Indigenous to the Mediterranean region, the historically renowned liver tonic, milk thistle, has been introduced to various areas of Europe, North and South America and Southern Australia. Well-designed clinical research has shed light on the plant's phytotherapeutic effects, particularly relating to liver disorders and gallbladder conditions. Documented effects include anti-cancer, antioxidant, anti-inflammatory, and anti-fibrotic. The parts used are the seeds which provide for standardized medicinal extracts composed of flavolignans, fixed oils, proteins, sterols and some mucilage.
Flavolignans
Silymarin is a mixture of flavolignans shown to exert antiheptotoxic activity and inhibition of cell lesion induction. Flavolignans constitute 1.5 to 3 percent of the seeds' active ingredients. Due to enterohepatic cycling, silymarin concentrations in liver cells are higher than in serum. The chemical compounds in silymarin are silybin, silydianin, and silychristin. According to James Duke, Ph.D, in his book "Dr. Duke's Essential Herbs", silybinin accounts for approximately 50% of silymarin. Numerous studies isuggest that silymarin is anti-inflammatory. It also increases lymphocyte proliferation, interferon gamma, and cytokine immune system signaling molecules (interleukin) responsible in the overall functioning of the immune system. Other related compounds isolated from the plant are silymonin and 3-deoxysilychristin.
Fixed Oils
Milk thistle seeds are comprised of 20% to 30% fixed oils. Approximately 60% is the polyunsaturated omega 6 fat linoleic acid; approximately 30% is the monounsaturated omega 9 fat oleic acid; and, nearly 9% is the monounsaturated fatty acid palmitic acid. Generally, unsaturated fatty acids help lower total cholesterol, particularly the bad type of cholesterol known as low-density lipoprotein (LDL). Linoleic acid is a precursor for arachidonic acid that is important in infant growth and oleic acid has been shown to slow the development of heart disease by promoting antioxidant production.
Other Constituents
Other plant constituents include protein (25% to 30%) and small amounts of tocopherol (0.038%), sterols (0.63%), and some mucilage. Generally plant sterols have shown to benefit the health of the heart, prostate, and the immune system. The sterols found in milk thistle include campeterol, stigmasterol, and sitosterol.
References
- American Family Physician: Milk Thistle
- "Dr. Duke's Essential Herbs"; James A. Duke, Ph.D.; 1999
- "Herbal Medicine - Expanded Commission E monographs"; Mark Blumenthal, Alicia Goldberg, and Josef Brinckmann; 2000
- "Medical Herbalism: the Science and Practice of Herbal Medicine"; David Hoffmann, FNIMH, AHG; 2003
- "Pharmacognosy"; Trease and Evans; 2003
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