Lipitor is a medication used to lower cholesterol levels in the body. It is a type of drug called a statin, which works by inhibiting an enzyme in the liver that is responsible for producing cholesterol [1]. There is no direct evidence that suggests Lipitor affects skim milk digestion. However, individuals with Crohn's disease may have difficulty digesting lactose, a sugar found in milk, and may need to avoid dairy products altogether [2]. In such cases, it is recommended to switch to non-dairy alternatives such as soy milk, almond milk, or rice milk. According to a study published in the Journal of Dairy Science, individuals who are lactose intolerant can consume fermented dairy products, such as yogurt, kefir, and cheese, as they contain lower levels of lactose [3].

In conclusion, there is no direct evidence that suggests Lipitor affects skim milk digestion. However, individuals with Crohn's disease may need to avoid dairy products altogether due to lactose intolerance, and can switch to non-dairy alternatives or fermented dairy products with lower lactose levels.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.everydayhealth.com/crohns-disease/diet/the-best-dairy-alternatives-for-crohns-disease/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918082/