The liver is a vital organ with essential roles in processing and detoxifying substances that we eat, breathe, and absorb through our skin (Dolce & Della Torre, 2023). It is crucial for maintaining overall health and for regulating biochemical processes that affect fat, protein, and glucose metabolism, blood volume, and immune function (Trefts et al., 2017). The liver’s role as a detoxification organ places it under tremendous oxidative stress, with regular exposure to pollution and viruses. Lifestyle factors like taking medication, alcohol consumption, and being overweight further contribute to its damage (Dolce & Della Torre, 2023).

Milk thistle has been traditionally used in herbal medicine as a liver protectant. The primary active components of milk thistle, collectively known as silymarin, consist of a group of antioxidant flavonoids. These compounds fight the free radicals responsible for oxidative stress and inflammation in liver cells, promote cellular repair, stabilize liver cell membranes, and enhance levels of the antioxidant glutathione (Li et al., 2024). Studies show that milk thistle extract standardized to silymarin can help support liver function across a variety of liver conditions. In a systematic review and meta-analysis of 26 randomized, controlled trials involving 2,375 patients with liver fat accumulation, researchers found that silymarin supplementation for 12–24 weeks significantly improved liver health. Silymarin reduced signs of liver injury, measured as reduced blood levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), reduced the accumulation of fat in liver cells, and decreased fatty liver index scores (Li et al., 2024).

Another meta-analysis examined 29 randomized, controlled trials that administered silymarin at doses of 140–420 mg per day across a diverse range of health conditions. Overall, 66% of the studies found that silymarin reduced liver enzyme levels associated with negative health, further supporting its liver-protective activities (Calderon Martinez et al., 2023).

Some medications can damage the liver when used at high doses or over extended periods. Milk thistle can facilitate the liver’s detoxification role by protecting it against damage. In a four-week, double-blinded, randomized, controlled trial, lung patients who supplemented with 140 mg of silymarin three times daily alongside their standard medication reduced their risk of drug-induced liver damage by 28% compared to the placebo group (Luangchosiri et al., 2015).

Being overweight stresses the liver. In an eight-week, randomized, placebo-controlled trial, obese patients with fatty livers took 560 mg of silymarin daily (divided into four doses) and followed a calorie-restricted diet. Patients receiving silymarin significantly improved liver function, indicated by a healthier AST/ALT ratio, compared to patients on the diet alone. Improved liver health was confirmed by ultrasound fatty liver grading. The percentage of patients with severe fatty liver (Grade III) dropped from 46% at baseline to 11% after taking silymarin, compared to the placebo, where Grade III cases decreased from 40% to only 28% (Mirhashemi et al., 2022).

Milk thistle is used in herbal medicine to help relieve digestive disturbances. It has longstanding use as a key ingredient in various European remedies for digestive complaints, such as bloating, belching, and indigestion, after eating large meals (HMPC, 2018; Ferubko et al., 2022).