The potential of bifidobacteria as a source of natural folate.

AIMS: To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media. METHODS AND RESULTS: HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 µg per 100 g dry matter (DM). The highest value of 9295 µg per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 µg per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH(3) -H(4) folate and H(4) folate were strain dependent. 5-CH(3) -H(4) folate dominated in most strains. CONCLUSIONS: Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. SIGNIFICANCE AND IMPACT OF THE STUDY: This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota.

Small bowel absorption of magnesium and calcium sulphate from a natural mineral water in subjects with ileostomy.

BACKGROUND: In many developed countries, magnesium and calcium intakes do not reach recommendations for a large part of the population. Mineral water may be a useful alternative source of dietary minerals, especially in groups of people at risk for developing deficiency due to low intakes. AIM: To assess if the addition of a natural and mineral-rich water increased small bowel mineral absorption in people with ileostomy. METHODS: A controlled randomised crossover study with two periods of two days each and a minimum 5 days of washout was performed in six ileostomy subjects. Apparent mineral absorption from 0.5 L of natural mineral water with either a high or a low mineral content consumed in the fasting state was compared. The daily addition of minerals corresponded to 2.3mmol magnesium, 6.9 mmol calcium and 7.7mmol sulphate. Ileostomy effluents were sampled and analysed for magnesium, calcium and total sulphate. RESULTS: When compared with the control, the median absorbed amount of magnesium increased from 0.8 (0-1.34) mmol/d to 1.2 (0.8-1.9) mmol/d,which corresponded to a 30% increase (P = 0.028). Median amount of calcium absorbed increased from 8.3 (6.7-13.6) mmol/d to 14.8 (8.3-20.4) mmol/d, i. e. a 45% increase (P = 0.027). The sulphate absorption increased from 1.9 (1.3-2.2) mmol/d to 5.1 (4.2-6.8) mmol/d,which corresponded to 197 % increase (P = 0.028). CONCLUSIONS: The mineral-rich water increased absorption of both magnesium and calcium and can therefore be used as an additional source of minerals. However, consumption with meals may be preferred.

Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast.

During food processing such as baking, phytate is dephosphorylated to produce degradation products, such as myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates. Certain myo-inositol phosphates have been proposed to have positive effects on human health. The position of the phosphate groups on the myo-inositol ring is thereby of great significance for their physiological functions. Using a combination of high-performance ion chromatography analysis and kinetic studies the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme from baker's yeast (Saccharomyces cerevisiae) was established. The data demonstrate that the phytate-degrading enzyme from baker's yeast dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P(5), D-Ins(1,2,5,6)P(4), D-Ins(1,2,6)P(3), D-Ins(1,2)P(2), to finally Ins(2)P (notation 3/4/5/6/1). Knowledge of the absolute stereochemical specificity of the baker's yeast phytase allows use of the enzyme to produce defined myo-inositol phosphates for kinetic and physiological studies.

Rapid analysis of inositol phosphates.

Fast and simple analytical methods for the determination of inositol bis- to hexakisphosphates or only inositol hexakisphosphate in foods and feces are presented. The methods are both faster and simpler with regard to analytical detection and sample pretreatment as compared to previously reported methods. The samples are pretreated using extraction and centrifugal ultrafiltration and analyzed using high-performance ion chromatography (HPIC) with gradient or isocratic elution. The analytes are detected using ultraviolet detection after postcolumn reaction. The methods are efficient, highly selective, and appropriate for analyzing inositol phosphates in food and feces samples. The between- and within-day variances were generally below 8 and 5% (relative standard deviation), respectively, for the presented HPIC method with gradient elution.

Production process for high-quality pea-protein isolate with low content of oligosaccharides and phytate.

A process for pea-protein isolate production, resulting in low content of phytate and oligosaccharides, has been developed. Oligosaccharides were removed from the protein fraction through ultrafiltration. Ultrafiltration of 50- and 100-kD molecular-weight cutoffs (MWCOs) were tested, and both effectively separated the oligosaccharides from the protein. Phytate degradation was achieved by incubation of the pea-protein solution by addition of exogenous phytase enzyme. An almost complete degradation of inositol hexa-, penta-, tetra-, and triphosphates was reached using an incubation time of 1 h. The reduced content of oligosaccharides and inositol phosphates is likely to result in reduced flatulence and improved mineral bioavailability. These qualities of the pea-protein isolate make it a suitable protein source for infant formula production.

Inositol hexaphosphate hydrolysis by Baker's yeast. Capacity, kinetics, and degradation products.

Phytases hydrolyze myo-inositol 1,2,3,4,5,6-hexaphosphate (IP(6)), yielding lower inositol phosphates and inorganic orthophosphate. Two commercial strains of baker's yeast (Saccharomyces cerevisiae), Y(1) and Y(2), were able to express phytase activity. This was determined by the capacity to grow in a synthetic medium with IP(6) as the sole phosphorus source. IP(6) hydrolysis was rapid for both strains, and after 24 h, all IP(6) was degraded. Control cultures contained inorganic orthophosphate (P(i)) and no IP(6). Growth rate in IP(6) medium was for both strains essentially identical to growth in P(i) medium, indicating a well-adapted metabolism for utilization of phosphorus from IP(6). There was some difference in growth yield (milligrams of biomass per milligram of glucose) between the two strains: 0.95 (Y(1)) and 1.35 (Y(2)) in IP(6) medium and 1.03 and 1. 35, respectively, in P(i) medium. The phytases were of the 3-phytase type, forming mainly DL-Ins(1,2,4,5,6)P(5), DL-Ins(1,2,5,6)P(4), and DL-Ins(1,2,6)P(3).

Inositol phosphates with different numbers of phosphate groups influence iron absorption in humans.

BACKGROUND: Inositol hexaphosphate (IP(6)) is a well-known inhibitor of iron absorption, whereas the effects of the less-phosphorylated derivatives of IP(6) are less known. OBJECTIVES: The objective was to investigate the effects of inositol tri-, tetra-, and pentaphosphates (IP(3), IP(4), and IP(5), respectively) on iron absorption in humans. DESIGN: Iron absorption was measured in 5 experiments from single meals by extrinsic labeling with (55)Fe and (59)Fe and determination of whole-body retention and the erythrocyte uptake of isotopes. In experiments 1-3 the meals contained white-wheat rolls to which 10 mg P as IP(5), IP(4), or IP(3), respectively, was added. Inositol 1,2,6-triphosphate [Ins(1,2, 6)P(3)] and a mixture of isomers of IP(4) and IP(5) were studied. White-wheat rolls contained 10 mg P as IP(3) + IP(4) and 2 mg P as IP(5) + IP(6) in experiment 4 and 20 mg P as IP(3) + IP(4) and 3 mg P as IP(5) + IP(6) in experiment 5; inositol phosphates were obtained via fermentation of sodium phytate. Each experiment had 8-11 subjects. RESULTS: In experiment 1, iron absorption was reduced by 39%, whereas there was no significant effect on iron absorption in experiments 2 and 3. In experiments 4 and 5, iron absorption was reduced by 54% and 64%, respectively, suggesting that IP(3) and IP(4) contributed to the inhibitory effect. CONCLUSIONS: IP(5) has an inhibitory effect on iron absorption, whereas IP(3) and IP(4) in isolated form have no such effect. IP(3) and IP(4) in processed food contribute to the negative effect on iron absorption, presumably by binding iron between different inositol phosphates. To improve iron absorption from cereals and legumes, degradation of inositol phosphates needs to be to less-phosphorylated inositol phosphates than IP(3).

Alginate, small bowel sterol excretion, and absorption of nutrients in ileostomy subjects.

The effect of alginate on ileostomy excretion of sterols and nutrients was investigated in six ileostomy subjects fed a constant low-fiber diet with or without supplementation with 7.5 g sodium alginate. A mean of 95% of uronic acids derived from the sodium alginate was recovered in the ileostomy contents. Supplementation with alginate increased fat excretion by 140% and decreased bile acids excretion by 12%. Sodium and potassium excretion were significantly increased whereas starch and nitrogen excretion were unchanged. Five of six subjects showed a decreased apparent absorption of iron and manganese with alginate, which, however, was not statistically significant. Absorption of phosphorus, calcium, magnesium, and zinc were unchanged. Almost no digestion of sodium alginate occurs in the stomach and small intestine. The increased fatty acids excretion may be explained by the binding or trapping of fatty acids in the gel matrix formed by alginate, which may also cause a reduced bile flow.

Degradation products of bran phytate formed during digestion in the human small intestine: effect of extrusion cooking on digestibility.

To investigate the digestion of phytate in the stomach and small intestine in humans, studies were performed in subjects with established ileostomy. A recently developed high performance liquid chromatography method made it possible to analyze phytate and its degradation products in food and digesta. The digestibility of phytate in raw bran and extruded bran was investigated in seven ileostomy patients. Each subject was studied for two 4-d periods while consuming a constant low fiber diet with the addition of either 54 g/d of a bran-gluten-starch mixture or the corresponding extruded product. During passage through the subject's stomach and small intestine 58%, on average, of the phytate in unprocessed bran was hydrolyzed to inositol penta-, tetra- and triphosphates. When bran was subjected to extrusion cooking, 25% of the inositol hexaphosphate was hydrolyzed to penta- and tetraphosphate and the phytase activity ceased. Essentially no phytate digestion occurred when the ileostomy subjects consumed the extruded product. The reduced digestibility might be due to the lost phytase activity or to formation of indigestible phytate complexes during extrusion cooking.

Effect of wheat bran and pectin on bile acid and cholesterol excretion in ileostomy patients.

The effect of addition of pectin or wheat bran to a constant low-fibre diet on bile acid and cholesterol excretion from the small intestine has been studied in ileostomy patients. The study was designed to minimize bacterial alteration of ileostomy contents. An addition of 15 g of citrus pectin increased bile acid excretion by 35 per cent (P less than 0.05) and net cholesterol excretion by 14 per cent (P less than 0.05) in six patients, while 16 g of wheat bran to another six patients caused no consistent change. Ileostomy fat excretion increased on the diet with added pectin (P less than 0.05) but not on that with bran. The results support the concept of dietary fibre exerting its effects on lipid metabolism by altering intestinal excretion of sterols.

Low-fat versus medium-fat enteral diets. Effects on bile salt excretion in jejunostomy patients.

Nine jejunostomy patients were given three low-residue enteral diets in random order through a nasogastric tube. Total bile salt excretion in the jejunostomy contents was 13-17% lower (p less than 0.05) on low-fat diets than on a medium-fat diet. Cholate excretion was 14-20% lower, but chenodeoxycholate excretion showed no difference on the low-fat diets. The study supports the idea of a lower excretion of bile salts to the colon as an explanation of reduced diarrhoea when a low-fat diet is prescribed to patients after ileal resection.