This paper describes the main methodological aspects of a cohort study, with emphasis on its recent phases, which may be relevant to investigators planning to carry out similar studies. In 1993, a population based study was launched in Pelotas, Southern Brazil. All 5,249 newborns delivered in the city's hospitals were enrolled, and subsamples were visited at the ages of one, three and six months and of one and four years. In 2004-5 it was possible to trace 87.5% of the cohort at the age of 10-12 years. Sub-studies are addressing issues related to oral health, psychological development and mental health, body composition, and ethnography. Birth cohort studies are essential for investigating the early determinants of adult disease and nutritional status, yet few such studies are available from low and middle-income countries where these determinants may differ from those documented in more developed settings. Resumo

and 3 Fundac Ëa Äo Seade, Brazil OBJECTIVE: This study aimed to describe the prevalence of overweight and obesity (OW O) among Brazilian adolescents and to identify risks for subpopulations de®ned according to the ®ve country macro-regions and situation (urban±rural) of the domiciles, income, years of school attendance, age and sex. DESIGN: A nationwide home-based survey representative of the Brazilian civilian noninstitutionalized population, performed in 1989. METHODS: The sampling plans followed a strati®ed, multistage, probability cluster design in The National Research of Health and Nutrition sample, which collected anthropometric data of 14,455 domiciles. In all, 13,715 adolescents ranging from 10 to 19 y of age were studied. The OW O was de®ned from a body mass index (BMI) equal or superior to the 85th percentile of the reference population of the NCHS. The prevalences in the different studied groups were compared using the adjusted odds ratio in logistic regression models. RESULTS: The prevalence of OW O was of 7.7%, reaching 10.6% within the female group and 4.8% within the male group. A direct relation could be established between the socioeconomic level and OW O. Adolescents of the most industrialized region of the country presented a risk of OW O 1.86 (95% CI 1.51 ± 2.30) times higher than that found in the least developed region. Male youngsters who lived in urban areas were more liable (OR 1.71, 95% CI 1.30 ± 2.25) to overweight than their counterparts of rural areas. The occurrence of menarche increased two and a half times (OR 2.58, 95% CI 2.11 ± 3.15) the risk of OW O within the female group of adolescents. CONCLUSIONS: The results demonstrate a low prevalence of OW O among Brazilian adolescents when compared with adolescents of more industrialized regions. The OW O is twice as high within the female group, which represents a much greater difference than the one encountered in industrialized countries, probably owing to the muscular work carried out preponderantly by male adolescents of lower socioeconomic levels. Higher prevalences in subpopulations of higher socioeconomic level and of more industrialized regions show the great need for differentiated actions to control overweight and obesity in the country.

Our results confirm the existence of gender differences in reporting household food insecurity. Furthermore, they indicate that households headed by women constitute a segment of the population that is particularly vulnerable to food insecurity.

O objetivo deste estudo foi descrever a freqüência de consumo de frutas, legumes e verduras por adultos de 20 a 69 anos de Pelotas, Rio Grande do Sul, Brasil, e analisar fatores associados. Foi realizado em 2006 um estudo transversal de base populacional, incluindo 972 adultos. A freqüência do consumo de frutas, legumes e verduras foi medida por meio de três perguntas referentes ao consumo habitual destes no ano anterior. O desfecho foi o consumo regular de frutas, legumes e verduras. Cerca de 1/5 da população adulta (20,9%) consumia regularmente frutas, legumes e verduras. Indivíduos do sexo feminino, com 60 anos ou mais, das classes A e B, ex-fumantes e não sedentários apresentaram maior prevalência de consumo de frutas e legumes e verduras. A freqüência do consumo de frutas, legumes e verduras na população adulta residente no Município de Pelotas está aquém das recomendações atuais do Ministério da Saúde, em especial entre os homens mais jovens, de menor nível sócio-econômico e que não praticam atividade física no lazer. Políticas públicas que estimulem uma alimentação saudável são urgentemente necessárias.

Freqüência de consumo de dietas ricas em gordura e pobres em fi bra entre adolescentes Frequency of high-fat and low-fi ber diets among adolescents RESUMO OBJETIVO: Descrever a freqüência e os fatores associados ao consumo de dietas ricas em gordura e pobres em fi bra em adolescentes.