"Well, there are certain foods that I prefer not to eat because they're just such a jolt to the system"

Mary Tyler Moore is expressing her individual preference for certain foods. She is stating that there are some foods that she chooses not to consume since they are too intense or frustrating for her. This could imply that the foods are too hot, too sweet, or too rich for her taste. It could also indicate that the foods are too unhealthy for her to take in. Whatever the case, Mary Tyler Moore is expressing her personal choice for certain foods and her desire to avoid them. She is stressing that these foods are excessive of a shock to her system, and she would rather not consume them. Mary Tyler Moore is making a conscious decision to avoid certain foods in order to preserve her health and well-being.