Nutrition and cataract in low-income Mexicans: experience in an Eye camp

Surgical Eye-camps for cataract treatment of low-income adult Mexicans have been undertaken over the last 10 years. Despite the high prevalence of cataracts among these subjects, no assessment of their nutritional or health status has ever been made. We compare the results obtained for 81 adults (44 men and 37 women) who received treatment in May 1997 with those for a "control" group of age and sex-matched but affluent individuals in Mexico City. alpha-Tocopherol and beta-carotene were assessed and analysed by HPLC and colorimetric procedures, respectively. The plasma tocopherol to cholesterol ratio did not reveal deficiencies of this vitamin, and only 5 patients (2 men and 3 women) had low beta-carotene plasma levels. The patients had high BMI values, with 32 of men and 30 of women overweight, and 2 and 14, respectively, obese, with higher glucose, cholesterol and triglyceride values reflecting enhanced insulin resistance and lipid abnormalities. The alkaline phosphatase values were elevated suggesting that many of these blind patients are osteomalacic because they now remain indoors. Although it has been suggested that an adequate intake of carotenes and tocopherol are associated with absence of cataract, this appears not to be the case in our study population. Surveys in Mexico have revealed, however, a highly prevalent deficiency of other vitamins such as niacin and riboflavin, both of which have been proved to be protective against cataract. It appears that nutritional deficiencies, obesity, incipient diabetes and lipid disorders co-exist in modern Mexico. We have identified a need for research to aid the design of preventive nutritional approaches at the population level that could be applied in parallel with ongoing surgical treatment.

The starch and total sugar content of Mexican fruit and vegetables / Contenido de almidón y azúcares totales en frutas y verduras de México

The starch and total sugar contents of 20 types of fruit, 28 types of vegetables and six differents herbs, grown in Mexico, were analysed. The selection was based on dietary surgery to identify those foods most widely consumed. Starch was determined by an enzymatic method whilst total sugar was determined gravimetrically. The foods were grouped according to the Southgate classification. Fruits contained little starch (range 0-4g/100g fresh weight (FW) except in the case of the plantain (31g/100g FW starch), ehereas vegetables showed a higher concentration with tubers in the range 10-20g/100g FW starch. Legumes contained 0-5g/100g FW; amongst the capsicum group the chilli poblano had the highest concentration at 1.3g/100g FW starch. The concentration of sugars in fruits ranged from 0,6g/100g FW to 21.1g/100g FW

Salt intake and blood pressure in rural and metropolitan Mexico

A selected group of 155 Mexican adults aged 20 - 64 years were studied to investigate the role of sodium(Na) intake in explaining blood pressure (BP) differences in a rural town and urban Mexico City. The subjects had their BP, height, weight and skinfolds measured and they collected 3 continuous 24 h urines. Adjusted for age differences, average BPs were significantly higher (p<.05) for the urban (112.7 systolic: 73.6 diastolic mmHg) than for the rural group (108.4 systolic: 70.8 diastolic mmHg). They were also higher for men (111.8 systolic: 74.3 diastolic mmHg) than for women (109.6 systolic: 70.2 distolic mmHg), the diastolic BP difference being significant (p<0.05). The average daily Na excretion was also higher in the urban (122.2 mmol/day) than in the rural community (98.0 mmol/day) (p<0.01). Potassium excretion rate showed similar differences in sodium excretion and blood pressure among communities were particularly marked in those over 30 years of age. The means for the four community-sex groups had the same rank order for both BP and Na. However, although some large surveys have suggested that half the observed differences in BP might be explained by different Na intakes, in this study the relationship between Na excretion and BP did not achieve statistical significance. Differences in the body mass index (BMI) accounted for 41 percent of the observed variance in BP

Defining cooking salt intakes for patient counselling and policy making / Como de valora el consumo de sal de cocina para dar consego a pacientes y definir políticas de consumo

The role of salt(NaCl) in the development of high blood pressure has been a matter of debate, however, the Intersalt Study showed that sodium (Na) ontake in varios areas of the World is related to the slope of blood pressure with age. Accurate amounts of the total salt intake or that coming from a particular source are needed, both, for physicians who need to consider the salt intake of their patients and for public health workers who are in charge of the implementation of public health programs where salt in used as a carrier of other nutrients. An analysis of the literature suggests that exaggerated values for total salt intakes have often been obtained from indirect estimates; discretionary salt use, i.e.home-cooking salt has invariably been overestimated. A method is described for measuring the contribution of cooking salt to total salt intake since it is a confusing area where inappropriate methods have been used to assess its contribution. The method described is based on the use of small amounts of lithium carbonate fused with NaCl. Validation experiments were undertaken to determine the naturally occurring lithium (Li) in a number of foods including fresh, frozen and tinned vegetables, and the use of Li tagged salt for cooking vegetables and for direct use in cooked foods. We also assessed whether Li was taken up proportionally with Na into foods during cooking. In general vegetables contained but only small amounts of Li except aubergine and spinach, and Li was taken up proportionally with Na in a variety of vegetables. Results showed that 36,35 and 21 por ciento of the salt added during cooking was carrots, runner beans and potatoes respectively, the rest being discarded in the cooking water. This suggest that about a third of salt added during the cooking of vegetables will be ingested by the household. Attempts to rely simply on the total use of household salt supplies will clearly exaggerate, markedly, the true intake of individuals

Accurate assessment of the quantitative significance of different sources of salt in the diet / Valoración exacta del significado cuantitativo de las diferentes fuentes de sal en la dieta

A metabolic study was conducted to assess the validity of using lithium tagged salt as a technique for monitoring the sources of salt in the diet. Discretionary sources, table and cooking salt, were separately labelled and studied, the table salt being available ad libitum whereas cooking salt intakes were controlled. The study showed that lithium excretion in the urine did provide an accurate measure of the amount the labelled salt ingested. Subsquent analysis suggest that Li is not excreted readily in sweat or faeces so it can be used on its own to ensure the completness of a series of 24h urines. Latin American studies on salt sources in the diet are needed as a base for programmens of primary prevention of hypertensión

Dietary fibre, what it is and how it is measured / Fibra dietary: que es y como se mide

Carbohydrates are the major compoment of the human diet and are an important source of energy. The World Health Organization recommends that 50-70 per cent of ingested carbohydrates should be in the form of polysaccharides such as starch. A smal proportion of dietary carbohydrate is in the form of non-starch polysaccharides (NSP) (Dietary Fibre). Dietary Fibre is a medically important component of the diet since epidemiological evidence links it with the etiology of various diseases. Scientists have engaged in trying to understand the mechanism by which dietary fibre prevents disease. This article highlighst the lack of consensus on its chemical definition and the advantages and disadvantages of the two main methods used to measure it. There are the enzymic gravimetric method (AOOAC) that measure fibre as the weight of residual matter following enzymic treatment of the food; and the enzymic chemical method that identifies and measures fibre from its chemical components. The latter method, proposed by Englyst and Cummings measures dietary fibre as NSP and gives detailed information about its components. This is important for interpreting epidemiological and physiological studies. The precise and confident measure of the different components of carbohydrates is important in Latin America. It will allow a coherent, scientific and rational approach to the role of carbohydrates in health

A metabolic unit for studies on human nutrition

In clinical nutrition we are used to dealing with the clinical management of patients, but of equal or greater importance is the study of how nutrition affects the development of diseases or modifies its manifestations. This field is complex and links physiological studies of nutrition to the epidemiological analyses which form the basis of thinking in public health in Mexico today. Thus a number of studies have investigated the nutritional risk factors leading to the development of diseases such as heart disease and cancer (1-10). This epidemiological research requires the difficult task of accurately assessing the food consumption of individuals: with poor methodologies the chances of erroneous results are very high. This has implications for both group and individual comparison. Physiological studies on the effects of highly controlled changes in food intake on risk factors then allows the epidemiology to be interpreted in metabolic terms. In this paper we illustrate some of the benefits of metabolic studies and some of the requirements for this successful conduct.

Muestras de orina de 24 horas necesarias para caracterizar la ingestión de sodio en voluntarios mexicanos sanos / 24 hour urine samples needed to characterize the intake of sodium in healthy mexican volunteers

En México, en los últimos años, la prevalencia de hipertensión arterial esencial ha ido en aumento y las cifras que se han informado son tan altas como del 34//. Esta prevalencia tan elevada seguramente ha contribuido para que actualmente las enfermedades cardiovasculares sean la primera causa de muerte en la población adulta de México. Se dice que la sal es un compuesto que eleva las cifras de tensión arterial en una proporción importante de la población, por lo que la cuantificación confiable de su consumo en México, para elaborar medidas de prevención primaria de hipertensión arterial, se hace necesaria. El objetivo principal de este trabajo fue calcular el número de colecciones de orina de 24 h que necesita colectar un individuo adulto en México, para caracterizar de una manera más confiable su consumo de sal. Estos resultados podrán aplicarse a estudios epidemiológicos en el futuro. Se estudiaron 10 sujetos adultos en el INNSZ, quienes colectaron siete orinas contiguas de 24 h. Para el análisis estadístico, se utilizó la propuesta de Liu y col. y se estimaron: coeficiente de correlación entre las mediciones, la variación intra individual y el porcentaje de disminución del coeficiente de correlación debido a la variación intra individual.Los resultados indicaron que para caracterizar de manera confiable la ingestión de sal de un individuo, se necesitan tres colecciones de orina de 24 h para alcanzar un porcentaje de exactitud del 98 por ciento

Consideraciones sobre la urbanización en la dieta, nutrición y estado de salud: definición de comunidades urbanas y rurales en el Estado de México / Urbanization on diet, nutrition, and health status: definition of urban and rural communities in the state of México

La urbanización es un fenómeno mundial y en Latinoamérica se calcula que para el año 2000, 80% de la población vivirá en áreas urbanas. Las implicaciones de este hecho sobre la nutrición y salud no han sido suficientemente documentadas. Algunos estudios muestran que migrar de área rurales a urbanas propicia el desarrollo de enfermedades cronicodegenerativas. Estas se asocian a un incremento en el consumo de ciertos nutrimentos como sal, azúcar y grasas. En México la enfermedad cardiovascular pasó a ser una de las primeras causas de muerte. Este cambio en los patrones de enfermedad afectará la economía y sociedad en general. Documentar el impacto, de la migración rural urbana en la nutrición y salud se vuelve prioritario y es importante definir en forma teórica y operativa las poblaciones del área a estudiar. Las clasificaciones obtenidas para 121 municipios del Estado de México permiten reducir la ambigüedad existente en procesos dinámicos de crecimiento metropolitano en países en desarrollo. Los municipios que presentaron niveles de bienestar altos, correspondieron con los más urbanizados mientras que los niveles bajos se encontraron en los municipios clasificados como rurales