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12 Assessment of Nutrient Needs
Pages 245-257

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From page 245...
... signs of deficiency, results of laboratory and functional tests, and dietary intake data. Special attention was given to physiologic changes during pregnancy changes that make it particularly difficult to assess the nutrient requirements and nutritional status of pregnant women.
From page 246...
... In the assessment of nutritional status during pregnancy, static measurements include determination of overt signs of clinical deficiency, which are extremely rare in pregnant women in the United States and Canada; estimates of tissue stores; and determination of levels of nutrients or metabolites in maternal and infant blood and in other body tissues and fluids. Functional measurements include determination of activity of nutrientdependent enzymes or amounts of hormones, nutrient-dependent metabolic or structural changes, rates at which maternal and infant anthropometric measurements change, and indicators of the course and outcome of preg
From page 247...
... For this reason, the subcommittee gave more weight to evidence showing that usual nutrient intakes were inadequate to support optimal function than to evidence of decreases in static levels of nutrients. For example, low serum zinc levels might be regarded as normal during pregnancy, but if linked to low dietary zinc intake and adverse pregnancy outcomes, this would provide a strong argument for recommending supplementation with this nutrient.
From page 248...
... Balance studies are conducted to estimate nutrient requirements based on measurements of all dietary intake and physiologic loss of the nutrient and its metabolites. During pregnancy, a nutrient requirement is considered to be that amount necessary to replace obligatory maternal nutrient losses and to allow for normal growth of fetal and maternal tissues and for accretion of nutrient stores.
From page 249...
... , and there is a need for research to develop and validate practical methods of assessing dietary intake for use in routine prenatal care. Quantitative intake data are useful in several areas, e.g., in nutrition research, in the evaluation of effects of interventions, and in surveys; however, even the most accurate methods for obtaining information on nutrient intakes are imprecise (Medlin and Skinner, 1988; Quandt, 1986)
From page 250...
... for the usual frequency with which specific foods are consumed over time. Both methods are useful for detecting poor dietary patterns and low intake of specific food groups; food frequency questionnaires have also provided a practical means of collecting data on relationships between dietary patterns and either nutrition or health outcomes (see the review by Sampson, 1985~.
From page 251...
... Practical methods for collecting dietary data from pregnant women, often tailored to specific ethnic groups, are available from the state departments of health, from the Supplemental Food Program for Women, Infants, and Children, the American Dietetic Association, and the American College of Obstetricians and Gynecologists. In general, the dietary assessment methods outlined above serve to identify nutritionally unsound dietary practices.
From page 252...
... When the subcommittee recommended supplements, the RDAs were considered in suggesting the amount of supplement to be provided. FACTORS INFLUENCING NUTRIENT REQUIREMENTS AND THE NEED FOR SUPPLEMENTATION Factors that may increase nutrient needs above the ordinary demands of pregnancy are poor nutritional status, young maternal age, a multiple pregnancy, closely spaced births, a continued high level of physical activity, certain disease states (e.g., malabsorption)
From page 253...
... Attempts have been made to categorize pregnant women as being at low, moderate, or high risk of nutrient inadequacy. Methods for making such assignments have included comparison of food or dietary patterns and nutrient intake with various standards or using such criteria as young maternal age, multiple gestation, closely spaced births, and substance abuse to identify high-risk women.
From page 254...
... SUMMARY In the laboratory and in routine clinical practice, there are serious limitations in diagnosing states of nutritional deficiency and in determining who may benefit from supplementation. Given that biochemical changes in pregnancy are often poorly understood, correction and prevention of functional impairments caused by nutrient deficiency are the most important
From page 255...
... It is important to have information on the usual dietary intake of individual women before recommendations can be made about their need for specific nutrient supplements. · The most practical method of evaluating the adequacy of usual food intake patterns is to use some type of food frequency questionnaire.
From page 256...
... 1978. Laboratory Indices of Nutritional Status in Pregnancy.
From page 257...
... 1989. A comparison of food frequency and diet recall methods in studies of nutrient intake of low-income pregnant women.


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