Redlining and its lasting impact on heart disease and diabetes

Heart disease, Type 2 diabetes, high blood pressure and obesity were more common and linked to reduced access to healthy foods among people who live in neighborhoods previously subjected to redlining, according to a preliminary study to be presented at the American Heart Association's Scientific Sessions 2024. The meeting, Nov. 16-18, 2024, in Chicago, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

According to the American Heart Association, the environments and conditions in which people live, work and play -; factors known as social determinants of health -; have a significant role in the development of cardiovascular disease and vary across racial and ethnic groups. Social determinants of health include economic stability, neighborhood safety, education, access to quality health care, access to healthy food and other factors.

We know that redlining leads to poor health outcomes, and even though redlining has been outlawed, it is still having an impact. We looked at what can we do to stop that relationship from continuing to happen. Many cardiovascular outcomes are diet-sensitive. So we wanted to find out if changing your diet in these neighborhoods might change your cardiovascular outcomes."

Rebekah J. Walker, Ph.D., lead study author, associate professor and chief of the division of population health, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo in Buffalo, New York

Redlining is the unjust practice that was effectively legal in the U.S. from 1933-1968 that limited homeownership based on a person's race. In 1933, the Home Owners' Loan Corporation (HOLC), a government agency created as part of The New Deal, began sponsoring low-interest mortgage loans to help people recover from the financial crisis of the Great Depression. The agency developed a color-coding system for neighborhoods across the country based on "risk for investment" criteria. Areas labeled as 'hazardous' were coded red, hence the term redlining, and were deemed "too risky" to insure mortgages.

Residents of these redlined neighborhoods were denied home loans, which lowered tax revenues in these communities. This led to years of reduced investment in schools and government programs and services, creating numerous inequities for residents for multiple generations despite the practice being outlawed by the Fair Housing Act of 1968.

In this study, researchers examined data from more than 11,000 U.S. Census tracts across 38 states to understand if access to healthy foods served as a pathway through which historical redlining leads to increased rates of heart disease, Type 2 diabetes and cardiovascular risk factors.

After controlling for population size, researchers found that neighborhoods that were redlined were more likely to have lower access to healthy foods and in turn higher rates of heart disease, high blood pressure, obesity and Type 2 diabetes.

Specifically, the analysis found:

• An average of 11.8% of people in redlined neighborhoods had Type 2 diabetes; an average of 31.9% had high blood pressure; an average of 6% had heart disease; and 31.8% had obesity.
• A direct association was found among communities that were affected by both redlining and reduced access to healthy food resulting in higher rates of Type 2 diabetes, high blood pressure, obesity and coronary heart disease.
• An indirect association between redlining and Type 2 diabetes, high blood pressure, coronary heart disease and obesity due to reduced access to healthy food.

"The direct relationships we found were that redlining is associated with food access, and food access is associated with higher prevalence of disease," Walker explained. "The indirect relationship was that redlining is associated with higher prevalence of disease via the pathway of food access.

"The impact that social factors, like access to healthy foods, have as a pathway through which structural racism impacts health is important to identify so health care professionals and policymakers are aware of the long-term impact of historical events on current living experiences affecting their patients' health."

According to the U.S. Department of Agriculture, about 1 in 10 U.S. households experienced food insecurity (lacking access to enough healthy food for an active life) in 2020. In 2022, an American Heart Association policy statement suggested achieving "nutrition security" by improving access to the availability and affordability of healthy foods and beverages that help prevent disease. A new initiative from the Association, Health Care by Food,™ explores the clinical and cost-effectiveness of incorporating healthy foods into a person's medical treatment to improve health outcomes, lower health care use and make care more affordable.

"Redlining's residual impact 100 years later is disheartening," said former American Heart Association volunteer president Clyde W. Yancy, M.D., M.Sc., FAHA.

"Without question, redlining has had a negative effect on not just healthy food access but also healthy living," said Yancy, vice-dean of diversity, equity and inclusion and chief of the division of cardiology at Northwestern University, Feinberg School of Medicine in Chicago.

"The greater question must address whether or not some form of "redlining" remains active? Not investing in vulnerable communities extends the consequence of redlining. The sobering awareness is not only the persistent effect of redlining but the still evident practices which "de facto" are redlining but via different means.

However, Yancy is optimistic about the future.

"We need not wring hands and hang heads over redlining," he said. "Disruptive new strategies, provocative voices and breakthrough science applied to healthier foods is our call to action. We can make redlining a historical footnote and that should be among the American Heart Association's goals for its next century."

The study is limited by its observational design that shows only an association, not cause and effect, between previous redlining and cardiovascular risks. Another limitation is that the study analyzed disease rates at a community level rather than by participants' specific address.

Study background and details:

• Researchers reviewed information from 11,457 census tracts in 201 counties in 38 states and redlining information from the Mapping Inequality Project by the Home Owners' Loan Corporation. This project scores neighborhoods on a scale from 1-4, where 1 is best and 4 is redlined.
• The analysis was conducted in December 2023 using data from the 2020 U.S. Census.
• Food access was determined by dividing the number of healthy food retailers by the total number of food retailers per census tract.
• Health records from the CDC PLACES database, which collects community health information across the U.S., determined community-level rates of heart disease, high blood pressure, obesity and Type 2 diabetes.
• The study used statistical methods to analyze the relationships between heart disease and related risk factors and how those related to 1) census tracts with more historical redlined neighborhoods and 2) less access to healthy foods.