No abstract

A meta-analysis of eight mortality trials indicates that improving the vitamin A status of children aged six months to five years reduced mortality rates by about 23% in populations with at least low prevalence of clinical signs of vitamin A deficiency. The observed effect of supplementation, described in terms of relative risk (RR), was RR =0.77 (95% confidence interval 0.68-0.88; p < .001) and did not differ by sex or age. However, the number of lives saved was greater at younger ages because of higher mortality. A significant RR was shown for deaths attributed to diarrhoea and measles, but not for respiratory infection. Variability among the trials in effects was apparent, but attempts to explain it by descriptors of the population (baseline anthropometric status, prevalence of xerophthalmia, age profile, baseline mortality) were unsuccessful. Owing to the lack of data, firm conclusions could not be reached about effectiveness in children of less than six months and in settings where biochemical but not clinical evidence of vitamin A deficiency exists. Information about morbidity outcomes from about two dozen studies was reviewed. No consistent effects on frequency or prevalence of diarrhoeal and respiratory infections were found. Improvement in vitamin A status did appear to reduce severe morbidity, particularly in children with measles.

Dietary intake cannot be estimated without error and probably never will be. The nature and magnitude of the error depends on both the dietary data collection methodology and the subjects studied. The impact of particular types of error depends on the question being asked and the analytical methodology used to address it. Examples of these phenomena are presented in this review paper. The future lies in improved estimation and understanding of the error terms and in the development of analytical and statistical methods of coping with these error terms rather than with "improvements" in dietary methodology per se.

A study of food insecurity and nutritional adequacy was conducted with a sample of 153 women in families receiving emergency food assistance in Toronto, Canada. Contemporaneous data on dietary intake and household food security over the past 30 d were available for 145 of the women. Analyses of these data revealed that women who reported hunger in their households during the past 30 d also reported systematically lower intakes of energy and a number of nutrients. The effect of household-level hunger on intake persisted even when other economic, socio-cultural, and behavioral influences on reported dietary intake were considered. Estimated prevalences of inadequacy in excess of 15% were noted for Vitamin A, folate, iron, and magnesium in this sample, suggesting that the low levels of intake associated with severe household food insecurity are in a range that could put women at risk of nutrient deficiencies. J. Nutr. 129: 672-679, 1999.Food insecurity, "the limited or uncertain availability of nutritionally adequate and safe foods or limited or uncertain ability to acquire acceptable foods in socially acceptable ways" (Anderson 1990), has become a matter of increasing concern among western nations in recent years. The assessment of this construct typically occurs through self-reported appraisals of the adequacy and security of the household food supply and individuals' accounts of their experiences of food deprivation. However, an understanding of the relationship between household or individual-level food insecurity and dietary adequacy is imperative in appraising the consequences of food insecurity for nutritional health and well-being. Some indication that perceived adequacy of the household food supply is related to individual members' dietary intakes has come from observed associations between household food sufficiency status and dietary intake data (Cristofar and Basiotis 1992, Rose and Oliveira 1997) and between household food security status and the available household food supply (Kendall et al. 1995) and dietary intake (Kendall et al. 1996).A study undertaken to assess food insecurity and nutritional adequacy among women in families who seek emergency food relief (Tarasuk and Beaton, unpublished data) provided an opportunity to examine the relationship between women's dietary intakes and a comprehensive, contemporaneous measure of household food security status. In this paper, women's intakes are examined in relation to reported household food security status and presence or absence of hunger in the household. To examine whether the women's intakes were in a range that suggested possible nutritional problems, the apparent prevalence of nutrient inadequacy was estimated. METHODSParticipant recruitment and data collection. Participants were recruited on a first come, first served basis when they came to seek food assistance at one of a stratified random sample of 21 of the 77 emergency food hamper programs operating in Metropolitan Toronto. (These are ad hoc, community-based, charitable food prog...

Intakes of minerals and factors that might affect their bioavailability were estimated for 255 toddlers aged 18-30 mo living in villages in Egypt, Kenya, and Mexico. Mean intakes over 1 y were compared with international-requirement estimates by using a probability approach. The prevalence of iron intakes likely to be inadequate to prevent anemia was estimated as 35% in Egypt, 13% in Kenya, and 43% in Mexico. The prevalence of zinc intakes likely to be inadequate to meet basal requirements was estimated as 57% and 25% in Kenya and Mexico, respectively, but only 10% in Egypt, where the use of yeast-leavened breads was judged to have improved zinc availability. There was no suggestion that estimated copper or magnesium intakes were inadequate, but calcium intakes in Kenya and Egypt were well below recommended amounts. Studies of factors affecting mineral bioavailability in the diets of these countries' populations could suggest dietary changes that might improve effective mineral intake with minimal cost.

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venez participer à la 90 e conférence annuelle de l'association canadienne de santé publique winnipeg, manitoba du 6 au 9 juin 1999 L'Annonce de la conférence a été incluse dans le numéro du printemps 1999 de Sélection Santé ACSP. Si vous n'êtes pas membre de l'ACSP et désirez en recevoir un exemplaire, veuillez contacter le Service des conférences de l'ACSP. co-parrainée par pour plus de renseignements : l'association pour la santé service des conférences de l'acsp publique du Manitoba 400-1565, avenue carling, ottawa (ontario) k1z 8r1 613.725.3769 613.725.9826

Two years ago, I reviewed the analytic effect of error in the estimation of dietary intake, describing the emphasis on the "random" day-to-day variation in reported intake. Interest in this area is increasing and there are signs of progress in analytic strategies. This paper focuses on two concerns about the use of dietary data in analyses. The effect of different methods of adjusting analyses of fat and a health outcome for energy is illustrated through an exploration of the association between fat intake and high body mass index in data sets from the US Department of Agriculture and a Dutch national survey. Both a shift in the analytic question and a change in the error structure occur as analysis strategies are changed, leading to confusion in interpretation. The paper also addresses the growing concern about bias in the estimation of intake and the possibility that differential bias moves with stratification variables of analytic interest. The increasing use of doubly labeled water estimates of energy expenditure as a gold standard for checking on overall bias in reporting is commendable. There will always be error in dietary assessments. The challenge is to understand, estimate, and make use of the error structure during analysis.