The company said it's removed artificial preservatives, flavors and added colors from its "classic burgers," which include the Big Mac as well as its hamburger, cheeseburger, double cheeseburger, McDouble, Quarter Pounder with Cheese and double Quarter Pounder.
The move comes as McDonald's faces competition from rivals such as Wendy's and Panera, with the former touting fresh ground beef and the latter its lack of preservatives.
McDonald's said almost two-thirds of its burgers and sandwiches will no longer contain artificial preservatives, artificial flavors or added colors from artificial sources. Its pickle still contains an artificial preservative, so the company is advising customers to skip the pickle if they are concerned.
Under Chief Executive Steve Easterbrook, McDonald's has improved its financial performance after years of stagnation, when critics said the chain's menu lost its appeal to younger consumers.
As part of that turnaround plan, McDonald's said in August that it would invest $6 billion to renovate most of its 14,000 restaurants. The makeover will include new furniture and decor, remodeled counters that allow for table service and "refreshed" exterior designs.
The Associated Press contributed to this report.