[Early maturation: a risk factor of overweight and obesity during puberty?]. / Maduración temprana: factor de riesgo de sobrepeso y obesidad durante la pubertad?

In the Caracas Longitudinal Study, 147 boys and 111 girls--8 to 16 years of age--who had been classified as early, average and late maturers, were analyzed in the context of risk of overweight and obesity. Differences in Body Mass Index (BMI), Arm Circumference (AC), Triceps and Subscapular Skinfolds (TRSK, SSSK) were assessed with an analysis of variance. A significant gradient early > average > late was found girls in all variables throughout follow-up and in AC in boys between 8 and 15 years of age and in BMI until age 11, although early maturers were significantly heavier at all ages. Skinfolds, in boys, presented this significant gradient up to age 11, while in girls it was found in TRSK between ages 8 and 15 and in SSSK between ages 11 and 15. Further analysis of sum of skinfolds, Arm Muscle Area (AMA) and Arm Fat Area (AFA) resulted in significant maturity gradients in girls for all the variables while, in boys, AMA presented this gradient up to age 15, whereas no gradients in and AFA were found from age 12 onwards. Early maturers of both sexes are at risk of overweight; girls are at risk of obesity throughout puberty and boys at prepuberty and early puberty only.

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.

[Requirements of nutrients which participate in erythropoiesis]. / Requerimientos de nutrientes que participan en la eritropoyesis.

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.