"The cleanest lettuce in the world" is getting recalled over salmonella contamination concerns.

Producer Kalera is voluntarily recalling 633 cases of Krunch, Butter and Romaine lettuce grown on its Orlando, Fla. farm The Food and Drug Administration said the recalled lettuce was sold to a "small number of retail and foodservice customers in Florida," including in Publix stores.

Some 1.35 million Americans are sickened by salmonella each year, according to Centers for Disease Control and Prevention. Infections cause nearly 26,500 hospitalizations and kill about 420 people each year.

Senior citizens, children under 5, and those with weakened immune systems are most vulnerable to salmonella. Symptoms can include fever, vomiting, stomachaches and diarrhea that can last four to seven days.