Fat Content Inside the Abdomen Helps Predict Whether Japanese Americans Develop Hypertension FREE

Previous studies suggest that people with expanded waists (central or abdominal obesity) have increased risks for high blood pressure. Some of these studies looked at people at a single point in time. Such studies cannot show how often obese patients become hypertensive later in life and whether the obesity precedes hypertension. The results of prospective studies, which follow people with and without expanded waists over a period of years, are mixed. Some experts think that people with large amounts of fat inside their abdomen (around the internal organs or viscera) rather than just under the skin are at increased risk for high blood pressure. Computed tomography (CT) scans detect fat both inside the abdomen and under the skin. No prospective studies use CT scans to measure fat, and, therefore, we cannot determine whether the fat inside the abdomen is really the fat that increases the risk for hypertension.

To learn whether a large amount of fat inside the abdomen predicts hypertension in persons who are followed up over several years.

300 second- or third-generation Japanese Americans, age 34 to 74 years, with normal blood pressure.

Participants with normal blood pressure were selected from a group of people who had volunteered to take part in a study called the Japanese American Community Diabetes Study between 1983 and 1988. All had blood tests to measure glucose and insulin levels, and all answered questions about exercise, smoking, and alcohol-drinking habits. Weight and waist circumference were measured, and CT scans measured the amount of fat beneath the skin and in the abdomen. Participants were then followed for up to 11 years to see who developed hypertension.

Almost 1 in 3 persons (92 of 300) developed hypertension. Compared with those having the least fat inside the abdomen, those with the largest amounts were more than 4 times more likely to be hypertensive at follow-up. This finding held up after adjustments for many other factors, such as age, sex, body weight, exercise, and smoking habits and glucose and insulin levels. Analyses that looked at many measures of fat showed that no other measures—even total fat and waist size—predicted hypertension.

Only Japanese Americans took part in the study. The findings might not apply to other ethnic groups. The study does not explain why a large amount of visceral fat increases the risk for hypertension. Amounts of fat were measured only at the start of the study and could have changed over time.

Japanese Americans who have large amounts of visceral fat more often develop hypertension than do those who have small or normal amounts of visceral fat.