Milk thistle often referred to as silymarin, one of the main components found in the plant's seeds is known for its antioxidant and anti-inflammatory properties. This in turn has made it quite a popular supplement for liver health. The question is of course whether or not Milk Thistle is actually any good.
The Link Between Milk Thistle and Liver Health
Over the last decade there have been a few studies conducted to test the potential benefits of milk thistle on liver health.
Whilst overall the results have been mixed  there is enough evidence to suggest that milk thistle could have positive effects for a few specific liver conditions.
Milk Thistle and Liver Inflammation
Liver inflammation is really where milk thistle seems to have the most evidence to support its use. Now, liver inflammation is a symptom of quite a few liver diseases, including everything from jaundice, fatty liver disease to cirrhosis. 
The active compound silymarin can seem to help reduce inflammation and promote cell repair in the liver. This could in theory lead to an improvement in symptoms.
Note: It is important to be aware that milk thistle has NOT been proven to be effective in treating hep c, the research has shown NO significant changes in virus levels compared to a placebo.  Despite many online claims.
Milk Thistle and Mushroom Poisoning
Intriguingly Milk thistle has shown promising results in treating poisoning caused by the Amanita phalloides mushroom. This deadly mushroom can cause severe liver damage and even liver failure, which whilst incredibly uncommon, is of course interesting. Several studies have demonstrated that silymarin can be effective in counteracting the toxins produced by the mushroom which is evidence that it does definitely do something when it comes to flushing liver toxins, as for how much it does for other things, we can’t be certain. 
Milk Thistle Side Effects
Milk thistle is generally considered safe when not taken in overly large amounts.
In terms of side effects some people have reported experiencing nausea, gas, diarrhea, loss of appetite, headache, or itchiness after consuming milk thistle.
There are also of course potential allergic reactions especially in individuals who are allergic to plants in the same family, including ragweed, daisies, marigolds, and chrysanthemums.
People with diabetes should speak to a healthcare provider before using milk thistle as there is some evidence to suggest it can lower blood sugar.
Studies on Milk Thistle and Liver Health
Now, the scientific bit, we’re going to cover a couple of the more often cited Milkthistle studies.
Study 1: Effects of Milk Thistle on Non-Alcoholic Fatty Liver Disease (NAFLD)
Non-alcoholic fatty liver disease is a the most prevalent liver condition.
It functionally means there is a build up of fat in the liver and research has shown that silymarin can have some positive effects on NAFLD.
The study which used patients with NAFLD gave them silymarin treatment for 12 months which then resulted in lower fasting insulin levels and improved insulin resistance. 
This study was confirmed in another trial which compared the effectiveness of silymarin to other medications commonly used for NAFLD.
The results showed that patients treated with silymarin had significantly lower liver enzyme levels compared to those treated with other medications. 
These studies are of course an incredibly promising start. However, further research is needed to fully understand the mechanisms and potential benefits of milk thistle for this condition.
Study 2: Milk Thistle and Alcoholic Liver Disease
Alcoholic liver disease is unsurprisingly, the result of excessive alcohol consumption. Milk thistle actually looks pretty positive here as well.
In a study that took patients with chronic alcoholic liver disease milk thistle treatment resulted in notable improvements in liver function tests. [7,8]
This includes tests including aminotransferases, albumin, and malondialdehyde levels.
However some studies have shown there wasn’t much difference between milk thistle and placebo groups. 
Whilst these studies suggest there could well be some benefits of milk thistle for alcoholic liver disease milk thistle should not be seen as a substitute for reducing or abstaining from alcohol consumption.
So, Is Milk Thistle Good For Your Liver?
Milk thistle does seem to have a reasonable amount of evidence to suggest that it could well be good for your liver. There have been several studies on NAFLD and on Alcoholic Liver Disease. But, it doesn’t look like it doesn’t anything for Hep C, despite many online claims.
1 - https://www.ncbi.nlm.nih.gov/books/NBK541075/
2 - https://www.ncbi.nlm.nih.gov/books/NBK11896/
3 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683986/
4 - https://pubmed.ncbi.nlm.nih.gov/25288004/
5 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10259499/
6 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7140758/
7 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4217313/
8 - https://pubmed.ncbi.nlm.nih.gov/9566830/
9 - https://pubmed.ncbi.nlm.nih.gov/15942440/