Rarest blood type has highest heart risk

People with blood types A, B, or AB have a higher risk for coronary heart disease compared with those with blood type O, U.S. researchers found. Senior author Dr. Lu Qi, an assistant professor in the nutrition department at the Harvard School of Public Health in Boston, and colleagues analyzed two large, well-known U.S. studies -- 62,073 women from the Nurses' Health Study and 27,428 adults from the Health Professionals Follow-up Study. Study participants were ages 30-75, and both groups were tracked for 20 years or more. In addition to blood type, the researchers also considered the study participants' diet, age, body mass index, gender, race, smoking status, menopause status and medical history. The study, published in the Arteriosclerosis, Thrombosis and Vascular Biology, found people with the rarest blood type -- AB, found in about 7 percent of the U.S. population -- had the highest increased heart disease risk at 23 percent. People with type B had an 11 percent increased risk, while those with type A had a 5 percent increased risk. About 43 percent of Americans have type O blood, Qi said. "While people cannot change their blood type, our findings may help physicians better understand who is at risk for developing heart disease," Qi said in a statement. "It would be interesting to study whether people with different blood types respond differently to lifestyle intervention, such as diet."