About 75% of Americans take dietary supplements, and 55% are regular users. Supplements are “vitamins, minerals, botanicals, probiotics, and similar products that consumers take to supplement their diet,” according to Cara Welch, PhD, the director of FDA’s Office of Dietary Supplement Programs in the Center for Food Safety and Applied Nutrition. More than 100,000 products are sold on the market, yet none are regulated or approved by the FDA.
This lack of regulation can be a serious issue, especially for anyone who has a chronic health condition. Supplements account for 20% of the cases of liver toxicity in the U.S. each year. People who have liver damage, such as from fatty liver disease, are even more at risk, says Robert J. Fontana, MD, professor of medicine at the University of Michigan Medical School in Ann Arbor.
Fontana, who is also the director of the university’s Transplant Hepatology Fellowship Program and part of the Drug-Induced Liver Injury Network, says the incidence of herbal and dietary toxicity is on the rise, and people may not know they’re in trouble until it’s too late. “You don’t realize you’re having a problem with your liver until you get really sick,” he says. “When you start to have mild injury, most liver diseases have no symptoms. There are a lot of people who have milder injuries, who are walking around and have no idea.” They could have fatty liver disease, or metabolic dysfunction-associated steatotic liver disease (MASLD), a condition where fat builds up in your liver. That buildup causes swelling and inflammation, and eventually scarring that damages your liver.
What Supplements Should You Avoid?
The liver sits in the upper right portion of your abdomen right below your diaphragm. Weighing about 3 pounds, the liver has more than 500 functions and plays a role in every metabolic process in the body. One of its main functions is acting as a filter, removing toxins and waste as well as bacteria and viruses.
It’s this filtering of toxins that puts your liver at risk from supplements and vitamins. The liver can be damaged from taking too much of any one supplement. Or it can be overloaded from a combination of too many supplements. The supplements often contain additives and ingredients that aren’t on the label, which makes shopping for them a risky affair. Choose the wrong option and you’re setting yourself up for problems, Fontana says.
Anyone with MASLD should talk to their doctors before adding a supplement to their daily routine, says Fontana. He adds that there are some supplements that everyone should be careful with or avoid. These include:
Turmeric
If you’ve ever been to your local warehouse club, you may have found product samples of turmeric drinks, pills, and powders. The spice, which is in the ginger family, is used by cooks to add flavor, color, and nutrition for good reason. It’s used in Chinese, Islamic, and Thai traditional medicine for its anti-inflammatory properties. Modern researchers have tested it for use in conditions such as osteoarthritis and MASLD.
The supplement industry is leaning into that research, marketing the spice for its anti-inflammatory benefits and selling it in drug stores, big box retailers, and gas stations in addition to vitamin and drug stores. Many of the products combine turmeric with black pepper, which enhances its absorption and can boost turmeric’s effects and potency, Fontana says.
So, turmeric should be used with caution and only at the manufacturer’s suggested dosage, Fontana says. “We honestly don’t know what’s a safe amount to take, but the big problem is that people who come to see me will say, ‘well, if the label says take two twice daily, maybe I’ll take four pills three times a day so it acts more quickly.’ People are impatient, and that creates so many issues.”
Try this instead. If you still want to add turmeric to your diet, consider cooking with it occasionally. You can also shoot for an anti-inflammatory diet rich in fruits and vegetables and omega-3 fatty acids.
Green tea extract
This derivative of green tea, a popular drink that is rich in antioxidants, is being sold to people looking to lose weight, lower blood pressure, control sugar levels, lower blood cholesterol levels, and protect against cancer and heart disease. To date, research has been spotty. Still, with all these potential benefits, you may have added this supplement to your diet.
However, Fontana calls green tea extract one of the “big, big offenders.” In its concentrated form, it can cause liver toxicity. That can lead to a mild rise in liver enzyme levels or to severe liver damage, he says. Because the extract is often combined with other stimulants and herbs — especially for weight loss — you may be getting a heavy load of chemicals that the liver has to process. Clinical studies say a single dose of up to 1.6 grams of green tea extract should be fine for someone without liver disease, but no one should go over the maximum tolerated dose of 9.9 grams per day — equivalent to 24 cups of green tea.
Try this instead. You can get the benefits of green tea by brewing a cup or two daily and drinking it if your doctor says it’s OK. Looking to tap its weight loss benefits? Try limiting your calorie intake and boosting the amount of exercise you get each day.
Red yeast rice
This reddish-purple fermented rice has lots of buzz as an alternative to statins, which lower blood cholesterol. It’s been around for centuries and is used in Chinese medicine as a digestive aid. Recent research has found it may contain monacolin K, a natural chemical that’s identical to lovastatin, a cholesterol drug. In rare cases, this can lead to liver failure. Fontana cautions his patients about the supplement, advising them to “skip it,” erring on the side of caution.
Try this instead. If you’ve been diagnosed with high cholesterol, talk to your doctor about statins. Adding soluble fiber, such as apples, oatmeal, and beans, can also help.
Black cohosh
This woodland herb is used as medicine, with some gynecologists suggesting it for menopausal symptoms, premenstrual syndrome (PMS), menstrual pain, and weak or brittle bones. While it has estrogen-like effects on the body, it isn’t a form of estrogen.
While most people can take black cohosh without issues, there have been more than 50 cases of clinically apparent liver injury. Some of the cases resulted in the need for a liver transplant. The National Library of Medicine’s LiverTox database scores black cohosh as an A grade — and that’s not a good thing. It means black cohosh carries the highest risk out of the hundreds of drugs and supplements examined and is a well-established cause of liver injuries.
Try this instead. There are plenty of evidence-based options that help with menopause symptoms and PMS. Some, such as hormone therapy, require a prescription. You can also try lifestyle changes, such as exercise and diet, to get rid of symptoms.
Kava kava
You’ve probably seen kava kava marketed as a relaxation aid. Or you may have seen this plant extract touted as a cure for anxiety, mental clarity, and insomnia. In addition, kava cafes have popped up across the U.S. as alternatives to bars that serve alcohol. None of the health claims have been supported by research, though. What has been found: It can cause liver damage. As a result, kava kava in various forms was banned in many countries, including Canada, Germany, and Switzerland, for some time.
Today, experts like Fontana say kava kava is not worth the risk to the liver.
Try this instead. Anxiety, insomnia, and brain fog may respond to mindfulness practices such as yoga, deep breathing exercises, and meditation. If lifestyle changes don’t work, consider talk therapy or a medical intervention such as antianxiety medication or a sleep aid.
Other supplements
Besides turmeric, black cohosh, and kava kava, some other options are equally risky, Fontana says. These include:
- Atractylis gummifera (Mediterranean thistle)
- Bodybuilding supplements
- Chinese knotweed (He Shou Wu/Fo-Ti)
- Comfrey
- Herbs containing pyrrolizidine alkaloid (coltsfoot, borage, senecio)
- Yohimbe
“These are over-the-counter, unregulated products that are very, very well marketed. They come out with really nice packaging. They have celebrities selling them. They get on TV. They’re in legitimate stores. They’re not like in some dark alleys,” he says. “And they have these vague claims going on outside the practice of medicine, and people don’t realize it, but herbal and dietary supplements are not regulated at all by the FDA. People take them, and then I end up seeing them as a liver expert.”
How Do Vitamins and Minerals Affect Your Liver?
Herbal supplements are just that — extra. Your body doesn’t need them. Your body does need vitamins and minerals, which can also affect liver health, says Fontana. Some may have positive effects on the liver, but some can be dangerous when taken too often or at too high doses. People who have MASLD must exercise caution, he says. He tells his patients to focus on eating foods rich in vitamins and minerals instead.
Vitamin A
If your mother ever told you to eat your carrots, it was because of the health benefits of vitamin A, which supports the eyes and immune system. If you’re too low in vitamin A, you can have night blindness and dry eyes, not to mention dry and scaly skin and a reduced ability to fight infection.
But as a fat-soluble vitamin, Vitamin A is stored in the liver. If you have liver disease, such as MASLD, there’s a chance that too much vitamin A may lead to toxicity, worsening the condition, Fontana points out. It’s important to check in with your doctor before starting this or any other supplement, he says.
Dosing. Aim for the recommended daily allowance of 700 mcg and 900 mcg for women and men over the age of 18, respectively.
Best sources. Consider liver, meat, and dairy options or foods high in beta carotene, which is converted to vitamin A by the body. Sweet potatoes, cantaloupe, broccoli, and other dark, leafy greens are good bets.
Niacin (vitamin B3)
Americans are unlikely to have niacin deficiency. That’s a good thing because it plays an important role in the digestive system, breaking down fats, carbohydrates, and alcohol. Niacin, also known as nicotinic acid and vitamin B3, affects the brain and supports heart health, regulating cholesterol and lowering oxidative stress on the organ.
Niacin is known to raise “good” HDL cholesterol levels and lower triglyceride levels. But in 2016, the FDA removed its approval for combining high doses of niacin with cholesterol-lowering medications, such as statins. That’s because of the potential risk of heart attack and stroke.
The amount of niacin in a multivitamin is safe. But high doses can be toxic to the liver and may affect those with MASLD even more.
Dosing. The Recommended Dietary Allowance (RDA) is 14 milligrams per day for women and 16 milligrams per day for men.
Best sources. Meats such as poultry, beef, and fish offer about 5-10 milligrams per serving. Nuts and legumes also contain niacin — about 2-5 milligrams per serving.
Iron
Menstruating women often struggle with iron deficiency, as do vegetarians, vegans, and those with MASLD. This is a problem because iron is needed to make hemoglobin, which carries oxygen from the lungs throughout the body. It also helps your body make hormones and grow healthy connective tissue.
Since it’s so important, iron is often added to many multivitamins and other supplements, so you should be careful not to get too much. When taken at high levels, it can cause serious toxicities, including liver damage. It’s possible to overdose on iron, which can lead to shock, collapse, and even death.
Dosing. The RDA is 8-11 milligrams per day for men and 8-18 milligrams for women who are not pregnant.
Best sources. You can’t beat lean meats and seafood for iron content. Fortified foods, such as cereals, breads, and flours, have iron added. Nuts, beans, and vegetables such as quinoa, pumpkin seeds, spinach, and kale are good sources, too. You can improve iron uptake by adding vitamin C to the mix. For example, add strawberries, oranges, or kiwis to your salad.
Vitamin E
Vitamin E protects cells and helps you maintain healthy skin and eyes. It also boosts your immune system. Recent small trials have pointed to the use of vitamin E supplements for those with MASLD. It’s been found to lower inflammation and liver cell injury. It also improved liver function. More research is needed to see if vitamin E can improve the fibrosis caused by fatty liver disease.
Dosing. Vitamin E deficiency is extremely rare. It is a fat-soluble vitamin, so excess vitamin E is stored in the liver. Healthy people should take 15 milligrams per day. If you’re interested in supplementing with vitamin E to support your liver, talk to your doctor for exact dosing instructions.
Best Sources. Nuts and seeds such as almonds, pumpkin seeds, and sunflower oil are good sources of vitamin E. Fruits and vegetables also contain the vitamin. Try avocado, spinach, and red bell peppers as well as fortified cereals.
Takeaways
Most people in the U.S. don’t need supplements unless their doctor says they lack certain vitamins or minerals. This advice becomes even more important if you’ve been diagnosed with MASLD and your liver is not working properly, which makes it more difficult to process excess nutrients.
Everyone should avoid combining supplements or taking more than the recommended dose. Since many supplements have more than one ingredient, you’ll need to read the directions and make sure you’re not doubling or even tripling up what you’re taking.
