Milk thistle has been used by physicians and herbalists since ancient times to treat liver disorders. In modern times, the range of uses of milk thistle has expanded to include treatment of diabetic and related conditions, use as an antioxidant and/or anti-inflammatory, treatment for mushroom poisoning, treatment of certain cancers, and even psychological conditions such as gambling addiction, methamphetamine addiction, and obsessive compulsive disorder. Clinicaltrials.gov lists 65 completed and on-going human trials for those and many other conditions. In fact, the components of milk thistle are some of the most prescribed of all natural compounds. Below, we highlight a couple of the principal uses of milk thistle that find support in research–for treatment of diabetes and of liver disease.
Diabetes mellitus, metabolic syndrome, and insulin resistance. A 2016 meta-analysis of the available research in humans given daily doses that ranged between 200 and 600 mg across the studies analyzed found that “Silymarin administration was associated with a significant reduction in fasting blood glucose levels . . . HbA1c levels”. The mean decrease in blood glucose levels was 26.86 mg/dL and in HbA1c levels was 1.07 percentage points.
An excellent 2014 review article highlighted several other promising studies of silybin in humans, including:
- diabetic and alcoholic liver cirrhotic patients given 600 mg/day for 6 months had significantly lower glucose levels (compared with pre-treatment period) without any increase in hypoglycemic episodes after 2 months of treatment. Moreover, after 6 months of treatment, HbA1c levels fell 0.5 percentage points;
- diabetic patients who had been on maximum-dose ACE inhibitors or angiotensin receptor blockers for at least 6 months (among other inclusion criteria) given 140 mg three times per day saw a 50% reduction in urinary albumin, TNF-alpha, and malondialdehyde (MDA, a marker of oxidative stress) levels in almost half the studied patients; and
- patients treated for four months with 200 mg three times per day (before meals) saw a significant reduction (with a mean reduction of 23 mg/dl) in blood glucose levels compared to an increase in the placebo group. They also saw HbA1c levels fall an average of 1.04 percentage points and significant reductions in HDL and LDL cholesterol, triglycerides, AST and ALT levels.
Animal studies have been equally promising. A study in rats showed that a compound containing milk seed extract (20 mg/kg bw/day given for 15 days) resulted in significant decreases in blood glucose levels in both normal and diabetic rats without affecting endogenous insulin production. Another rat study found that silymarin (200 mg/kg bw, twice per day) prevented increases in both plasma glucose and pancreatic lipid peroxidation (a form of cell degradation) after administration of a drug that ordinarily causes severe necrosis of pancreatic beta cells (alloxan). The above studies suggest that milk thistle extract may be an effective treatment both for reducing blood glucose and HbA1c levels and for protection of the pancreas more generally.
Liver disease and injury. As noted, this is both the historic and the current principal use of milk thistle. A recent series of experiments illustrates why. In those experiments, mice were restrained to induce stress and then either treated with 100 mg/kg body weight with silymarin (the main compound in milk thistle extract) twice per day or left untreated. Liver function enzymes (including the ALT and AST levels you have probably seen on your own bloodwork) and oxidative stress markers were measured and, in each case, the silymarin-treated mice had significantly lower levels. Moreover, in the silymarin-treated mice levels of beneficial compounds (including SAMe) were restored to or nearly to the levels found in mice that were not subjected to stressors at all. The silymarin also significantly prevented increased serum levels of several important inflammatory markers. Finally, silymarin blocked the effects of a major pathway for inducing cell apoptosis (death). These experiments dramatically demonstrate milk thistle’s ability to restore normal levels of liver enzymes, block oxidative stress, restore levels of beneficial molecules such as SAMe, block inflammation and inhibit apoptosis. Other small scale studies and case reports have found similar results for dogs and cats. (See here at 3.1, here, and here.)
While we aren’t familiar with any similar experiments in humans or other non-human animals (besides mice, dogs and cats), these results are consistent with milk thistle’s use for the last 2,000 years in treating liver ailments.