Too much abdominal fat amongst the Mexican Americans population predicts the beginning of atherosclerosis, but researchers at McGovern Medical School at the University of Texas Health Science Center at Houston, TX, report that this is only true for those who were born in the US.
"From a clinical perspective, this suggests we should probably be targeting second- or higher-generation Hispanics with public health initiatives to improve their cardiometabolic risk," said lead author, Dr Susan T Laing, a professor of medicine at McGovern Medical School at the University of Texas Health Science Center at Houston.
In the study, ‘Association of Visceral Adipose Tissue and Subclinical Atherosclerosis in US‐Born Mexican Americans but not First Generation Immigrants’, published in the Journal of the American Heart Association, the researchers evaluated the clinical and metabolic correlates of VAT, its association with subclinical atherosclerosis, and the factors affecting this association in Mexican Americans.
They used ultrasound to measure the wall thickness of the carotid arteries in 527 Mexican Americans living near the US-Mexico border in Brownsville, TX. They also used a high-precision X-ray, known as a DXA scan, to measure the amount of visceral adipose tissue in the abdomen.
The results showed that those in the highest quartiles of visceral adipose tissue were more likely to have hypertension, hypertriglyceridemia, low high‐density lipoprotein, diabetes mellitus and metabolic syndrome. Increased carotid intima media thickness was more prevalent in those in the highest quartile for visceral adipose tissue (57.4% vs 15.4% for the lowest quartile; p<0.001). There was a graded increase in mean carotid intima media thickness with increasing visceral adipose tissue, after adjusting for covariates; for every 10 cm2 increase in visceral adipose tissue, there was an increase of 0.004 mm (SE=0.002; p=0.0299) in mean carotid intima media thickness.
However, this association was only seen among second or higher generation US‐born Mexican Americans but not among first generation immigrants (p=0.024).
Laing said her findings suggest US-born Mexican Americans had been acculturated to an American lifestyle full of unhealthy, calorie-rich foods and sedentary behaviours.
"What we found among the Mexican Americans in this cohort was that the second or higher generations generally did not know how to cook and relied more on fast food, compared to their parents who had more traditional values and ate a lot of beans and vegetables," she explained. "Second-generation Mexican Americans had fewer traditional behaviors that were healthier, whereas first-generation Mexicans who had moved to America held onto their traditional diet. This decreased with each succeeding generation."
Dr Jorge Saucedo, a professor of medicine and division chief of cardiology at Medical College of Wisconsin in Milwaukee and medical director of the Heart and Vascular Service Line at Froedtert Health System, said more research is needed on what happens after people from Mexico move to the US: “I think it's fair to say that the environment in America and the lifestyle here is affecting people. In Mexico, if you are overweight, there might be some pressure to exercise. But here, there's not as much social pressure and there's less focus on a healthy lifestyle."
Laing's research showed the link between visceral fat and atherosclerosis occurred regardless of a person's body mass index (BMI). While many people may be aware of their BMI, it is harder for them to know whether they have an excess amount of visceral fat, which may not give an appearance of being overweight, she cautioned.
"The more dangerous fat is the one that's hidden. You don't know if you have it or not. Your BMI may be normal, but you may have visceral fat and that increases your metabolic risk."
While there's no easy way for the average person to find out how much visceral fat they have, one way to estimate whether you have too much is to measure your waist, Laing said. The larger the waist circumference, the higher the amount of visceral fat.
"It's imprecise, though," she said. And the amount of visceral fat also increases with age and is higher among men than women.
The way to reduce or prevent gaining visceral fat is no different than how to prevent other weight gain, Laing said. "You gain visceral fat through physical inactivity and a poor diet."
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