The American Journal of Public Health reports that 90% of Americans will develop high blood pressure as they age. This increases the risk for heart disease and stroke. In a study at the University of Maryland that was conducted on 15,000 people, Stephen Havas, MD, professor of the Department of Epidemiology and of the Department of Preventive Medicine found that the average systolic blood pressure (the top number) of people ages 45 to 64 increased by five points. The study points to long-term exposure to sodium in processed and restaurant foods as the main factor in the increase.