Early atherosclerosis (measured by increased thickness of the carotid arteries) is associated with excess amounts of abdominal fat in U.S.-born Mexican Americans but not first-generation immigrants, according to research by The University of Texas Health Science Center at Houston (UTHealth). The findings were published recently in the Journal of the American Heart Association.
“Many studies have focused on the various risk factors associated with excess amounts of abdominal fat in non-Hispanics. To our knowledge, this is one of the few studies to highlight cardiovascular risk associated with visceral adipose tissue in the Hispanic population,” said Susan T. Laing, MD, the study’s senior and corresponding author and professor of cardiology at McGovern Medical School at UTHealth. “The distribution of abdominal fat varies between racial and ethnic groups, and it’s important that we research the significance of these differences to better understand risk for cardiovascular disease.”
Currently the third fastest growing population in the United States, estimates suggest the Hispanic population could increase to 111 million by 2060.
The research team studied participants from the Cameron County Hispanic Cohort in the Rio Grande Valley. They measured the thickness of the inner two layers of the carotid artery (the intima and media) via ultrasound to observe for any evidence of early atherosclerosis, a progressive inflammatory disease that causes hardening of the arteries. If left untreated, atherosclerosis can lead to cardiovascular disease events and injuries such as heart attacks, strokes, and sudden cardiac death.
They also conducted dual-energy X-ray absorptiometry on participants to evaluate levels of visceral adipose tissue, also known as abdominal fat.
Of the 527 participants, 57.8% were female, and the average age was 53. Over half (69.2%) identified as a first-generation immigrant and 30.8% identified as a second- or third-generation Mexican American. More than 25% of participants were diabetic and nearly half (49%) were hypertensive. More than 80% of participants were classified as overweight or obese, and 44.9% were diagnosed with metabolic syndrome.
Those with the highest levels of abdominal fat were most likely to have high blood pressure, high blood sugar, low levels of high-density lipoprotein (good cholesterol), metabolic syndrome, and diabetes. Nearly half of the participants had an abnormal carotid ultrasound, which suggested a high prevalence of early stage atherosclerosis. Increased carotid artery thickening was more prevalent in individuals with the highest levels of visceral adipose tissue. This type of fat tissue secretes large quantities of free fatty acids, which can result in insulin resistance and metabolic syndrome.
“What was unique about this study is we discovered the association between visceral adipose tissue and early atherosclerosis was significant among second or higher generation Mexican Americans and not among first-generation immigrants,” said Joseph McCormick, MD, a study co-author and director of the Hispanic Health Research Center at UTHealth School of Public Health in Brownsville.
According to the study team, one of the most likely contributors for this association is the effect the U.S. obesogenic social culture and acculturation has on U.S.-born Mexican Americans. Factors of this culture include a greater prevalence of sedentary lifestyles and diets rich in saturated fats and excess trans fats, which contribute to greater instances of obesity. However, based on the study team’s survey results, those who identified as first-generation immigrants were more likely to consume a diet rich in beans, fruit, and vegetables, and were less likely to consume fast food or desserts compared to their U.S.-born Mexican American counterparts.
The research team hopes their findings will help with developing important preventive and therapeutic objectives for future public health planning for this rapidly growing population.
Other UTHealth study authors include Clarence Gill, MD; Nahid Rianon MBBS, DrPH; Beverly Smulevitz, BS; David D. McPherson, MD; Susan Fisher-Hoch, MD; and Miryoung Lee, PhD, MPH. Kristina Vatcheva, PhD, with The University of Texas Rio Grande Valley, is also a co-author.
This research was funded by a Clinical and Translational Award funded by the National Institutes of Health (UL1 TR000371).
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