Boston: Replacing saturated fats like butter with unsaturated fats such as olive oil may help you live longer, a new study has claimed.

Researchers from Harvard T H Chan School of Public Health in the US found that higher consumption of saturated and trans fats was linked with higher mortality compared with the same number of calories from carbohydrates.

Replacing saturated fats with unsaturated fats conferred substantial health benefits, researchers said.

They suggest that replacing saturated fats like butter, lard and fat in red meat with unsaturated fats from plant-based foods - like olive oil, canola oil and soybean oil - can confer substantial health benefits and should continue to be a key message in dietary recommendations.

"This study documents important benefits of unsaturated fats, especially when they replace saturated and trans fats," said Dong Wang from Harvard Chan School.

The study included 126,233 participants from two large long-term studies who answered survey questions every 2-4 years about their diet, lifestyle, and health for up to 32 years.

During the follow-up, 33,304 deaths were documented. Researchers examined the relationship between types of fats in the participants' diets and overall deaths among the group during the study period, as well as deaths due to cardiovascular disease, cancer, neurodegenerative disease, and respiratory disease.

Different types of dietary fat had different associations with mortality, researchers found. Every 2 per cent higher intake of trans fat was associated with a 16 per cent higher chance of premature death during the study period.

Higher consumption of saturated fats was also linked with greater mortality risk. When compared with the same number of calories from carbohydrate, every 5 per cent increase in saturated fat intake was associated with an 8 per cent higher risk of overall mortality, researchers said.

Conversely, intake of high amounts of unsaturated fats - both polyunsaturated and monounsaturated - was associated with between 11 per cent and 19 per cent lower overall mortality compared with the same number of calories from carbohydrates, they said.

Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death, researchers said.

"Our study shows the importance of eliminating trans fat and replacing saturated fat with unsaturated fats, including both omega-6 and omega-3 polyunsaturated fatty acids," said Frank Hu from Harvard Chan School.

"In practice, this can be achieved by replacing animal fats with a variety of liquid vegetable oils," said Hu.

The findings were published in the journal JAMA Internal Medicine.