Research Designed to Improve Health of Asian American Immigrants

Dr. Jisook Ko has launched two pilot studies with one focusing on Korean Americans who are experiencing high blood pressure and another focusing on Asian Americans who have developed Type 2 diabetes.

By Ginger Hall Carnes

Ethnic minorities who have immigrated to the United States have experienced health issues—namely high blood pressure and Type 2 diabetes–and a Korean American researcher at UT Health San Antonio’s School of Nursing wants to find out why.

Jisook Ko, Ph.D., M.S.N., RN, assistant professor of nursing, came to the United States in 2011 after earning her B.S.N. and M.S.N. at Yonsei University in South Korea.

In her lab, Jisook Ko, Ph.D., M.S.N., RN, assistant professor, uses study participants’ blood samples to investigate a salt sensitivity biomarker that is a critical factor of individual variability to dietary sodium intake.

After earning her Ph.D. in Nursing at The University of Texas at Austin in 2016 and remaining for postdoctoral training in self-management science for two years, Dr. Ko joined UT Health San Antonio in December 2018.

During her first year, she assembled a multi-disciplinary research mentoring team and launched two pilot studies—one focusing on Korean Americans who are experiencing high blood pressure and another focusing on Asian Americans who have developed Type 2 diabetes.

For the first study of Korean Americans, who are one of the fastest-growing Asian subgroups in the U.S., she is using a finding from her dissertation that Korean Americans “consume 2.5 times more dietary sodium compared with the current recommendations.” Due to “bicultural diet patterns,” she said Korean Americans are mixing the western diet with the Korean contemporary diet, and this contributes to exceptionally high sodium consumption.

Diet is a key modifiable risk factor for chronic disease including high blood pressure. While many people take medication to control their high blood pressure, older Korean Americans are hesitant about taking medication. “They don’t want to start taking the medicine because they think it’s forever,” Dr. Ko explained. “They prefer a dietary approach instead of medication.”

However, most do not benefit from the full potential of dietary modification protective effects. This is due to a number of reasons, including high individual variability in response to certain diets or dietary guidelines and programs. It is now well acknowledged that in order to gain the full benefit of dietary regimes, it is essential to take into account the individual’s response to the diet.

This relationship is likely due to the variance of blood pressure response to alterations in dietary sodium intake as well. Salt sensitivity, defined as greater blood pressure response to sodium intake than average, is a major risk factor for high blood pressure and increased cardiovascular risk and is highly relevant given that 99 percent of U.S. adults exceed the recommended daily intake for salt. Salt sensitivity is more prevalent in African Americans and Asian populations, including Korean Americans, than their white counterparts.

Dr. Ko is now conducting a feasibility study of investigating a salt sensitivity biomarker that is a critical factor of individual variability to dietary sodium intake. Until now, there are no validated rapid tests or diagnostic markers to identify salt sensitivity of blood pressure in clinical practice. Dr. Ko is proposing examining salt sensitivity using a genetics approach which is published in a recent article in her feasibility study. She is collaborating with Teresa Johnson-Pais, Ph.D., associate professor/research of urology in the Long School of Medicine and co-director of the UT Health San Antonio Biobanking and Genome Analysis Core Laboratory, and Darpan Patel, Ph.D., associate professor of nursing and director of the Biobehavioral Research Laboratory in the School of Nursing.

Dr. Ko has identified a sample of 40 Korean Americans in San Antonio with high blood pressure. Study participants were asked to have their blood drawn for the genetic testing of salt sensitivity and provide a urine sample for assessing their sodium level.

The pilot study is funded by $12,000 from the Nursing Advisory Council at the School of Nursing and $1,500 from an external nursing organization, Sigma Theta Tau Delta Alpha-at-Large Chapter.
After the pilot study, Dr. Ko will use a larger sample. “Then I can develop the personalized sodium reduction program concerning the sodium-sensitivity biomarker, and the final step can be modifying the dietary recommendations based on the identified mechanism,” she said.

The second study is focusing on why Asian Americans over 65 years of age get Type 2 diabetes. Funded by $35,000 from the Asian Resource Center for Minority Aging Research supported by the National Institute on Aging, a division of the National Institutes of Health, Dr. Ko is seeking Asian Americans in San Antonio who are first-generation immigrants from Korea, China, and South Asia, which includes Filipinos and South Indians.

Although Asian Americans tend to maintain a healthy weight with a lower body mass index compared with whites and Hispanics, they have higher prevalence rates of Type 2 diabetes, worse diabetes control, and higher rates of complications due to limited English proficiency and health literacy. Dr. Ko wants to see if diet is a factor.

Older Asian Americans don’t usually eat a lot of sugar, Dr. Ko said, but they are still consuming traditional grains of rice and noodles as their major source of carbohydrates. She wants to see what kind of foods they are eating and what kind of food sources contribute to their high blood glucose.

She has chosen metabolites as the measurable tool to gauge the response to their diet. Although researchers cannot see every single metabolite, some studies have identified metabolites relating to Type 2 diabetes.

Her collaborators are Yan Du, Ph.D., M.P.H., RN, post-doctoral student concentrating on the Chinese population; Rozmin Jiwani, Ph.D., RN, who will help recruit South Asians; and Jing Wang, Ph.D., M.P.H., M.S.N., RN, FAAN, vice dean for research for the School of Nursing and director of the school’s Center on Smart and Connected Health Technologies.

“This population still needs culturally tailored care for their chronic disease,” Dr. Ko said, pointing to the precision health approach. “Advances in the field of nutritional science have facilitated the shift from the general population-based guidelines to more precise dietary recommendations. In addition to the culturally tailored guidance for ethnic minority populations, we need to provide more precise approaches based on their response to the current dietary recommendations.”

An appropriate method for measuring and assessing dietary intake is required. Digital health technology can collect not only real-time food intake but also health data from people on their own timeline. It also contributes to enabling more personalized self-management of chronic disease through acquiring personal data and formulating the most individualized interventions. Thus, study participants will have the opportunity to use digital health technology, such as a wearable device and its companion dietary mobile app and wireless monitors of blood pressure and blood glucose.

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