Heart disease is the leading killer of adults nationwide, and South Asians, the second fastest-growing ethnic group in America, have a higher death rate from the disease than any other ethnic group. People of South Asian descent, which includes countries like India, Pakistan, Bangladesh, Nepal, Sri Lanka, Bhutan and the Maldives, have four times the risk of heart disease compared to the general population, and they develop the disease up to a decade earlier.
Experts are only now beginning to uncover why rates of heart disease are so high in this group. For the last seven years, a team of researchers at the University of California, San Francisco and Northwestern University has followed more than 900 South Asians in Chicago and the Bay Area. Their ongoing study, known as Masala, for Mediators of Atherosclerosis in South Asians Living in America, has found that South Asians tend to develop high blood pressure, high triglycerides, abnormal cholesterol and Type 2 diabetes at lower body weights than other groups.
South Asian men are also prone to high levels of coronary artery calcium, a marker of atherosclerosis that can be an early harbinger of future heart attacks and strokes. In November, the American Heart Association and other medical groups issued updated cholesterol guidelines that, for the first time, urged doctors to consider ethnicity when determining a patient’s cardiovascular risk and treatment options.
Citing studies by the Masala researchers, the guidelines identified South Asians as a ‘high risk’ group and ‘stronger candidates’ for statin medications when other risk factors are present. Some of the most striking findings to come out of Masala relate to body composition. Using CT scans, it was found that South Asians have a greater tendency to store body fat in places where it should not be, like the liver, abdomen and muscles. Fat that accumulates in these areas, known as visceral or ectopic fat, causes greater metabolic damage than fat that is stored just underneath the skin, known as subcutaneous fat. Studies show that at a normal body weight — generally considered a body mass index, or BMI, below 25 — people of any Asian ancestry, including those who are Chinese, Filipino and Japanese, have a greater likelihood of carrying this dangerous type of fat.
Despite having lower obesity rates than whites, Asian-Americans have twice the prevalence of Type 2 diabetes, which promotes heart attacks and strokes. Heart risks tended to be greatest in South Asians, the Masala researchers found. In one recent study, in the Annals of Internal Medicine, they found that 44 percent of the normal weight South Asians they examined had two or more metabolic abnormalities, like high blood sugar, high triglycerides, hypertension or low HDL cholesterol, compared to just 21 percent of whites who were normal weight.
The Masala researchers also found that using the standard cutoff point to screen for diabetes, a BMI of 25 or greater, would cause doctors to overlook up to a third of South Asians who have the disease. The findings helped prompt the American Diabetes Association to issue updated guidelines in 2015 that lowered their screening threshold for diabetes, to a BMI of 23 for Asian-Americans. Setting the guidelines to include ethnicity will help doctors provide better medical care to South Asians who may be at high risk and likely neglecting their health.