5 Milk Thistle Benefits and How to Choose the Best Supplement

Despite its name, milk thistle is not actually a dairy product. So what is milk thistle? It’s an herb derived from the milk thistle plant, found in the Mediterranean region and central Europe, which has been used largely to help improve liver function, says Jeremy Wolf, a naturopathic doctor and wellness advisor for LuckyVitamin.

One of the active ingredients in milk thistle is silymarin, which is extracted from the plant’s seeds. Silymarin is a flavonoid, which has been shown to have antioxidant properties, says Wolf.

“Because of the antioxidant properties of the plant, you’d get those antioxidant benefits from a milk thistle supplement,” he says.

5 Milk Thistle Benefits


Milk thistle is widely known for the role it may play in supporting liver function, says Wolf, including hepatitis, cirrhosis, and gallbladder problems.

That said, the National Center for Complementary and Integrative Health notes that there have only been “a few well-designed clinical studies” to look at these benefits in people. Results from these clinical trials have been mixed, and two found no benefit (1).

A 2008 study found that people with hepatitis C who used milk thistle, or silymarin as it’s often called, had fewer and milder symptoms of liver disease and somewhat better quality of life. The researchers note that there was no change in virus activity or liver inflammation (2).

There are two ways milk thistle is thought to work in promoting liver function. It may alter the structure of the outer membrane of the liver cells to prevent the penetration of liver toxins, and it may help with the formation of liver cells, promoting the liver’s ability to regenerate, says Wolf.


Because milk thistle may help improve liver function, it could also help improve detoxification. The liver, explains Wolf, is a detox organ, and milk thistle may help support the elimination of waste products through the detox process.


A small 2006 study found that people with diabetes—who often also have high cholesterol—saw significant reductions in their cholesterol levels after taking milk thistle in conjunction with conventional diabetic medication (3).

Wolf also points out that milk thistle may help cholesterol metabolism in people with normal metabolism levels, but there haven’t been clinical studies to support this.


A handful of small studies have found that milk thistle might help control blood sugar levels in people with diabetes, reduce inflammation, and lower cholesterol levels (3, 4). Milk thistle may also improve insulin resistance in people with diabetes.

But remember: diabetes is a serious condition, and any treatment should be discussed with a health care professional.


The gallbladder is a sac that sits under the liver, and it stores and concentrates bile that is produced in the liver. Gallstones are blockages in the ducts that lead to the gallbladder, and if severe, can be life-threatening.

Milk thistle may help prevent gallstones or treat gallbladder disorders, including gallstones and inflammation (5).

How to Choose the Best Milk Thistle Supplement

The only way to take milk thistle extract is through a supplement, commonly in a powder or capsule form, says Wolf. There are liquid supplements (tinctures) available, but they tend to taste bad and are not necessarily more effective than other forms.

When choosing a milk thistle supplement, it’s important to make sure it has an extract concentration of 70 to 80 percent because it’s poorly absorbed, says Wolf.

Recommended doses vary based on the person, says Wolf, but according to clinical studies, 420 milligrams per day in divided doses is considered safe for up to 41 months (6).

Milk thistle also comes as an herbal tea.

Side Effects of Milk Thistle

When taken in recommended doses, milk thistle has been shown to be safe, according to the National Center for Complementary and Integrative Health. People have reported gastrointestinal side effects, including diarrhea, nausea, and bloating.

Milk thistle may also cause allergic reactions in people who are allergic to plants in the same family, like ragweed, chrysanthemum, marigold, and daisy.

Do you take milk thistle? If so, how has it helped you? Let us know in the comments section below!


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