (1) the MEDI-Quest score well correlate with MDS, and (2) the adherence to the Mediterranean diet is not particularly high due to less cultural roots. It could be necessary to improve people’s knowledge about food and nutrition, taking into consideration believes embedded in their family, tradition and religion.

Micronutrient Intake in a Cohort of Italian Adults with Type 1 Diabetes: Adherence to Dietary Recommendations.

Micronutrients are of fundamental importance in maintaining health status. However, data on their dietary intake are few particularly in persons with diabetes. The aim of this study was to evaluate in adults with type 1 diabetes (T1DM) attending a tertiary-level diabetes center in Southern Italy the intake of micronutrients (both vitamins and minerals) and the adherence to recommendations. Seven-day food records of 60 T1DM patients were analyzed. Micronutrient intake was evaluated based on the Italian food composition tables and expressed as amount per 1000 kcal of energy intake to adjust for possible underreporting. Adherence to recommendations for vitamins A, B6, B12, and C and niacin was acceptable in both sexes (ranging from 77% to 100%). Half of the patients did not adhere to folate recommendation, even less to vitamin E, and no patient reached the recommended intake for vitamin D. As for minerals, adherence was low for potassium and selenium (0–23%); intermediate for zinc, copper, and magnesium; low and intermediate for calcium in men and women, respectively; and low for iron in women. In conclusion, the diet followed by T1DM patients may not have a sufficient content of different micronutrients. Therefore, an adequate intake of low-fat dairy products, fish, legumes, and vegetables should be encouraged as components of a healthier dietary pattern.