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Biomedical subjects

I Leets

Publications and source records attributed to I Leets.

At least 19 recordsLinked to original sources
PubMed2005

High prevalence of folic acid and vitamin B12 deficiencies in infants, children, adolescents and pregnant women in Venezuela.

BACKGROUND: There is increased worldwide concern about the consequences of folic acid and vitamin B12 deficiencies on health, which include megaloblastic anemia, neural tube defects and cardiovascular disease. OBJECTIVE: This study intended to determine the prevalence of folic acid and vitamin B12 deficiencies in vulnerable groups in labor and poor socioeconomic strata of the Venezuelan population. METHODS: A total of 5658 serum samples were processed to determine folic acid and vitamin B12 concentrations. The study involved three surveys performed during 2001-2002 and included infants, children, adolescents and pregnant women from labor and poor socioeconomic strata of the population. The method used was a radio immunoassay designed for the simultaneous measurement of serum folic acid and vitamin B12. RESULTS: The prevalence of folic acid deficiency was higher than 30% for all groups studied, reaching 81.79% in adolescents. Vitamin B12 deficiency was 11.4% in samples collected nationwide, but there was also a similar prevalence of high serum levels. The prevalence of folic acid and vitamin B12 deficiencies in pregnant women reached 36.32 and 61.34%, respectively. CONCLUSION: This work shows that there is a high prevalence of folic acid deficiency, especially in women of reproductive age, pregnant adolescents and in the whole population studied in Vargas state. This situation requires immediate intervention as supplementation or food fortification programs.

Adolescent↗
PubMed2000

Beta-carotene and inhibitors of iron absorption modify iron uptake by Caco-2 cells.

A National fortification program instituted in Venezuela in 1993 reduced iron deficiency and anemia by half in only 1 y. The fortification mixture contained ferrous fumarate, vitamin A and other vitamins. We conducted experiments to characterize ferrous fumarate uptake by Caco-2 cells. Increasing amounts of ferrous fumarate, vitamin A, phytate, tannic acid and beta-carotene were added to incubation mixtures using a range of concentrations that included the molar ratios used in the Venezuelan fortification program. Cells were incubated for 1 h at 37 degrees C with 37 kBq (59)Fe and the compound to be evaluated. They were then rinsed, trypsinized and counted to measure uptake. Effects of ascorbic acid, days in culture and use of flasks or inserts were also evaluated. Optimal conditions for uptake experiments were pH 5.5, in the presence of ascorbic acid and at 16 d in culture. Use of flasks or inserts did not affect uptake. Vitamin A did not significantly increase iron uptake under the experimental conditions employed. However, beta-carotene (6 micromol/L) significantly increased iron uptake compared to no beta-carotene addition (114.9 +/- 6.3 and 47.2 +/- 5.9 pmol/mg cell protein, respectively). Moreover, in the presence of phytates or tannic acid, beta-carotene generally overcame the inhibitory effects of both compounds depending on their concentrations. We conclude that beta-carotene improves iron uptake and overcomes the inhibition by potent inhibitors of iron absorption. These experiments also validated the usefulness of Caco-2 cell model system to evaluate iron metabolism.

Absorption↗
PubMed2000

Iron bioavailability in humans from breakfasts enriched with iron bis-glycine chelate, phytates and polyphenols.

This study was conducted to determine the bioavailability of iron amino acid chelate (ferrochel) added to fortify breads prepared from either precooked corn flour or white wheat flour + cheese and margarine compared with the same basal breakfast enriched with either ferrous sulfate or iron-EDTA. The inhibitory effect of phytate and polyphenols on iron absorption from ferrochel was also tested. A total of 74 subjects were studied in five experiments. Iron absorption from ferrochel was about twice the absorption from ferrous sulfate (P: < 0.05). When ferrous sulfate and ferrochel were administered together or in different meals, absorption from ferrochel was about twice the absorption from ferrous sulfate (P: < 0.05). Polyphenols present in coffee and tea inhibited iron absorption in a dose-dependent manner. American-type coffee did not modify iron absorption significantly, whereas both espresso-type coffee and tea reduced iron absorption from ferrochel by 50% (P: < 0. 05). Ferrochel partially prevented the inhibitory effect of phytates. Because of its high solubility in aqueous solutions even at pH 6, its low interactions with food and high absorption, ferrochel is a suitable compound for food fortification.

Adolescent↗
PubMed2000

New property of vitamin A and beta-carotene on human iron absorption: effect on phytate and polyphenols as inhibitors of iron absorption.

One hundred and seventy four human subjects were studied to find out the interaction of vitamin A or beta-carotene with the inhibitors of iron absorption, from a basal breakfast containing bread from either 100 g of precooked corn flour or 100 g of white wheat flour, 50 g of cheese and 10 g of margarine. Bread was labeled with either 55Fe or 59Fe. This bread was made from commercially flours fortified with iron as ferrous fumarate and vitamins. It was noticed that the percentage of iron absorption from the breakfast prepared with precooked corn flour given alone and with different concentrations of coffee was practically the same, while the iron absorption from the breakfast prepared from wheat flour decreased from 6% when the breakfast was given alone, to less than 2% when it was given with different concentrations of coffee. The only ingredient present in precooked corn flour and not in wheat flour was vitamin A. This difference encouraged the authors to perform further experiments using precooked corn and wheat flours fortified only with ferrous fumarate. These studies demonstrated that vitamin A inhibits the effect of the polyphenol and partially inhibits the effect phytate on iron absorption. HPLC and spectrophotometric studies demonstrated an interaction between vitamin A and iron. Other experiments, which included 100 volunteers, were performed to test the effect of vitamin A and beta-carotene on iron absorption from corn, wheat and rice. The presence of vitamin A increased iron absorption up to 3 times for rice, 2.4 times for wheat and 1.8 times for corn. beta-carotene increased absorption almost 3 times for the three cereals tested, showing that both compounds were capable of preventing the inhibitory effect of phytates on iron absorption. This information suggest that vitamin A and beta-carotene form a complex with iron keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.

Antioxidants↗
PubMed1999

[Anemia in indigenous population of the West of Venezuela].

The purpose of the study was to investigate the frequency of nutritional anemia among western venezuelan indians. Three hundred and ninety nine Yucpa indians from the communities of Aroy, Marewa and Peraya were studied. The concentrations of hemoglobin, serum iron, total iron binding capacity, serum ferritin, serum folate and serum vitamin B12 and the frequency of anemia and nutrient deficiency were determined. Anemia was found in 71.7% of people from Aroy, 52.25 from Marewa and in 74.4% from Peraya. No nutrient deficiencies were found in 48.1% of cases with anemia, while iron deficiency anemia was present in 39% of the population studied, and folate and or vitamin B12 deficiency were associated with anemia in only 12.9% of cases. The high frequency of anemia, unrelated to nutrient deficiency, among the Yucpa indians, is attributed to the prevalence of chronic infectious diseases such as hepatitis and parasitic infections, as well as skin and respiratory infectious processes.

Adolescent↗
PubMed1998

Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans.

After the rapid decrease in the prevalence of iron deficiency and iron-deficiency anemia in the Venezuelan population when a national program for fortification of flours with iron and vitamins was instituted, we studied micronutrient interactions in Venezuelan diets. One hundred human adults were fed three cereal-based diets, labelled with either 59Fe or 55Fe in six studies. Each diet contained different concentrations of vitamin A (from 0.37 to 2.78 micromol/100 g cereal) or beta-carotene (from 0.58 to 2.06 micromol/100 g cereal). The presence of vitamin A increased iron absorption up to twofold for rice, 0.8-fold for wheat and 1.4-fold for corn. beta-carotene increased absorption more than threefold for rice and 1.8-fold for wheat and corn, suggesting that both compounds prevented the inhibitory effect of phytates on iron absorption. Increasing the doses of vitamin A or beta-carotene did not further significantly increase iron absorption. We measured the iron remaining in solution performing in vitro studies in which the pH of solutions was adjusted from 2 to 6 in the presence of vitamin A or beta-carotene. All of the iron from ferrous fumarate was soluble after changing the pH of the solution containing 3.4 micromol of beta-carotene to 6.0. Vitamin A was less effective. However, 78 +/- 18% of iron was soluble in the presence of 3.3 micromol of vitamin A, whereas with no vitamin addition, only 26 +/- 13% of iron was soluble (<0.05). Vitamin A and beta-carotene may form a complex with iron, keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.

Absorption↗
PubMed1997

Prevalence of anemia, iron, folic acid and vitamin B12 deficiency in two Bari Indian communities from western Venezuela.

The hematological status of 406 Bari indians from two communities was studied. One hundred and seventy nine individuals were from Campo Rosario a village located in a low arid plain south to the Perijá mountain range and 287 were from Saimadoyi, a fertile valley in the heart of the mountain. Anemia was found in 54% and 31% of the people from Campo Rosario and Saimadoyi respectively. Low serum iron was present in 28% of the population in both communities while low serum ferritin levels were encountered in 20% of the population from Campo Rosario and 5% of the people from Saimadoyi. A high prevalence of serum folate and vitamin B12 deficiency (91% and 64% respectively) was found in Campo Rosario, in contrast only 5% of the population from Saimadoyi had low folate and none were vitamin B12 deficient. While there was a positive significant correlation between hemoglobin and serum iron concentrations (r = 0.517, p < 0.001), no significative correlation was found between the other parameters studied. The high prevalence of anemia and nutrient deficiency among the Bari indians, can be attributed to inadequate diets and the varied diseases encountered in the population.

Adolescent↗
PubMed1995

Iron bioavailability from diets consumed by different socioeconomic strata of the Venezuelan population.

The iron bioavailability from three typical diets consumed by socioeconomic stratum IV (SES IV--working class) of the Venezuelan population was determined by the extrinsic label method. Although the iron content of the SES IV diets was about the same (250 mumol/d) as that of upper (SES I-III) and lower (SES V) socioeconomic strata diets, iron-replete subjects absorbed 43 and 61% more iron from the SES I-III diets than from the SES IV and V diets, respectively, and absorption from the main meal of the SES I-III diets was 100% greater. However, iron deficient subjects absorbed about the same amount of iron (45 mumol/d) from the SES IV diets as from the SES I-III diets. The SES I-III diets contained more iron absorption enhancers (ascorbic acid and meat protein) and less of the inhibitor phytate, than the SES IV and V diets. Iron absorption from the meals of four diets consumed at different times during the day was also measured. There was no significant difference in the percentage iron absorption from the same meals eaten in the morning after an overnight fast, and when eaten at the customary time of day.

Absorption↗
PubMed1994

Fortification of precooked maize flour with coarse defatted maize germ.

The possibility of improving the dietary value of precooked maize flour through fortification with 11% coarse defatted maize germ was investigated. The results of tests in humans presented here show that the total iron absorption from the fortified preparation is similar to that from the precooked maize alone, but with the advantage of being richer in several nutrients: protein (25%), zinc (61%), potassium (47%) and magnesium (112%), as well as fiber (34%). Fortification lowers (by 20%) rather than raises the cost of the flour, and may be an important contribution to the diet of those populations where maize bread is a major component of the diet.

Absorption↗
PubMed1993

The relationship between iron deficiency and anemia in Venezuelan children.

The iron status of 3228 subjects from the nutrition survey Proyecto Venezuela was studied. The sample included children from 1 to 16 y of age grouped by age and sex. Values for three indicators of iron status were compared: hemoglobin concentration, serum ferritin concentration, and percentage saturation of serum transferrin. In all groups there was a strong overlap in the hemoglobin concentration distribution curves for non-iron-deficient and iron-deficient subjects classified as such according to the other two indexes. The prevalence of iron deficiency ranged from 35% in 1-3 y olds to 10% in adolescent males, the values being almost identical in the nonanemic group compared with the total population. In the different groups, 80-97% of the subjects with abnormal values of at least one of these two indexes were not anemic. The difficulties involved in establishing a state of iron deficiency according to these indexes are discussed.

Adolescent↗
PubMed1988

Relationships among iron absorption, percent saturation of plasma transferrin and serum ferritin concentration in humans.

The percent absorption of iron from four dietary sources was compared in 2018 human subjects with three indicators of iron status, serum ferritin concentration, percent saturation of plasma transferrin and iron absorption from a reference dose of ferrous sulfate. Higher correlation coefficients (r) were obtained by comparing dietary iron absorption with the reference dose absorption rather than with serum ferritin; for example, r = +0.61 and r = -0.38, respectively, for a meat and vegetable meal. However, in practice serum ferritin is almost as efficient as the reference dose absorption in estimating dietary iron absorption, because the 95% confidence limits calculated from the regression equations were very similar. The values of r calculated for iron absorption versus transferrin saturation were comparable to those obtained with the other indicators only in the range of transferrin saturation values below 25%, whereas in more iron-replete subjects (transferrin saturation greater than 25%), this correlation virtually disappeared. This indicates that, although both serum ferritin and transferrin saturation reflect iron status in iron-depleted subjects, the control of iron absorption in iron-replete subjects is more dependent on iron stores as reflected in the serum ferritin concentration than the percent saturation of transferrin.

Diet↗
PubMed1988

[Requirements of nutrients which participate in erythropoiesis].

Proteins, some minerals and vitamins, play important roles in erythropoiesis and the survival of the red blood cell. This article deals specifically with the physiological requirements and recommended intakes of iron, folate and vitamin B12. A comparison of the physiologic iron requirements according to age and sex, and the amount of iron which is actually absorbed from the diets consumed by the lower socioeconomic strata of the Venezuelan population; indicates that these diets do not satisfy the requirements at all ages. Such disparity is most marked in children below three years of age, in adolescents and in women during their reproductive age. Failure to do so leads to varying degrees of iron deficiency. This low bioavailability of the Venezuelan diet is also observed in other Latin American diets consumed by the same low socioeconomic strata, which explains the high prevalence of iron-deficiency anemia in the vulnerable groups. The low intake of fruits and vegetables by the lower socioeconomic strata of the Latin American population prevents these sectors from consuming an adequate intake of folate, failing to fulfill the daily recommended intake (3.3 - 3.6 micrograms/kg body weight). This situation is aggravated in pregnant and lactating women who require an additional intake of 300 micrograms and 100 micrograms, respectively. Prevalence of folate deficiency in the first stage may be in the order of 30% in some regions. In the second stage of deficiency, characterized by megaloblastic changes in the bone marrow and an erythrocyte folate concentration of less than 50 micrograms/lt, it could be as high as 40% in pregnant women. Nutritional vitamin B12 deficiency does not constitute a health problem in Latin America. Various surveys in the lower socioeconomic strata have reported normal or higher than normal serum B12 concentrations, compared to well-nourished populations.

Adolescent↗
PubMed1987

[Hematologic profile and absorption of iron from diets consumed by a population of low socioeconomic level of 2 Venezuelan states].

Hematologic studies carried out in inhabitants of the State of Carabobo revealed that 19% of the subjects studied presented iron deficiency, this being more prominent in women and in children. Iron deficiency anemia was absent in men, while in the other groups its frequency, as registered, was from 5 to 13%. Tests for iron absorption from foods which form the average diet of the population in the Carabobo State, and the diet consumed by adults from the low socioeconomic strata in the States of Carabobo and Yaracuy, demonstrated that in normal subjects, bioavailability is lower than physiological requirements of men, women and children. In the iron-deficient subjects, its bioavailability can cover physiological needs. It is estimated that an important proportion of the population strata consuming such diets, suffer from iron nutritional deficiency, especially women during the reproductive age, and children.

Adolescent↗
PubMed1986

Heme, ferritin and vegetable iron absorption in humans from meals denatured of heme iron during the cooking of beef.

The iron absorption from heme, ferritin and vegetable foods was tested in 63 humans (10 males and 53 females). The iron absorption from heme in beef exposed to prolonged heating was markedly reduced, following the degree of denaturation of the heme. The iron absorption from ferritin was about 31% of the absorption of the reference dose when administered with meat alone, falling to 11% of the reference dose when administered in a meal containing meat and vegetable foods. The absorption of ferritin iron was less than half that of vegetable iron. The data confirm a previous proposal that ferritin forms part of a subgroup of the non-heme iron pool.

Animals↗
PubMed1984

Effect of histidine, cysteine, glutathione or beef on iron absorption in humans.

One hundred thirteen subjects participated in iron absorption studies in which histidine, cysteine, reduced glutathione or beef were administered with test meals. Increasing doses of histidine from 416 to 2080 mg did not affect the absorption of 2 mg of corn iron. Reduced glutathione significantly increased the absorption from nonheme and heme iron present in black beans, corn and hemoglobin. Increasing doses of either cysteine or glutathione produce the same trend in the increase of absorption from corn iron as that observed from beef. The results suggest that the effect of cysteine on iron absorption is similar in the peptide form and as a single molecule.

Absorption↗
PubMed1984

Effect of exposure to low temperature on normal and iron-deficient subjects.

Twenty-one Venezuelan peasants were segregated into three groups on the basis of measurements of iron status: seven normal subjects, six iron-deficient subjects with normal hemoglobin and eight iron-deficient subjects with a hemoglobin concentration of less than 9 g/dl. All subjects were placed in a water bath at an initial temperature of 36 degrees C. The water temperature was then rapidly lowered to 28 degrees C, and observations were made over the period of 1 h. Mean oral temperature of the first group fell 0.2, the second group 0.5, and the third group 0.9 degrees C. Mean plasma norepinephrine levels in both groups of iron-deficient subjects were significantly higher at 36 degrees C and during cold exposure compared with control subjects. Oxygen consumption was also significantly increased in both groups of iron-deficient subjects after cold exposure.

Adult↗
PubMed1975

Ferritin iron absorption in man.

The iron absorption from ferritin and hemosiderin biosynthetically labeled with radioiron was studied in 108 subjects. The geometric mean absorption of ferritin iron in both normal and iron-deficient subjects was 1.9 percent. Its mean absorption ranged from 0.9 percent in normal subjects to 2.5 percent in subjects with moderate iron deficiency and 5.7 percent in subjects with marked iron deficiency. The administration of this iron compound with vegetals in a meal showed distinctly lower absorption values than the absorption from either maize, wheat, or soybean. Ferritin iron absorption was also different from that of ferric chloride when they were administered together as a drink or mixed with maize or liver. The iron absorption from ferritin was markedly increased when it was administered with either meat or liver, but it did not reach the absorption level of these foods. It is still to be elucidated whether the difference in iron absorption between ferritin and vegetable foods administered together reflect that this iron is incompletely miscible with a nonheme iron pool or that it really forms a third iron pool.

Administration, Oral↗