The "Vitamins to Health" website lists parsley among the natural herbs used traditionally for kidney cleansing. This is based on the premise that toxic products such as urea pass through the kidneys, and if the volume of fluid going through the kidneys increases, as is seen when parsley is used, these toxins leave the body at a faster rate, which cleans the kidneys. The kidney cleansing effect of parsley has not been clinically proven, however, and you should consult your doctor before using it for this purpose.
A Natural Diuretic
A diuretic is a substance that decreases the fluid volume in the body by increasing urine output. Parsley is known as a natural diuretic, and the increased flow of fluids through the kidneys as urine production and output increases may have a cleansing effect on the kidneys as bacteria and germs are flushed out.
What's In It?
Parsley owes its diuretic effect to the presence of two ingredients, apiol and myristicin, which are found in parsley oil. The amount of these substances varies across the more than 30 varieties of parsley, and the amount of oil varies in different parts of the plant, being more concentrated in the leaves than in the root. The German agency Commission E indicates that parsley may be used for ridding the body of kidney stones. There is currently no clinical evidence to support this, according to the Tufts Medical Center, but increased urine flow could potentially have this effect.
A study published in the "Journal of Ethnopharmacology" in March 2002 recorded the effect of parsley seed extract on urine output in rats. The experiment found that rats that drank parsley seed extract produced significantly more urine over a 24 hour period than those that drank water.
Dried parsley leaf or root is often used as a tea, with 2 g steeped in 150 ml of water and taken three times per day for the kidney cleansing effect. The dosage for the extract is 2 ml three times per day and, if the seeds are used, 1 g of seeds per cup of tea, up to three times per day. Be careful when using large amounts of parsley if you are pregnant, as both apiol and myristicin can cause uterine contractions, and myristicin may cause an increase in fetal heart rate. If you are taking lithium, do not use parsley without medical supervision. Other possible side effects of excessive use of parsley oil include headaches, loss of balance, convulsions and renal failure.