Our analyses allowed us to demonstrate some striking contrasts between white and black Adventists that warrant further exploration. The finding of shorter sleep duration for blacks is one of these differences. Other studies have found similar results by race for women (33
) and evidence of different sleep physiology between the two racial groups (34
). The link between sleep and obesity also warrants further examination. Despite our finding that the habits of black Adventists were somewhat less healthful than those of their white counterparts, their health habits on available comparison measures were considerably better than those of non-Adventist blacks: rates of smoking, drinking, and meat consumption were lower, and rates of vegetarianism and water consumption were higher (35
The differences between black and white Adventists in self-reported disease prevalence are in line with data from other sources. Prevalences of hypertension and diabetes are known to be higher for blacks than for whites. That these disease rates are lower in our study than the comparable national rates for both blacks and whites, with the most strikingly lower rates being for black men, is noteworthy (36
). More importantly, against expectations from the national data, the self-reported prevalence of diagnosed high serum cholesterol, emphysema, and cancer (except prostate) was actually lower for black than for white Adventists (38
Although black respondents reported less healthy lifestyle practices overall than did whites, their low rates of current tobacco and alcohol use were similar to those of whites. The tendency of blacks to become Adventists at a later age than do whites may contribute to their longer lifetime use of both substances. Another possible explanation for the lifestyle differences between the two groups is that a larger proportion of white respondents are multigenerational Adventists and have a longer history of adherence to, and greater cultural support for, the recommendations of the church. Even though lifestyle behaviors were poorer for blacks than for whites in this cohort, their low current rates of smoking and alcohol use and their lifestyle behaviors, which are generally better than those of the total U.S. black population, may help explain why their health outcomes were better than those reported for blacks nationally.
Although these data should be interpreted cautiously, the power implicit in the large sample size used in the analyses of this study is strong. These results are encouraging but suggest a need for further study. For instance, the importance of spirituality in black U.S. culture and its known value as a disease mediator (41
) raise the question of whether this life component somehow mediates stress more for these Adventists and contributes to our finding that prevalences of a number of chronic diseases were lower for black than for white Adventists.
A number of study limitations must be considered when interpreting these findings. First, the data are self-reported, and health risk behaviors and disease states may be underreported. Second, observed differences in health outcomes may result at least partially from underdiagnosis among black respondents. Evaluation and treatment are often less aggressive for blacks than for whites with similar signs and symptoms, leading many to argue that health care system barriers and racism are behind underdiagnoses and late diagnoses, which are likely to result in poorer health outcomes (43
). This discrepancy in care is unlikely to account entirely for the observed differences, however, given that the education level was higher for this black cohort (35% bachelor's degree or higher) than for blacks nationally (15% bachelor's degree or higher) (44
Also, national data indicate that 80.3% of blacks and 88.7% of whites have health insurance (45
). Although we do not have insurance data for the study population, national rates are most likely lower than those of this black cohort, whose education and full-time employment levels are higher than those for blacks nationally. Again, these facts may diminish the chances that all or most of the observed differences are accounted for by underdiagnosing alone. On the other hand, studies have found that blacks have less dyslipidemia, consistently higher HDL cholesterol, and sometimes lower LDL cholesterol than do whites (46
). Published data on the prevalence of myocardial infarction among blacks are scarce. If the incidence of myocardial infarction is similar for blacks and whites, the explanation may be that mortality from myocardial infarction is higher for blacks and, thus, prevalence is lower.
Although the overrepresentation of women in our study should be noted as a concern, church-going populations usually have more women than men (48
). The more pronounced difference for blacks is not surprising, given that church life plays a more central role in black than in white culture (49
). The younger age of black respondents, although a result of eligibility requirements, should be noted as a potential study limitation even though all analyses were age-adjusted. Although we found that personal income was higher for black than for white women, we did not find this difference between black and white men. The reason may be that black women continue to work at later ages than do white women and are more often single heads-of-households, possibilities that are supported by the significantly lower household incomes among black than among white women. Exploring such complex issues as whether the stronger health benefits we observed for black men as compared with black women might be associated with added stress in black women's lives will be of interest. A final source of potential bias is the differential recruitment of black and white respondents to the study. We believe, however, that the need to recruit successfully far outweighs concerns about not using the same protocol for the two racial groups, a practice that has resulted in numbers too low for meaningful analyses in other studies.
The numbers in our study were large enough to allow us to explore whether the health benefits of lifestyle practices observed for white Adventists hold for black Adventists (7
). Although the results for hypertension and diabetes were poorer for blacks than for whites, health outcomes in a number of categories were actually better for black than for white Adventists and especially better for black Adventists than for blacks nationally. With a full enrollment goal for AHS-2 of approximately 100,000 participants, 30,000 of whom are black, we will have adequate numbers to further investigate the hypothesis that black participants benefit even more than whites from a healthy diet and a tobacco-free, active lifestyle.
For these analyses, we plan to examine the independent effects of components of the Adventist lifestyle and their relative effects in these two groups by looking at high and low adherers to each lifestyle practice. We will also attempt to separate effects among blacks of Caribbean descent and those of American descent. This analysis will be limited, however, because blacks of Caribbean descent make up only 15% of the black study population, and not all endpoints are represented in this small group. Finally, because this cohort is recruited through churches, exploration of the role of spirituality as either a supplementary or a confounding factor is particularly relevant, and a separately funded study is already exploring this issue.
The potential contribution of our current and future findings to the national dialogue on health disparities is substantial. Evidence from this study acknowledges that black Adventists have a broad range of lifestyles, but just as the profile of health habits for white Adventists is better than that of white non-Adventists, the profile for black Adventists is better than that of their non-Adventist counterparts. Given the challenges of many other contributors to health disparities, including racism, housing segregation, employment discrimination, limited educational opportunity, and poorer health care, the study of the relative advantages of the Adventist lifestyle for blacks holds promise for helping to close the gap in health status between blacks and whites nationally.