The liver is a marvelously sophisticated chemical laboratory, capable of carrying out thousands of chemical transformations on which the body depends. The liver produces important chemicals from scratch, modifies others to allow the body to use them better, and neutralizes an enormous range of toxins.

However, this last function of the liver, neutralizing toxins, is also the organ’s Achilles’ heel. The process of rendering toxins harmless to the body at large may bring harm to the liver itself.

Alcohol is the most common chemical responsible for toxic damage to the liver, causing fatty liver, alcoholic hepatitis, and, potentially, cirrhosis of the liver. Exposure to industrial chemicals may harm the liver. Many prescription medications may damage the liver as well, including cholesterol-lowering drugs in the statin family and high-dose niacin (also used to reduce cholesterol levels.) The over-the-counter drug acetaminophen (Tylenol) is highly toxic to the liver when taken to excess. Finally, numerous natural herbs and supplements contain chemicals that may cause or accelerate harm to the liver. (See Herbs and Supplements to Use Only With Caution below.)

Chemicals aren’t the only source of harm to the liver. Viruses may infect it, causing viral hepatitis; hepatitis C, in particular, may become chronic and gradually destroy the liver. In addition, during pregnancy, the liver may become backed up with bile, a condition called cholestasis of pregnancy.

Conventional treatment of liver disease depends on the source of the problem. People who abuse alcohol will at the very least avoid further liver damage by stopping alcohol use, and, in cases short of liver cirrhosis, full liver recovery may be expected. When drugs are at fault, it may be possible to switch to a different drug.

Conventional treatment of liver injury caused by chronic viral hepatitis involves sophisticated immune-regulating therapies, which have become fairly successful. In extreme cases of liver injury, a liver transplant may be necessary.

Principal Proposed Natural Treatments

Natural treatments for alcoholic hepatitis, cirrhosis, and viral hepatitis are each discussed in their own articles. In this article, we discuss natural treatments for other forms of liver disease. In addition, we address the herbs and supplements that may harm the liver and that, therefore, should not be taken by people who already have liver disease.

The herb milk thistle has shown promise for a wide variety of liver conditions, and for this reason it is often said to have general liver protective properties.

Some evidence suggests benefit for viral hepatitis (especially chronic hepatitis), cirrhosis of the liver, alcoholic hepatitis, and liver toxicity caused by industrial chemicals, mushroom poisons, and medications.1-25 However, as yet the evidence that milk thistle really works remains incomplete and contradictory.

For example, a double-blind, placebo-controlled study performed in 1981 followed 106 Finnish soldiers with alcoholic liver disease over a period of 4 weeks.18 The treated group showed a significant decrease in elevated liver enzymes and improvement in liver histology (appearance of cells under a microscope), as evaluated by biopsy in 29 subjects.

Two similar studies provided essentially equivalent results.9,11 However, a 3-month, randomized, double-blind study of 116 people showed little to no additional benefit, perhaps because most participants reduced their alcohol consumption and almost half stopped drinking entirely.20 Another study found no benefit in 72 patients followed for 15 months.7

Study results similarly conflict on whether milk thistle is helpful in liver cirrhosis.

In a double-blind, placebo-controlled study of 170 people with alcoholic or non-alcoholic cirrhosis, researchers found that the 4-year survival rate was 58% in the group treated with milk thistle as compared to only 38% in the placebo group.10 This difference was statistically significant.

A double-blind, placebo-controlled trial that enrolled 172 people with cirrhosis for 4 years also found reductions in mortality, but they just missed the conventional cutoff for statistical significance.4 Yet another study, a 2-year, double-blind, placebo-controlled trial of 200 people with alcoholic cirrhosis, found no reduction in mortality attributable to the use of milk thistle.1

Other double-blind studies of people with cirrhosis have found improvements in tests of liver function,6,16 although one did not.3

A 2007 review of published and unpublished studies on milk thistle as a treatment for liver disease concluded that benefits were seen only in low-quality trials, and, even in those, milk thistle did not show more than a slight benefit.56

Milk thistle is also used in a vague condition known as minor hepatic insufficiency, or "sluggish liver."26 This term is mostly used by European physicians and American naturopathic practitioners—conventional physicians in America don't recognize it. Symptoms are supposed to include aching under the ribs, fatigue, unhealthy skin appearance, general malaise, constipation, premenstrual syndrome, chemical sensitivities, and allergies.

For more information, including dosage and safety issues, see the full Milk Thistle article.

The body manufactures S-adenosylmethionine (SAMe) for use in converting certain chemicals to other chemicals (specifically, through the processes of transmethylation and transsulfuration). Some evidence suggests that SAMe taken as an oral supplement may have value in the treatment of various liver diseases, including chronic viral hepatitis, liver cirrhosis, jaundice of pregnancy, and liver toxicity caused by drugs or chemicals.27-31,51-54

Perhaps the best evidence regards cholestasis (backup of bile in the liver) caused by serious liver disease. In a 2-week, double-blind study of 220 people with cholestasis, use of SAMe (1,600 mg daily) significantly improved liver-related symptoms as compared to placebo.28 Most participants in this study had chronic viral hepatitis.

Another large study evaluated the potential benefits of SAMe for the treatment of people with alcoholic liver cirrhosis.27 This 2-year, double-blind, placebo-controlled study of 117 people failed to find SAMe helpful for the group as a whole. However, in a subgroup of those with less advanced disease, treatment with SAMe appeared to reduce the number of people who needed a liver transplant, or who died.

Gilbert’s syndrome is an unexplained but harmless condition in which levels of bilirubin rise in the body, causing an alarming yellowing of the skin (jaundice). Weak evidence hints that SAMe may help reduce bilirubin levels in this condition.32

For more information, including dosage and safety issues, see the full SAMe article.

Other Proposed Natural Treatments

Probiotics have been studied as possible treatment for liver disease. In one such study, 84 adults (aged 18-65) with liver disease ( cirrhosis or hepatitis ) were randomized to receive yogurt (1 cup, 3 times daily) with or without the probiotics B. bifidus, L. acidophilus, L. bulgaricus, and S. thermophilus.58 After 2 weeks, the people in the probiotics group experienced an improvement in their symptoms, including less debilitation and better appetite. Chronic liver disease with cirrhosis can lead to a potentially life-threatening brain abnormality, called hepatic encephalopathy. A 2011 review of 7 randomized trials involving 550 people found inconclusive evidence to support the use of probiotics as a treatment for this condition.59

One double-blind study found evidence that a beverage made from sweet potato could improve measures of liver function in people with mild hepatitis of unspecified cause.55

Very preliminary evidence suggests that the supplement betaine (trimethylglycine, or TMG—not to be confused with betaine hydrochloride) may be helpful for treating fatty liver caused by alcohol and other causes, and also for protecting the liver from toxins in general.33-37

Despite early promise, the herb phyllanthus does not appear to be helpful for viral hepatitis.38-45

Green tea has long been considered to play a protective role against liver disease. However, the evidence to date is unconvincing.57

Numerous other herbs and supplements have shown a bit of promise in test tube studies for protecting the liver, including:

Hundreds of others are included on this list. However, it is a long way from test tube studies to effects in people, and none of these treatments should be regarded as having proven or even probable liver-protective properties.

Herbs and Supplements to Use Only With Caution

Many natural products have the capacity to harm the liver. Furthermore, due to the generally inadequate regulation of dietary supplements that exists at the time of this writing, there are real risks that herbal products, at least, may contain liver-toxic contaminants even if the actual herbs listed on the label are safe. For this reason, we recommend that people with liver disease do not use any medicinal herbs except under the supervision of a physician. Here, we list some specific information to aid in your decision-making process.

High doses of the supplements beta-carotene and vitamin A are thought to accelerate the progression of alcoholic liver disease in people who abuse alcohol.46,47 (Nutritional supplementation at the standard daily requirement level should not cause a problem.)

All forms of vitamin B3, including niacin, niacinamide (nicotinamide), and inositol hexaniacinate, may damage the liver when taken in high doses. (Again, nutritional supplementation at the standard daily requirement level should not cause a problem.)

A great many herbs and supplements have known or suspected liver-toxic properties, including but not limited to: chaparral, coltsfoot, corydalis, comfrey, germander, germanium (a mineral), greater celandine, green tea extracts (despite its proposed benefits), kava , kombucha, mistletoe, noni, pennyroyal, pokeroot, sassafras, and various herbs and minerals used in traditional Chinese herbal medicine.

In addition, herbs that are not toxic to the liver in themselves are sometimes adulterated with other herbs of similar appearance that are accidentally harvested in a misapprehension of their identity (for example, germander found in skullcap products). Furthermore, blue-green algae species such as spirulina may at times be contaminated with liver-toxic substances called microcystins, for which no highest safe level is known.

Some articles claim that the herb echinacea is potentially toxic to the liver, but this concern appears to have been based on a misunderstanding of its constituents. Echinacea contains substances in the pyrrolizidine alkaloid family. However, while many pyrrolizidine alkaloids are toxic to the liver, those found in echinacea are not believed to have that property.

Whole valerian contains liver-toxic substances called valepotriates; however, valepotriates are thought to be absent from most commercial valerian products,48 and case reports suggest that even very high doses of valerian do not harm the liver.49,50