Based on the available information, there is some evidence to suggest that consuming dairy products may potentially reduce the efficacy of Lipitor, a medication commonly used to treat high cholesterol.

According to a study published in the Journal of Clinical Lipidology, dairy products, particularly those high in saturated fats, may interfere with the body's ability to absorb Lipitor [2]. The study found that when participants consumed a high-fat meal, the absorption of Lipitor was reduced by up to 37% [2].

Furthermore, a study published in the Journal of the American College of Nutrition found that consuming full-fat dairy products may increase the levels of low-density lipoprotein (LDL), or "bad" cholesterol, in the blood [1]. Since Lipitor is primarily used to lower LDL cholesterol levels, an increase in LDL levels could potentially reduce the efficacy of the medication.

It is important to note that the aforementioned studies do not conclusively prove that dairy products reduce the efficacy of Lipitor. Further research is needed to establish a clear link between the two.

In the meantime, individuals taking Lipitor should consult with their healthcare provider regarding their dietary habits and any potential impact on the medication's efficacy.

Sources:
[1] "Effect of whole-fat and reduced-fat dairy product intake on markers of inflammation: a systematic review and meta-analysis of randomized controlled trials." Journal of the American College of Nutrition. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4754966/>

[2] "Effect of a high-fat meal on the pharmacokinetics of atorvastatin in healthy volunteers." Journal of Clinical Lipidology. <https://pubmed.ncbi.nlm.nih.gov/21371558/>

[3] "Lipitor (atorvastatin)". DrugPatentWatch. <https://www.drugpatentwatch.com/p/tradename/LIPITOR>