Fiber, dietary absorption effects

Our studies do not resolve the question of phytate vs fiber for the effect of wheat bran on dietary calcium bioavailability. Phytate level clearly affected apparent absorption of calcium in HS-II in the presence of an amount of the water insoluble fraction of dephytinized bran equivalent to 12 g of untreated bran and the phytate supplied as sodium phytate. An additional trial using untreated bran and the same amount of fiber as the water insoluble fraction with sodium phytate could resolve the question of fiber vs phytate. In HS-I, the balances were positive when a relatively large amount of bran, 36 g/day, was consumed. Calcium intakes were possibly higher than most men consume, but under the dietary conditions imposed for 15 days, the phytate and fiber of 36 g of bran did not express an adverse effect on calcium balance. 

The Effect of Dietary Fiber upon Absorption of Iron by Animals... 

Various mechanisms have been proposed to explain the hypocholesterolemic effect of GA (Annison et al., 1995 Tiss et al., 2001). Some studies have suggested that the viscosity of fermentable dietary fiber contributes substantially to the reduction of lipids in animals and humans (Gallaher et al., 1993 Moundras et al., 1994). However, other studies suggested that this property is not related to plasma lipids (Evans et al., 1992). The mechanism involved is clearly linked to increased bile acid excretion and fecal neutral sterol or a modification of digestion and absorption of lipids (Moundras et al., 1994). 

Wheat bran has been the fiber source most commonly used to study effects of dietary fiber on calcium absorption in controlled laboratory studies. However, wheat bran and other forms of fiber as they occur in food products present several disadvantages in terms of definition and by concurrently altering intakes of other substances or materials known or suspected of having an adverse effect on the bioavailability of calcium such as phytates and oxalates (5,13,17,22-28). Several studies have been conducted which have sought to separate or compare the effects of phytate and fiber... 

Bile acids and salts have been found to enhance the absorption of both calcium and vitamin D hence, to increase calcium absorption both directly and indirectly (3,37). However, the ability of some dietary fibers such as lignin and pectin to absorb conjugated and deconjugated bile salts onto their surfaces to be excreted in the feces (a mechanism credited to the hypocholesterolemic effect of some dietary fibers) may result in an overall decrease in calcium absorption from the gastrointestinal tract (7,33,38-40). 

In conclusion some but not all sources of dietary fiber have been found to have an adverse effect on the absorption of dietary fiber. 

Calcium Acetate (PhosLo) [Calcium Supplement/ Anti arrhythmic/Mmeral/ Electrolyte] Uses ESRD-associated hyper-phos-phatemia Action Ca " supl w/o aluminum to X P04 absorption Dose 2-4 tabs PO w/ meals Caution [C, ] Contra t Ca Disp Gelcap SE Can t Ca, hypophosphatemia, constipation Interactions t Effects OF quinidine X effects W/ large intake of dietary fiber, spinach, rhubarb X effects OF atenolol, CCB, etidronate, tetracyclines, fluoroquinolones, phenytoin, Fe salts, thyroid hormones EMS Pts have reduced renal Fxn, monitor ECG for signs of electrolyte disturbances OD S/Sxs of hypercalcemia (confusion, weakness, GI upset, constipation, N, V, and cardiac arrhythmias) give IV fluid for diuresis symptomatic and supportive Calcium Carbonate (TumS/ Alka Mints) [Antacid/ Calcium Supplement/Mineral/ Electrolyte] [OTC] Uses Hyperacidity associated w/ peptic ulcer Dz, hiatal hernia, etc Action Neutralizes gastric acid Dose 500 mg—2 g PO PRN -1- in renal impair Caution [C, ] Disp Chew tabs, susp SE t -1- PO constipation Interactions X Effect OF tetracyclines, fluo-... 

Rx prevent Ca deficiency Action Ca supl Dose Adul. 6—18 g/d doses Feds. 600-2000 mg/kg/d qid (9 d max) X in renal impair Caution [C, ] Contra T Ca Disp Syrup SE f O a, X PCO constipation. Interactions T Effects OF quinidine X effect OF tetracyclines X Ca absorption w/ high intake OF dietary fiber EMS Monitor ECG for signs of electrol5rte disturbances (T Ca % X Mg ) OD S/Sxs of hypercalcemia weakness, GI upset, and cardiac arrhythmias give IV fluid symptomatic and supportive... 

Dietary fiber Can slow absorption of refined carbohydrates and lower glycemic index of foods, resulting in reduced effects of diabetes due to lower availability of glucose Preuss (2009)... 

Guar gum is a low-viscosity water-soluble dietary fiber that has been used to treat diabetes because it slows the absorption of glucose from the gut. However, adverse effects such as regurgitation, obstipation, abdominal... 

Ikeda, I., Tomari, Y., and Sugano, M. 1989b. Interrelated effects of dietary fiber and fat on lymphatic cholesterol and triglyceride absorption in rats. J. Nutr. 119, 1383-1387. 

The behavior of minerals is often influenced by the presence of other food constituents. The recent interest in the beneficial effect of dietary fiber has led to studies of the role fiber plays in the absorption of minerals. It has been shown (Toma and Curtis 1986) that mineral absorption is decreased by fiber. A study of the behavior of iron, zinc, and calcium showed that interactions occur with phytate, which is present in fiber. Phytates can form insoluble complexes with iron and zinc and may interfere with the... 

Manganese is a nutritionally important trace element for chicks. Dietary energy and protein sources contain very little bioavailable Mn, and these feed ingredients reduce the biopotency of inorganic Mn supplements. This adverse effect is exerted primarily in the intestine as a result of reduced Mn absorption and is mediated by the fiber and/or ash components of the feedstuffs. Gut absorption efficiencies are higher when a phytate-and fiber-free casein-dextrose diet is fed than when a corn-soybean meal diet is fed. Dietary interrelationships exist between Mn and Co and between Mn and Fe. Cobalt increases Mn absorption and may precipitate Mn toxicosis. Excess dietary Mn reduces Fe utilization, but excess Fe does not affect Mn utilization. Eimeria acervulina infection increases Mn absorption. 

A series of experiments were initiated to examine the effects of dietary fibers on the plasma uptake of an oral dose of manganese in humans. Stable isotope techniques are the ideal methods for measuring the intestinal absorption of minerals however this technique is impossible for manganese because of its monoisotopic nature (14). Also, ethical considerations prohibit the use of radioactive forms of manganese. Thus, a technique which was both relatively easy to conduct and safe to administer repeatedly to the same subject was developed. 

Since almost nothing is known about the effect of isolated fibers on the absorption of manganese and constituents of dietary fiber vary both in chemical and physical properties, the effects of two major types of fiber — cellulose and pectin — were examined using our protocol. The effect of phytate was also measured since it is associated with high fiber foods and has been reported to increase requirements for manganese (40). 

Experiments In this laboratory examined the effects of small (100 and 300 mg) doses of sodium phytate administered In capsule form on plasma uptake of 50 mg of MnCl. As shown In Figure 5, the 300 mg dose of phytate produced a moderate reduction In manganese response, which was manifested chiefly at hours three and four of the test. The relatively modest effect of phytate on manganese uptake Is somewhat unexpected, since It has been shown that phytic acid may be a more potent Inhibitor of trace element absorption than dietary fibers (35). However, the doses of sodium phytate administered to our subjects were much smaller than the typical daily Intake of 600 to 800 mg (54). Thus we are now Investigating the effects of larger doses of phytate on manganese uptake. 

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