Certain snacks can interfere with the effectiveness of Lipitor, a medication used to lower cholesterol levels. According to the American Heart Association, grapefruit and grapefruit juice can interact with Lipitor, potentially leading to an increase in the level of the medication in the bloodstream, which can increase the risk of side effects. It is recommended to avoid consuming grapefruit or grapefruit juice while taking Lipitor. Other snacks or foods may not have a significant impact on Lipitor's effectiveness, but it is always advisable to consult with a healthcare provider or pharmacist for personalized advice on food interactions with medications like Lipitor. [3]

Sources:
[3] https://www.heart.org/en/health-topics/consumer-healthcare/medication-information/medication-interactions-food-supplements-and-other-drugs.