Eating a diet rich in fiber – especially the kind of fiber found in whole grains – reduces the risk of dying at an early age from a range of causes, a new government study suggests.

Fiber’s beneficial effects on heart health have been known for decades, so it wasn’t surprising that eating a lot of fiber was associated with a lower risk of death due to heart attack and heart disease. But fiber intake also appears to lower the risk of dying from respiratory diseases (such as pneumonia and chronic bronchitis) and infectious diseases, the study found.

The study, which was funded by the National Cancer Institute, also found a link between fiber consumption and a reduced risk of death from cancer, but only in men.

The source of the fiber appears to be critical. Consuming fiber from whole grains was most strongly linked to a lower risk of dying during the study, while fiber from vegetables and beans appeared to have a minimal impact on death risk. The fiber in fruit seemed to offer no protection at all.

This unexpected finding suggests that the antioxidants and other nutrients in whole grains- not just the fiber- may be partly responsible for promoting health and long life.