Duke Department of Medicine is honored to recognize March as Women’s History Month, celebrating the many women who have made significant contributions to move medicine forward.
Crystal Tyson, MD, MHS, assistant professor of Medicine in the Division of Nephrology, is empowering patients with chronic kidney disease (CKD) to take charge of their health. She’s studying how the right diet can slow disease progression.
“Patients with CKD are complicated, which makes them more vulnerable. Not only are you dealing with CKD but you’re also dealing with the illnesses that led to it,” Dr. Tyson said. “When patients are complicated, a lot of people tend to shy away from them. I felt like they needed champions and that’s where I could make a difference.”
Kidney disease is the fastest growing non-communicable disease in the US and is one of the top 10 leading causes of death in the United States. Black, Hispanic/Latino, Native American, and Asian populations are at increased risk for developing kidney disease and kidney failure.
Dr. Tyson is a board-certified nephrologist and clinical hypertension specialist that treats patients with CKD and kidney failure twice a week in the Duke Nephrology Clinic and Duke Cardiometabolic Clinic.
Growing up in Detroit, Michigan, utilizing public assistance programs, Dr. Tyson understood at a young age how much illness can affect a person. “I always hated being sick. I realized how even colds, profoundly impacted my life and I didn’t like that feeling. That translated into me wanting to help other people in those situations.”
She’s now dedicated to making her patients feel like they’re more than their diagnosis. “They need to feel heard. We must remember that we’re treating a person that has values and preferences. We need to make sure they understand what’s going on, even though we’re moving at a fast pace to try and address their issues,” Dr. Tyson said.
Dr. Tyson earned a full academic scholarship to college and attended Wayne State University School of Medicine, where she noticed the glaring disparities of CKD. “When we rounded in the kidney wing of the hospital, it wasn't lost on me that almost every room we went in, we were treating Black patients. The disparities became obvious to me, not from statistics, but from my everyday interactions rounding on the nephrology service.”
While Black Americans represent just 13.5% of the US population, they make up about one third of the people who are on dialysis. Black Americans are four times as likely to develop kidney failure than white Americans. Black patients are less likely to receive a transplant evaluation, have less access to the waitlist, spend longer on the transplant list, are less likely to survive on the waitlist, and have lower rates of graft survival post-transplant.
“When you go to a dialysis unit, most patients are there because of diabetes and high blood pressure. The people who are more vulnerable to developing those conditions are those from impoverished backgrounds, who don't have access to exercise facilities, outdoor spaces, and healthy foods, which overwhelmingly affects Black people.”
Her unwavering passion for medicine was solidified while training under a hypertension specialist during residency. “Watching an expert who looks like you, educate patients and other health care professionals, that impressed me. That representation made me realize, ‘I can do something like this’.”
The DASH Diet
In 2016, Dr. Tyson began studying the DASH Diet, which stands for Dietary Approaches to Stop Hypertension. It’s a diet that’s proven to lower high blood pressure and involves eating fruits, vegetables, nuts, whole grains, fish, and beans daily.
“When a patient is first diagnosed, they want to know what’s within their power to do and not end up on dialysis,” Dr. Tyson said. “They always ask, ‘if I drink more water, eat certain foods, or do certain exercises, will it help?’ It always comes from in that realm, even though it's hard to change behavior.”
Dr. Tyson and a team of Duke School of Medicine faculty first had to prove that the DASH diet was beneficial to CKD patients. There was concern it was too high in foods that contained phosphorus and potassium.
“As your kidneys get worse, the body has trouble eliminating potassium. High potassium levels can cause irregular heart rhythm, which can be fatal,” Dr. Tyson said. Foods that are high in potassium are leafy green vegetables, citrus fruits, bananas, and avocados.
“When kidney function declines, the body also holds on to extra phosphorus which increases the risk of bone disease. When combined with the calcium in the blood, it can calcify or harden the blood vessels, making the patient more likely to have cardiovascular issues.” Foods that are high in phosphorus are beans, nuts, whole grains, and certain cheeses.
The team then enrolled participants in a trial to teach them how best to follow the diet. This increased patient participation, but researchers found Black Americans didn’t follow the diet as well as other participants due to social determinants of health like, not having access to stores that carried healthy foods, and a lack of transportation, funds, or support from others in their household. But others faced issues that tend to be overlooked.
“A patient, an elderly woman, said she didn't feel safe walking outside because there are stray dogs in her neighborhood. When I was growing up, I would be afraid to walk to school in certain areas for the same reason,” Dr. Tyson said. “We tell people to go to the mall and walk since they open early. But what if you don't have a car to get to the mall? Those are barriers we don’t think about.”
She designed a qualitative study to address the barriers, which earned her a career development award. The team enrolled 31 Black patients with advanced CKD. Half of them participated in a 12-week diet counseling program, where they met with a dietician to learn how to follow the DASH diet. That data is currently being analyzed, and Dr. Tyson plans to conduct a larger study on whether the DASH Diet improves kidney function.