Self-reported racial discrimination, response to unfair treatment, and coronary calcification in asymptomatic adults--the North Texas Healthy Heart study

Racial/Ethnic Discrimination and Cardiometabolic Diseases: A Systematic Review

INTRODUCTION

Racial discrimination has been identified as a risk factor for cardiometabolic diseases, the leading cause of morbidity and mortality among racial/ethnic minority groups; however, there is no synthesis of current knowledge on the association between discrimination and cardiometabolic diseases. The objective of this systematic review was to summarize evidence linking racial/ethnic discrimination and cardiometabolic diseases.

METHODS

The review was conducted based on studies identified via electronic searches of 5 databases (PubMed, Google Scholar, WorldWideScience.org, ResearchGate and Microsoft Academic) using terms related to discrimination and cardiometabolic disease.

RESULTS

Of the 123 eligible studies included in the review, 87 were cross-sectional, 25 longitudinal, 8 quasi-experimental, 2 randomized controlled trials and 1 case-control. Cardiometabolic disease outcomes discussed were hypertension (n = 46), cardiovascular disease (n = 40), obesity (n = 12), diabetes (n = 11), metabolic syndrome (n = 9), and chronic kidney disease (n = 5). Although a variety of discrimination measures was employed across the studies, the Everyday Discrimination Scale was used most often (32.5%). African Americans/Blacks were the most frequently studied racial/ethnic group (53.1%), and American Indians the least (0.02%). Significant associations between racial/ethnic discrimination and cardiometabolic disease were found in 73.2% of the studies.

DISCUSSION

Racial/ethnic discrimination is positively associated with increased risk of cardiometabolic disease and higher levels of cardiometabolic biomarkers. Identifying racial/ethnic discrimination as a potential key contributor to the health inequities associated with cardiometabolic diseases is important for addressing the significant burden borne by racial/ethnic minorities.

Perceived Interpersonal Racism and Incident Stroke Among US Black Women

Importance

Black individuals in the US experience stroke and stroke-related mortality at younger ages and more frequently than other racial groups. Studies examining the prospective association of interpersonal racism with stroke are lacking.

Objective

To examine the association of perceived interpersonal racism with incident stroke among US Black women.

Design, Setting, and Participants

The Black Women's Health Study, a prospective cohort study of 59 000 Black women from across the US, assessed the longitudinal association between perceived interpersonal racism and stroke incidence. Stroke-free participants were followed up from 1997 until onset of stroke, death, loss to follow-up, or the end of the study period (December 31, 2019). Cox models were used to estimate hazard ratios (HRs) and 95% CIs, adjusting for major confounders, including education, neighborhood socioeconomic environment, and cardiometabolic factors. Data analysis was performed from March 2021 until December 2022.

Exposure

On a questionnaire completed in 1997, participants reported experiences of racism in everyday life and when dealing with situations that involved employment, housing, and interactions with police.

Main Outcomes and Measures

Strokes were identified through self-report on biennial questionnaires, medical records adjudication, and linkage with the National Death Index.

Results

In 1997, 48 375 Black women (mean [SD] age, 41 [10] years) provided information on perceived interpersonal racism and were free of cardiovascular disease and cancer. During the 22 years of follow-up, 1664 incident stroke cases were identified; among them, 550 were definite cases confirmed by neurologist review and/or National Death Index linkage. Multivariable HRs for reported experiences of racism in all 3 domains of employment, housing, and interactions with police vs no such experiences were 1.38 (95% CI, 1.14-1.67), a 38% increase, for all incident cases and 1.37 (95% CI, 1.00-1.88) for definite cases. For comparisons of women in the highest quartile of everyday interpersonal racism score vs women in the lowest quartile, multivariable HRs were 1.14 (95% CI, 0.97-1.35) for analyses that included all incident stroke and 1.09 (95% CI, 0.83-1.45) for analyses that included definite cases only.

Conclusions and Relevance

In this study, Black women who reported experiences of interpersonal racism in situations involving employment, housing, and interactions with police appeared to have an increased risk of stroke, even after accounting for demographic and vascular risk factors, suggesting that the high burden of racism experienced by Black US women may contribute to racial disparities in stroke incidence.

Complex Racial Trauma: Evidence, Theory, Assessment, and Treatment

Racial trauma refers to experiences related to threats, prejudices, harm, shame, humiliation, and guilt associated with various types of racial discrimination, either for direct victims or witnesses. In North American, European, and colonial zeitgeist societies, Black, Indigenous, and people of color (BIPOC) experience racial microaggressions and interpersonal, institutional, and systemic racism on a repetitive, constant, inevitable, and cumulative basis. Although complex trauma differs from racial trauma in its origin, the consistency of racist victimization beyond childhood, and the internalized racism associated with it, strong similarities exist. Similar to complex trauma, racial trauma surrounds the victims’ life course and engenders consequences on their physical and mental health, behavior, cognition, relationships with others, self-concept, and social and economic life. There is no way to identify racial trauma other than through a life-course approach that captures the complex nature of individual, collective, historical, and intergenerational experiences of racism experienced by BIPOC communities in Western society. This article presents evidence for complex racial trauma (CoRT), a theoretical framework of CoRT, and guidelines for its assessment and treatment. Avenues for future research, intervention, and training are also presented.

Physical Aggression and Coronary Artery Calcification: A North Texas Healthy Heart Study

BACKGROUND

The purpose of this study was to determine the association between aspects of hostility and coronary artery calcification (CAC) scores. Specifically, analyses differentiated between subtypes of hostility and their relation to CAC.

METHODS

A sample of 571 patients aged 45 or older with no history of cardiovascular disease completed assessments of demographic, psychosocial, and medical history, along with a radiological CAC determination. Logistic regression was used to determine the association between hostility and CAC. Hostility was measured using the Aggression Questionnaire, which measured total aggression and how aggression is manifested on four scales: Physical, Verbal, Anger, and Hostility Aggression.

RESULTS

Regression analyses indicated that only the physical aggression parameter was related to CAC: a 5% increase in odds of CAC presence was indicated for every point increase in physical aggression. The association remained significant in adjusted analyses. Other factors associated with CAC in adjusted analyses included: age, gender, race/ethnicity, BMI, and dyslipidemia.

CONCLUSIONS

Psychosocial factors, such as physical aggression, are emerging factors that need to be considered in cardiovascular risk stratification.

Interactive Relations Across Dimensions of Interpersonal-Level Discrimination and Depressive Symptoms to Carotid Intimal-Medial Thickening in African Americans

OBJECTIVE

This study aimed to examine within-race interactions of multiple dimensions of self-reported discrimination with depressive symptoms in relation to carotid intimal-medial thickness (IMT), a subclinical marker of atherosclerosis prospectively implicated in stroke incidence, in middle-aged to older African American and white adults.

METHODS

Participants were a socioeconomically diverse group of 1941 African Americans (56.5%) and whites from the Healthy Aging in Neighborhoods of Diversity across the Life Span study (30-64 years old, 47% men, 45.2% with household income <125% federal poverty threshold) who underwent carotid IMT measurement. Discrimination was assessed across four dimensions (everyday, frequency across various social statuses, racial, and lifetime burden). The Center for Epidemiologic Studies Depression scale was used to assess depressive symptoms.

RESULTS

In cross-sectional hierarchical regression analyses, two interactions were observed in African Americans: more frequent discrimination across various social statuses (b < 0.001, p = .006) and a higher lifetime discrimination burden (b < 0.001, p = .02) were each related to thicker carotid IMT in those with greater depressive symptoms. No significant findings were observed within whites.

CONCLUSIONS

Among African Americans, those reporting high levels of discrimination and depressive symptoms have increased carotid atherosclerosis and may be at greater risk for clinical end points compared with those reporting one or neither of these risk factors. Findings suggest that assessment of interactive relationships among social and psychological factors may elucidate novel pathways for cardiovascular disease, including stroke, among African Americans.

Differential associations between everyday versus institution-specific racial discrimination, self-reported health, and allostatic load among black women: implications for clinical assessment and epidemiologic studies

PURPOSE

Black women have the highest estimated allostatic load (AL). AL and self-perceived health are strong health predictors and have been linked to racial discrimination. Research suggests that everyday and institution-specific racial discrimination may predict different AL and self-reported health (SRH) outcomes. Furthermore, discrepancies between AL and self-perceived health could widen disparities. We estimated associations between everyday versus institution-specific racial discrimination with AL and SRH.

METHODS

Data are from a San Francisco Bay Area community sample of 208 black women aged 30-50 years. Participation involved a questionnaire, self-interview, blood draw, and anthropometric measurements. Adjusted generalized linear regression models estimated associations of racial discrimination with AL and SRH.

RESULTS

After adjusting for age, socioeconomic position, and medication use, institution-specific discrimination was negatively associated with AL (i.e., better health), whereas everyday experiences showed no association. Those reporting very-high (vs. moderate) institution-specific discrimination had lower AL (β = -1.31 [95% CI: -2.41, -0.20]; AL range: 0-15). No racial discrimination-SRH association was found.

CONCLUSIONS

For black women, (1) institution-specific racial discrimination may be differentially embodied compared with everyday experiences and (2) institutional racism may contribute to physiologic stress-regulation regardless of self-perceived health status. Potential factors that may contribute to an inverse racial discrimination-AL association, and future research, are discussed.

Links between discrimination and cardiovascular health among socially stigmatized groups: A systematic review

BACKGROUND

There is a high prevalence of cardiovascular disease across diverse groups in the U.S. population, and increasing research has identified stigma as a potential barrier to cardiovascular disease prevention and treatment. This systematic review examines evidence linking discrimination and cardiovascular health among socially stigmatized groups.

STUDY DESIGN

Six databases were systematically reviewed from inception through February 2018 for studies with adult subjects, focusing on cardiovascular health indicators among social groups stigmatized because of their gender, race/ethnicity, age, body weight/obesity, or sexual orientation. The Newcastle-Ottawa Scale was used to evaluate the methodological quality and risk of bias for nonrandomized studies, and the Cochrane Collaboration 7-item domain for randomized controlled and experimental trials.

RESULTS

The search identified 84 eligible studies published between 1984 and 2017. Studies retrieved were categorized according to demonstrated links between stigma and cardiovascular disease risk factors including blood pressure (n = 45), heart rate variability (n = 6), blood/saliva cardiovascular biomarkers (n = 18), as well as other indicators of cardiovascular health (n = 15). Based on the findings from included studies, 86% concluded that there was a significant relationship among stigma or discrimination and cardiovascular health indicators among socially stigmatized groups. However, there were varying degrees of evidence supporting these relationships, depending on the type of discrimination and cardiovascular health indicator. The current evidence implies an association between perceived discrimination and cardiovascular health. However, a majority of these studies are cross-sectional (73%) and focus on racial discrimination (79%), while using a wide variety of measurements to assess social discrimination and cardiovascular health.

CONCLUSIONS

Future research should include longitudinal and randomized controlled trial designs, with larger and more diverse samples of individuals with stigmatized identities, using consistent measurement approaches to assess social discrimination and its relationship with cardiovascular health.

Perceived Discrimination and Cardiovascular Outcomes in Older African Americans: Insights From the Jackson Heart Study

OBJECTIVE

To assess the associations of perceived discrimination and cardiovascular (CV) outcomes in African Americans (AAs) in the Jackson Heart Study.

PATIENTS AND METHODS

In 5085 AAs free of clinical CV disease at baseline enrolled in the Jackson Heart Study from September 26, 2000, through March 31, 2004, and followed through 2012, associations of everyday discrimination (frequency of occurrences of perceived unfair treatment) and lifetime discrimination (perceived unfair treatment in 9 life domains) with CV outcomes (all-cause mortality, incident coronary heart disease [CHD], incident stroke, and heart failure [HF] hospitalization) were examined using Cox proportional hazards regression models.

RESULTS

Higher levels of everyday and lifetime discrimination were more common in participants who were younger and male and had higher education and income, lower perceived standing in the community, worse perceived health care access, and fewer comorbidities. Before adjustment, higher levels of everyday and lifetime discrimination were associated with a lower risk of all-cause mortality, incident CHD, stroke, and HF hospitalization. After adjustment for potential confounders, we found no association of everyday and lifetime discrimination with incident CHD, incident stroke, or HF hospitalization; however, a decrease in all-cause mortality with progressively higher levels of everyday discrimination persisted (hazard ratio per point increase in discrimination measure, 0.90; 95% CI, 0.82-0.99; P=.02). The unexpected association of everyday discrimination and all-cause mortality was partially mediated by perceived stress.

CONCLUSION

We found no independent association of perceived discrimination with risk of incident CV disease or HF hospitalization in this AA population. An observed paradoxical negative association of everyday discrimination and all-cause mortality was partially mediated by perceived stress.

Perceived Ethnic Discrimination and the Metabolic Syndrome in Ethnic Minority Groups: The Healthy Life in an Urban Setting Study

OBJECTIVE

Ethnic differences in the metabolic syndrome could be explained by perceived ethnic discrimination (PED). It is unclear whether PED is associated with the metabolic syndrome. We assessed this association and quantified the contribution of PED to the metabolic syndrome.

METHODS

Baseline data were used from the Healthy Life in an Urban Setting study collected in the Netherlands from 2011 to 2014. The population-based sample included South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, and Moroccan participants (aged 18 to 70 years). PED was measured using the Everyday Discrimination Scale. The metabolic syndrome was determined according to the harmonized definition of the International Diabetes Federation, American Heart Association, and others. Logistic regression was used for analysis. population-attributable fraction was used to calculate the contribution of PED.

RESULTS

PED was positively associated with the metabolic syndrome in South-Asian Surinamese, African Surinamese, and Moroccan participants (odds ratio [95% confidence interval] = 1.13 [0.99-1.30], 1.15 [1.00-1.32], and 1.19 [1.03-1.38], respectively) after adjusting for potential confounders and mediators. No significant association was observed among Ghanaian and Turkish participants. For the individual components, the associations were statistically significant for blood pressure, fasting glucose, and waist circumference among Surinamese participants. PED was associated with dyslipidemia in Moroccan participants. The population-attributable fractions were 5% for South-Asian Surinamese and Moroccan participants, and 7% for African Surinamese participants.

CONCLUSIONS

We found a positive association of PED with the metabolic syndrome in some ethnic groups, with PED contributing around 5% to 7% to the metabolic syndrome among Surinamese and Moroccans. This suggests that PED might contribute to ethnic differences in the metabolic syndrome.

Exposure to Racial Discrimination and Ambulatory Blood Pressure in Women with Type 2 Diabetes

Diabetes is the only disorder in which women's risk for heart disease exceeds men's. Elevated blood pressure (BP) increases cardiovascular risk in people with type 2 diabetes. Racial discrimination and neuroticism are both associated with BP levels but have not been examined in concert. This study investigated self-reported racial discrimination, neuroticism and ambulatory BP in women with type 2 diabetes. Thirty-nine Black and 38 White women completed a race-neutral version of the Schedule of Racist Events; BP was evaluated using ambulatory monitoring devices. Actigraphy and diaries were used to document times of sleep and wakefulness. Racial discrimination interacted with neuroticism to predict systolic and diastolic BP both while awake and during sleep, after adjustment for covariates. For each, the influence of racist events was stronger at lower levels of neuroticism. Racial discrimination is associated with higher levels of 24-h BP in diabetic women who are low in neuroticism. Copyright © 2015 John Wiley & Sons, Ltd.

Black-White Disparity in Young Adults' Disease Risk: An Investigation of Variation in the Vulnerability of Black Young Adults to Early and Later Adversity

PURPOSE

Socioeconomic adversity in early years and young adulthood are risk factors for poor health in young adulthood. Population differences in exposure to stressful socioeconomic conditions partly explain the higher prevalence of disease among black young adults. Another plausible mechanism is that blacks are differentially vulnerable to socioeconomic adversity (differential vulnerability hypothesis), which has not been adequately investigated in previous research. The present study investigated variation in the vulnerability of black young adults leading to cardiometabolic (CM) disease risk.

METHODS

We used a nationally representative sample of 8,824 adolescents who participated in the Add Health study. Early and later adversity was measured using a cumulative index of social and material adversity in adolescence and young adulthood. CM disease risk was assessed using nine biomarkers. Path analysis within a structural equation modeling framework was used.

RESULTS

The findings indicated that both early and later socioeconomic adversity act as stressors with independent additive influences on young adults' CM disease risk, consistent with the differential exposure hypothesis. Moreover, the results showed that black youth are less vulnerable to early socioeconomic adversity than whites, but they are more vulnerable to later adversity.

CONCLUSIONS

The findings provide support for the unique and additive influences of early and later socioeconomic adversity on CM disease risk contributing to the black-white health disparity in young adulthood. The results also suggest that vulnerability to adversity varies depending on the life stage, which highlights the need for life-stage specific interventions to mitigate the existing black-white disparity in young adults' physical health.

The specter of discrimination: Fear of interpersonal racial discrimination among adolescents in Chicago

This analysis examines fear of interpersonal racial discrimination among Black, Hispanic, and White adolescents. The extent and correlates of these concerns are examined using survey data from the Project for Human Development in Chicago Neighborhoods. Borrowing from the fear-of-crime literature, the contact hypothesis, and group threat theory, several hypotheses are developed linking discrimination fear to direct personal experience with discrimination, indirect or vicarious experience, and environmental signals of discrimination. Results show that about half of Blacks and Hispanics have feared discrimination in the past year. Multivariate results indicate that fear is most likely if one has experienced victimization first-hand and when one's parent is affected by discrimination. Further, a larger presence neighborhood outgroups produces greater fear. Overall, discrimination fear constitutes an additional obstacle for minority adolescents as they transition to adulthood. The phenomenon warrants increased scholarly attention and represents a fruitful avenue for future research.

Racism as a Determinant of Health: A Systematic Review and Meta-Analysis

Despite a growing body of epidemiological evidence in recent years documenting the health impacts of racism, the cumulative evidence base has yet to be synthesized in a comprehensive meta-analysis focused specifically on racism as a determinant of health. This meta-analysis reviewed the literature focusing on the relationship between reported racism and mental and physical health outcomes. Data from 293 studies reported in 333 articles published between 1983 and 2013, and conducted predominately in the U.S., were analysed using random effects models and mean weighted effect sizes. Racism was associated with poorer mental health (negative mental health: r = -.23, 95% CI [-.24,-.21], k = 227; positive mental health: r = -.13, 95% CI [-.16,-.10], k = 113), including depression, anxiety, psychological stress and various other outcomes. Racism was also associated with poorer general health (r = -.13 (95% CI [-.18,-.09], k = 30), and poorer physical health (r = -.09, 95% CI [-.12,-.06], k = 50). Moderation effects were found for some outcomes with regard to study and exposure characteristics. Effect sizes of racism on mental health were stronger in cross-sectional compared with longitudinal data and in non-representative samples compared with representative samples. Age, sex, birthplace and education level did not moderate the effects of racism on health. Ethnicity significantly moderated the effect of racism on negative mental health and physical health: the association between racism and negative mental health was significantly stronger for Asian American and Latino(a) American participants compared with African American participants, and the association between racism and physical health was significantly stronger for Latino(a) American participants compared with African American participants. Protocol PROSPERO registration number: CRD42013005464.

Coping with racism: the impact of prayer on cardiovascular reactivity and post-stress recovery in African American women

BACKGROUND

Prayer is often used to cope with racism-related stress. Little is known about its impact on cardiovascular function.

PURPOSE

This study examined how prayer coping relates to cardiovascular reactivity (CVR), post-stress recovery, and affective reactivity in response to racism-related stress.

METHODS

African American women (n =81; mean age=20 years) reported their use of prayer coping on the Perceived Racism Scale and completed anger recall and racism recall tasks while undergoing monitoring of systolic and diastolic blood pressure (DBP), heart rate, heart rate variability (HRV), and hemodynamic measures. Prayer coping was examined for associations with CVR, recovery, and affective change scores using general linear models with repeated measures.

RESULTS

Higher prayer coping was associated with decreased state stress and DBP reactivity during racism recall (p's<0.05) and with decreased DBP and increased HRV during racism recall recovery(p's<0.05).

CONCLUSIONS

Coping with racism by utilizing prayer may have cardiovascular benefits for African American women.

The Association of Free Testosterone Levels in Men and Lifestyle Factors and Chronic Disease Status: A North Texas Healthy Heart Study

PURPOSE

Hypogonadism is highly prevalent in men older than 45 years and is associated with an increased risk of chronic diseases, including obesity, metabolic syndrome, diabetes, and cardiovascular disease. The objective of this study was to determine whether lifestyle factors such as smoking, diet, and exercise are associated with reduced testosterone levels.

METHODS

In this cross-sectional study, 147 men older than 44 years were recruited from a collaborative network of primary care clinics in the Dallas/Fort Worth, Texas, metropolitan area. Free testosterone levels were measured in plasma samples via an enzyme-linked immunosorbent assay-based method, and analyzed by simple and multiple linear regression in relationship to age, race/ethnicity, smoking, diet, exercise, obesity, diabetes, hypertension, and dyslipidemia.

RESULTS

The participants had a mean free testosterone level of 3.1 ng/mL (standard deviation [SD] = 1.5) and mean age of 56.8 years (SD = 7.9). In simple regression analysis, free testosterone levels were associated with increased age (β = -0.04; P = .02), diet (β = -0.49; P = .05), diabetes (β = -0.9; P = .003), and hypertension (β = -0.55; P = .03) but not with race/ethnicity, smoking, exercise, obesity, or dyslipidemia. In multiple regression analysis, free testosterone values were significantly associated only with age (β = -0.05; P = .01) and diet (β = -0.72; P = .01).

CONCLUSIONS

This study implicates diet, in addition to advanced age as a possible risk factor in the development of reduced testosterone levels.

Social adversity, stress, and alcohol problems: Are racial/ethnic minorities and the poor more vulnerable?

OBJECTIVE

Experiences of racial/ethnic bias and unfair treatment are risk factors for alcohol problems, and population differences in exposure to these social adversities (i.e., differential exposure) may contribute to alcohol-related disparities. Differential vulnerability is another plausible mechanism underlying health disparities, yet few studies have examined whether populations differ in their vulnerability to the effects of social adversity on psychological stress and the effects of psychological stress on alcohol problems.

METHOD

Data from the 2005 U.S. National Alcohol Survey (N = 4,080 adult drinkers) were analyzed using structural equation modeling to assess an overall model of pathways linking social adversity, depressive symptoms, heavy drinking, and alcohol dependence. Multiple group analyses were conducted to assess differences in the model's relationships among Blacks versus Whites, Hispanics versus Whites, and the poor (income below the federal poverty line) versus non-poor (income above the poverty line).

RESULTS

The overall model explained 48% of the variance in alcohol dependence and revealed significant pathways between social adversity and alcohol dependence involving depressive symptoms and heavy drinking. The effects of social adversity and depressive symptoms were no different among Blacks and Hispanics compared with Whites. However, the poor (vs. non-poor) showed stronger associations between unfair treatment and depressive symptoms and between depressive symptoms and heavy drinking.

CONCLUSIONS

Contrary to some prior studies, these findings suggest that racial disparities in alcohol problems may be more a function of racial/ethnic minorities' greater exposure, rather than vulnerability, to chronic stressors such as social adversity. However, observed differences between the poor and non-poor imply that differential vulnerability contributes to socioeconomic disparities in alcohol problems. Efforts to reduce both differential exposure and vulnerability might help to mitigate these disparities.

Significant differences in global genomic DNA methylation by gender and race/ethnicity in peripheral blood

Reduced levels of global DNA methylation are associated with genomic instability and are independent predictors of cancer risk. Little is known about the environmental determinants of global DNA methylation in peripheral blood. We examined the association between demographic and lifestyle factors and levels of global leukocyte DNA methylation in 161 cancer-free subjects enrolled in the North Texas Healthy Heart Study aged 45-75 years in 2008. We used in-person interviews for demographics and lifestyle factors, a self-administrated Block food frequency questionnaire for diet, and bioelectrical impedance analysis and CT-scan for body composition. We measured genomic DNA methylation using bisulfite conversion of DNA and pyrosequencing for LINE-1. Body composition measures including body mass index, waist circumference, areas of subcutaneous fat and visceral fat, percent of fat mass and fat-free mass were not associated with global genomic DNA methylation after controlling the effect of age, gender and race/ethnicity. Instead, female gender was significantly associated with a reduced level of global methylation (β = -2.77, 95% CI: -4.33, -1.22). Compared to non-Hispanic whites, non-Hispanic blacks (β = -2.02, 95% CI: -3.55, -0.50) had significantly lower levels of global methylation. No association was found with age, cigarette smoking, alcohol drinking and dietary intake of nutrients in one-carbon metabolism. Global leukocyte DNA methylation differs by gender and race/ethnicity, suggesting these variables need to be taken into consideration in studies of global DNA methylation as an epigenetic marker for cancer.

Dietary patterns are associated with levels of global genomic DNA methylation in a cancer-free population

Animal studies have provided direct evidence that dietary factors induce changes in DNA methylation patterns. In humans, studies on diet and DNA methylation have yielded inconsistent findings. Because humans tend to consume foods and nutrients that are highly interrelated, study of dietary patterns may have improved the power of detecting the effect of diet on DNA methylation. Using data collected from 149 participants aged 45-75 y in the North Texas Healthy Heart Study, we examined the relationship between dietary patterns and levels of genomic DNA methylation in peripheral blood leukocytes. Dietary data were collected from study participants using the Block FFQ. Genomic DNA methylation was measured using bisulfite conversion of DNA and real-time PCR (MethyLight) for LINE-1. Two dietary patterns were identified using factor analysis: a "prudent" dietary pattern characterized by a high intake of vegetables and fruits, and a "Western" dietary pattern characterized by a high intake of meats, grains, dairy, oils, and potatoes. The prudent dietary pattern was associated with a lower prevalence of DNA hypomethylation (Q(4) vs. Q(1); OR = 0.33, 95% CI: 0.12-0.92) and the association was dose dependent (P-trend = 0.04). There was no apparent association between the Western dietary pattern and global leukocyte DNA methylation (Q(4) vs. Q(1); OR = 1.28, 95% CI: 0.47-3.47; P-trend = 0.55). Thus, a dietary pattern characterized by a high intake of vegetables and fruits may protect against global DNA hypomethylation. Future studies with a larger sample size need to confirm that this association holds longitudinally.