There is limited information available on whether garlic can reduce the effectiveness of Lipitor. Lipitor is a brand name for atorvastatin, which is a medication used to lower cholesterol levels in the blood. Garlic, on the other hand, is a natural supplement that has been used for various health benefits, including reducing cholesterol levels.

According to Drug Patent Watch [1], there is no known interaction between Lipitor and garlic. However, it is important to note that garlic can interact with other medications, such as blood thinners, and should be used with caution.

A study published in the Journal of Nutrition [2] found that garlic supplements did not significantly lower LDL cholesterol levels in individuals with moderately high cholesterol levels. The study also did not find any adverse effects of garlic supplementation on lipid levels or liver function.

In contrast, a recent study published in JAMA [3] found that statins, such as Lipitor, were vastly superior to supplements in reducing cholesterol levels. The study found that while some supplements, such as omega-3 fatty acids, may have some modest benefits, they were not as effective as statins in reducing LDL cholesterol levels.

In conclusion, while there is no known interaction between Lipitor and garlic, the effectiveness of garlic in reducing cholesterol levels is limited. It is important to consult with a healthcare provider before taking any supplements or making changes to medication regimens.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3326922/
[3] https://jamanetwork.com/journals/jama/article-abstract/2782878