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POVERTY AND NUTRITION RISK 41 2 Poverty and Nutrition Risk An underlying premise of the WIC program (Special Supplemental Nutrition Program for Women, Infants, and Children) is that low-income predisposes women, infants, and children to poor nutrition status and health outcomes. By using both an income standard of up to 185 percent of the federal poverty level and nutrition risk criteria in determining eligibility for participation in the WIC program, the WIC program attempts to target scarce program resources to those individuals with limited economic resources who are at the highest risk of poor outcomes. Before reviewing (in subsequent chapters) the scientific evidence relating to the nutrition risk criteria used to establish eligibility for participation in the WIC program, this chapter presents evidence of low-income, or poverty, as a predisposing nutrition risk factor for women, infants, and children. DEFINITION OF POVERTY Considerable controversy exists over how to define and measure poverty. A recent expert panel defined poverty as ''economic deprivation," reflecting inadequate economic resources for the consumption of basic goods and services (NRC, 1995). Poverty standards are generally called absolute measures and are based on the assumption that there is some objective minimum level of either income or consumption such that if economic resources are less than this minimum standard, individuals and families do not have adequate resources to satisfy their basic needs (Ruggles, 1990). Families and individuals are classified as being in poverty if their incomes are less than official poverty thresholds. The poverty measure was initially constructed by determining the cost of a nutritionally adequate low-cost food plan (then the Economy Food Plan, now the
POVERTY AND NUTRITION RISK 42 Thrifty Food Plan) designed by the U.S. Department of Agriculture (USDA) for families of different sizes and compositions and then multiplying the cost by a factor of three. This approach was based on analysis of the 1955 Household Food Consumption Survey, which showed that food consumption represents one-third of family income (Orshansky, 1963, 1965). Official poverty thresholds are derived by using the Consumer Price Index (CPI) to update this measure annually. Over time, several criticisms of official poverty statistics have emerged, each with different implications for estimating the prevalence of poverty. The first type of criticism is conceptual and questions whether absolute measures of poverty truly reflect what is meant by being poor in U.S. society. Alternative poverty measures include both relative and subjective measures and may better reflect current living and consumption standards (Ruggles, 1990). However, such measures rarely have been considered official measures of poverty. A second and more common criticism of official poverty statistics focuses on the specific components used to construct the poverty thresholds (Lewit, 1993; NRC, 1995; Ruggles, 1990). Three specific issues are important. First, current poverty thresholds are based on 1955 food consumption and expenditure patterns and do not reflect the resources required for a minimally adequate standard of living today. Second, measures of family income do not account for in-kind benefits such as food stamps, free or reduced-price school meals under the child nutrition programs, donated USDA commodity food, Medicaid, and public housing subsidies, nor do they consider fixed expenses, such as child care and child support, taxes, housing, and medical expenses. Since the 1960s, when the poverty concept was introduced, there has been tremendous growth both in the value of benefits from in-kind programs and in fixed expenses. Finally, the CPI, as opposed to an index based on the price of food, is used to update poverty thresholds. If poverty is theoretically linked only with having a minimally adequate amount of food, then official poverty statistics will over-state the prevalence of poverty during periods of rapid inflation in the price of nonfood items. In addition, use of the CPI alone to update poverty thresholds ignores the substantial geographic variation in the cost of housing. Despite considerable controversy over official poverty thresholds and statistics, the measures in use form the basis for determining the size of the population in need, designing and evaluating antipoverty programs, and assessing economic well-being over time. Poverty guidelines used as the basis for determining income eligibility in the WIC program are those published annually by the U.S. Department of Health and Human Services (Federal Register, February 19, 1994, 59(28):6277â6278).
POVERTY AND NUTRITION RISK 43 PREVALENCE OF POVERTY Compared with other industrialized nations, poverty in the United States is widespread and disproportionately affects children. In 1993, the poverty rateâthe percentage of individuals with a family income less than the federal poverty lineâ was 15.1 percent for the U.S. population and 22.7 percent for children under 18 years of age (U.S. Bureau of the Census, 1995). The poverty rate for children in the United States is generally considered to exceed the rate for children in almost all other industrialized countries: during the 1980s, the poverty rate of U.S. children was more than three times the poverty rates of children in Sweden and Switzerland and more than twice the poverty rates of children in Germany and Norway (Duncan, 1991). Trends in poverty among children show that the rate increased through the 1970s, 1980s, and early 1990s, despite uninterrupted economic growth from 1982 through 1989 and the recent recovery from the 1990â1991 economic recession (Children's Defense Fund, 1991, 1994; Duncan, 1991; Li and Bennett, 1994). In 1993, poverty among children was more prevalent than in any year since 1965. Increases in poverty are particularly dramatic among very young children. More than 1 in 4 children under 6 years of age is poor, and among very young poor children, nearly half live in families with an income less than 50 percent of the poverty level (Center on Budget and Policy Priorities, 1994). The implications for the WIC program of the high prevalence of measured poverty among women, infants, and children are dramatic. In 1993, 9.5 million infants and children 1 to 4 years of ageâalmost one-half of all infants and children in this age groupâlived in families within the WIC program's guidelines for eligibility on the basis of income and as defined by WIC state agencies (Trippe and Schirm, 1994). The WIC program served only 4.6 million, or half, of these income eligible infants and young children. The largest discrepancy between the number of people eligible for participation on the basis of income and the number served occurs for children 1 to 4 years of age. The discrepancy results from the fact that the WIC program is not fully funded. POVERTY AND NUTRITION RISK FOR WOMEN Evidence linking poverty and nutrition risk for women served by the WIC program is obtained almost exclusively from the relationship between poverty and (1) poor perinatal outcomes and (2) risk factors for poor perinatal outcomes. The relationship between low-income and poor perinatal outcomes is well established in the literature. Using median family income within census tracts identified from birth certificates, Gould and LeRoy (1988) analyzed rates of low birth weight for large cohorts of births in Los Angeles County from 1982 to 1983 and found that median family income was a strong predictor of the relative
POVERTY AND NUTRITION RISK 44 risk of low birth weight. For both black and white infants, increases in median family income were associated with decreases in the percentage of low-birth- weight infants. These differences persisted after controlling for maternal age and education and the adequacy of the prenatal care that was received. Other studies also confirm the relationship between geographic variation in perinatal outcomes and socioeconomic status (Brooks, 1980; Gortmaker, 1979; Knox et al., 1980). In addition, cross-sectional data collected over the past decade, such as the National Longitudinal Survey of Youth (NLSY) and the National Maternal and Infant Health Survey, include data on family income and such birth outcomes as birth weight, adequacy of prenatal care, and infant mortality. Starfield and colleagues (1991) used data from the NLSY to examine the effects of income and race on the risk of low birth weight. The risk of low birth weight among poor women was higher than that among nonpoor women, especially for white mothers. In addition, the study findings show the importance of factors antecedent to pregnancy, such as long-term poverty or poverty before pregnancy, in understanding variations in the risk of low birth weight. Although the relationship between poverty and poor perinatal outcomes is well established, the mechanisms by which poverty or low socioeconomic status exerts an influence on perinatal outcome are less clear. Poverty is likely to affect perinatal outcomes in one or more of the following ways: restricting access to health care; affecting nutrition before, during, and after pregnancy; and producing stress, which can result in other risk factors such as smoking, teen pregnancy, drug use or abuse, poor mental health, and inadequate shelter and living conditions. As confirmation of these potential mechanisms, Gould and LeRoy (1988) found that median family income is strongly associated with risk factors for low birth weight, including the percentage of teen pregnancies and increases in the percentage of women with late or no prenatal care. The Institute of Medicine (IOM) also concluded that risk factors for low birth weight are greatest for women of low socioeconomic status (IOM, 1985, 1988). Data from the Pregnancy Nutrition Surveillance System indicate that low-income women receive less prenatal care and receive care later in pregnancy than higher-income women (Kim et al., 1992). With regard to dietary status, findings from analyses of the Continuing Survey of Food Intakes of Individuals (CSFII) conducted in 1985 and 1986 and from the second National Health and Nutrition Examination Survey (NHANES II) suggest that diet quality differs between low-income and higher-income women. Block and Abrams (1993) analyzed CSFII dietary data from 4 nonconsecutive days for women ages 19 to 50 years and found that for every nutrient analyzed (protein, vitamin A, vitamin E, vitamin C, vitamin B6, folate, calcium, iron, and zinc), the proportion of women with intakes less than 70 percent of the Recommended Dietary Allowance (RDA) and the proportion
POVERTY AND NUTRITION RISK 45 of women with intakes less than 100 percent of the RDA were greater in the lowest-income group.1 The women showed marked differences in fruit and vegetable consumption: 82 percent of the women in the higher-income group reported eating a vegetable at least once in the 4 nonconsecutive days, compared with only 54 percent of the women in the lowest-income group. Women in the lowest-income group were half as likely to report consuming a dark green vegetable (7 versus 14 percent) and were significantly less likely to report consuming any fruit or juice in the 4 days (67 versus 87 percent). In addition, an analysis of NHANES II dietary data for white non-Hispanic women found that the risk of a poor diet was increased by poverty (Guendelman and Abrams, 1995). POVERTY AND NUTRITION RISK FOR INFANTS AND CHILDREN Poverty among children is associated with impaired growth and cognitive development. Empirical evidence shows that poverty is related to almost all indicators of child growth and development and to almost all intervening risk factors for delayed growth and development. Cross-sectional data from early national surveys of U.S. children document the deficits in nutrition status as determined by height and weight for children living in poverty (Jones et al., 1985). Cycle II of the Health Examination Survey, 1963â1965, examined children 6 to 11 years of age and found that the mean height and weight for low-income children was lower than the mean height and weight for higher-income children (Hamill et al., 1972). The Ten-State Nutrition Survey, 1968â1970, further confirmed this finding; these data showed that children from families with an income less than 150 percent of the poverty level were more often of low weight and short stature than children from families with incomes above this cutoff (CDC, 1972). Likewise, the Pre-school Nutrition Survey, 1968â1970, found decreased growth in children living in low-income families (Owen et al., 1974). Finally, data from the first and second National Health and Nutrition Examination Surveys (NHANES I, 1971â1975, and NHANES II, 1976â1980) also show lower mean values for all of the growth measures examinedâheight, weight, triceps skinfold thickness, and subscapular skinfold thicknessâfor children living in homes below the poverty threshold compared with the mean values for children living in homes above the poverty threshold (Jones et al., 1985). Between the NHANES I and NHANES II 1 It is important to note the limitations of using the proportion meeting the RDA in assessing dietary status. The RDAs for most dietary components are set so that the recommended amount will meet the needs of most healthy individuals. However, the nutrition requirements of individuals vary considerably, and many people remain healthy even if the amount of a nutrient consumed is less than the RDA. With the exception of food energy, a usual intake below the RDA does not necessarily signal a nutrient deficiency (NRC, 1989).
POVERTY AND NUTRITION RISK 46 surveys, however, the differences in children's growth measures by poverty status declined in magnitude. More recently, data from the NLSY suggest that the income-related deficits in growth and development are more severe for children living in chronic or persistent poverty than for children experiencing short-term poverty (Miller and Korenman, 1994). NLSY data include measures of family income for each year from 1978 to 1990 and measures of height, weight, and cognitive development of children in 1986, 1988, and 1990. Miller and Korenman (1994) reported both a higher prevalence of wasting (low weight-for-height) and stunting (low height- for-age) among poor children than among nonpoor children and greater differentials according to long-term rather than short-term measures of poverty. These detrimental effects of chronic poverty persist after controlling for other mediating factors such as maternal age and education, family structure, race, height and weight of the mother, and newborn birth weight. Data from the Pediatric Nutrition Surveillance System (PedNSS) of the U.S. Centers for Disease Control and Prevention also show a higher-than-expected prevalence of stunting among low-income children under 5 years of age (Yip et al., 1992). Although the PedNSS data do not show a higher-than-expected prevalence of wasting among low-income children, these data are collected only for children who participate in public health and nutrition programs and may underestimate the prevalence among all low-income children. Among the nutrition deficiencies of infants and children, iron deficiency anemia is one of the most prevalent and important U.S. public health problems (IOM, 1993). The prevalence of anemia among low-income infants and young children (through 2 years of age) participating in public health programs in 1991 ranged between 20 and 30 percent, compared to 5 percent for the nation as a whole (Yip et al., 1992). Although anemia can be caused by many factors, most cases (80 to 90 percent) can be attributed to iron deficiency. Studies also find a relationship between measures of cognitive development of children and socioeconomic status or income. Research on iron deficiency anemia, which is more prevalent among low-income children than among higher-income children, consistently shows that infants and young children with iron deficiency anemia score lower than iron-replete controls on a wide range of psychological tests (Lozoff, 1990; Oski and Honig, 1978; Pollitt, 1994). The literature on nutrition status and cognitive development also suggests that stunting is associated with cognitive deficits among children (Wachs, 1995; Wilson, 1981). Two recent studies examined the effects of poverty on cognitive development and found that children who experience long-term or persistent poverty score lower on IQ tests and other cognitive measures than children who experience transitory poverty, who in turn score lower than children who were never poor (Duncan et al., 1994; Miller and Korenman, 1993).
POVERTY AND NUTRITION RISK 47 In summary, the available literature provides strong evidence that children born into poverty are at greater risk of impaired growth and delays in cognitive development. As is the case for women, the actual mechanism by which poverty exerts a biologic influence on child health outcomes is through one or more of the following: nutrition and dietary quality, limited access to health care, and exposure to such other risk factors as passive smoking, inadequate housing, and poor food preparation facilities. Interestingly, despite the overwhelming evidence documenting the deficits in growth among children in low-income families, income is not strongly related to variations in energy or nutrient intake. The many studies that examine the relationship between family income and children's nutrient intake report either no effect of household income or small positive effects (Adrian and Daniel, 1976; Basiotis et al., 1983; DHHS/USDA, 1986). Data from NHANES I and NHANES II found lower mean values of all growth measures for children in families with incomes below the poverty level but no differences in intakes of food energy between poor and nonpoor children (Jones et al., 1985). Recent analyses based on the 1987â1988 Nationwide Food Consumption Survey show similar results. For example, in a study of nutrient intakes over 3 days among children 1 to 10 years of age, household income had no significant effect on either micronutrient intakes or any measures of dietary quality after controlling for social and demographic characteristics (Johnson et al., 1994). Certain dietary differences by poverty status, however, are found for children. Using 4 days of dietary intake data from the 1985â1986 CSFII, Cook and Martin (1995) found that the proportions of low-income children with intakes less than 70 percent of the RDA are significantly higher than the proportions of nonpoor children for 10 of 16 nutrients examined. In addition, CSFII data also suggest that low-income children have diets that are very high in fat and cholesterol. Thompson and Dennison (1994) found that children in families with incomes less than 130 percent of the poverty level were more likely to have fat intakes exceeding 40 percent of their total food energy intakes, consume higher amounts of saturated fat, and have higher cholesterol intakes than children in higher-income households. EFFECTS OF WIC PROGRAM PARTICIPATION Through the provision of supplemental nutritious foods, nutrition education, and health and social service referrals, the WIC program is expected to improve the nutrition status of low-income women, infants, and children by addressing the risk factors for poor outcomes. Evidence on poverty and nutrition risk for pregnant women and infants, in conjunction with fairly convincing evidence of the positive effects of the WIC program on perinatal outcomes and the prevalence of iron deficiency anemia, suggests that eligibility for participation
POVERTY AND NUTRITION RISK 48 in the WIC program could rely solely on income for pregnant women and infants. Numerous studies have found positive effects of prenatal WIC program participation on perinatal outcomes, although the magnitude of these effects varies owing to differences in methodologic approaches. In particular, controlling for the confounding effects of self-selection in WIC program evaluations has proved to be extremely difficult (Devaney et al., 1992), and virtually no studies have been able to disentangle the impacts of prenatal WIC program participation from those of underlying differences between participants and non-participants. By far the most common perinatal outcome examined is birth weight, and most studies find a significant effect of prenatal WIC program participation on birth weight (Devaney et al., 1992; Edozien et al., 1979; Kennedy et al., 1982; Metcoff et al., 1985). Several studies also examined the effects of prenatal participation in the WIC program on health care costs after birth and found substantial savings in Medicaid costs during the first 60 days after birth resulting from participation in the WIC program during pregnancy (Devaney et al., 1990, 1992). In the National WIC Evaluation, Rush (1988) compared longitudinal data for 5,205 prenatal WIC program participants with those for 1,358 non-WIC program participants at prenatal clinics across the country. The findings for prenatal WIC program participants were as follows: no statistically significant effect on newborn birth weight; increased infant head circumference; increased birth weight and head circumference with better WIC program quality; no statistically significant effect on gestational age; appreciable but not statistically significant reduction in the incidence of fetal death; and increased maternal intakes of protein, iron, calcium, and vitamin C (four of the five nutrients targeted by the WIC program). In contrast to the large body of literature examining the effects of prenatal participation in the WIC program, fewer studies focus on the effects of WIC program participation on infants and children, and these usually were conducted with small samples of infants and children from local areas. Nevertheless, some of the studies reported positive effects of participation in the WIC program, especially among infants. Data from PedNSS indicate that the prevalence of anemia among low-income children decreased during the 1980s, a finding largely attributed to improvements in iron nutrition status and to the positive effects of the WIC program (Yip et al., 1987, 1992). In the National WIC Evaluation, Rush (1988) found significant effects of participation in the WIC program on children's height and weight-for-height (kg/m2 among children who had entered the WIC program in utero or by age 3 months). Children's intakes of iron, vitamin C, thiamin, niacin, and vitamin B6 were improved if they participated in the WIC program (Rush, 1988). The WIC program's priority system is currently designed to serve pregnant women and infants first, then children. As a result, coverage rates among infants
POVERTY AND NUTRITION RISK 49 and pregnant women whose incomes make them eligible for participation in the WIC program are very high (e.g., an estimated 96 percent of eligible infants participate) (Trippe and Schirm, 1994). In a recent report to the U.S. Congress, the U.S. General Accounting Office (GAO) recommended that pregnancy itself be used as a nutrition risk criterion for low-income women and, on the basis of estimates of program costs and expected benefits, estimated that the federal government would save $24 million if all pregnant women whose incomes made them eligible for the WIC program were served by the program (GAO, 1992). Subsequently, the additional provision in the legislation reauthorizing the WIC program in 1994 gives the states the option of certifying pregnant women whose incomes make them eligible for participation as presumptively eligible for WIC program services, even if the results from health and nutrition screenings are not known. Screening results, however, must be available within 60 days and must establish nutrition risk. REFERENCES Adrian, J., and R. Daniel. 1976. Impact of socioeconomic factors on consumption of selected food nutrients in the United States. Am. J. Agric. Econ. 58:31â38. Basiotis, P., M. Brown, S.R. Johnson, and K.J. Morgan. 1983. Nutrient availability, food costs, and food stamps. Am. J. Agric. Econ. 65:684â693. Block, G., and B. Abrams. 1993. Vitamin and mineral status of women of childbearing potential. Ann. N.Y. Acad. Sci. 678:244â254. Brooks, C.H. 1980. Social, economic, and biologic correlates of infant mortality in city neighborhoods. J. Health Soc. Behav. 21:2â11. CDC (Center for Disease Control). 1972. Ten-State Nutrition Survey, 1968â1970. III. Clinical, Anthropometry, Dental. DHEW Pub. No. (HSM) 72-8131. Atlanta: CDC. Center on Budget and Policy Priorities. 1994. Despite Economic Recovery, Poverty and Income Trends are Disappointing in 1993. Washington, D.C.: Center on Budget and Policy Priorities. Children's Defense Fund. 1991. Child Poverty in America. Washington, D.C.: Children's Defense Fund. Children's Defense Fund. 1994. The State of America's Children, 1994. Washington, D.C.: Children's Defense Fund. Cook, J.T., and K.S. Martin. 1995. Difference in Nutrient Adequacy Among Poor and Nonpoor Children. Center on Hunger, Poverty and Nutrition Policy. Medford, Mass.: Tufts University School of Nutrition. Devaney, B., L. Bilheimer, and J. Schore. 1990. The Savings in Medicaid Costs for Newborns and Their Mothers from Prenatal Participation in the WIC Program, Vol. I . Office of Analysis and Evaluation, Food and Nutrition Service, U.S. Department of Agriculture. Washington, D.C.: U.S. Government Printing Office.
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POVERTY AND NUTRITION RISK 52 Trippe, C., and A. Schirm. 1994. Number of Infants and Children in WIC Income-Eligible Families in 1993 and 1992 Based on March 1994 CPS and Revised March 1993 CPS. Memorandum to Office of Analysis and Evaluation, Food and Nutrition Service, U.S. Department of Agriculture (USDA). Contract No. 53-3198-3-038-243. Washington, D.C.: USDA. U.S. Bureau of the Census. 1995. Income, Poverty, and Valuation of Non-Cash Benefits: 1993. Current Population Reports, Consumer Income, Series P-60, No. 188. Washington, D.C.: U.S. Government Printing Office. Wachs, T.D. 1995. Relation of mild-to-moderate malnutrition to human development: Correlational studies. J. Nutr. 125(suppl.):2245Sâ2254S. Wilson, A.B. 1981. Longitudinal Analysis of Diet, Physical Growth, Verbal Development and School Performance. Malnourished Children of the Rural Poor. Boston: Auburn House. Yip, R., N.J. Binkin, L. Fleshood, and F.L. Trowbridge. 1987. Declining prevalence of anemia among low-income children in the United States. J. Am. Med. Assoc. 258:1619â1623. Yip, R., I. Parvanta, K. Scanlon, E.W. Borland, C.M. Russell, and F.L. Trowbridge. 1992. Pediatric nutrition surveillance systemâUnited States, 1980â1991. Morbid. Mortal. Weekly Rep. 41 (SS-7):1â24.