The liver is the main detox hub. It works hard to remove toxins and built-up metabolic waste from the body before they do much harm. Many natural supplements support liver health, but a number of them do the opposite. Read on for a complete list of foods and supplements you should avoid to prevent liver damage.
32 Herbs and Supplements that May Be Bad for Your Liver
We have already talked about supplements and foods that are good for the liver. In this post, we’ll hone in on the ones you should avoid.
Natural medicine can go a long way in improving liver health, even in people with liver disease. It generally works even better for prevention, so the sooner you know what to take and what to avoid, the better.
Some compounds are downright bad for your liver and you should make sure you’re not inadvertently taking them. Study this list carefully, especially if you are at risk of liver problems. You may only take these supplements if your doctor determines that the benefits outweigh the risks in your case. Remember to monitor your liver enzymes and seek medical attention if you experience any signs of liver damage such as jaundice, abdominal pain, or vomiting.
Fo-ti (Polygonum multiflorum, PMT) ranks among the top five of herbs toxic to the liver, both when used alone or in Traditional Chinese Medicine (TCM) formulations .
According to multiple clinical studies, this herb can damage the liver, lead to severe injury, and even death [2, 3, 4, 5].
The processed roots of fo-ti might be less toxic, according to animal studies. But since their effects may be different in humans, we recommend avoiding this herb altogether, especially if you already have liver problems .
2) Cassia Cinnamon
Cassia Cinnamon (Cinnamomum cassia) is Chinese cinnamon. It has higher quantities of coumarin compared to the regular, Ceylon cinnamon. Taking in too much of this herb can cause liver damage [7, 8].
The German Federal Institute for Risk Assessment warned against consuming large amounts of Cassia cinnamon in 2006
3) Gotu Kola
According to one study, three women (61, 52 and 49 years old) developed jaundice after taking gotu kola. All of them improved after stopping this supplement. Gotu kola also induced liver toxicity in one child [9, 10].
Hepatitis and cirrhosis have also been reported. Avoid this herb or use it with extreme caution .
4) High Doses of some Vitamins
High doses or prolonged ingestion of even moderate amounts of vitamin A may cause liver damage [12, 13].
Long-term or high doses of niacin (time-release preparations) have led to liver failure or hepatotoxicity in some people. It’s possible that niacin is transformed into NAD, which can damage the liver in excessive amounts [14, 15].
High doses of beta-carotene worsened alcohol-induced liver injury in rats, while lower doses were protective .
To sum it up, most vitamins are not harmful in normal doses. Avoid megadoses, especially of niacin and beta-carotene.
Chaparral is a shrub that grows in California and Mexico. Clinical and animal studies reveal it’s toxic to the liver .
In one study, patients taking chaparral suffered acute to chronic irreversible liver damage with sudden liver failure [18, 19].
One review reported 18 toxicity cases after ingesting chaparral, with jaundice as the main sign of liver disease .
In the US, kava kava is usually sold as pills. These pills may contain various toxic solvents.
Traditional kava kava drinks are prepared differently, after grinding the roots by chewing and spitting them out. Needless to say, this not an option for commercial preparations. It’s possible that enzymes in saliva inactivate kava kava’s liver-toxic compounds – or that something else in the process makes this herb less dangerous.
What’s worse, some people report using kava kava with alcohol, which strays from its traditional uses and can amplify its liver-damaging potential.
The studies that point to liver toxicity after kava kava intake included patients with a history of alcohol consumption. In other cases, kava kava was taken with other prescribed drugs, so the specific contribution of kava kava to the damage is unclear [21, 22].
Since the early 2000s, 11 cases of kava kava-related liver injuries have been reported, four of which resulted in death. As a result, kava kava was banned in Canada and a number of European countries .
There was one case of acute hepatitis associated with kava-kava in a 14-year-old girl. She recovered after a liver transplant .
All in all, it’s still unknown if kava kava itself causes much liver damage. But until more studies are out, people with liver problems are better off avoiding it.
7) Red clover
In one study on 20 men, oral administration of 60 mg of red clover (Trifolium pratense) increased liver transaminases by >30%, possibly due to its high amounts of isoflavones .
According to another study, red clover might interact with non-steroidal anti-inflammatory drugs, particularly aspirin, and cause adverse reactions. Such adverse events are common in herbal supplements that contain coumarin .
8) Greater Celandine
Liver toxicity caused by greater celandine (Chelidonium majus) was reported in 16 patients [27, 28].
One person developed acute hepatitis after consuming an herbal preparation of this plant .
Surprisingly, greater celandine protected mice and rats from liver damage in several studies [30, 31, 32, 33].
More research is needed, but evidence suggests this herb is toxic to the liver.
Germander (Teucrium chamaedrys) may cause hepatitis and even liver cirrhosis, as has been reported in some case studies [34, 35, 36, 37, 38, 39].
In 1992, germander powder-containing capsules were banned from the French market after an epidemic of 30 cases of hepatitis .
Sassafras (Sassafras albidum) oil has been classified as a liver carcinogen of low grade due to its main component safrole. A derivative of this compound also caused liver toxicity in mice [24, 40].
11) Usnic acid
The daily oral intake of a fat-burning supplement with usnic acid (300-1,350 mg/day) over weeks has led to severe liver toxicity in a number of persons [41, 42].
Usnic acid can induce oxidative stress and inhibit mitochondrial function in liver cells, which may contribute to its hepatotoxicity [43, 44].
Comfrey (Symphytum spp) poses a “substantial health hazard” to the liver. It caused various levels of damage, potentially leading to liver failure in several cases. The effects were possibly due to its pyrrolizidine alkaloids [45, 46, 47].
13) Aloe vera
Liver injury associated with oral administration of Aloe vera was first reported in 2005. The injury, which occurs in rare cases only, typically arises between 3 and 24 weeks of starting oral aloe .
According to one report, three women (aged 55, 57 and 65) suffered acute hepatitis after taking aloe preparations for months. Liver enzymes returned to normal upon discontinuation of the oral aloe preparations .
In 2 other cases, two women (27 and 73 years old) were admitted to the hospital for acute hepatitis after taking aloe vera preparations for several weeks [50, 51].
Mistletoe (Viscum album) has been reported to cause liver injury (increased levels of the markers AST and ALT) and hepatitis in several people [52, 53, 54].
In South Africa, impila (Callilepis laureola) has been associated with some cases of hepatitis and kidney damage. In one case, a mother who consumed impila died of liver necrosis. It’s hard to pinpoint the exact cause, but it would be best to avoid this herb due to the lack of safety data [55, 56].
Valerian is usually safe when taken at typical doses for 4-8 weeks. However, some compounds in valerian are toxic and can cause cell damage. Avoid long-term use and high doses .
Not many studies speak to its liver-damaging effects. Still, there are enough data to recommend against it in people with liver problems.
In one patient, valerian caused acute hepatitis. In others, it caused liver damage. Lastly, high doses of valerian oil had toxic effects on rat liver and cultured hepatoma cells in one lab experiment [58, 24, 59, 60].
17) Black cohosh
Liver damage has been reported in a few people taking black cohosh (Actaea racemosa). However, a meta-analysis concluded that there is no such evidence that it harms the liver .
According to one study, two women developed acute liver necrosis after taking black cohosh .
In another case study, a 44-year-old woman developed liver injury within a month of using black cohosh to resolve her hot flashes .
These cases are uncommon. If you’re taking black cohosh for hormonal problems, talk to your doctor about checking your liver enzymes regularly.
18) Saw palmetto
Saw palmetto (Serenoa repens) preparations have caused cholestatic hepatitis in some patients .
One man, a former alcoholic, developed acute hepatitis and pancreatitis after taking the herb. In another case report, saw palmetto caused sudden liver damage [65, 66].
19) Pau D’arco
The Pau d’arco tree is indigenous to the Amazonian rainforest and has a long history of traditional use. Although the evidence is sparse, it might also be toxic to the liver. A 28-year-old man developed jaundice after taking Pau d’arco and skullcap for 6 months for multiple sclerosis. His condition progressed to liver failure .
A 37-year-old man suffered from acute cholestatic hepatitis induced by corydalis (Corydalis speciosa Max). He complained of jaundice and a mild abdominal discomfort .
One patient had a transient increase in liver transaminase activity after using calcium sodium EDTA. The toxicity resolved after its discontinuation [69, 70].
22) Yerba Mate
Consumption of large amounts of yerba mate tea over a period of years caused liver disease in one young woman [71, 72].
A 52-year-old woman developed acute liver failure from regularly drinking tea containing senna (Cassia angustifolia). The toxic effects of senna are ascribed to its major constituents, sennosides .
Nutmeg (Myristica fragrans) was toxic to the liver in mice with liver damage and has also been reported to cause hepatotoxicity and anxiety in an 18-year-old student who used it for recreational purposes [74, 75].
Because nutmeg is normally used in tiny amounts as a spice, it is generally safe.
25) Clove oil
Ingestion of clove oil resulted in coma, fits, blood clotting issues, and acute liver damage in a 2-year-old boy .
Coltsfoot is a plant of the daisy family commonly used in folk medicine for lung problems. A baby developed reversible liver disease after being given coltsfoot tea, possibly due to its pyrrolizidine alkaloids .
Based on animal studies, coltsfoot is likely safe in adults at typical doses. Exercise some caution when using it, though .
Borage (Borago officinalis) seed oil has complex molecules called pyrrolizidine alkaloids, which are toxic to the liver. Their concentration must be lower than 200 ppt or 0.001% for the safe usage of this oil. However, no liver toxicity cases from taking borage seed oil have been reported [79, 80].
Pennyroyal (Mentha pulegium) oil is also called spraw mint. It is said to be highly toxic, and animal studies have reported its toxicity to the liver – possibly due to the presence of pulegone, a highly poisonous compound .
29) Coleus forskohlii root extract
Forskolin has some potential benefits such as increasing energy levels and promoting weight loss, but may cause liver damage. In a study in mice, Coleus forskohlii root extract with 10% forskolin caused liver injury, as seen by increased markers of liver damage .
30) Peppermint Oil
At 2–3 times the recommended human dose, peppermint oil (Mentha× piperita) could be toxic to liver cells [60, 83].
Chronic treatment with peppermint oil resulted in some degree of liver impairment in animals, although no other parameters of liver function were impaired .
In one study, high doses of peppermint oil increased bile and markers of liver damage (ALT) on rat liver and cultured human liver cells over a long period of time .
Low doses probably won’t do much harm, but it’s still better to stay on the safe side and avoid oral peppermint oil if you have liver problems.
31) Bitter melon
Bitter melon (Momordica charantia) extracts increased markers of liver damage in mice (ALP) but didn’t lead to any other liver changes .
32) Olive leaf extract
Olive leaf extract is very safe in general. However, high doses induced liver changes in mice [86, 87].
5 Compounds in Foods/Supplements that May Be Bad for Your Liver
The following compounds are found in some foods and supplements, being responsible for some of the liver toxicity cases previously mentioned. Make sure to minimize your intake of these compounds, monitor your liver enzymes, and discuss the potential toxicity of any food/herb/supplement that contains them with your doctor.
Coumarin is a natural substance found in many plants. It is moderately toxic to the liver and kidneys with a lethal dose (LD50) of 275 mg/kg – this is extremely high, of course. At high doses, coumarin causes liver damage in rats and mice .
This compound is only somewhat dangerous to people at moderate doses and safe at low doses.
European health agencies have warned against high consumption of Cassia cinnamon bark due to its high coumarin content .
Coumarin is found naturally in various other edible plants like strawberries, black currants, apricots, and cherries. Its levels in these fruits are practically negligible, though .
According to one study, coumarins might also damage the brain. They can cause mild neurological dysfunction in children after prenatal exposure. The content of coumarin in foods is regulated in Europe .
34) Pyrrolizidine alkaloids
Pyrrolizidine alkaloids are produced by plants as secondary metabolites. There are over 600 PAs and PA N-oxides identified in over 6,000 plants and more than half of them are toxic to the liver .
Herbal remedies containing PAs can damage the liver. There is an ongoing controversy over whether the use of such herbs for short periods of time is safe. Their negative effects certainly accumulate over time, and long-term use should be avoided .
Fortunately, some companies now make pyrrolizidine-free comfrey. Such products can be used safely and confidently for longer periods of time.
Eugenol is a pale yellow oily liquid extracted from certain essential oils like clove leaf oil (80-88%), nutmeg , cinnamon, sweet basil , African basil , Japanese star anise , and bay leaf . It is toxic to the liver and may cause liver damage [99, 100].
Furano-diterpenoids, which are toxic to the liver and may cause hepatitis and even liver damage, are found in certain herbs like germander .
Whole valerian contains liver-toxic substances called valepotriates. However, these compounds are thought to be absent from most commercial valerian products. Case reports suggest that even high doses of valerian do not harm the liver .
A Note About Alcohol
Alcohol consumption is directly associated with liver disease .
It’s safe to say that alcohol is probably the most dangerous substance out there, based on the number of deaths it causes each year [104, 105].
In advanced countries, mortality due to liver diseases is directly proportional to alcohol consumption (30 g of pure alcohol per day is regarded as a “safe dose”). Serious alcoholic hepatitis has a mortality record of up to 50% .
Fatty liver develops in 90% of individuals who drink more than 16 g of alcohol/day but resolves once they stop drinking .
Many reports have claimed that the liver toxicity of paracetamol (acetaminophen) is increased in chronic alcoholics. People not only carry an increased risk of severe and fatal liver damage after acute overdoses, but liver damage may also occur at therapeutic doses .
This all goes to say that you should avoid alcohol if you want to take care of your liver. An occasional drink is probably fine if you’re healthy, but both binge drinking and alcoholism will damage your liver faster than anything else.
Plus, many of the supplements listed above become dangerous only when combined with either alcohol or drugs.
Herbs and Supplements to Use Only With Caution
As you can see, many natural products have the capacity to harm the liver.
Plus, some herbal products on the market don’t go through adequate quality control. Some may contain heavy metals, toxic solvents, and additives, or other contaminants – even if the actual herbs listed on the label are safe.
Herbal products are sometimes adulterated with other toxic herbs of similar appearance (for example, germander found in skullcap products).
Blue-green algae species such as spirulina may be contaminated with liver-toxic substances called microcystins, for which no highest safe level is known.
Some articles claim echinacea is potentially toxic to the liver, which isn’t true. Echinacea contains substances in the pyrrolizidine alkaloid family. However, its pyrrolizidine alkaloids in echinacea are harmless.
If you have liver disease, you need to be particularly careful about what you’re taking. Ask for quality certificates, monitor your liver enzymes, and talk to your doctor about all the supplements you’re taking to avoid drug interactions.