Effects of meal size reduction on postprandial variables in male volunteers.

To investigate the effects of meal size reduction on postprandial variables, adult male volunteers consumed at noon hot lunches composed of cooked white rice, fried chicken fillet, raisins, bigarreaus and curry sauce with carbohydrate/fat ratios of either 0.77 or 2.04 (37-57 en% carbohydrate, respectively). Prior to the actual experiment, the individual meal sizes were determined by allowing the volunteers to eat a self-preferred amount of the high carbohydrate meal. The test meals were adjusted to either 70 or 100% of the energy content of this individually chosen meal size. A higher degree of satiety was detected up to 4 h after the 100%-size carbohydrate-rich meal as compared to that after the fat-rich meals and the 70%-size carbohydrate-rich meal. The reduction in meal size had only small effects on the postprandial curves of glucose, insulin, free fatty acid and total glycerol in the blood relative to those induced by the variation in carbohydrate/fat ratio in the meals. No significant effects of meal size were detected on the postprandial curve of free glycerol. Thus limited restriction in the size of a meal relative to the ad libitum intake of an individual may be expected to lead to only minor effects on the various postprandial curves in meal-eating studies.

Minor difference in postprandial responses of men between starch and sugar when replacing fat in a normal meal.

Healthy male volunteers consumed hot lunches consisting of cooked white rice, fried chicken fillet, raisins, bigarreaus (sweet cherries) and curry sauce with carbohydrate: fat ratios of either 0.77 or 2.04, and polysaccharide: (mono + di)saccharide ratios (P:MD) varying between 5.3 and 0.95. Before and at various time intervals after the start of the meal, blood samples were analysed for glucose, insulin, triacylglycerol (TG), free glycerol (FG), free fatty acids (FFA) and cholesterol. Elevated postprandial glucose and insulin peaks were induced by the meals containing a larger amount of carbohydrate. The type of carbohydrate in the meal appeared to have little or no effect on the peak maximum. A small second glucose peak was seen at 2 h after the meals with P: MD greater than 3.1. The TG concentration in the blood showed a similar and rapid rise. After the meal containing the largest amount of simple sugars, the TG curve levelled off 1 h after the start of the meal and then remained at a nearly constant level (1.5 mM). In contrast, a larger amount of complex carbohydrates induced a TG concentration which rapidly rose to a maximum of 1.75 mM, and subsequently decreased slowly to somewhat below that of the simple sugar-rich meal at 4 h. The postprandial curves after the fat-rich meals showed a continuous rise of TG up to a maximum of about 2 mM at 2 h, and a subsequent slow decrease. FG and FFA all showed a rapid drop immediately after the start of the consumption of the meals, followed by a rebound at 1 h. The postprandial curves of total cholesterol, as well as the areas below the curve of both total cholesterol and free, unesterified cholesterol were lower after the carbohydrate-rich meals than after the fat-rich meals. This is attributed to the larger amount of cholesterol in the fat-rich meals.

Effects of varying the carbohydrate:fat ratio in a hot lunch on postprandial variables in male volunteers.

1. Healthy male volunteers consumed at noon, hot test meals with four different carbohydrate:fat ratios varying between 2.64 and 0.50, and composed of fried beefsteak, mashed potatoes, French beans, and a dessert of custard with mashed peaches. The energy content of the meals was 40% of the daily intake of the volunteers, estimated from their individual dietary histories. 2. Before, and at different times after the start of the meal, blood samples were taken and a number of indices of carbohydrate and lipid metabolism were determined in the samples, i.e. glucose, insulin, free fatty acid, free and total glycerol, free and total cholesterol, high-density-lipoprotein (HDL)-cholesterol and low-density-lipoprotein (LDL)-cholesterol. 3. Increasing the carbohydrate:fat ratio resulted in higher postprandial peaks of glucose and insulin. In addition, the peak area under the postprandial glucose curve showed a significant increase. The peak area under the postprandial insulin curve had also increased, indicating that a larger amount of insulin was secreted by the pancreas on increasing the carbohydrate content in the meal. There was no significant correlation between the height of the postprandial peak of blood glucose and the size of the meal. 4. All four meals caused elevated postprandial blood triacylglycerol levels. However, the decline of this elevated level took a much longer time after the meals with the lower carbohydrate:fat ratios, i.e. containing larger amounts of triacylglycerols. There was a significant decreasing linear relation between the carbohydrate content of the meals and the peak area under the postprandial triacylglycerol curve. Free glycerol and free fatty acids showed lower postprandial levels in the blood after the meals with the higher carbohydrate:fat ratios, and the peak areas of the postprandial curves of both variables displayed a significant decrease. Little or no effect of the meal carbohydrate:fat ratio was observed on the postprandial concentrations of total cholesterol, unesterified cholesterol, HDL-cholesterol or LDL-cholesterol.

Effect of low cholesterol, linoleic acid enriched diet on thrombotic tendency and plasma lipoproteins in patients with angina pectoris.

Eighteen patients with an established angina pectoris aged 46-74 years were investigated. These patients received a low cholesterol, linoleic acid enriched diet during a period of three months. Of these patients seventeen terminated the three months period. The adherence to the diet was assessed by determining the fatty acid pattern in cholesterol and triglycerides. Both were found to increase significantly and to the same extend. When comparing the values between the entry to the study and after three months of dietetic intervention we found a significant improvement in the fibrinogen level, haematocrit, the aggregation of platelets, the PAT I test according to Breddin and in the test according to Wu and Hoak. However, the fibrinolytic activity before occlusion of an arm was disminished. The changes in ADP -, collagen -, adrenalin and thrombin induced platelet aggregation were not uniform. We found a significant lowering of VLDL, LDL, phospholipids and total cholesterol. HDL did not change significantly. It seems that the diet had a favourable effect on several thrombotic and lipoprotein parameters in these patients.

The effect of dietary carbohydrate:fat ratio on energy intake by adult women.

The effect of the dietary carbohydrate:fat (C:F) ratio on the spontaneous energy intake by healthy adults was investigated by comparing a high-carbohydrate diet (fat 24%, carbohydrate 58%, protein 18% of energy) and a high-fat diet (fat 47%, carbohydrate 35%, protein 18% of energy) in a 2 X 2 week cross-over design. Subjects were 22 healthy nuns in a Trappist convent with very regular activities. The diets consisted of combinations of liquid formula (75%) and standardized snacks (25%). The difference in C:F ratio was concealed: energy density, taste and appearance were similar. Energy consumption was recorded continuously. The mean daily energy intakes remained constant: 8276 kJ (1978 kcal). The difference in mean daily energy intake between diets was 73 kJ +/- 180 (SEM). Small changes in body weight were observed, but these are argued not to indicate definitive effects. It is concluded that changing the C:F ratio within commonly occurring ranges does not influence the spontaneous energy intake of healthy adults. The composition of the dietary fat was kept constant. Under practical conditions a change in the C:F ratio will also induce a change in the fatty acid composition of the diet, which might affect the energy intake regulation. Other experiments are required to see whether the C:F ratio can affect body composition or other physiological parameters in the long run.

Relationship between the type of dietary fatty acid and arterial thrombosis tendency in rats.

The effect of dietary fatty acids on the formation and growth of intra-arterial occlusive thrombi in rats was investigated. It appeared that fats containing a large amount of saturated fatty acids promote arterial thrombus formation, whereas dietary linoleic acid has a specific anti-thrombotic effect. Oleic acid on its own does not seem to act as an anti-thrombotic substance. However, the replacement of thrombogenic fatty acids by oleic acid results in a decrease of the dietary thrombogenic potency. Moreover, the results indicated that the thrombogenicity of the saturated fatty acids increases with their chain length. As for the anti-thrombotic effect of cis fatty acids and their trans isomers, no obvious differences have been observed. Almost identical results were obtained when thrombogenicity was related to either absorption or to composition of the dietary fatty acids. Further research can therefore be restricted to this latter criterion. For the majority of the fats tested, thrombosis tendency and ADP-induced platelet aggregation were closely associated. It is therefore highly probable that platelet aggregation is involved in the mechanism by which dietary fats affect arterial thrombus formation.