Effects of cellulose added to diets of low and high fiber content upon the metabolism of calcium, magnesium, zinc and phosphorus by man

Dietary cellulose prevents gut inflammation by modulating lipid metabolism and gut microbiota

A Western diet comprising high fat, high carbohydrate, and low fiber content has been suggested to contribute to an increased prevalence of colitis. To clarify the effect of dietary cellulose (an insoluble fiber) on gut homeostasis, for 3 months mice were fed a high-cellulose diet (HCD) or a low-cellulose diet (LCD) based on the AIN-93G formulation. Histologic evaluation showed crypt atrophy and goblet cell depletion in the colons of LCD-fed mice. RNA-sequencing analysis showed a higher expression of genes associated with immune system processes, especially those of chemokines and their receptors, in the colon tissues of LCD-fed mice than in those of HCD-fed mice. The HCD was protective against dextran sodium sulfate-induced colitis in mice, while LCD exacerbated gut inflammation; however, the depletion of gut microbiota by antibiotic treatment diminished both beneficial and non-beneficial effects of the HCD and LCD on colitis, respectively. A comparative analysis of the cecal contents of mice fed the HCD or the LCD showed that the LCD did not influence the diversity of gut microbiota, but it resulted in a higher and lower abundance of Oscillibacter and Akkermansia organisms, respectively. Additionally, linoleic acid, nicotinate, and nicotinamide pathways were most affected by cellulose intake, while the levels of short-chain fatty acids were comparable in HCD- and LCD-fed mice. Finally, oral administration of Akkermansia muciniphila to LCD-fed mice elevated crypt length, increased goblet cells, and ameliorated colitis. These results suggest that dietary cellulose plays a beneficial role in maintaining gut homeostasis through the alteration of gut microbiota and metabolites.

Nutritional Implications of Dietary Interactions: A Review

A large number of dietary interactions have been described. Of these, only a relatively small number have been proved of relevance for human nutrition under the conditions of real diets. These interactions most often occur at the intestinal lumen, but they may also take place during utilization or storage of nutrients. Traditional diets of developing countries, which usually include non-refined cereals and other sources of fibre, may inhibit the bioavailability of mineral nutrients, contributing to specific deficiencies. Drug-nutrient interactions may also impact on nutritional status, particularly in population groups such as the elderly, who frequently receive prolonged medication and may have an inadequate food intake.

Re-evaluation of celluloses E 460(i), E 460(ii), E 461, E 462, E 463, E 464, E 465, E 466, E 468 and E 469 as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion re-evaluating the safety of microcrystalline cellulose (E 460(i)), powdered cellulose (E 460(ii)), methyl cellulose (E 461), ethyl cellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methyl cellulose (E 464), ethyl methyl cellulose (E 465), sodium carboxy methyl cellulose (E 466), enzymatically hydrolysed carboxy methyl cellulose (E 469) and cross-linked carboxy methyl cellulose (E 468) as food additives. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) 'not specified' for unmodified and modified celluloses. Celluloses are not absorbed and are excreted intact in the faeces; in addition, microcrystalline cellulose, powdered and modified celluloses could be fermented by the intestinal flora in animals and humans. Specific toxicity data were not always available for all the celluloses evaluated in the present opinion and for all endpoints. Given their structural, physicochemical and biological similarities, the Panel considered it possible to read-across between all the celluloses. The acute toxicity of celluloses was low and there was no genotoxic concern. Short-term and subchronic dietary toxicity studies performed with E 460(i), E 461, E 462, E 463, E 464, E 466 and E 469 at levels up to 10% did not indicate specific treatment related adverse effects. In chronic toxicity studies performed with E 460(i), E 461, E 463, E 464, E 465 and E 466, the no observed adverse effect level (NOAEL) values reported ranged up to 9,000 mg/kg body weight (bw) per day. No carcinogenic properties were detected for microcrystalline cellulose and modified celluloses. Adverse effects on reproductive performance or developmental effects were not observed with celluloses at doses greater than 1,000 mg/kg bw by gavage (often the highest dose tested). The combined exposure to celluloses (E 460-466, E 468 and E 469) at 95th percentile of the refined (brand-loyal) exposure assessment for the general population was up to 506 mg/kg bw per day. The Panel concluded that there was no need for a numerical ADI and that there would be no safety concern at the reported uses and use levels for the unmodified and modified celluloses (E 460(i); E 460(ii); E 461-466; E 468 and E 469). The Panel considered an indicative total exposure of around 660-900 mg/kg bw per day for microcrystalline, powdered and modified celluloses.

In vitro fermentation of chewed mango and banana: particle size, starch and vascular fibre effects

Fruits (and vegetables) contain cellular structures that are not degraded by human digestive enzymes. Therefore, the structure of the insoluble fraction of swallowed fruits is mostly retained until intestinal microbial fermentation. In vitro fermentation of mango and banana cell structures, which survived in vivo mastication and in vitro gastrointestinal digestion, were incubated with porcine faecal inoculum and showed intensive metabolic activity. This included degradation of cell walls, leading to the release of encapsulated cell contents for further microbial metabolism. Production of cumulative gas, short chain fatty acids and ammonia were greater for mango than for banana. Microscopic and spectroscopic analyses showed this was due to a major fermentation-resistant starch fraction present in banana, that was absent in mango. This study demonstrated distinctive differences in the fermentability of banana and mango, reflecting a preferential degradation of (parenchyma) fleshy cell walls over resistant starch in banana, and the thick cellulosic vascular fibres in mango.

Effects of exposure to dietary chromium on tissue mineral contents in rats fed diets with fiber

This study evaluated the effects of diets with fiber (cellulose and/or pectin) supplemented with chromium(III) on homeostasis of selected minerals in femurs, thigh muscles, livers, and kidneys of rats. For 6 weeks, male rats were fed experimental diets: a fiber-free diet (FF), a diet containing 5% cellulose (CEL), 5% pectin (PEC), or 2.5% cellulose and 2.5% pectin (CEL+PEC). These diets had 2.53 or 0.164 mg Cr/kg diet. The tissue levels of Ca, Mg, Zn, Fe, and Cr were determined by using atomic absorption spectrometry. Supplementing diets with Cr resulted in significantly higher Cr levels in the femurs of rats fed the CEL diet and significantly higher Cr and Fe levels in the rats fed the CEL+PEC diet compared to the rats fed FF diet. Muscle Ca content was significantly lower in the rats fed the CEL+PEC+Cr diet compared to the rats fed FF+Cr diet. The rats consuming the PEC+Cr diet had the highest liver Cr content. The highest kidney Zn content was observed in the rats fed diets containing Cr and one type of fiber. These results indicate that diets containing chromium at elevated dose and fiber have a significant effect on the mineral balance in rat tissues.

Human zinc deficiency: discovery to initial translation

Ananda S Prasad first suspected zinc deficiency in 1958 after he, at the request of James A Halsted, evaluated a patient with severe iron deficiency. In addition to iron deficiency, the patient appeared ∼10 y old and was severely stunted and prepubertal, though his chronological and bone age were much older. He also had hepatosplenomegaly and ate clay. The condition was not rare in that 11 cases were reported. In 1961 Prasad joined the Vanderbilt Nutrition Group led by William J. Darby at the US Naval Medical Research Unit-3, Cairo, Egypt. Prasad et al. studied 40 males similar to the index case. Contrasts with the index case included no clay eating and infection with schistosomiasis and hookworm. Zinc kinetics confirmed the zinc deficiency. Endocrine studies showed hypopituitarism. Treatment with zinc and an omnivorous diet was more efficacious for growth than no treatment, diet alone, or iron and diet. Later, Halsted et al. confirmed these findings in stunted Iranian farmers. The key role of diet in the illness became evident when Prasad found 16 severely stunted farmers from 2 oases who were not infected with schistosomiasis or hookworm. Later, Reinhold et al., in Halsted's group, reported that phytate and other indigestible zinc-binding ligands in unleavened bread prepared from high-extraction wheat flour suppress zinc absorption.

The role of minerals in food selection in a black howler monkey (Alouatta pigra) population in Belize following a major hurricane

As plants may contain low levels of some minerals including sodium, copper, and phosphorous, herbivores may become deficient in these nutrients. In 2001, Hurricane Iris hit the Monkey River Forest in Belize causing substantial damage to the food supply of the black howler monkey population (Alouatta pigra) living there. This included an 18-month absence in fruit production and a complete loss of figs that are high in calcium. In this article, we describe the post-hurricane diet of this monkey population and compare the mineral content of food items to each other and to recommendations for non-human primates [NRC 2003]. We also investigate food selection in relation to potentially limiting minerals. Behavioral data from four groups of howlers (2002-2006) and samples of all ingested food items were collected and a sample of 99 plant from 18 food species was analyzed for mineral content. Unexpectedly, the post-hurricane diet contained more mature leaves than new leaves despite the availability of new leaves. Leaves contained higher amounts of minerals than reproductive parts and with the exception of Cecropia peltata stems, plant parts were low in sodium. Cecropia peltata is a pioneer species that grows following habitat disturbance thus the ingestion of these stems may be a potential mechanism to avoid sodium deficiency in this damaged forest. Calcium and zinc were found above recommended values in most food items; however, both positively predicted food selection, which may reflect a difference between their abundance and their bioavailability. However, as mature leaves contained more calcium than other plant parts, their high post-hurricane consumption may also be a response to the absence of figs and the need to find an alternate calcium source. This study highlights how habitat disturbance may affect mineral abundance and the dietary choices of primates.

Apparent zinc absorption and zinc status of weanling rats fed moderately zinc-deficient diets enriched with beef tallow or sunflower oil

The aim of the study was to compare apparent Zn absorption and Zn status of weanling rats fed diets that differed in Zn level, fat level and fat source. Semi-synthetic diets, which were about isoenergetic and contained 3% soyabean oil, were supplemented with 7 or 100 mg Zn/kg to create a mild Zn deficiency (LZ) or a high Zn supply (HZ) and with 0 (LF), 22% beef tallow (BT) or 22% sunflower oil (SF) according to a 2 × 3 factorial design of treatments. They were fed ad libitum to 6 × 8 rats for 28 days. Energy intake and growth rates were comparable among the HZ groups. Weight gains in the LZ-LF, LZ-BT and LZ-SF groups averaged 5.54, 4.95 and 4.15 g/day, and apparent Zn absorption averaged 79.4, 60.3 and 48.0 μg Zn/day, respectively, whereas faecal Zn excretion was comparable among these groups. Apparent Zn absorption, and plasma and femur Zn concentrations were lower in the high-fat groups than in the LF group, possibly due to the high cellulose content of the BT and SF diets. Plasma Zn concentrations were higher in the animals fed the BT-based than in the SF-based diets, whereas femur and soft tissue Zn concentrations were comparable among these groups. The differences between the LZ-BT and LZ-SF groups in growth rate, Zn absorption rate and Zn status were confirmed in a second experiment. The results indicate that moderately Zn-deficient diets enriched with SF in relation to BT affect Zn metabolism of weanling rats by a yet unknown mechanism.

A tube-fed liquid formula diet containing dietary fiber increased stool weight in bed-ridden elderly patients

OBJECTIVE

The number of bedridden elderly patients who need a liquid diet has been increasing. We evaluated the usefulness of a tube-fed liquid diet containing cellulose and oligosaccharide for elderly bedridden patients.

METHODS

Twenty-two elderly bedridden patients were given a liquid diet containing cellulose and lafinose for 4 wk. Parameters associated with blood and stool weight were measured during this period.

RESULTS

Stool weight increased by 32.0 g in men and 8.8 g in women at 2 wk and remained at these weights up to 4 wk (P < 0.05 before and after 2 wk, 3 wk, and 4 wk in men, and P < 0.05 before and after 3 wk in women). Body weight increased in men (0.5 kg) and women (0.7 kg) 15 d after starting the diet and then remained at these values up to 29 d thereafter, and statistically significant differences were not seen. There were no changes in nutritional parameters such as total protein.

CONCLUSION

No significant changes were observed in the general condition of elderly patients, with the exception of a positive increase in fecal weight, by 30-d supplementation of a liquid diet containing cellulose and lafinose.

Nutritional effects of supplementing liquid-formula diet with dietary fiber on elderly bed-ridden patients

In the past few decades, the number of bed-ridden elderly patients has been increasing. This group of patients is frequently fed with a liquid formula diet. The aim of this study was to evaluate the usefulness of a liquid formula diet containing dietary fiber (DF) for elderly bed-ridden patients. Eighteen elderly, bed-ridden patients were given L-3 Fiber, a DF-containing liquid formula diet (DF-LFD), for 4 weeks, while a number of parameters were monitored, including serum levels of total cholesterol, triglyceride, total protein, creatinine, uric acid, glucose, sodium, potassium, and calcium, urine protein/sugar, and defecation frequency. Total protein, albumin and total cholesterol significantly increased following the administration of the DF-LFD, associated with an average increase in body weight of 1.94 kg (5.0%). Defecation frequency significantly increased one week after DF-LFD administration was started, but this effect was transient. Although a few patients complained of nausea, vomiting or abdominal pain, no severe side effects were seen. In conclusion, DF-LFD supplementation appears to be beneficial for elderly bed-ridden patients, and can increase nutritional-related parameters, such as body weight, total protein, albumin and total cholesterol, without severe side effects.

Effect of dietary rhubarb stalk fiber on the bioavailability of calcium in rats

Ground rhubarb stalk fiber containing, on a dry weight basis, 74% total dietary fiber (66% insoluble and 8% soluble) was prepared from rhubarb plants. This fiber source has been shown to have a pronounced lipid lowering effect in mice. Its high oxalic acid content may, however, be a limiting factor for its use. The present study was undertaken to determine the safe dose level of the fiber in terms of its effect on calcium bioavailability. Male weanling Sprague-Dawley rats were fed a semi-purified diet (AIN 76) for 4 weeks containing 0, 1, 3, or 5% rhubarb fiber, or pure oxalic acid equivalent to 5% rhubarb fiber. The fiber content of each diet was brought to 5% by adding cellulose, and the calcium level of all diets was the same. As the rhubarb stalk fiber content of the diet increased, a consistent trend of increasing total retention and apparent absorption of calcium was manifested. In contrast, however, cellulose, due to its increased effect on intestinal motility resulted in a decreased calcium bioavailability. Overall results suggest that an addition of rhubarb stalk powder up to the level of 5% in a diet does not have detrimental effect on calcium bioavailability.

Hypochlorhydria from short-term omeprazole treatment does not inhibit intestinal absorption of calcium, phosphorus, magnesium or zinc from food in humans

OBJECTIVE

Low gastric pH is generally believed to be an important factor in intestinal mineral absorption. Thus, hypochlorhydria could be an important risk factor for mineral malabsorption and the development of marginal mineral status. We studied whether the hypochlorhydria associated with treatment with the anti-ulcer medication omeprazole, a potent gastric proton pump inhibition, would affect intestinal calcium, phosphorus, magnesium, or zinc absorption from food.

METHODS

Thirteen normal, healthy adults were assigned to either a control group (n = 5) receiving no drug treatment or an omeprazole treatment group (n = 8) to produce increased gastric pH. Omeprazole treatment of normal volunteers resulted in a significant change in postprandial gastric pH (pH 6.4 +/- 0.3 vs. 3.6 +/- 0.5 in control subjects, p < 0.01) and baseline fasting pH (pH 5.8 +/- 0.5 vs. pH 1.8 +/- 0.3 in controls, p < 0.01) after an overnight fast. Net mineral absorption from a standard test meal was measured using a whole gut lavage technique. Mineral absorption was measured twice in each subject, once with 120 mL of 0.1 mol/liter hydrochloric acid and a second time with 120 mL of distilled water alone.

RESULTS

We found that despite marked changes in gastric pH due to drug treatment or administration of exogenous HCl, no change in the intestinal absorption of calcium, phosphorus, magnesium or zinc from a standard test meal was evident.

CONCLUSIONS

These findings suggest that changing the gastric pH alone does not modify the net intestinal absorption of several minerals from food. Therefore, it is unlikely that moderate hypochlorhydria resulting from short-term omeprazole treatment substantially increases the risk for developing calcium, phosphorus, magnesium, or zinc deficiencies due to mineral malabsorption.

Influence of type of diet and incubation time on in sacco release of Cu, Fe, Mn and Zn from Italian ryegrass, untreated and ammonia treated wheat straw

Artificially dried ryegrass, untreated and ammonia-treated wheat straw were ground and incubated in nylon bags in the rumen of three sheep each fed with diets based on roughage or concentrate. Dry matter degradability, the concentration and the release of the trace elements Cu, Fe, Mn and Zn from the incubated feeds were measured after 0 (washing loss), 6, 12, 24, 48 and 72 h rumen incubation time. Dry matter degradability, trace element concentration and their release were significantly influenced by the kind of incubated feeds, incubation time and feeding of sheep. Cu- (1.8-6.9 mg kg-1 DM) and Zn concentrations (36-103 mg kg-1 DM) of straw residues in the bags were much higher than those of original straw (1.2-1.6 and 8.1-9.9 mg kg-1 DM resp.). The inflow of Cu and Zn in the bags containing straw residues was higher than their release. The Cu-, Fe- and Mn-release from ryegrass was similar to the dry matter degradability, but the Zn-release was much lower.

Colonic diverticulitis. Recognizing and managing its presentations and complications

Diverticulitis usually manifests as pain of abrupt onset in the lower left quadrant. Complications may occur with or without an acute attack. Plain abdominal films are crucial for initial workup and follow-up. Endoscopic examination is often indicated, but barium enema study should usually be avoided during an acute attack. Computed tomography offers the best means of determining extracolonic extension of diverticulitis. Therapy is usually medical and consists of "resting" the bowel, administering antibiotics to resolve infection, and preventing or minimizing complications. Surgery is reserved for refractory, recurrent, or complicated disease.

Trace minerals in the nutrition of children

Trace elements perform important functions in growth and development. However, little information exists about their dietary requirements during the demanding period of infancy. Opportunities to add to knowledge of the physiologic significance and dietary adequacy of trace elements in human nutrition are provided by recent analytic advances. Specific, sensitive, and reliable methods for the detection of trace element imbalances are sorely needed. Although several factors influence the dietary needs of these essential elements, the basis for establishing dietary needs in infants is hindered by the death of studies that have assessed their bioavailability in this age group. Thus until it has been conclusively shown otherwise, the physiologic response to human milk is used as the standard for infant feeding practices. This review is limited primarily to the physiologic significance and bioavailability of zinc, copper, manganese, molybdenum, chromium, fluoride, and selenium. The space devoted to each trace element is not meant to represent the element's importance but, rather, to reflect some of the present understanding of its metabolism and utilization.

Mineral retention in young men consuming soy-fiber-augmented liquid-formula diets

The effect of a nutritionally complete liquid-formula diet without soy polysaccharide or with the fiber source at 20, 30, or 40 g/d on mineral retention in young men was examined. Addition of 20 g soy polysaccharide to the liquid formula significantly (p less than 0.05) improved the retentions of copper, iron, zinc, and magnesium over the diet without added fiber. The highest level of soy polysaccharide (40 g/d) resulted in significantly (p less than 0.05) lower Cu, Zn, Fe, and Mg retentions than did the 20-g diet and the 30-g diet had an intermediate effect. Except for slightly negative Cu (-0.1 +/- 0.4 mg) and Fe (-0.6 +/- 3.7 mg) retentions on the 40-g diet, retentions of all minerals remained positive throughout this study. The liquid-formula diet supplemented with 40 g soy polysaccharide could have a deleterious effect on mineral retentions in persons consuming the diet as their sole nutritional source.

The effect of vegetables and beet fibre on the absorption of zinc in humans from composite meals

1. The absorption of zinc in humans from composite meals, was determined by extrinsic labelling of the meals with 65Zn and measurement of the whole-body retention of the radioisotope. 2. Low-Zn (mean 25 mumol) chicken meals with 150 g white bread or 225 g potatoes, carrots, turnips, cabbage or green peas were studied. The effect of a beet-pulp-fibre preparation used as a breakfast cereal, in bread and as a meat extender on Zn absorption was also studied. 3. The mean percentage absorption from the chicken meals with white bread, carrots and cabbage was significantly different from the meals with potatoes, turnips and green peas. When the amount of Zn in the meals was taken into account a slightly higher absorption was observed from the white-bread meal compared with the meals with potatoes and cabbage, while no differences were seen between the vegetable meals. 4. The beet-pulp-fibre preparation did not affect the extent of Zn absorption when used as a meat extender. The absorption of Zn was higher when the beet fibre was included in bread than when used as müesli. 5. The results obtained suggest that, besides the low-Zn content in vegetables, a large intake of vegetables or a pure-vegetable-fibre preparation has no significant effect on Zn availability from animal-protein-based meals.

Dietary fibre and mineral metabolism

Current dietary recommendations urge, inter alia, an increased consumption of fibre-containing foods. Some experimental studies made on various animals and man indicate that the associated increases in intakes of fibre and phytic acid may prejudice mineral status respecting calcium, magnesium, iron and zinc. An examination has been made of the experimental evidence, also of the epidemiological evidence on numerous types of populations, past and present, developing and developed. It has been concluded that diets high in fibre, characteristically do not have meaningful ill effects on well-being or unequivocally enhance morbidity. In particular populations in certain regions where deleterious effects have been reported it is judged that local factors, not wholly understood, are in operation. In assessing the extent of the benefit to be derived from the dietary changes urged, results must be viewed holistically and not in isolation. It is believed that the beneficial effects respecting reduced pronenesses to various degenerative diseases are likely to far outweigh the possible adverse effects of reduced bioavailability of mineral nutrients.

Effects of cellulase from Trichoderma viride on nutrient utilization by broilers

Studies were conducted to evaluate the effects of cellulase from Trichoderma viride in a diet for broilers containing high levels of wheat bran. Broiler-type, mixed-sex chicks were fed from 3 to 8 weeks of age. Wheat bran was added at 0, 10, and 20% levels. A fourth group received the 20% wheat bran plus the cellulase enzyme added at the level of .008%. A portion of the chicks was used in a digestibility study with chromic oxide as an indicator. The summarized data showed that cellulose treatment had a significant effect on reducing feed consumption (P less than .01) and an apparent effect in improving feed-to-gain ratio. Cellulase supplementation significantly improved the digestibility of cell wall components (P less than .01). Calcium, phosphorus, iron, zinc, and copper associated with cell walls were solubilized by cellulase. Iron balance was negative in the groups without cellulase; however, iron, which is bound by the bran, apparently was made available for absorption by cellulase.

Effect of fiber and phytate source and of calcium and phosphorus level on phytate hydrolysis in the chick

Broiler chicks were fed a corn-soybean meal diet or a corn-soybean meal diet containing either 15% rice bran, 15% wheat bran, 15% alfalfa meal, 10% cellulose, or 10% cottonseed hulls. All diets contained 3190 kcal/kg of metabolizable energy, 22.8% protein, and either 1.0% calcium and .5% nonphytate phosphorus (Pnp) or .85% calcium and .42% Pnp. The diets were fed for 3 weeks at which time a digestion trial was conducted to determine the amount of phytate hydrolyzed. Chicks consuming diets containing the lower levels of calcium and Pnp hydrolyzed more phytate than those fed the higher levels of calcium and Pnp except when the diet contained rice bran. Less phytate was hydrolyzed in the rice bran diet at the lower calcium and Pnp levels. Phytate hydrolysis was not affected by wheat bran but was reduced by cottonseed hulls. At the lower levels of calcium and Pnp, alfalfa meal and cellulose significantly increased phytate hydrolysis by chicks. The hydrolysis of phytate was influenced more by calcium and by source than by fiber or by level of phytate fed.

Physiological effects of fibre-rich types of bread. 1. The effect of dietary fibre from bread on the mineral balance of young men

1. Twelve young adult male volunteers were given a low-fibre white bread diet (9 g neutral-detergent fibre (NDF)/d) and a medium-fibre coarse-bran bread diet (22 g NDF/d), each lasting 20 d. In ad third period of 20 d the volunteers were subdivided in groups of four, consuming a high-fibre coarse-bran bread diet (35 g NDF/d), a medium-fibre fine-bran bread diet (22 g NDF/d, bran particle size less than 0.35 mm) or a wholemeal bread diet (22 g NDF/d). Retention of calcium, magnesium, iron, zinc and copper were determined during each 20 d period. 2. An increase of the amount of dietary fibre (through bran) from 9 g to 22 g NDF/d resulted in a significantly increased mineral intake, but also faecal excretion increased significantly; mineral retention remained almost constant. 3. Both intake and faecal excretion of all minerals studied, except faecal Ca, increased further (P less than 0.05) on the diet providing 35 g NDF/d; only Fe balance decreased significantly. No significant differences with respect to intake, excretion (except urinary Ca) and balance of the minerals could be detected between the coarse-bran bread and fine-bran bread diets providing 22 g NDF/d. Faecal Fe, Cu balance and Mg balance increased significantly during the wholemeal bread period compared to the coarse-bran bread diet providing 22 g NDF. 4. Serum cholesterol increased significantly, i.e. by 0.3 mmol/l, during the coarse-bran bread diet providing 22 g NDF, compared to the white-bread diet. 5. It is concluded that increasing the amount of bran in bread does not appear to affect mineral balance considerably but there seems to be an influence on mineral availability. The increased intake was accompanied by increased faecal excretion.

Trace elements in nutrition

Advances in trace element research over the last decade have done much to elucidate the function of these nutrients at the biochemical level. Five new trace elements have been identified and the general relevance of microelements in human nutrition has undergone reassessment. Deficiencies of iodine, iron and fluorine remain important problems and necessitate supplementation. Suboptimal nutrition in chromium, copper, selenium, zinc and possibly vanadium has been suggested, and these elements are generally acknowledged to be of concern in human nutrition. Genetic factors and other "conditioning" agents have been implicated in the aetiology of a number of trace element deficiencies in apparently well nourished communities. Tissues under anabolic stress have been recognized to be especially sensitive to trace element deficits, and the particular vulnerability of the fetus has been demonstrated on a number of occasions. In practical dietary terms, the loss of microelements during the refining and processing of food has been widely illustrated. Also, the generally lower levels of trace elements in plant material and the lower availability of minerals from these food sources has been well established. Of the newer trace element deficiencies, zinc impoverishment appears to be especially important, as a state of physiological zinc deficiency rapidly follows dietary insufficiency, and the consequences on all growing tissues are particularly serious. In general, recent developments suggest that marginal deficiencies of microelements are more widespread in human nutrition than was previously appreciated. Greater attention to trace element status seems to be indicated in circumstances in which physical condition and vigour are unaccountably poor and especially in situations accompanied by active anabolism.

Recent progress in dietary fiber (plantix) in human nutrition

Dietary fiber was extensively discussed in an article by G.A. Spiller and R.J. Amen in this journal in 1975 (Volume 7 Issue 1). The progress in this field has been tremendous in the past 2 years. What was an uncertain field in 1975 and what at that time to some investigators still appeared as a hypothesis or fad without much proof has turned into a much more respected part of nutritional sciences. The scientific quality of recent studies on dietary fiber in human nutrition shows a great deal of sophistication and care. Improved analytical methodologies are being used more extensively. Many nutritionists and clinicians have accepted the fact that a reasonable increase in the dietary fiber intake in the U.S. and U.K would be advisable. In this article, the possible beneficial effects of dietary fiber on health, the possible harmful side effects, and the food science aspects are carefully discussed after an update on chemistry, analytical procedures, and nomenclature. Undoubtedly, dietary fiber has found a new niche in the sciences of nutrition, medicine, epidemiology, and foods.