Iron absorption from a breakfast cereal: effects of EDTA compounds and ascorbic acid.

Sodium iron ethylenediaminetetracetic acid (NaFeEDTA) has been recommended for food fortification programmes to improve iron status but its performance in commercial products has not been evaluated. The effect of EDTA on iron absorption from fortified cornflakes, given as part of a typical Western breakfast, was determined in a double-blind randomised study with 20 non-anaemic female volunteers, using experimentally prepared iron compounds, enriched with 58Fe, and faecal monitoring. Five meals were compared: hydrogen reduced iron, hydrogen reduced iron plus Na2EDTA (molar ratio EDTA:Fe 1:2), hydrogen reduced iron plus NaFe(III)EDTA at two different molar ratios (EDTA:total Fe 1:3 and 1:2), and hydrogen reduced iron plus 15 mg ascorbic acid (ascorbic acid:Fe 1.3:1). The iron and EDTA compounds were accurately weighed into gelatine capsules and taken with unfortified cornflakes, semi-skimmed milk and tea on two consecutive days; the iron dose per meal was 3.75 mg. Iron absorption from all five test meals was measured in each volunteer with a minimum wash-out period of 2 weeks between tests. Geometric mean iron absorption (%) from the 5 tests was 14.1, 17.6, 20.6, 24.4 and 17.5 respectively (equivalent to 0.5-0.9 mg absorbed iron). There was a significantly higher iron absorption from the mixture of reduced iron and NaFe(III)EDTA (EDTA:Fe 1:2) than from reduced iron alone (p = 0.014). It is not known whether the higher absorption was from reduced iron or NaFeEDTA or both. Absorption was not increased significantly with NaFe(III)EDTA (EDTA:Fe 1:3), Na2EDTA (EDTA:Fe 1:2) or ascorbic acid (15 mg).

Effects of saponins and glycoalkaloids on the permeability and viability of mammalian intestinal cells and on the integrity of tissue preparations in vitro.

The effects of potato and tomato glycoalkaloids and a saponin mixture from Gypsophila were investigated in cytotoxicity studies (neutral red uptake, mitochondrial MTT reduction and release of lactate dehydrogenase), using cultured cell lines of rat and human intestinal mucosal epithelium. Experiments to assess the effects of these compounds on the integrity of the intestinal epithelium were also carried out using preparations of isolated rat jejunum in vitro. By investigating the effect of these compounds on cultured cells and on intestinal tissue preparations, changes in membrane integrity, as evidenced by lactate dehydrogenase leakage in cell culture, could be confirmed in a system more relevant to the whole gut. Of the compounds tested, alpha-tomatine was consistently the most potent in all tests, and indications of a synergistic effect on membrane depolarization were observed between alpha-chaconine and alpha-solanine at total glycoalkaloid concentrations of less than 1 mM (< 0.86 mg/ml), with an optimum when the former comprised 25% of the mixture. An increase in the apparent permeability of the brush border was observed at sublethal concentrations of the compounds, and this may have important implications with respect to enhanced uptake of macromolecules, such as allergens, whose passage through the epithelium is normally somewhat restricted.

Dietary corn oil and guar gum stimulate intestinal crypt cell proliferation in rats by independent but potentially synergistic mechanisms.

The effects of corn oil, guar gum and cellulose on mucosal proliferation were investigated in rats. Animals were allocated to three groups and fed a fiber-free diet or diets containing 100 g/kg of cellulose or guar gum. Each group was subdivided to receive corn oil at 40 or 80 g/kg. The crypt cell production rate (CCPR) was determined after 28 d. Consumption of guar gum or corn oil led to greater CCPR in the ileum and cecum. In a second experiment, animals were allocated to two groups and fed diets containing either cellulose or guar gum (100 g/kg). Each group was again subdivided to receive either corn oil (80 g/kg) or minimal lipid (linolenic acid, 10 g/kg). The trophic effect of guar gum occurred even in the low lipid-fed group, indicating that guar gum exerts a positive effect on cell turnover independently of any interaction with luminal lipid. However, the highest CCPR occurred in animals fed guar gum and corn oil. Postprandial enteroglucagon and gastrin concentrations were highest in animals fed both guar gum and corn oil. Thus, corn oil and guar gum exert independent trophic effects on the intestinal mucosa. The combination of effects led to a three- to four-fold increase in colon mucosal CCPR.

Effects of conventional sucrose-based, fructose-based and isomalt-based chocolates on postprandial metabolism in non-insulin-dependent diabetics.

Milk chocolate is rich in both sucrose and fat, and is therefore considered unsuitable for diabetics. Nevertheless there is little information on the metabolic effects of conventional chocolate or specialized formulations with reduced sucrose content. In the present study six male non-insulin-dependent diabetes mellitus patients (age range 35-60 years; body-mass index less than 28) consumed test meals of chocolate (75 g) on three separate occasions. The control chocolate contained sucrose (45.5% w/w); the test chocolates contained either fructose (45.5% w/w) or isomalt (45.1% w/w). The latter is a sweet disaccharide alcohol which has no glycaemic effect when consumed as a pure compound. Venous blood samples were obtained at 30 min intervals for 5 h, and analysed for glucose, insulin, lactate and triglycerides. All three chocolates provoked a sustained rise in blood glucose, which reached a maximum at 90 min after ingestion and returned to baseline values by 5 h. The highest blood glucose levels occurred after conventional chocolate, and differences were statistically significant at 60 and 90 min (P less than 0.05). The area under the glycaemic curve for isomalt chocolate was 36% smaller than that for conventional chocolate (P less than 0.05), and there were differences in insulin and lactate levels, consistent with the lower glycaemic effect. The glycaemic response to the fructose-based chocolate was also lower than that to control chocolate but the difference was not significant. All three chocolates led to a similar sustained rise in serum triglyceride levels. Isomalt appears to be a palatable alternative sweetener capable of reducing the glycaemic effect of diabetic confectionary.

The biological effects and digestible energy value of a sugar-beet fibre preparation in the rat.

A sugar-beet fibre preparation (SBF) was incorporated into a semi-synthetic rat diet at a level of 100 g/kg. The material caused no feed aversion, and gain of live weight was unimpaired. SBF appeared to be slightly more fermentable than wheat bran and only marginally less effective as a faecal bulking agent when compared with equalized intakes of non-starch polysaccharide. SBF did not stimulate mucosal cell turnover in the small intestine. Some enlargement of the caecum was observed in animals given SBF, but it was no greater than that of animals given wheat bran. Animals given SBF had a lower serum cholesterol concentration than both the fibre-free controls and those given wheat bran. This hypocholesterolaemic effect was less than that of guar gum however. The partial digestibility of energy for SBF was 0.64, and its partial digestible energy value was 11.3 kJ (2.7 kcal)/g. The partial digestibility of energy for non-starch polysaccharide in SBF was estimated to be 0.53 and its partial digestible energy value was 9.1 kJ (2.2 kcal)/g. This value was not significantly different from that expected for unavailable carbohydrate in mixed human diets.