Mineral bioavailability

GREGERj L (1999) Nondigestible carbohydrates and mineral bioavailability. 129 1434S-5S. 

In conclusion, phytic acid forms soluble complexes with Ca2+ at intestinal pH under a variety of conditions and fails to inhibit Ca2 bioavailability to mice in our experimental system. Despite the hazard in direct extrapolation of results obtained with animals kept on a well-defined dietary regimen to humans consuming a complex diet, many elements of which affect Ca2+ bioavailability, our data demonstrate the need for a reevaluation of the putative antinutritional properties of dietary phytate. Our further contention that adequate levels of dietary phytate may actually be beneficial due to its food preserving properties and its protection against colonic cancer will warrant a prospective epidemiological human study designed to assess the longterm effects of dietary phytate on mineral bioavailability and inflammatory bowel diseases. 

At low and medium doses, it is well established that the nutritional value of proteins, carbohydrates, and fats as macronutrients are not significantly impaired by irradiation, and neither the mineral bioavailability is impacted. Like all other energy depositing process, the application of ionizing radiation treatment can reduce the levels of certain sensitive vitamins. Nutrient loss can be minimized by irradiating food in a cold or frozen state and under reduced levels of oxygen. Thiamin and ascorbic acid are the most radiation sensitive, water-soluble vitamins, whereas the most sensitive, fat-soluble vitamin is vitamin E. In chilled pork cuts at the 3 kGy maximum at 0-10°C, one may expect about 35 0% loss of thiamin in frozen, uncooked pork meat irradiated at a 7 kGy maximum at —20°C approx., 35 % loss of it can be expected [122]. 

Minerals from plant sources are less bioavailable than from animal sources (102). Because most functionally-modified proteins are of plant origin, one must be particularly concerned about what effect plant protein modification has upon mineral bioavailability. 

Recent review articles (, 104-109) have described general factors that affect mineral utilization from foods. General factors such as the digestibility of the food that supplies the mineral, chemical form of the element, dietary levels of other nutrients, presence of mineral chelators, particle size of the food or supplemented minerals and food processing conditions all play a role in the ultimate mineral bioavailability (104). Many unit food processing operations can be shown to directly or indirectly alter the level or chemical form of minerals or the association of minerals with other food components. 

Fermentation of plant foods generally increases mineral bioavailability. Studies by Ranhotra and coworkers (121, 122 for example) have shown increased available zinc from breads and cookies that have undergone yeast fermentation. Also, iron was shown by these workers to be more highly available from unfortified breads than from breads fortified with wheat bran, soy flour or other whole grain vegetable flours. 

Grases F., Bartolome M.S., Prieto R.M. and March J.G. 2001. Dietary phytate and mineral bioavailability. Journal of Trace Elements in Medicine and Biology 15 221-228. 

Prebiotics and synbiotics containing fructooligosaccharides enhance mineral bioavailability by improving the absorption of minerals in the colon, especially calcium, iron, and magnesium (Caers, 2004 Coudray, 2004 Hidaka et al., 2001 Ohta et al., 1994 Roberfroid, 2005). The mechanism... 

Toma, R.B., and D.J. Curtis. 1986. Dietary fiber Effect on mineral bioavailability. Food Technol. 40, no. 2 111-116. 

Phytate. Phytic acid is an organic polyphosphate found widely in plants, particularly cereals, nuts and legumes. It has been shown to complex with various divalent cations in the gastrointestinal tract and thus reduce mineral bioavailability (33,44,52). Davis et al. (53) reported that feeding a diet based on isolated soybean... 

Often overlooked in the evaluation of the effects of diet upon mineral availability is the role that food processing plays in the formation of or breaking of ligand-metal complexes. Several individual or unit processing steps are needed to produce a soy concentrate, a bread or a spray-dried egg white. Some or all steps may have a bearing upon final mineral bioavailability. Soy concentrate from company A is not produced in precisely the same manner as from company B. In fact, lot to lot variation for the same product may be quite variable, particularly in mineral content. 

Mg in Measurements of Mineral Bioavailability from Dietary Sources. One of the most convenient methods for measuring dietary mineral bloavailabillty is to follow the absorption of a tracer... 

Lopez, H.W., Duclos, V., Coudray, C., Krespine, V., Feillet-Coudray, C., Messager, A., Demigne, C., and Remesy, C. 2003. Making bread with sourdough improves mineral bioavailability from reconstituted whole wheat flour in rats. Nutrition 19, 524-530. 

In contrast with some other fiber sources such as wheat bran no significant decrease in mean transit times has been reported by most researchers (7,9,18,29,30) investigating the effect of pectin on bowel function or mineral bioavailability. Only one study ( 5) reported a significant decrease in transit time from a starting time averaging 63 hours. No significant difference in transit time between high and low methoxyl pectins was observed by Judd and Truswell (19). 

Human data on phytochemicals concentrate largely on measurement of urinary metabolites in combination with stable isotope labeling this is a valid method for studying mineral bioavailability, since the difference between the amount absorbed and excreted is retained in the body and, excluding the amount stored in body pools, assumed to be bioavailable. 

Phytic Acid. Recent reviews (67,68,69) summarized the literature covering the relationship between phytic acid and mineral bioavailability in soy protein products. The formation of phytate-proteln-mineral complexes (particularly zinc chelates in flours, concentrates, and Isolates prepared from mature soybeans) may be responsible for reduced mineral availability. However, the iron in Fe-labeled mature soybeans is more available to iron-deficient rats than the iron in green-immature soybeans, even though mature soybeans contain three times more phytic acid (70). The factor(s) responsible for this difference in bioavallablllty has not been identified. 

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