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Milk Thistle Dosage: How Much Should You Take?
Dosages of herbal preparations are often elusive and difficult to clinically establish due to a lack of well-designed studies and the presence of confounding variables such as the form of supplement, supplement blends, bioavailability issues and absorption confounders. No standardization of dosages currently exists, and dosages are based on anecdotal evidence, clinical studies, and professional opinions.
In this article we will take a look at milk thistle dosages for adults and children. We’ll also explore milk thistle dosages for specific health conditions, including non-alcoholic fatty liver disease.
Milk thistle has been used for over 2,000 years originating in ancient Greece where it initially was used for snakebites. In the middle ages it was used to treat liver problems and in the 1500s it was used for emotional distress. Clearly, this has been an herb of healing for many years subject to a variety of dosage therapies and dosage adjustments.
What Issues Affect Dosage Considerations?
As with any herb, there are several confounders that affect dosage considerations.
Among these include:
- condition being treated
- types of supplements used
- bioavailability and absorption concerns
- safety standards
- and clinical efficacy data
A general, reoccurring dosage for milk thistle is 140 mg three times per day for adults. A review of the literature shows dosages for children are similar to that of adults.
Conditions for Which Milk Thistle Dosages Have Been Determined Effective
- Diabetes and Insulin Resistance: Clinical data has shown that 140 mg 3x daily for 45 days statistically reduced fasting glucose by 11% and HBA1C (Hemoglobin A1C) by 14% and improved insulin resistance as compared to baseline. Taking a higher amount, 200 mg/day for four months reduced fasting glucose by 23-43 mg/dl and HBA1C by 1% to 1.5% compared to baseline (1).
- Dyspepsia: A combination product (Iberogast) appears to improve dysphagic symptoms resulting from gastrointestinal upset. A dosage of 1 ml of this compounded blend including milk thistle taken orally 3x/day for four weeks improved symptoms of gastric pain, cramping, nausea, and vomiting compared to placebo (1).
- Non-Alcoholic Fatty Liver Disease: In a study done on patients given approximately 400 mg/day of silymarin in a phosphatidylcholine base, it was found that plasma liver enzymes fell, indices of liver fibrosis decreased, and there was a persistent reduction in liver steatosis (fat in liver) (2).
Milk thistle is thought to exert its protective effects on the liver through the promotion of liver cell growth and the prevention of oxidation and inflammation in the liver.
- Non-Alcoholic Steatohepatitis (NASH): An animal study compared a placebo group with a group given 200 mg/kg body weight silymarin for 12 weeks to two groups of rats with NASH. The placebo group went on to develop all the indices of advanced NASH while the treatment group showed improved steatosis, decreased inflammation, improved insulin response, and decreased lipid peroxidation (2). However, more studies in humans are needed.
Conditions for Which More Clinical Evidence Is Needed
- Allergic Rhinitis: One clinical study indicated that a 140 mg tablet of silymarin taken three times per day plus Zyrtec eliminated the constant rhinitis as compared to placebo with just Zyrtec (2).
- Body Building: Many body builders take supplements that are potentially toxic to their livers but combine it with milk thistle with the intrinsic theory that the milk thistle will protect their liver from the deleterious damage caused by the other drugs they are taking into their systems. This practice was recently vehemently attacked in a statement published in Endocrine Abstracts that highlighted the following: “our case demonstrates severe risks associated with the use of anabolic steroids (acute hepatitis/ hypogonadism) compounded by patients’ belief that they are taking simultaneous ‘antidotes’ and fail to follow medical advice (3).”
Directions for taking milk thistle for body building are even misleading. An internet source states to take 2-15 grams of dried herb with a meal (4). As we shall see later, this is not the way to take milk thistle for optimum absorption.
- Benign Prostatic Hyperplasia (BPH): Preliminary clinical studies indicate that taking 190 mg of silymarin along with 80 mcg selenium orally three times daily for six months may improve lower urinary tract symptoms, increase urinary flow rates and reduce residual volumes in men aged 45-70 years (1).
- Radiation Dermatitis: Preliminary data shows that milk thistle in a .25% standardized base applied to the skin might be beneficial for radiation dermatitis from chemotherapy for breast cancer. Topical lotion containing milk thistle applied to the skin surface prolonged the time for dermatitis to develop after radiation as compared to a panthenol containing cream (1).
- Beta-thalassemia and Children’s Dosages: In this disease, where there is too much iron in the body and is found mostly in children, silymarin acts to decrease iron in the blood. Singularly or combined with other medication, 140 mg three times daily can be taken. Preliminary evidence shows that patients 12 years and older with beta-thalassemia can take silymarin safely for 3 months at 140 mg/day (1, 5). Up to 420 mg three times per day have been used in beta-thalassemia trials without adverse effects.
Children and Milk Thistle Dosages
A specific milk thistle product was given to a child up to a year in the amount of 320 mg/day without event (1). According to Dr. T. LowDog, MD the correct dosage for a child is 5-10 mg/kg. per day. So, if a child weighs 80 lbs., divide by 2.2 and then multiply by 5 mg.- 10 mg = 182 – 364 mg/day.
- Hepatotoxicity in Childhood Acute Lymphoblastic Leukemia (ALL): In children with acute lymphoblastic leukemia, the administration of chemotherapeutic agents is frequently interrupted because of liver toxicity, primarily during the maintenance phase of therapy. There are currently no substitute chemotherapy agents that provide the same effectiveness against ALL and preserve liver function at the same time.
In a recent clinical study a dosing of 5.1 mg/kg/day was followed and the following dosages were prescribed:
- 15-20 kg children received 80 mg/day
- 21-40 kg children received 160 mg/day
- 41-60 kg children received 240 mg/day
- 61-70 kg patients received 320 mg/day
The conclusions were that a short course of milk thistle therapy could safely be used during chemotherapy without reductions in said chemotherapy or delays in therapy treatment. Their preclinical data demonstrate that milk thistle does not compromise the therapy and allows therapy to continue without interruption (1, 6).
This is not a comprehensive list of all conditions being studied for the benefits of milk thistle but highlights some of the most recent and relevant research regarding this herb.
Types of Supplements Affecting Milk Thistle Dosage
Supplements come in all forms:
- pills
- capsules
- liquids
- and even IV
One would think a liquid might be absorbed the fastest, but you must use caution. Read the label. A liquid may have a milk thistle blend in it, and you may not be getting the most effective form of silymarin for the condition being treated or in the dosage being prescribed. IV dosage has been used in cases of mushroom poisoning.
Bioavailability and Absorption
The standardized extracts of silymarin contains the following flavonoids (4, 6):
- Silybin (50-70% of milk thistle)
- Silydianin
- Silychristian
Silybin is contained in milk thistle in the greatest quantity and is the most bioavailable and effective extract.
Bioavailability is increased by the addition of phytosomes, and the phosphatidylcholine phytosomes complex is one of the strongest and most bioavailable form to take milk thistle – theoretically reducing dosage requirements.
Crumbled leaves taken with food is one of the least bioavailable ways to take milk thistle. Tea, likewise, is not well absorbed due to its poor water solubility.
Milk thistle should be taken on an empty stomach without any other concurrent medications or food (5). To increase bioavailability the dosage schedule should be broken down into 3 dose regimens (7).
Time of Day to Take Milk Thistle
Because milk thistle increases bile secretion, the optimum time of day to take it is in the morning. But, more importantly, it is essential to take it on an empty stomach in divided doses.
Safety
According to 2019 literature, silymarin is safe in doses of up to 700 mg three times per day (6).
Side effects may include:
- Diarrhea
- Nausea
- G.I. discomforts
- Allergies in those allergic to the Asteraceae family (daisies, marigolds, chrysanthemums)
- Rashes
Use in pregnancy is not discouraged and no anomalies have historically been cited. Even so, caution should be exercised during pregnancy and breastfeeding.
Drug-Nutrient Interactions
There is some confusion as to drug-nutrient interactions, but moderate interactions may exist for some drugs such as diabetes medication, morphine sulphate, valium, chemotherapy drugs and others with a narrow therapeutic window (6, 7). Whereas milk thistle may act to help lower blood sugar and yield better control, it may also lead to a hypoglycemic event in someone on oral hypoglycemic agents who take milk thistle concurrently without blood sugar monitoring, for example.
Always discuss the addition of any herb to your supplement routine with your doctor who can better guide you as to any potential drug interactions.
1. Milk Thistle. (n.d.) TRC Natural Medicines Database. Retrieved 1/10/2020 from https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=138
2. Abenavoli, L, Aviello G., Capasso, R., Mille, N & Capasso, F. (2011). Milk thistle for treatment of nonalcoholic fatty liver disease. Hepatitis Monthly, 22(3):173-177. Retrieved from https://s3.amazonaws.com/academia.edu.documents/45528394/Milk_thistle_for_treatment_of_nonalcohol20160510-18304-1jw7jh7.pdf?response-content-disposition=inline%3B%20filename%3DMilk_thistle_for_treatment_of_nonalcohol.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWOWYYGZ2Y53UL3A%2F20200109%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20200109T155003Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=cea9bd1a94724f5501ef6799c75c78d3b2f091c6ed2a89cac6023486c1e0c168
3. Lewandowski, K., Kawalec., J., Debrowska, K. & Lewinski, A. (2018). Hypogonadism and acute hepatitis caused by ingestion of epistane (EAST ®) for body-building purposes. Endocrine Abstracts, 59: EP55. http://dx.doi.org/10.1530/endoabs.59.EP55
4. Croswell, J. (2017, August 14). How to take Milk Thistle for bodybuilding. Healthfully. Retrieved 1/9/2020 from https://healthfully.com/74176-milk-thistle-bodybuilding.html
5. Soleimani, V., Delghandi, P.S., Moallem, S.A. & Karimi, G. (2019, May 8). Safety and toxicity of silymarin, the major constituent of milk thistle extract: An updated review. Phytotherapy Research, 33(6). Abstract retrieved from https://doi.org/10.1002/ptr.6361
6. Ladas, E.J., Kroll, D.J., Oberlies, N. H., Cheng, B, Ndao, D.H., Rheingold, S.R. & Kelly, K.M. (2010). A randomized, controlled, double-blind, pilot study of Milk Thistle for the treatment of hepatotoxicity in childhood acute lymphoblastic leukemias (ALL). Cancer, 116:506-13. Retrieved from: https://acsjournals.onlinelibrary.wiley.com/doi/abs/10.1002/cncr.24723
7. Roy, K & Iyer, U. (2019). Role of silymarin in the management of non-alcoholic fatty liver disease: Time to clear the mist. Functional Foods in Health and Disease, 9(5):126-133. https://doi.org/10.31989/bchd.v2i5.622
About the Author
Kathy Shattler has been a Registered Dietitian for over 25 years and currently runs her own Telehealth Clinic while freelance writing in her spare time. She graduated with a Master of Science degree in Human Nutrition from Michigan State University and has a plethora of experience in both clinical nutrition as well as public health. She has been deemed a trailblazer in her profession and continues to strive for excellence in public health education in integrative medicine.
