Your Blood Type May Boost Your Heart Risk, Study Finds

TUESDAY, Aug. 14 (HealthDay News) -- Your blood type may influence your heart health, with types A, B and AB slightly increasing the odds of heart disease, a new study suggests.

You can, however, counter this genetic predisposition by living a healthy lifestyle that includes a balanced diet, exercise and well-controlled blood pressure, cholesterol and weight, experts say.

"Our data suggests the importance of knowing blood type as one factor in susceptibility to cardiovascular disease," said lead researcher Dr. Lu Qi, an assistant professor in the department of nutrition at the Harvard School of Public Health in Boston.

"Although we continue to recommend healthy lifestyle to everyone, those who carry high-risk blood types may need to pay more attention to reducing their risk," he added.

The report is published in the Aug. 14 issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology. Although it found an association between blood type and increased risk of heart disease, a cause-and-effect relationship was not determined.

For the study, Qi's team collected data on more than 60,000 women who took part in the Nurses' Health Study and more than 17,000 people in the Health Professional Follow-up Study. Participants, who were between 30 and 75 years old, were followed for more than 20 years.

The researchers found that people with type AB -- the rarest blood type -- had a 23 percent increased risk for heart disease compared to people with type O blood. The increased risk was 11 percent for people with blood type B, and 5 percent for those with type A.

About 7 percent of Americans have type AB, while about 43 percent have type O, the most common blood type, the researchers noted.

To isolate the contribution of blood type to heart disease risk, Qi's group accounted for factors such as diet, age, weight, sex, race, smoking, menopause and medical history.

The study participants were mostly white, so whether these findings apply to other racial groups isn't known, Qi said. Neither are the reasons for the increased risk associated with certain blood types.

There is evidence, however, suggesting type A is associated with higher levels of low-density lipoprotein cholesterol (LDL), the so-called bad cholesterol, the researchers said.

Also, type O may contain a factor that helps blood flow and prevents clotting, they said.

Dr. Gregg Fonarow, spokesman for the American Heart Association and professor of cardiology at the University of California, Los Angeles, was not surprised by the findings.

"Prior studies have reported that there is a relationship between non-O blood group and an increased risk of coronary heart disease," he said.

Blood type may be related to cardiovascular risk in a variety of ways, he said. Key factors involved in clotting are higher in non-O blood type individuals, and cholesterol levels also have been shown to vary by blood group. Inflammatory and immune responses also may differ by blood group, Fonarow said.

"Nevertheless, the risks associated with the non-O blood group are modest, and far greater risk is imparted by age, blood pressure, cholesterol levels, smoking, diabetes and other traditional risk factors, which should remain the key focus of cardiovascular risk detection and prevention," he said.