Milk thistle is a flowering plant used medicinally as an herbal supplement. Most often, the herb is claimed to be useful for treating or preventing liver diseases, although people use it for other uses as well.
As a plant, milk thistle contains many different compounds.
Of these compounds, it appears that silymarin (which is actually a mixture of four different flavonolignans) is the medicinally active component of milk thistle. Silymarin has many different effects in the body.
Silymarin may work for liver disease in several ways. It helps liver cells to regenerate and changes the outer membrane of liver cells to decrease the penetration of toxins. Silymarin may also decrease inflammation and fibrosis, and may also affect the immune system. It may also help prevent the liver from metabolizing certain substances into toxic byproducts.
Silymarin also acts as an antioxidant, which may explain how milk thistle works for several different conditions, including
diabetes. Because oxidative stress may damage the
pancreas in people with diabetes, compounds with antioxidant activity may preserve the ability of the pancreas to produce
insulin.
Certain parts of the milk thistle plant seem to have estrogenic effects, which might explain how it works for
prostate cancer and various other conditions.
Is Milk Thistle Effective?
Early studies have shown that milk thistle may be useful for treating
type 2 diabetes,
heartburn, and indigestion (although more research is necessary to confirm these findings). It is not clear if it is effective for other uses, including liver diseases
(see Does Milk Thistle Work? for more information).
There is no established standard milk thistle dosage, although general guidelines may be obtained from the clinical studies that evaluated certain uses of the supplement.
People often assume that natural products are free of side effects. However, this is not usually the case. Some of the reported side effects of milk thistle include:
- Nausea
- Diarrhea
- Indigestion or heartburn
- Gas
- Bloating
- Loss of appetite.
(Click Milk Thistle Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
Reasonable usage of this supplement (at reasonable doses) is probably safe for many people. However, some people are more likely to experience problems due to milk thistle than others. Therefore, you should talk with your healthcare provider prior to taking milk thistle medicinally if you have:
- Any chronic medical condition
- Cancer (or a history of cancer)
- Endometriosis
- Uterine fibroids
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about any other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
What If I Take an Overdose?
It is not known what exactly to expect from an overdose of this supplement. If you think you or someone else may have taken too much milk thistle, it is important to seek immediate medical attention.
Storage Methods for Milk Thistle
Refer to the label of your individual product for information on how best to store milk thistle supplements. Keep all medications and supplements out of the reach of children.
