Dandelion leaf

The leaf of the common lawn dandelion, Taraxacum officinale, dried and milled. We use the leaf. The root is a separate herbal drug with its own EU monograph and its own dose.

The leaf is rich in potassium, reported at up to around 4.5 per cent of dry weight, and carries bitter sesquiterpene lactones. The potassium is the usual explanation offered for the diuretic reputation, and the bitters are the usual explanation for the appetite and digestion use. Neither mechanism has been established in humans to any useful standard. Inulin, which can reach a quarter or more of dry weight, and the heaviest concentrations of the bitter sesquiterpene lactones sit in the root, which is the part we are not using.

The EMA registers dandelion leaf as a traditional herbal medicinal product for one indication: to increase the amount of urine to achieve flushing of the urinary tract, as an adjuvant in minor urinary complaints. That registration attaches to the medicinal preparations and doses printed above. It is not a claim for this capsule, which is a food supplement. Here the leaf is one of eight botanicals in a daily maintenance blend.

Anyone taking it as one part of a botanical blend rather than as the active ingredient. Not for anyone with gallstones, biliary obstruction, an active peptic ulcer or existing liver disease. Not for people who react to daisies and ragweed. Not for anyone with renal failure, heart failure or diabetes. Not for anyone on a prescription diuretic, a blood-sugar medicine or an immunosuppressant without asking a pharmacist first.

100 mg daily with food, as part of the LIVER blend. Nothing to time. If you take a prescription diuretic, a blood-sugar medicine, an immunosuppressant or anything with a narrow margin that is cleared by CYP1A2, CYP3A4 or glucuronidation, raise it with a pharmacist before you start. Adequate fluid intake matters more than the capsule does.

Nothing you will notice. At 100 mg it will not change how often you pass urine, and it is not there to. Judge the blend over months rather than this ingredient over days.

The European Medicines Agency's HMPC monograph on Taraxaci folium (EMA/HMPC/579636/2008, adopted 12 November 2009) grants traditional-use status for one indication only: to increase the amount of urine to achieve flushing of the urinary tract, as an adjuvant in minor urinary complaints. There is no liver indication for the leaf, and the monograph lists liver diseases among the contraindications. Under interactions it says, in full, 'None reported', so the interaction list in our cautions comes from Memorial Sloan Kettering's herb database rather than from the EMA. The single human trial is Clare, Conroy and Spelman, Journal of Alternative and Complementary Medicine, 2009: 17 subjects, a fresh-leaf hydroethanolic extract taken three times in one day, with a significant rise in urination frequency in the five hours after the first dose and a significant rise in the excretion ratio after the second. No control group, one day, described by its authors as a pilot. MSKCC records that dandelion's supporting data are largely preclinical and that clinical trials are still needed to determine the conditions under which it may be safe and effective. Not supported: any claim that dandelion leaf treats, protects, cleanses or detoxifies the liver.