Cardiovascular disease is the leading cause of death in people with chronic kidney disease (CKD), yet researchers are still working to understand why cardiovascular risk can differ so significantly from patient to patient.
For Ester Oh, PhD, an assistant professor in the Division of Renal Diseases and Hypertension at the University of Colorado Anschutz Department of Medicine, answering those questions has become the focus of her research.
Oh studies vascular function, cardiovascular disease risk, and dietary interventions in patients with CKD, with a particular focus on women’s cardiovascular health. Her research examines how blood vessel health changes over time, why cardiovascular risk differs between men and women, and how lifestyle interventions such as diet may help improve long-term health outcomes.
“We know patients with CKD are at very high cardiovascular risk,” Oh says. “What we are still trying to understand is why those risks differ between men and women and what interventions may help improve vascular health earlier.”
Her work focuses on understanding how kidney disease can affect cardiovascular health and how lifestyle factors such as diet may help reduce risk.
Understanding the heart-kidney connection
Kidney disease and cardiovascular disease are closely linked, though many people may not immediately recognize the connection.
CKD occurs when the kidneys gradually lose their ability to properly filter waste and excess fluid from the blood. The condition affects millions of people worldwide and significantly increases the risk of heart attack, stroke, and other cardiovascular complications.
“Cardiovascular disease is the leading cause of death in patients with CKD,” Oh says. “Many people are surprised to learn that because they often think kidney disease only affects the kidneys.”
One reason for that increased risk is vascular dysfunction, which refers to problems with how blood vessels work.
Healthy blood vessels expand and contract easily to move blood throughout the body. However, in patients with CKD, inflammation and damage to the blood vessels can make them less flexible and more difficult for the cardiovascular system to regulate properly over time.
“Vascular function refers to how well blood vessels respond and adapt to maintain healthy blood flow,” Oh explains. “It is an important early indicator of cardiovascular health.”
Oh’s research aims to better understand the biological mechanisms driving these vascular changes and whether dietary interventions may help, slow, or improve them.
Examining sex differences in cardiovascular disease
A major focus of Oh’s work is understanding how cardiovascular risk differs between men and women.
Historically, cardiovascular research has focused primarily on men, leaving important gaps in scientists’ understanding of how heart and vascular disease affect women.
“We know there are differences between men and women in cardiovascular risk, but we still do not fully understand the biological reasons behind those differences,” Oh says.
Hormones, aging, metabolism, and kidney function may all contribute to those differences, particularly during periods of hormonal transition such as menopause. Oh’s research also examines compounds such as equol, a molecule produced by gut bacteria after consuming soy-based foods, which may affect vascular health differently in men and women.
In recent research, Oh and her collaborators found that women with CKD had a lower cardiovascular mortality risk than men, although kidney function markers may influence mortality risk in women with CKD, but not in men. The biological mechanisms behind those differences remain unclear.
“There are likely sex-specific mechanisms that influence vascular function,” she says. “Understanding those mechanisms is important because it could eventually help us develop more personalized approaches to prevention and treatment.”
Oh says women’s cardiovascular health has historically been understudied, particularly across different stages of life.
“There is still a need to better understand how cardiovascular risk changes over time and how we can intervene earlier,” she says.
Her work focuses on improving women’s cardiovascular health from early adulthood through older age.
Studying diet as a tool for prevention
Diet is a major focus of Oh’s research, particularly its potential role in improving vascular function and reducing cardiovascular risk.
Although medications are often important in treating CKD and cardiovascular disease, Oh says lifestyle interventions such as diet can also play a meaningful role.
“We are interested in understanding whether certain dietary approaches can improve blood vessel function and potentially reduce cardiovascular risk,” she says.
Her research explores how nutrients and dietary patterns may influence inflammation, blood vessel flexibility and nitric oxide availability, all factors closely tied to vascular health.
Nitric oxide helps blood vessels relax and expand properly. Reduced nitric oxide availability has been linked to vascular dysfunction and increased cardiovascular risk.
“When blood vessels cannot dilate properly, it can contribute to hypertension and other cardiovascular problems,” Oh explains.
One area of Oh’s research focuses on how equol may support vascular health, particularly in postmenopausal women, when cardiovascular risk begins to rise.
“Not everyone can produce equol naturally,” Oh says. “We are interested in understanding whether oral equol supplementation may help improve vascular function.”
Researchers hope these findings may eventually lead to practical dietary interventions that help reduce cardiovascular risk.
One of the most promising aspects of this research, Oh says, is its potential real-world impact.
“Diet is something patients can potentially modify in their everyday lives,” she says. “If we can identify interventions that meaningfully improve vascular health, that could have important implications for prevention.”
Advancing prevention and personalized care
Ultimately, Oh hopes her research encourages people to think about kidney health, cardiovascular health and lifestyle as all being interconnected.
Rather than relying solely on treatments after disease develops, she believes earlier intervention may help improve long-term outcomes.
“We want to better understand who is at risk, why they are at risk, and what interventions may be most effective for different populations,” she says.
That includes understanding how biological differences between men and women may influence treatment responses.
“In the future, research like this could help us move toward more individualized approaches to care,” Oh says. “Not every patient experiences disease in the same way.”
Her research continues to explore the relationship between kidney disease, vascular health, nutrition, and sex-specific cardiovascular risk.
“There is still so much we do not know,” she says. “But the more we understand these mechanisms, the more opportunities we have to improve prevention and patient care.”
For Oh, the ultimate goal is helping patients live healthier lives.
“I hope people understand that kidney health, heart health and lifestyle are all connected,” she says. “Prevention matters, and even small changes over time can have a meaningful impact on long-term health.”
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