TUESDAY, April 28 (HealthDay News) -- Want to reduce your risk of dying prematurely? Don't smoke and keep a healthy blood pressure level.

Each of those factors accounts for about one in five deaths among U.S. adults, according to new research.

Although both factors had previously been shown to be linked with premature death, the magnitude of the effect found in the new study was not expected, said Majid Ezzati, an associate professor of international health at the Harvard School of Public Health and the study's lead author. The findings were published in the April issue of the online journal PLoS Medicine.

Ezzati and his research colleagues found that other dietary, metabolic and lifestyle factors also accounted for a substantial number of deaths in the United States, including:

• Smoking
• Physical inactivity
• High salt intake
• Low intake of fruits and vegetables
• High blood sugar levels
• High "bad" cholesterol
• Overweight or obesity
• High intake of trans fat
• High intake of salt
• Low intake of polyunsaturated fatty acids
• Low intake of omega-3 fatty acids (found in fish)
• Alcohol intake

Using data from national health surveys and from the U.S. National Center on Health Statistics, the researchers estimated how many lives would be saved and deaths prevented if a risk factor were at the optimal level, creating what they called a comparative risk assessment. The optimal level for smoking, for instance, would be no smokers.

"We put these surveys of levels of these risk factors together with epidemiological studies that tell us how bad they are, and this led to estimates of the number of deaths that are caused by each risk factor," Ezzati said.

Being overweight or being physically inactive each accounted for 1 in 10 deaths. The dietary risks associated with the highest risk of death were high salt intake, low omega-3 intake and high trans fat intake.

Dr. Ramachandran Vasan, chief of the section of preventive medicine and epidemiology at Boston University School of Medicine and senior investigator for the Framingham Heart Study, said the researchers tried to quantify risk factors that included metabolic, dietary and lifestyle issues.

Their findings have "a lot of public health importance," he said. Vasan had no involvement with the study.

Ezzati agreed, saying the study results would show public health officials that "efforts to reduce smoking and lower blood pressure seem to have run out of steam."

Asked if the blood pressure risk factor was due to controlled or uncontrolled blood pressure, he said: "Controlled is an arbitrary term. Many people [with high blood pressure] who are controlled [on medication] are still at risk, because it is still high."

But Vasan said that, on an individual level, the study offers an important take-home point. "It reinforces the idea that it's a good idea to stop smoking and to periodically visit your doctor to get your blood pressure and your cholesterol checked," he said.

• More News on Health Statistics
• More News on High Blood Pressure
• More News on Smoking

Related MedlinePlus Pages:

• Health Statistics
• High Blood Pressure
• Smoking