Asian Americans Have More Metabolic Syndrome Risk Despite Lower BMIs

Many studies in the past have shown that, apart from body mass index (BMI), genetic factors also play a role in the development of metabolic syndrome and coronary artery disease. The researchers of the present study examined the relationship between metabolic syndrome and BMI in non-Hispanic whites (NHW) and Asian Americans, especially those of Korean origin. “In spite of the lower BMI values and lower prevalence of overweight/obesity than NHWs, Asian Americans have higher rates of metabolic syndrome over the range of BMI.” A single general BMI index cannot be used for all populations and BMI ranges for Asians should be lower than for non-Hispanic whites, due to general body size differences. The researchers believe the threshold for what’s considered high BMI for Asians needs to be amended.

Metabolic syndrome is a condition that is characterized by increased fasting glucose levels, hypertension, elevated blood lipid levels and obesity. Patients with metabolic syndrome have a higher risk of developing coronary artery disease. Obesity is generally measured in terms of BMI. Normal BMI is less than 25. If it is more than 30s, then that person is considered obese. People who are obese often develop metabolic syndrome after some time. However, it has been observed that people of Asian origin, in spite of having a lower BMI, suffer more frequently from metabolic syndrome than non-Hispanic whites. This study was carried out to understand the exact prevalence of metabolic syndrome in American Asians and to understand its relation with BMI.

* The study involved retrieving electronic health records of 43,507 patients who had come to Palo Alto Medical Foundation for primary health care from January 1, 2006, to December 31, 2008. All of them were over 35 years of age.
* From the clinical details, the BMI of 413 people of Korean origin, and 32,406 non-Hispanic whites was calculated.
* In addition, from the laboratory test results, the number of people in each group suffering from metabolic syndrome was measured. Prevalence of metabolic syndrome in different BMI categories was calculated.

* The percentage of people who were obese was less in Asian Americans.
* Impaired fasting glucose, decreased high-density lipoprotein (good cholesterol), and increased triglyceride levels were all more common among Asians than non-Hispanic whites.
* At an average BMI of 25 in women, the incidence of metabolic syndrome was 12 percent in non-Hispanic whites, while it was 30 percent in Asians.

Shortcomings/next steps
The sample size of Asian Americans was not sufficient, making it difficult to generalize the findings over a larger population. Moreover, most of the people who get treatment in Palo Alto Medical Foundation are covered by insurance. So this study does not represent the population which is medically underserved. Also, all the participants were living in the same area in the United States. The habits and cultures of Asians in their native counties may be very different.

This study has highlighted the higher prevalence of metabolic syndrome in Asian Americans in spite of having lower BMI. This increased susceptibility is probably because of genetic differences. Increased resistance to insulin in Asians has been strongly predicted for the higher prevalence of metabolic syndrome that they have. Compared to other methods, such as computed tomography or dual energy X-ray absorptiometry, measuring BMI is the most economic way of diagnosing obesity. Results of this study point out that the BMI cut-offs for diagnosing obesity in Asians must be lowered, so that the preventive measures against development of coronary artery disease can be initiated early enough.

For More Information:
Asian Americans have Greater Prevalence of Metabolic Syndrome despite Lower Body Mass Index
Publication Journal: International Journal of Obesity, August 2010
By L. P. Palaniappan; E. C. Wong; Palo Alto Medical Foundation Research Institute, Palo Alto, California

*FYI Living Lab Reports Are Summaries of the Original Research.

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