Seven men with well-controlled, noninsulin-dependent (type 2) diabetes ingested on two different mornings, in random order, meals with or without a 5.0-g sodium alginate supplement (algae-isolate, 75% soluble fiber). The meals contained similar amounts of digestible carbohydrates, fat and protein. The gastric emptying rate of the meal containing sodium alginate, measured by detection of 51Cr mixed into the meals, was significantly slower than that of the fiber-free meal. Sodium alginate also induced significantly lower postprandial rises in blood glucose, serum insulin and plasma C-peptide. The diminished glucose response after the addition of sodium alginate could be correlated to the delayed gastric emptying rate induced by the fiber (rs = 0.92, P less than 0.01).

Background Lactic fermentation of foods increases the availability of iron as shown in a number of studies throughout the years. Several explanations have been provided such as decreased content of inhibitory phytate, increased solubility of iron, and increased content of lactic acid in the fermented product. However, to our knowledge, there are no data to support that the bioavailability of iron is affected by lactic fermentation. ObjectivesThe objective of the present study was to investigate whether the bioavailability of iron from a vegetable mix was affected by lactic fermentation and to propose a mechanism for such an event, by conducting human and cell (Caco-2, HepG2) studies and iron speciation measurements (voltammetry). We also investigated whether the absorption of zinc was affected by the lactic fermentation.ResultsIn human subjects, we observed that lactic-fermented vegetables served with both a high-phytate and low-phytate meal increased the absorption of iron, but not zinc. In vitro digested fermented vegetables were able to provoke a greater hepcidin response per ng Fe than fresh vegetables, indicating that Fe in the fermented mixes was more bioavailable, independent on the soluble Fe content. We measured that hydrated Fe3+ species were increased after the lactic fermentation, while there was no significant change in hydrated Fe2+. Furthermore, lactate addition to Caco-2 cells did not affect ferritin formation in response to Fe nor did lactate affect the hepcidin response in the Caco-2/HepG2 cell system.ConclusionsThe mechanism for the increased bioavailability of iron from lactic-fermented vegetables is likely an effect of the increase in ferric iron (Fe3+) species caused by the lactic fermentation. No effect on zinc bioavailability was observed.

Meals (425 kcal) containing various doses of guar gum (0, 2.5, 7.5 or 12.5 g) were ingested by nine healthy male subjects after a 12-h fast. The rise in blood glucose was higher after the control meal without guar gum than after the guar gum-containing meals, which all gave a similar rise in glucose. In contrast, increased doses of guar gum led to a greater reduction in the postprandial rise in insulin. The postprandial increase in serum hydroxyproline, an amino acid added to all meals, was decreased in a similar manner by all of the guar gum doses. Gastric emptying was measured after the control meal without guar gum and the meal containing 12.5 g of guar gum by monitoring 51Cr, which was added to the meals. Guar gum was found to reduce the variation between individuals, as well as the initial rate of gastric emptying, which correlated with changes in both serum hydroxyproline (rs = 0.93, P less than 0.01) and blood glucose (rs = 0.83, P less than 0.01). The effectiveness of guar gum in reducing postprandial response was lost after heating and homogenization for canning. A threshold in the reduction in rise of glucose or hydroxyproline was reached with the lowest dose (2.5 g) of viscous guar gum; larger doses had no additional effects. The reduced absorption seems to be an effect of a slower gastric emptying rate.

Summary. The effects on postprandial glycaemic reactions of adding a glass of water to a meal were studied in 7 healthy male subjects and 20 Type 2 (non-insulin-dependent) diabetic patients for a period of up to 3 h. The subjects were served a meal of potatoes and meat, with or without 300 ml of water, in random order on two mornings after a 12-h fast. The diabetic patients were considered as well-controlled or not well-controlled according to HbAlc and blood glucose fasting values. Water addition increased the peak blood glucose (p < 0.02) and serum insulin (p < 0.02) levels in healthy subjects, and the blood glucose concentration in well-controlled diabetic patients (p < 0.02). The addition of water also increased the overall blood glucose response, calculated as the positive incremental area, in healthy subjects by 68 + 25% (p < 0.02) and in well-controlled diabetic patients by 40 + 14% (p < 0.01). In poorly-controlled diabetic patients, however, the addition of water did not display significant effects, probably due to the varying fasting glycaemia in these patients. Thus, altering the physical property of a meal by dilution with water can affect the physiological responses; the results are considered to be relevant for the on-going discussion concerning the use of physiological responses to foods as a basis for diet instructions to diabetic patients.Key words: Type2 (non-insulin-dependent) diabetes, postprandial glycaemia, water ingestion, glycaemic index.Physiological responses to carbohydrate foods have been suggested as a basis for instructions to diabetic patients [1, 2] preferable to the traditional exchange system built on quantity and molecular weight of the carbohydrate content [3]. This is a conclusion from studies which have shown varying postprandial blood glucose responses after the ingestion of comparable and isocaloric food items. The blood glucose rise following the consumption of potatoes is higher than after the consumption of most other starchy foods [1,4,5]. Moreover, the plasma glucose response in healthy subjects is 40-60% lower when a monosaccharide or starch is served as a solid meal, than when the same carbohydrate is given as a liquid [6]. The physical property of starchy foods has also been shown to affect blood glucose and hormonal levels following meals [7,8].The identification of meal characteristics that attenuate the glycaemic response is far from complete. In many countries, it is common to drink during a meal, but knowledge of the effects of adding liquids to meals on the postprandial response is limited. It has been reported in abstracts that adding water to meals can increase the glycaemic response in healthy subjects [9,10]. The effect of drinking during meals on the glycaemic response in diabetic patients is, however, virtually unknown. The rate of gastric emptying affects the absorption rate of meal components and is related to the postprandial blood glucose level after meals [5,11,12]. Solid foods of meat, labelled by radioactive isotopes to measure gastric emptying, h...

Two meals of mashed-bean or potato flakes and meat were served in random order to six healthy male subjects to determine effects on gastric emptying and glycemic reactions. The meals had comparable physical appearance and contained similar amounts of digestible carbohydrate, fat, and protein. No difference in gastric emptying, recorded by gamma camera after mixing 51Cr with the meals, was found between the meals. The bean-flakes meal gave significantly lower blood glucose (p less than 0.01) and serum insulin (p less than 0.05) concentrations than did the potato-flakes meal. The overall blood glucose response, calculated as incremental area under the curves for 2 h, also differed between the meals (p less than 0.05) whereas the overall insulin response did not differ significantly. The low glycemic response after bean flakes could not be explained by the gastric emptying rate, which provides additional evidence for the slow digestion of bean starch in the small intestine.