Late introduction of fish and eggs is associated with increased risk of allergy development - results from the FARMFLORA birth cohort.

The prevalence of allergy is markedly low in children growing up on farms. An increasing number of studies indicate that the timing of food introduction may affect allergy development. We aimed to investigate if protection against allergy in farm environments may be mediated through differences in food-introduction practices between farm and non-farm families, using an explorative approach. Twenty-eight farm and 37 non-farm children were included in the FARMFLORA birth cohort. Practices of breastfeeding and introduction of formulas and complementary foods were collected by questionnaires at 6, 12, and 18 months of age. Allergy was diagnosed by pediatricians at 3 years of age. The only difference in food-introduction practices observed between farm and non-farm children was an earlier introduction of nuts in farmers (median month: 11 [IQR: 8-6] in farmers, 15 [12-19] in non-farmers). One farm child (4%) and 10 non-farm children (27%) were allergic at 3 years of age. Lower risk of allergy development was associated with early exclusive breastfeeding (continuous variable; OR = 0.59, 95% CI: 0.39-0.89), but also having received eggs (OR = 0.08, 95% CI: 0.13-0.54) and fish (logistic regression not applicable, P = 0.01 in likelihood ratio testing [χ2]) at 10 months of age or earlier compared to later. Our results were not affected by reverse causation, as judged by a questionnaire sent to the families in retrospect. Timing of introduction of complementary foods is unlikely to contribute to the lower risk of allergy among farm children. Although early exclusive breastfeeding was associated with a lower rate of allergy development, postponed introduction of complementary foods might increase the risk of developing allergy. Owing to the limited sample size, our results are only indicative, but support prior findings.

A maternal diet of fatty fish reduces body fat of offspring compared with a maternal diet of beef and a post-weaning diet of fish improves insulin sensitivity and lipid profile in adult C57BL/6 male mice.

AIM: The maternal diet during pregnancy and lactation may affect the long-term health of the offspring. Our aim was to study how a fish or meat diet perinatal and after weaning affects body composition, insulin sensitivity and the profile of n-3 and n-6 polyunsaturated fatty acids (PUFAs) in breast milk, fat depots, skeletal muscle and liver in male adult mice offspring. METHODS: During gestation and lactation, C57BL/6 dams were fed a herring- or beef-based diet. Half of the pups in each group changed diets after weaning. In offspring, body composition measured by DEXA, plasma lipid profile and insulin sensitivity measured by euglycemic clamp or QUICKI were monitored to adulthood. Analysis of total FAs by GC-MS were performed in the diet, breast milk and in different tissues. RESULTS: At 9 week of age, offspring of herring-fed dams had less body fat than offspring of beef-fed dams. Mice fed herring after weaning had increased insulin sensitivity at 15 week of age, reduced total plasma cholesterol and triglyceride levels, and compared with beef-fed mice, larger interscapular brown adipose tissue depots. The FA composition of the maternal diet was mirrored in breast milk, and the herring diet significantly affected the FA profile of different tissues, leading to an increased content of n-3 PUFAs. CONCLUSION: A herring-based maternal diet reduces body fat in the offspring, but the insulin sensitivity, plasma lipids and amount of brown adipose tissue are affected by the offspring's own diet; the herring diet is more beneficial than the beef diet.

Low breast milk levels of long-chain n-3 fatty acids in allergic women, despite frequent fish intake.

BACKGROUND: Long-chain n-3 polyunsaturated fatty acids (PUFAs) have immune regulating and anti-inflammatory effects. However, their role in allergic disease is unclear. Allergic diseases are immunologically heterogeneous, and we hypothesized that n-3 fatty acid composition in serum and breast milk may vary according to clinical manifestations. Further, animal studies have shown reduction of serum-PUFA levels during allergic inflammation. OBJECTIVE: To investigate fatty acid composition in breast milk and serum from women with different atopic disease manifestations. Secondly, to determine whether low PUFA levels reflected insufficient intakes. METHODS: Fatty acids were analysed in breast milk and serum of women with atopic eczema and respiratory allergy (n=16), only respiratory allergy (n=7), as well as healthy women (n=22). Dietary intake of foods expected to affect long-chain n-3 PUFA levels were estimated by food-frequency questionnaire. The fatty acid pattern was related to diagnostic group and intake of relevant food items using a multivariate pattern recognition method (partial least squares projections to latent structures and discriminant analysis). Results Women with a combination of eczema and respiratory allergy had lower breast milk levels of several PUFAs (arachidonic acid, eicosapentaenoic acid, EPA, docosahexaenoic acid, DHA, and docosapentaenoic acid, DPA), and a lower ratio of long-chain n-3 PUFAs/n-6 PUFAs. Their PUFA levels differed not only from that of healthy women, but also from that of women with only respiratory allergy. The latter had a fatty acid pattern similar to that of healthy women. Despite low EPA, DHA and DPA levels women with eczema and respiratory allergy consumed no less fish than did healthy women. CONCLUSION & CLINICAL RELEVANCE: Our data suggest that reduced levels of long-chain n-3 fatty acids in serum and breast milk characterize women with extensive allergic disease including eczema, and are not related to low fish intake. Consumption of PUFAs during the allergic process may explain these findings.

Long-chain polyunsaturated fatty acids are consumed during allergic inflammation and affect T helper type 1 (Th1)- and Th2-mediated hypersensitivity differently.

Studies have shown that atopic individuals have decreased serum levels of n-3 fatty acids. Indicating these compounds may have a protective effect against allergic reaction and/or are consumed during inflammation. This study investigated whether fish (n-3) or sunflower (n-6) oil supplementation affected T helper type 1 (Th1)- and Th2-mediated hypersensitivity in the skin and airways, respectively, and whether the fatty acid serum profile changed during the inflammatory response. Mice were fed regular chow, chow + 10% fish oil or chow + 10% sunflower oil. Mice were immunized with ovalbumin (OVA) resolved in Th1 or Th2 adjuvant. For Th1 hypersensitivity, mice were challenged with OVA in the footpad. Footpad swelling, OVA-induced lymphocyte proliferation and cytokine production in the draining lymph node were evaluated. In the airway hypersensitivity model (Th2), mice were challenged intranasally with OVA and the resulting serum immunoglobulin (Ig)E and eosinophilic lung infiltration were measured. In the Th1 model, OVA-specific T cells proliferated less and produced less interferon (IFN)-gamma, tumour necrosis factor (TNF) and interleukin (IL)-6 in fish oil-fed mice versus controls. Footpad swelling was reduced marginally. In contrast, mice fed fish oil in the Th2 model produced more OVA-specific IgE and had slightly higher proportions of eosinophils in lung infiltrate. A significant fall in serum levels of long-chain n-3 fatty acids accompanied challenge and Th2-mediated inflammation in Th2 model. Fish oil supplementation affects Th1 and Th2 immune responses conversely; significant consumption of n-3 fatty acids occurs during Th2-driven inflammation. The latter observation may explain the association between Th2-mediated inflammation and low serum levels of n-3 fatty acids.

Influence of herring (Clupea harengus) and herring fractions on metabolic status in rats fed a high energy diet.

AIM: Few dietary studies have looked beyond fish oil to explain the beneficial metabolic effects of a fish-containing diet. Our aim was to study whether addition of herring, or sub-fractions of herring, could counteract negative metabolic effects known to be induced by a high-fat, high-sugar diet. METHODS: Rats were given six different diets: standard pellets; high energy diet with chicken mince (HiE control); high energy diet with herring mince (HiE herring); and high energy diet with chicken mince and either herring oil (HiE herring oil), herring press juice, PJ (HiE PJ) or herring low molecular weight PJ (HiE LMW-PJ). Factors associated with the metabolic syndrome were measured. RESULTS: There were no differences in energy intake or body weight between the groups, but animals fed high energy diets had a higher body fat content compared with the pellet group, although not statistically significant in all groups. Mesenteric adipocyte size was smaller in the HiE herring oil group compared with the HiE control. Glucose clamp studies showed that, compared with the pellet group, the HiE control and HiE herring diets, but not the HiE herring oil diet, induced insulin resistance. Addition of herring or herring oil to the high energy diet decreased total cholesterol levels, triacylglycerols and the atherogenic index compared with the HiE control group. CONCLUSIONS: The results suggest that addition of herring or herring oil counteracts negative effects on blood lipids induced by a high energy diet. The lipid component of herring thus seems to be responsible for these beneficial effects.

Herring (Clupea harengus) supplemented diet influences risk factors for CVD in overweight subjects.

OBJECTIVE: To assess the effect of a 4-week herring diet compared to a reference diet on biomarkers for cardiovascular disease in obese subjects. DESIGN: Randomized crossover trial. SETTING: Department of Internal Medicine, Sahlgrenska University Hospital. SUBJECTS: Fifteen healthy obese men and women (age 24-70 years) included, 13 completed. INTERVENTION: Subjects were randomly assigned to four weeks of herring diet (150 g baked herring fillets/day 5, days/week) or reference diet (pork and chicken fillets) and switched diets after 2 weeks washout. P-total cholesterol, p-TAG, p-HDL, p-HDL(2), p-HDL(3), p-LDL, p-apolipoprotein A, p-apolipoprotein B, p-Lipoprotein (a), p-fibrinogen, p-C- reactive protein and p-antioxidative capacity were analysed at 0,2,4,6,8 and 10 weeks. RESULTS: P-HDL was significantly higher after the herring diet period compared to after the reference diet period; 1.22 vs 1.13 mmol/l (P=0.036). There was a small, but not statistically significant, decrease in TAG but no effect on other biomarkers. TEAC and FRAP, but not ORAC-values, indicated that plasma antioxidants may have been reduced. CRP tended to be lower after the herring diet compared to after the reference diet. CONCLUSIONS: Consumption of oven-baked herring (150 g/day, 5 days/week) for 4 weeks, compared to consumption of pork and chicken fillets, significantly increased p-HDL. Patients with insulin resistance and obesity, who commonly have low HDL, may therefore benefit from addition of herring to the diet.

Hydrothermal treatment and malting of barley improved zinc absorption but not calcium absorption in humans.

OBJECTIVE: To study whether hydrothermal treatment or malting of barley (cv. Blenheim) improves zinc and calcium absorption in humans. DESIGN: : Two groups of 10 and 12 healthy subjects, respectively, were in a period of 2 months in a fasting state, served two single meals each containing porridge or breakfast cereals prepared from processed or unprocessed (control) barley (60 g). The meals included 200 g of milk, extrinsically labelled with (65)Zn and (47)Ca. Whole-body retention of both minerals was measured. SETTING: The study was carried out at the Department of Radiation Physics, Sahlgrenska University Hospital, Göteborg. SUBJECTS: The subjects were recruited among students at the Göteborg University. None dropped out. INTERVENTIONS: The activities of (65)Zn and (47)Ca were measured by whole-body counting four to five times over a 4-week period after each meal. RESULTS: Zinc absorption from hydrothermally treated barley porridge, containing 28 mg P as inositol tri- to hexaphosphates (InsP(3)-InsP(6)), was significantly higher (P<0.001) than from control porridge containing 111 mg P as InsP(3)-InsP(6), 25.2+/-6.9 vs 11.0+/-2.5% (n=12). Calcium absorption did not differ (P>0.05), 21.1+/-6.8 vs 19.5+/-4.7% (n=12). Zinc absorption from breakfast cereals of malted barley with phytase activity and containing 70 mg P as InsP(3)-InsP(6,) was significantly higher (P<0.05) than from flakes of barley, containing 108 mg P as InsP(3)- InsP(6) and no phytase activity, 22.9+/-5.8 vs 14.8+/-4.6% (n=10). The calcium absorption was 21.3+/-6.5 vs 18.5+/-4.3% (n=10) and did not differ significantly (P>0.05). CONCLUSION: Improvements of zinc absorption in breakfast meals can be achieved by optimised hydrothermal treatment or malting of barley. Calcium absorption was not influenced in the meals in this study. SPONSORSHIP: Supported by Semper AB, Sweden, Oy Lahden Polttimo, Finland, the SL-Foundation, Sweden, Swedish National Board for Industrial and Technical Development (NUTEK), the Nordic Industrial Foundation, Swedish Council for Forestry and Agricultural Research (SJFR, project no 50.0306/97).

Phytate degradation by micro-organisms in synthetic media and pea flour.

AIMS: To screen micro-organisms for the ability to produce phytase enzyme(s) and to use promising strains for the fermentation of pea flour. METHODS AND RESULTS: Two methods using the indirect estimation of phytate degradation were evaluated and both shown to be inadequate. A third method, measuring the inositol phosphate (IP3-IP6) content directly during fermentation, was used instead of the indirect estimations of phytate degradation. In synthetic media, some strains required customized conditions, with no accessible phosphorus sources other than phytate, to express phytase activity. The repression of phytase synthesis by inorganic phosphorus was not detected during fermentation with pea flour as substrate and seemed to be less significant with a higher composition complexity of the substrate. None of the tested lactic acid bacteria strains showed phytase activity. CONCLUSIONS: The methodology for the phytase screening procedure was shown to be critical. Some of the screening methods and media used in previous publications were found to be inadequate. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper highlights the pitfalls and difficulties in the evaluation of phytase production by micro-organisms. The study is of great importance for future studies in this area.

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.

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.

Optimal conditions for phytate degradation, estimation of phytase activity, and localization of phytate in barley (cv. Blenheim).

Using a multivariate experimental design, optimal conditions for phytate degradation were found to be pH 4.8 and 57 degrees C in barley flour (cv. Blenheim) and pH 5.2 and 47 degrees C in a crude extracted phytase from barley. Three methods for measuring phytase activity in raw and hydrothermally processed barley were compared. Incubation at pH 5 and 55 degrees C for 60 min did not give significantly different results (p > 0.05), whereas incubation at pH 5 and 50 degrees C for 10, 20, 30, and 60 min gave significantly different results (p < 0.001) between methods. The change in microstructure of phytate globoids during hydrothermal processing showed that the degradation was highest in the scutellum cells and less in the aleurone layer.

Determination of the retention of 47Ca by whole-body counting.

Retention of intravenously or orally administered 47Ca in the human body are described by a two-parameter function. It is then sufficient to make only a few whole-body measurements to determine the retention function, avoiding faeces sampling and stool markers. Seven days after intake the non-absorbed calcium was excreted and the model agreed with the measured relative retention. Absorption of calcium could then, in some cases (e.g. comparative studies), be described by relative retention at the 7th day after intake.

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 influence iron uptake in Caco-2 cells.

Phytate, inositol hexaphosphate (InsP(6)), may be hydrolyzed to inositol phosphates with lower degree of phosphorylation, i.e., inositol penta- to monophosphates (InsP(5)-InsP(1)), during food processing. Each of these lower inositol phosphates exists in different isomeric forms. The objective of this study was to determine if different isomers of InsP(3)-InsP(5) (Ins(1,2,4)P(3), Ins(1,2,3)P(3), Ins(1,2,6)P(3), Ins(1,3,4)P(3), Ins(1,2,3,4)P(4), Ins(1,2,5,6)P(4), Ins(1,2,4,5,6)P(5), and Ins(1,3,4,5,6)P(5)) and InsP(6) affect the uptake of iron. We studied the iron absorption in vitro using the human intestinal epithelial cell line, Caco-2. Addition of a 2-fold molar excess of InsP(6) or InsP(5) in proportion to Fe (1 h incubation at 37 degrees C) reduced iron uptake by 46-52% (p < 0.001). Neither InsP(4) isomers nor InsP(3) isomers affected iron uptake significantly at 1 h incubation with a molar InsP:Fe level of 2:1. Iron uptake was shown to not be a function of the isomeric form of inositol phosphates. The inositol phosphate isomers did not seem likely to interact with each other through iron to form more stable iron complexes. At a molar InsP:Fe level of 20:1 an inhibitory effect of InsP(4) was found, while InsP(3) did not affect the iron absorption even at a 20-fold molar excess.

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).

Processing of quinoa (Chenopodium quinoa, Willd): effects on in vitro iron availability and phytate hydrolysis.

The effect of different processing techniques was studied on in vitro iron availability and phytate hydrolysis in high and low saponin content quinoa (Chenopodium quinoa, Willd) seeds. Water slurries of ungerminated and germinated quinoa flour were processed by cooking, soaking, and fermentation using Lactobacillus plantarum as starter. Iron solubility under physiological conditions (in vitro) was measured and used as an estimation of iron availability. Phytate (inositol hexaphosphate/IP6) and its degradation products were analysed by an HPLC method. The IP6 + IP5 content was reduced by cooking with 4 to 8%, germination with 35 to 39%, soaking with 61 to 76% and by fermentation with 82 to 98%. The highest reduction, about 98%, was obtained after fermentation of the germinated flour. Cooking had no effect on the amount of soluble iron. Iron solubility increased, however, two to four times after soaking and germination, three to five times after fermentation and five to eight times after fermentation of the germinated flour samples and was highly correlated to the reduction of IP6 + IP5 (P < 0.001). There was no difference between the quinoa varieties with regard to phytate reduction and iron solubility. The pH in fermented samples was reduced from 6.5 to about 3.5, due to lactic acid formation.

Mixed-linked beta-glucan from breads of different cereals is partly degraded in the human ileostomy model.

The purpose of this investigation was to study the degradation of beta-glucan in the small intestine and the molecular weight of beta-glucan in the excreta of nine ileostomy subjects after consumption of different diets based on bread made with oat bran (oat bread), a fiber-rich barley fraction (barley bread), or wheat flour (wheat bread) as the main ingredients. Oat bread with enzymatically degraded beta-glucan was also used (oat + enzyme bread). The beta-glucan intake from the four diets was 12.5, 12.9, 1.1, and 4.0 g/d, respectively. On the basis of dry matter, the night effluents accounted for approximately 15% of the total amount of the excreta, with the highest proportion (22%) being for the wheat-bread diet. A notable loss of beta-glucan (0.7-2.4 g/d, or 13-64%) was found when intake was compared with excretion. In vitro, a higher viscosity development with time for dispersions of oat bread compared with barley bread was noted, which could be related to the higher molecular weight of the beta-glucan in this bread. There seemed to be a depolymerization of the beta-glucan both during bread making and transit through the upper gastrointestinal tract.

Substrates available for colonic fermentation from oat, barley and wheat bread diets. A study in ileostomy subjects.

Nutrients not absorbed in the small bowel will form substrates for microbial growth in the colon which may have implication for the development of colon cancer. The aim of the present study was to investigate whether fibre-rich oat and barley diets increase the excretion of energy-supplying nutrients from the small bowel compared with a low-fibre wheat diet, and whether a possible increase could be related to the beta-glucan content. Nine ileostomy subjects were served four types of bread together with a low-fibre basal diet (12 g dietary fibre/d). The breads were based on either wheat flour (W diet, 7 g dietary fibre/d), oat bran (OB diet, 29 g dietary fibre/d), the same amount of oat bran with addition of beta-glucanase (EC 3.2.1.4) (OBE diet, 19 g dietary fibre/d) or a fibre-rich barley fraction (B diet, 35 g dietary fibre/d). An increased ileal excretion of starch was observed with the barley diet but no effect of the oat beta-glucan on starch recovery was found. The NSP + Klason lignin in the ileostomy effluents accounted only for 24, 31, 24 and 35% of the gross energy excretion in the W, OB, OBE and B diet periods respectively. A large part of the dry weight and energy (30, 21, 28 and 27%, in the W, OB, OBE and B diets respectively) in the effluents could not be identified as fat, protein, total starch or NSP + Klason lignin. This unidentified part was probably made up of oligosaccharides, endogenous losses and nutrient complexes. Methods for identifying and analysing these components should be developed and their role as substrates for colonic fermentation and colon cancer development ought to be investigated.

Improved zinc and iron absorption from breakfast meals containing malted oats with reduced phytate content.

The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 65Zn and of bread rolls with 55Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from malted-oat porridge with a phytate (inositol hexaphosphate) content of 107 mumol was 18.3%, and significantly higher (P < 0.05) than from the control porridge containing 432 mumol phytate (11.8%). Fe absorption from the meal containing malted-oat porridge with 107 mumol phytate (Expt 2) was also significantly improved (P < 0.05) compared with that from the meal containing control porridge with 437 mumol phytate. The average increase in Fe absorption was 47%, or from 4.4 to 6.0%. In the breakfast meal containing malted porridge with 198 mumol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25% more than that from the meal containing control porridge (with 599 mumol phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups.

Dietary Aspergillus niger phytase increases iron absorption in humans.

Phytate is an inhibitor of iron absorption that can be removed before the intestinal site of absorption by microbial phytase, thereby increasing iron absorption from a meal. The effects of two kinds of dietary phytase, cereal phytase and microbial phytase from Aspergillus niger, on iron absorption were investigated. Iron absorption was measured from single meals containing white wheat rolls supplemented with wheat bran with or without phytase activity (expt. 1) and phytase-deactivated wheat bran with or without addition of microbial phytase from A. niger (expt. 2). Each experiment had 10 subjects and two different radio iron tracers: 55Fe and 59Fe were used for comparison of the absorption from the test meals in each experiment. No differences in iron absorption were found between meals containing wheat brain with or without phytase activity. Addition of microbial phytase to the meal containing phytase-deactivated wheat bran increased iron absorption from 14.3 +/- 2.6% to 26.1 +/- 3.8% (P < 0.0001). Two pH optima, one at pH 2.0 and one at pH 6.0, were found for A. niger phytase at 37 degrees C, but activity occurred at all pH values between 1.0 and 7.5. The results suggest that effective and complete degradation of phytate occurred in the stomach when A. niger phytase was given with the meal. This may be explained by high activity of microbial phytase at physiological pH conditions of the stomach, whereas wheat phytase has a different pH optimum.