Joe and Margene Clyde knew that they were onto a good thing. The Winchester, Oregon, couple—he’s 77, she’s 75—went vegan just over a year ago, and it wasn’t long before they were reaping the benefits. Margene’s body mass index dropped from a lofty 29 to a svelte 22, and Joe lost 20 pounds.

But when Joe saw his neurologist this past summer, he got some unexpected good news: The doctor said that his was the slowest-progressing case of Parkinson’s disease that he’d ever seen.

The Clydes attribute the slowdown to going vegan. They’ve always been active and ate lots of fruits and veggies, but they also ate meat, dairy foods, or eggs about once a day.

Research supports their decision. A study in the American Journal of Epidemiology showed a link between the consumption of dairy foods and an increased risk of developing Parkinson’s disease, and researchers have found that communities in rural Africa, China, and Japan that eat mostly plant-based foods have substantially lower rates of the disease. Vegan foods could also help Parkinson’s patients—and everyone else—by promoting vascular health.

Joe has the numbers to back that up. His cholesterol level dropped from 210 to 178, and his cardiovascular profile has been given a thumbs-up.

Need any more reasons to go vegan? Vegans also have lower rates of cancer, heart disease, obesity, diabetes, and other ailments.