Native to the Mediterranean region but now growing wild throughout the world, milk thistle grows about 5-10 feet tall. Milk thistle leaf is wide and spiny but when de-spined, it can be eaten and may be used as a substitute for spinach. When crushed, both the leaves and stems give a milky white fluid, thus the herb’s name.
The herb milk thistle (Silybum mariamum) belongs to the Compositae/Asteraceae family. The milk thistle leaves and the fruits, which are erroneously referred as seeds, are commonly used for medicinal purposes. However, if we look at milk thistle in herbal literature, the most common reference is to the silymarin that is found in the fruits.
The milk thistle fruits contain flavonolignans, also known as silymarin. Silymarin is a plant compound containing about 50% silbinin, silicristin, silidianin and silimonin as well as silandrin, isosilichristin, silhermin, isosilibinin, 2,3-dehydrosilibinin, neosilihermins A and B and tri- to pentamers of silibinin. There is extensive scientific proof that supports the use of milk thistle seed extracts or silymarin as a medicinal herb specifically beneficial as a hepatoprotective agent. However, there is little information on the leaf’s medicinal benefits. It is because the aerial parts of milk thistle (leaves) are less studied even despite the fact that the plant has had a long history of use (one extending throughout centuries) in the treatment of liver, gallbladder and spleen disorders, and has even been used as an antimalarial agent. Based on other studies, the milk thistle leaf extracts acts as emmenagogues, which are herbs that stimulate blood flow in the uterus and pelvic area and encourage menstruation.
Only a few products containing leaf extracts from milk thistle are available nowadays despite some evidence claiming milk thistle herb having some remarkable medicinal properties. For instance, a recent study reports that extracts from the aerial parts of milk thistle may adjust estrogen receptors. Data shows that the phytochemical profiles of the herbs change considerably as the plant grows to its adult state. Preliminary tests on biological activity of the aerial parts demonstrate a correlation between its toxicity data and antioxidant activity and the developmental stage. Put together, the data reinforces the importance of harvesting milk thistle during the right developmental stage to get the best material with high phytochemical quality. These preliminary tests support some of the claims on the medicinal functions of milk thistle leaf. But of course, additional research will be needed to further distinguish these activities.
There are various ways to use milk thistle leaf for medicinal and cooking purposes. Crushing the leaves, roots and stems can be used to ease liver congestion and counteract the effect of alcohol. Eating tender leaves in vegetable salad can also treat hair loss. It is useful in the treatment of baldness, preventing seborrhea, dandruff and dry hair. In food, the plant can be fried given that the spines are cut off with scissors. It can also be eaten raw in salads and as a substitute for spinach. It can be boiled as well together with roots, which is very useful for the liver. The best time to collect leaves and fruits is during spring season because they shall be fresh.