The study found that African-Americans and Hispanics both have obesity rates of about 48 percent among their respective populations, as well as diabetes rates of about 21 percent. Only 23 percent of African-Americans, however, have NAFLD, compared with 45 percent of Hispanics.
Similarly, African-Americans are less likely to have high levels of triglycerides and abdominal fat both characteristics of insulin resistance when compared with Hispanics or Caucasians, even though overall rates of insulin resistance among all groups are the same, researchers found.
"This presents something of a paradox," Dr. Browning said.
The explanation might lie in where different ethnic groups typically store fat.
Obese Hispanics tend to deposit fat in the liver and visceral adipose tissue the area around the belly. Obese African-Americans deposit fat predominantly in subcutaneous adipose tissues the area around the hips and thighs, Dr. Browning said.
"This may be protective," Dr. Browning said. "In animal studies, if subcutaneous fat is increased as opposed to visceral fat, you can actually reverse fatty liver disease."
Scientists aren't sure why the location of fat storage matters.
"This seems to argue that there is a fundamental difference in the lipid metabolism between African-Americans and Hispanics or Caucasians, and this difference is maintained even when insulin resistance is present," Dr. Browning said.
Differences in liver-fat content in Caucasians seem to be based on gender. Caucasian males are at the highest risk for NAFLD, on par with the risk faced by Hispanics in general. Caucasian females are on par with the African-American population, at about 23 percent. Caucasian females, like African-Americans, might benefit from the greater predilection to store fat in lower extremities.
"Research studies traditionally have been based on examining Caucasian males, but this informatio
|Contact: LaKisha Ladson|
UT Southwestern Medical Center