Racial heterogeneity and nutritional status
An advantage of heterogeneous groupings of black/African American subjects in health studies is that they can account for genetic diversity, social determinants, regional residence, US nativity, ethnicity, and acculturation [1, 6, 25, 31, 51, 56]. In this study, we stratified the age groups of adult subjects of African descent by US nativity/citizenship level in our regression models and found that the level of US citizenship based on citizenship status and years of US residence influenced diet quality scores among adults of African descent after controlling for confounding variables. We observed similar trends in which high US-born and moderately high citizenship levels were associated with lower diet quality. These findings are consistent with prior studies that reported poorer dietary patterns [3, 4, 19] and a greater prevalence of chronic diseases/risk factors among US-born residents and US-born offspring of immigrants of African descent [8, 17].
Social Determinants and Diet Quality
Sex, age, and income significantly influenced the diet quality scores. Lower HEI scores were observed for male subjects, the 20–39 age group, and subjects with the lowest income level than for female subjects, the 65 + age group, and subjects with the highest income level (p < 0.001), respectively.
Deterioration of healthy eating patterns among African Americans in the US can be traced back to circumstantial dietary adaptations to colonization after the transatlantic slave trade, which subjected them to limited rations of food access in addition to the adoption of some culinary preferences of Europeans [23, 40]. Consequently, legislation of the Dawes Act of 1887 displaced Indigenous populations, with whom many African Americans intermingled and shared mixed ancestry, from land that they were accustomed to using for hunting/gathering, growing edible crops, and fishing [28, 32]. Other factors included decreased access to farmland for fresh crop production following the Great Migration of a multitude of US Black individuals from the American South to the North and other urban communities for greater economic opportunity [11].
Furthermore, there were higher rates of economic hardship among black farmers who were denied business loans by the USDA to aid in their ability to maintain crop production and distribution [9]. At present, environmental factors such as education, income, housing, urbanization, technological advances, and neighborhood food access have remained influential determinants of dietary patterns among the entire US population. In general, Americans do not meet the recommendations for fruit, vegetable, and whole grain intake based on the USDA Dietary Guidelines for Americans [20, 24, 30]. However, Black/African Americans are disproportionately affected by disparities in education, median income, employment, single-parent households, healthcare access/treatment by providers, and residential proximity to full-service grocery chains [12].
Acculturation/Citizenship Level and Diet Quality
Despite the small sample of non-US-born subjects of African descent, we found significant associations between levels of US citizenship and diet quality scores among this cohort. A greater percentage of adults with high-US-born and moderately high levels of US citizenship had poor diet quality/HEI scores than did adults with low-foreign-born and moderately low levels of US citizenship. In addition, a substantially small subset of adults within all groups had good diet quality. Our findings among these subjects of African descent align with studies concerning the “Immigrant Health Paradox” and the impact of assimilation into the US and adaptation to the typical American diet among Asian and Hispanic groups [50].
A distinctive aspect of this study is our investigation into patterns and influences of acculturation/US nativity and diet among individuals of African ancestry within groups that have not been widely studied in this area of research. Due to the divergent origins of African Americans and Black immigrants in the US, there are several nuances to the mere definition of acculturation among this population. To that end, researchers developed and validated the African American Acculturation Scale (AAS), which accounts for cultural distinctions between African Americans and mainstream Caucasian Americans based on traditional norms associated with eight dimensions of African American culture, including health beliefs and eating patterns [22]. In addition, bidimensional and multidimensional methods of measuring acculturation can be applied to African, Afro-Caribbean, and Afro-Latino subgroups.
Traditional eating patterns of the African diaspora could serve as one of many tools for altering the trajectory of health among US Black individuals. One study evaluated quantifiable measures of colon cancer risk and disproportionate rates among African Americans, where African Americans and rural Africans underwent a two-week diet exchange to a traditional rural African diet high in fiber and a typical American diet high in animal protein and fat, respectively [36]. Investigators observed significant reductions in biomarkers of inflammation indicative of colon cancer risk among African Americans who switched to the traditional African diet, whereas a rise in inflammatory biomarkers of colon cancer risk was noted among rural Africans who transitioned to a diet high in animal protein and fat [36].
Last, with the inclusion of dairy in the USDA food guide, another factor to account for when measuring adherence to US Dietary Guidelines among individuals of African, Asian, and Indigenous ancestry is the approximate 68% prevalence of lactase malabsorption among these racial and ethnic groups as well as a cultural tendency to consume fewer servings of milk compared to individuals of European ancestry [48]. Therefore, future studies that include HEI instrumentation should consider the use of other modified HEI tools if warranted. One study that investigated a large cohort of subjects from the NHANES revealed that neither the HEI nor the AHEI was more beneficial than the other in demonstrating how well diet intake can predict diabetes management and other health indicators [2].
Interestingly, there has been a notable increase in cardiometabolic risk among the West African cohort of Black immigrants since the 1990s [7, 34, 46]. This paradigm shift from traditional African diets low in fat/sugars and high in fiber, herbs, and spices has been attributed to westernized assimilation to diets high in fat, salt, and sugar and low in fiber, especially in urban areas of West African countries [27, 34]. This transition has been influenced by urbanization, improvements in socioeconomic status, and technological innovations [27]. Comparatively, a twin-city study of African immigrants in Minnesota revealed a very low incidence of CVD risk factors and increased self-reported protective lifestyle behaviors among subjects from East African countries and the opposite trend among immigrants from West African countries [45]. At the systemic level, there has been a substantial increase in the availability of energy-dense and animal protein foods combined with a minuscule increase in the availability of fruits and vegetables in higher-income countries of West Africa, such as Ghana [13, 16].
Limitations
The diet quality measures that were assessed via two-day food records were based on self-reported information, and some participants did not complete day two of their food records. The research design of this study was not experimental but observational. Therefore, we could determine the association between our tested variables of US citizenship level and diet quality, but not causality. Due to the small frequency of subjects who reported African descent in the NHANES, especially foreign-born subjects, we could not stratify the results into categories of US-born, Caribbean-born, and African-born US residents who identified as non-Hispanic Black/African American in this smaller preliminary sample of our extended analysis plan. Instead, we developed an ordinal scoring system to measure the level of US citizenship for our regression model based on country of birth, US citizenship (yes or no), and number of years residing in the US. However, of the four ordinal levels of citizenship, the highest and lowest were US-born and foreign-born residents, respectively. This method is a parallel alternative considering research findings concerning relationships between time-based exposures to Westernized countries and deteriorated actual and self-rated health.
These data were limited to a unidimensional approach for measuring acculturation, which does not take beliefs, values, or other cultural customs into account. Therefore, we did not approach this study from the traditional lens of the acculturation construct but rather from the US citizenship level. The most common unidimensional parameters for acculturation, including non-English native languages, are not applicable to African Americans, who represented most of the subjects in this sample. Most of these subjects of African descent were born in the US, the dominant culture in this study, and English is their primary language [44, 52]. English is also a commonly spoken language among black immigrants from British-colonized countries in Africa [5] and the Caribbean [57]. In addition, there was an inadequate sample of non-Hispanic subjects of African descent who reported speaking a second language to add it as a measure of acculturation/citizenship. Conversely, various acculturation studies among Hispanic and Asian populations include language as a parameter. Considering that many African and Caribbean countries are British-colonized and that English is the predominant language spoken in the US, English is the dominant language of most non-Hispanic Black individuals in the US [5, 57].
Multiple sources of data suggest that the poorest health outcomes of obesity and noncommunicable diseases in the US are among the American South population, irrespective of race/ethnicity [33, 42, 55]. Therefore, it is imperative to consider regional differences in the eating patterns and food culture of any racial/ethnic community as well.