Nearly half of American adults have high blood pressure, high cholesterol or diabetes, and one in seven is not aware of having at least one of these chronic conditions, all of which are associated with heart disease, the leading cause of death in the United States, says a new CDC study.

The new study was conducted by researchers from the US Centers for Disease Control and Prevention's (CDC's) s National Center for Health Statistics and was published online this week.

For the study the authors analyzed data from the National Health and Nutrition Examination Survey (NHANES) 1999-2006.

Their key findings reveal that: 45 per cent of US adults had at least one of three diagnosed or undiagnosed chronic conditions: hypertension (high blood pressure), hypercholesterolemia (high cholesterol), or diabetes.