Objective: To develop an in vitro digestion method to assess the impact of heat treatment, particle size and presence of oil on the accessibility (available for absorption) of a-and b-carotene in carrots. Design: Raw and cooked carrots were either homogenized or cut into pieces similar to chewed items in size. The carrot samples, with or without added cooking oil, were exposed to an in vitro digestion procedure. Adding a pepsin -HCl solution at pH 2.0 simulated the gastric phase. In the subsequent intestinal phase, pH was adjusted to 7.5 and a pancreatin -bile extract mixture was added. Carotenoids released from the carrot matrix during the digestion were extracted and quantified on highperformance liquid chromatography (HPLC). Results: Three percent of the total b-carotene content was released from raw carrots in pieces. When homogenized (pulped) 21% was released. Cooking the pulp increased the accessibility to 27%. Addition of cooking oil to the cooked pulp further increased the released amount to 39%. The trends for a-carotene were similar to those for b-carotene. Conclusion: The described in vitro digestion method allows a rapid estimation of carotene accessibility in processed carrots, which may reliably predict in vivo behavior.
A nutrition survey was conducted in the rural Lindi District of Tanzania to determine the magnitude of anemia and iron deficiency in different age and sex groups as related to nutritional status, parasitic infections, food iron intake, and socioeconomic factors. In a 30-cluster sampling design, 660 households were randomly selected and a total of 2320 subjects aged 6 mo to 65 y were examined. Iron status was assessed by measuring hemoglobin and erythrocyte protoporphyrin in a finger-prick sample: 55% of the subjects had anemia and 61% of the anemia was associated with iron deficiency (erythrocyte protoporphyrin > 125 mol/mol heme). Preschool children (aged < 5 y) were the most affected; 84% were anemic (hemoglobin < 110 g/L). Fifty percent of the nonanemic preschool children and Ϸ90% of all the severely anemic subjects were iron deficient. Hemoglobin was lower in schoolchildren (aged 5-14 y) and in adolescent and adult males (aged ≥ 15 y) with a low body mass index. Parasitic infections were only associated with anemia and iron deficiency in schoolchildren and adolescent and adult males. Malaria was associated with anemia (P < 0.001), whereas schistosomiasis was associated with anemia and iron deficiency (P < 0.001 and P < 0.05, respectively). Hookworm infestation was associated with iron deficiency (P < 0.05) and with anemia (P < 0.01) only in adolescents and adults. A mainly cereal-based diet with additional legumes and green vegetables was found by in vitro tests to contain high amounts of total iron but of low bioavailability. Estimation of the amount of iron absorbed confirmed inadequate iron nutrition. Although anemia is a result of a synergism of a variety of causes, iron deficiency remains the major cause.Am J Clin Nutr 1998;68:171-8.
The effects of inositol tri-, tetra-, penta-, and hexaphosphates on iron solubility were studied in vitro. Pure inositol phosphates (0.125-10 wmol) were added to lg of freeze-dried wheat roll and digestion was performed simulating physiological conditions. Soluble iron was used as an index of iron bioavailability.The pure inositol phosphate fractions were prepared by hydrolysis of sodium phytate and separation on anion exchange resin. The inositol phosphates were identified and quantified by HPLC. Addition of 10 pmol inositol hexa-and pentaphosphate reduced iron solubility from 39% (reference) to 0.2% and 6%, respectively, while the same amount of inositol tetra-and triphosphate slightly increased the iron solubility.Thus, degradation of inositol hexa-and pentaphosphates seemed to significantly reduce the inhibiting effect on iron availability.
Phytate (inositol hexaphosphate) hydrolysis by endogenous and exogenous phytases was studied for their effect on increasing iron availability in cereals. Wheat bran and whole meal flours of rye and oats were soaked at optimal conditions for phytase activity (55°C pH 5) for different time intervals. Phytate and its degradation products were detemrined by HPLC and related to iron solubility under simulated physiological conditions. Small amounts of phytate (< lbmol/g) had a strong negative effect on iron solubility. When inositol hexa-and pentaphosphates of wheat bran and rye flour were completely hydrolyzed by activating endogenous phytase, iron solubility under simulated physiological conditions increased from 3 to 53% (wheat) and 5 to 21% (rye). Addition of wheat phytase to uncooked oatmeal increased iron solubility from 4 to 11 and in precooked to 18%, while endogenous phytase of uncooked oatmeal had less effect on phytate digestion and iron solubility.
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