We all know that fiber-rich foods offer great health benefits. But here’s a surprise: Only fiber from grains such as oatmeal, cornmeal and brown rice—and not from fruits and vegetables—reduces the risk of early death, according to findings published in the Archives of Internal Medicine and reported by U.S. News & World Report.

For the study, researchers analyzed data from nearly 400,000 men and women, ages 50 to 71, who participated in the National Institutes of Health’s AARP Diet and Health Study. Scientists found that participants who consumed the most fiber where 22 percent less likely to die from any cause during the nine-year study period.

In addition, of those who consumed the most fiber, researchers found that men were 24 to 56 percent and women 34 to 59 percent less likely to die of heart and infectious or respiratory diseases.

Researchers weren’t sure why fiber reduced the risk of early death, but they suggested that this benefit might be caused by fiber’s ability to lower “bad” LDL cholesterol levels, improve blood glucose levels, reduce inflammation and flush cancer-causing agents out of the body, said Yikyung Park, ScD, lead study author.

“Whole grains are rich sources of fiber, but also good sources of vitamins, minerals and other phytochemicals that provide health benefits,” Parks said, adding that grains have powerful antioxidants and anti-inflammatory properties as well.

But even though grain fiber is so beneficial, don’t toss out your fruits and veggies, said other docs. Why? Well, for starters, these foods can also benefit heart health.

Click here to learn how eating more whole grains could also reduce your diabetes risk.