Bread bioavailability

Algae can be cultivated easily and quickly when compared to plants. They produce very high quantities of carotenoids compared to other sources (3.0 to 5.0% w/w on a dry weight basis). They contain both cis and trans isomers of carotenoids for high bioavailability and bioefflcacy, and also contain oxygenated carotenoids (xantho-phylls), which have greater bioactivity and better anticancer properties. The proteins from Dunaliella biomass can be utilized for bread and other products and whole cells can be utilized for animal, poultry, and fish foods because they are safe. ... 

More than 40 years ago, calcium absorption from brown (whole wheat) bread which was fed to human subjects was found to be poorer than was that when white (extracted wheat flour) was fed 04,5). Since then, many studies have sought to define the extent of inhibition of calcium intestinal bioavailability by various forms of dietary fiber with mixed results and conclusions (6-18). 

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. 

Phytate has been studied extensively with regard to mineral (mostly Zn and Ca) status of animals, and it has been shown to reduce whole-body Mn retention in rats (12). Phytate, however, is not present in the neutral detergent fiber or in the ash component of feedstuffs. Therefore, phytate does not appear to be responsible for the reduction of Mn uptake in chicks fed corn, soybean meal, wheat bran or fish meal (9). That phytate negatively impacts Mn nutriture also disagrees with the research of Reinhold et aK (13), who reported that fiber, and not phytate, was the pTTmary factor determining bioavailability of divalent mineral elements in breads. 

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. 

Knowledge about how an optimal absorption could be obtained from whole grain products is of great value, since this is an important source of zinc in our diet. It is important to notice that it is not only the bioavailability of zinc from bread which is important, it is the bioavailability of zinc from the composite meal where bread is one of the components which gives the most interesting and useful information. 

Even if there is a lot of unanswered questions around bioavailability of zinc from the diet, these studies could give us important information for obtaining an optimal zinc absorption from composite bread meals. 

Ferrous sulphate eneapsulated in soy lecithin liposomes has been used to deliver iron. These preparations have improved bioavailability compared to ferrous sulphate directly added in milk and dairy products (Boccio et al. 1997 Uicich et al. 1999). Albaldawi et al. (2005) reported that the addition of encapsulated haem iron in lecithin/cholesterol liposomes resulted in improved rheological properties of bread dough and the sensory properties of baked bread. 

Bioavailabilitv of methvlmercurv in food. Measurements of absorption and toxicity have generally been made using aqueous solutions of methylmercury. The absorption and bioavailability of methylmercury in food, specifically fish and bread, may be affected by dietary components. Potential confounders that may affect bioavailability of methylmercury are dietary phytate and other dietary fibrous materials found in bread and the complexation of methylmercury with selenium in fish. 

Dietary iron level does not seem to affect the efficiency with which dietary iron is converted into hemoglobin when ferrous sulfate (Table 1) or when ferric orthophosphate (Table 2) is the primary source of dietary iron. This is also true for white bread (Table 2) however, the source of the iron in the enriched flour used in the bread is unknown. That the efficiency of converting food iron into hemoglobin is not affected by dietary iron concentration is important to bioavailability testing because it is often difficult to formulate diets with precise amounts of iron, especially when foods are the sources of iron. 

Based on USDA estimates of per capita consumption of wheat flour, one-third of the adult woman s Recommended Dietary Allowance (RDA) for iron could be obtained if we consumed whole wheat products Q). The iron in wheat, however, is thought to be poorly bioavailable to humans, primarily attributable to the effect of phytate. British investigators found that the iron balance of individuals was lower when they ate largely whole meal bread than when they ate bread made with white flour (2). When the test bread made with white flour contained either sodium or ferric phytate, postprandial serum iron rise was depressed ( ). They theorized that the phytate present in the brown bread formed an insoluble iron salt and rendered the iron unabsorbable. That theory was supported by the work of Moore et al. (4) at Washington University, who tested the response of anemic individuals administered therapuetic doses of ferric... 

Bread is a major wheat-derived food product consumed in the United States. We tested the bioavailability to rats of monoferric phytate either with bread or baked in bread. Either the monoferric phytate or reference iron compound, ferrous ammonium sulfate, was baked in bread at three concentrations of iron. 

Figure 4. Bioavailability of monoferric phytate baked into bread. Rats were the test species and change in hemoglobin concentration during a 2-week repletion period was bioassay criterion.

Animal studies. A series of bioassays in our laboratory showed that in its bioavailability to rats the iron in wheat and its major milling fraction is equivalent to the iron of ferrous ammonium sulfate. Both prophylatic and therapeutic hemoglobin responses were tested and the 95% confidence interval showed no significant difference from ferrous ammonium sulfate (16). However, the RBV of iron in some wheat-based food products has significantly lower bioavailability. In three of four different bioassays of whole wheat bread, the RBV differed significantly from ferrous ammonium sulfate (16). 

Approximately 70f of the monoferric phytate baked into bread could be recovered in extracts of the bread. He have not tested the bioavailability or the chemical form of iron when an iron salt and sodium phytate are baked into bread as was done by McCance et al. (3). If an insoluble ferric phytate of any ion composition was formed, we would expect the iron to be poorly bioavailable. Hussain and Patwardhan (22) did not specify whether they added sodium phytate to the food during preparation or administered it orally when young men ate the meals in their study using a vegetarian menu. They found decreased iron balance when the percentage of phytate phosphorus to total phosphorus was increased from 8 to 40 by addition of sodium phytate. 

Liljeberg, H. and Bjorck, I. 1994. Bioavailability of starch in bread products. Postprandial glucose and insulin responses in health subjects and in vitro resistant starch content. Eur. J. Clin. Nutr. 48, 151-164. 

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. 

Beef other red meats and seafood are excellent sources of bioavailable zinc, whereas spinach, milk, yogurt and bread have poor zinc bioavailability. According to a review by Solomons (1982) the mean absorption rates are 36-41% for poultry and meat, and 14-17% for whole-wheat bread. 

The minerals are nsed to fortify various types of products, especially bread and baked goods, breakfast cereals, dairy products, and vegetables. Moreover, they are often mixed with some vitamins and homogeneously distributed in the products. However, in some formulations, it is necessary to adopt measures to protect the micronutrients by some factors that may cause their loss or decrease of bioavailability, such as the use of microencapsulation technique. - ... 

In his Natural History (1826), Pliny the Elder stated that those persons who are dieted npon fermented bread are stronger in body , which is an early statement on the health benefits of sourdough breads. Whole meals of cereals are a good source of minerals. Their bioavailability is limited, as they are often bound to phytic acid (myo-inositol-hexophospate). Wheat and rye contain about 1.2% of dry matter (Fretzdorff Briimmer, 1992). With the drop in pH during sourdough fermentation, endogenous phytases of the cereals are activated and the bound minerals are released (Fretzdorff Briimmer, 1992). Lactic acid bacteria and yeasts also possess phytase... 

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