When Venus Williams was diagnosed with Sjögren's syndrome in 2011, her tennis career almost came to a grinding halt. After a rough season of injuries and match withdrawals, she announced that she was suffering from the fairly common autoimmune disease that causes dry eye and dry mouth, as well as crushing joint pain and fatigue. The condition severely hindered athletic performance, ultimately causing her to withdraw from the 2011 U.S. Open in the second round. But after taking time off, Williams was able to step back onto the court with newfound strength, thanks to proper treatment—and a drastic diet change.