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Leptin is closely related to obesity and its complications. In order to determine serum levels of this hormone in children and adolescents, and its associations to age, gender, socioeconomic status, nutritional anthropometrical status and dietary intake, 166 children and adolescents (91 normal and 75 obese, aged 2 to 15 years), from low socioeconomic status were assessed. A socioeconomic evaluation (Grafffar-Mendez C method), dietary intake (24 hour recalls), anthropometrical assessment and leptin by ELISA were performed. Normal or eutrophic was defined as weight for height (W/H) or Body mass index (BMI) and fatty area between 10th and 90th percentile. Obesity when indicators were over 90th percentile. Leptin was significantly higher in obese than in normal, without differences by gender or age. Leptin percentile distribution showed 11.53 microg/L and 24.29 microg/L as 90th percentile for normal and obese children, respectively. There was a tendency to inverse correlation among leptin, fat dietary intake and waist-thigh ratio. Excessive fat intake was associated to lower serum leptin. Results suggest that obese children had leptin resistance, independently of age and gender. It is recommended to develop nutritional education programs regarding obesity and dietary intake in order to prevent and control infantile obesity.

Nutrition is a critical determinant of immune response being the most common cause of immunodeficiency in the world. 104 preschool children, apparently healthy, from a private school were chosen to determine lymphocyte subpopulations and to evaluate its relationship to the anthropometric nutritional status and serum zinc. Nutritional status was measured by the indicator weight for height, lymphocyte subpopulations by flow cytometry and serum zinc by atomic absorption spectrophotometry A high percentage of the population (87.5%) belonged to socioeconomic level II (Graffar). Nutritional deficit was present in 9.5 percent of the studied children, while 16.2% were overweight. Values for lymphocytes subpopulations and serum zinc were within reference ranges, similar to other reports and there were no significant differences by sex, age or nutritional status. Low concentrations of serum zinc were present in 6.7% of children. There was a tendency to lower values of the T lymphocyte populations in hypozincemic children but it did not reach statistical significance. As there are not reference values for lymphocyte subpopulation in Venezuelan children, these results could be used as reference for future investigations. Continuity of research is needed to understand relationship of micronutrients levels and immune response.

Vitamin A is an essential micronutrient for growth, especially in highly proliferative and development stages as in pregnancy. When maternal vitamin A is deficient, fetal demands does not allow to maintain maternal reserves and subclinical deficiency appears. Due to the fact that pregnancy is a period of vulnerability to nutritional deficiencies, 75 pregnant adolescent (16.4 +/- 1.2 years old), were studied along prenatal control visits during pregnancy for vitamin A status. Data on serum retinol was obtained in each trimester through fasting blood collection, and determination by high pressure liquid chromatography. Two-24 hour recalls during each trimester were used to assess dietary intake. Statistical analysis (descriptive, frequency distribution, paired t-test and Fisher's exact test) were performed. Mean serum retinol values decreased significantly (p < 0.05) along trimesters. There was not vitamin A deficiency by serum retinol indicator at any trimester, but at third trimester, 30.3% of the women showed marginal serum retinol values (20-30 mg/gL). Dietary intake, adjusted for recommendations for each trimester, increased significantly as pregnancy continued. These findings indicate that even though serum retinol (vitamin A) deficiency was not present at any time during pregnancy in these adolescents, risk of deficiency increased toward the end; and that the increase of vitamin A intake at the end of pregnancy does not change the decline in serum retinol. Monitoring and nutritional intervention of this vulnerable group is recommended in order to promote a healthy mother and newborn.

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.

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.

Immunoglobulin E, Parasitic Infestation and Nutritional Status of Pre-School Children from Valencia, Venezuela 43

The interaction of vitamin A and inhibitors of iron absorption from a basal breakfast containing bread from either 100 g of precooked maize flour or 100 g of wheat flour + 50 g of cheese + 10 g of margarine was studied. These breads were labeled with either 55Fe or 59Fe. This basal breakfast was given alone on the first day of the study, and a beverage containing coffee or tea at different concentrations was administered with this breakfast on the following days. In the first three experiments performed, the bread was made from commercially available flours, fortified with iron as ferrous fumarate and vitamins. It can be noticed that whereas the iron absorption from the breakfast containing wheat bread was significantly reduced when given with different concentrations of coffee beverages, the bioavailability of iron from the breakfast containing precooked maize bread remained the same in spite of being administered with increasing concentrations of coffee beverages. The only ingredient present in precooked maize bread and not in wheat bread was vitamin A. In the other experiments, iron and vitamin A were added to the non-fortified precooked maize flour in our laboratory. In presence of vitamin A, nonheme iron absorption from the basal breakfast containing either coffee or tea was not statistically different from the breakfast without coffee, meaning that vitamin A can overcome the inhibition of coffee and tea on iron absorption and also prevents the inhibitory effect of phytates. The high performance liquid chromatography and spectrophotometric studies seem to indicate that during the digestive process, iron and vitamin A form a new prouct or complex, that keeps iron soluble even at pH6. All these data suggest that vitamin A binds iron liberated during digestive process and acts as a quelating agent, keeping iron soluble in the intestinal lumen and preventing the inhibition of polyphenols and phytates on nonheme iron absorption.