摘要：Objectives. To expand the understanding of potential pathways through which food insecurity is associated with adverse health outcomes, we investigated whether food insecurity is associated with nutritional levels, inflammatory response, and altered immune function. Methods. We performed a cross-sectional analysis of the National Health and Nutrition Examination Survey (1999–2006) with 12 191 participants. We assessed food insecurity using the US Department of Agriculture food security scale module and measured clinical biomarkers from blood samples obtained during participants’ visits to mobile examination centers. Results. Of the study population, 21.5% was food insecure. Food insecurity was associated with higher levels of C-reactive protein (adjusted odds ratio [AOR] = 1.21; 95% confidence interval [CI] = 1.04, 1.40) and of white blood cell count (AOR = 1.36; 95% CI = 1.11, 1.67). White blood cell count partly mediated the association between food insecurity and C-reactive protein. Conclusions. These findings show that food insecurity is associated with increased inflammation, a correlate of chronic diseases. Immune response also appears to be a potential mediator in this pathway. An estimated 17 million US households were food insecure in 2008, representing a particularly vulnerable subpopulation of Americans. 1 Food insecurity reflects the uncertainty of having or the inability to acquire adequate food intake for all household members 1 and stems in large part from the lack of sufficient resources to obtain adequate food intake. Income level has been strongly correlated with food insecurity, with low-income families more likely to experience food insecurity. 1,2 However, income and poverty do not fully predict food insecurity, suggesting other factors, such as the ability to effectively budget available resources, are important in determining an individual’s propensity to be food insecure. Identifying additional risk factors for food insecurity may provide targets for prevention among at-risk populations. Numerous studies in the United States have demonstrated that food insecurity is associated with adverse health outcomes, including diabetes, hypertension, and cardiovascular disease. 3–7 The mechanisms by which food insecurity predisposes one to chronic diseases, however, have not been well studied but are hypothesized to include shifts in dietary quantity and quality. 8 Recent literature has established a seemingly paradoxical relationship between food insecurity and obesity in the United States. 9–12 It is thought that food insecurity induces individuals to obtain foods that provide a higher caloric value per dollar spent; subsequently, these high-calorie diets lead to obesity and the associated adverse health outcomes. 4,5 However, this model does not account for alternative pathways whereby food insecurity may lead to poor health through undernourishment. For example, those with food insecurity may be able to obtain less food altogether or may experience increased psychological stress, leading to reduced net caloric intake and, ultimately, chronic disease risk from undernourishment. By expanding our understanding of all the potential pathways through which food insecurity is associated with adverse health outcomes, we can develop more effective public health programs. It is possible that the stress and shifts in dietary patterns that characterize food insecurity incite an inflammatory state and alter immune function in food-insecure individuals. This hypothesis may account for why body mass index (BMI; defined as weight in kilograms divided by the square of height in meters) does not fully mediate the relationship between food insecurity and diabetes as well as why food-insecure households do not have significantly different energetic intakes. 4,5,8 C-reactive protein (CRP), a systemic and nonspecific inflammatory marker, has been linked to health conditions such as diabetes, peripheral arterial disease, and cardiovascular disease. 13–18 Specific nutritional markers, including vitamin A, vitamin B12, and folate, have been identified in biological and epidemiological studies as associated with inflammatory states and innate immune function and increased risk of some infections. 19–27 Therefore, nutritional status and its impact on inflammation and immunological processes may help explain how food insecurity influences health outcomes, such as diabetes and cardiovascular disease. Using a representative sample of the United States, we assessed sociodemographic predictors of food insecurity. In addition, we tested the hypothesized association between food insecurity and increased inflammation as measured by CRP levels. We further hypothesized that food insecurity may be associated with poorer nutritional status—as measured by levels of key nutrients—and an increased susceptibility to infection—as captured by white blood cell count, which could then lead to immune system activation and increased inflammation. Nutrients and white blood cell count may be mediators on the pathway from food insecurity to increased inflammation.
