I've already tripped onto more studies making the same statement as the one above. Olive oil REDUCES the amount of long chain fatty acids in the liver, and REDUCES the risk of non-alcoholic fatty liver disease (something that I was diagnosed of, and reversed by replacing all oils with olive oil, butter and coconut oil - red palm oil is not readily available in the mid-west.) The study also notes that NAFLD leads to fibrosis and cirrhosis of the liver. Anyone can research many subjects at Pubmed online. Many of the studies are highly technical in terms, but just copy and paste the words you don't understand into your search bar, and you'll find them explained somewhere.
following is a study showing that bile acids are CRITICAL in fat digestion. Making olive oil and lemon juice some of the necessary foods for enabling the bile to flow.
Other foods helpful for making bile flow are: beets, brocolli and cauliflower, cabbage, sauerkraut (fermented cabbage) dandelion leaves, and dandelion root. There are more, but I encourage everyone to look these things up and learn about why your diet is VERY important to your life, your emotional well-being, and your physical health.
Studies are available. Just not direct liver cleanse studies. You have to break it down into components, and then draw conclusions. (that may be with error nonetheless.) Happy hunting all!