This page on Limonene is currently marked as in-progress. We are still compiling research.
D-Limonene is a compound known as 'lemon extract' and is found in high levels in lemon juices.
It itself, as well as its related product known as 'perillic acid', are known to be anti-carcinogenic (cancer fighting) and liver healthy. Consumption of D-Limonene in either supplemental form or as freshly squeezed and pulp-containing lemonade has been shown to reduce the formation of some tumor growths and alleviate fat buildup in the liver induced by diet.
Although commercial juices tend to have low levels of D-Limonene, freshly squeezed 'Mediterranean Style' juice with the pulp has high levels of it.
Lemon Extract, D-Limonene
30-40 liquid oz. of Mediterranean Style (pulp in) lemonade confers approximately 500mg D-Limonene, which can be seen as an active dose.
Otherwise, many benefits are seen with 1g of D-Limonene daily.
Limonene has its name derived from 'Lemon', the food source that is most abundant in limonene and among the first sources discovered. It is found in:
Limonene is known as a monoterpene molecule (having one isoterpene in its structure) as well as a cyclic terpene (having a six-carboned ring structure). Alongside Limonene, a well-researched compound is its metabolite 'Perillyl Aldcohol'.
Limonene is colourless hydrocarbon compound that smells of oranges. Despite the scent, it is at highest levels in the rinds of lemons, where it acquires its name from.
Limonene is rapidly and almost wholly absorbed in the GI tract after ingestion, and then gets divided to various body tissues after first pass metabolism in the liver where it may be subject to metabolism into carveol metabolites or perillyl metabolites by CYP2C enzymes of which inter-species differences exist.
After a 1.6g dose, between 52-83% of the dose is excreted in 48 hours and no build up of the compound is seen 21 days after cessation. The half-life of D-limonene in humans is estimated to be between 12 and 24 hours.
The primary metabolites of limonene in humans are perillic acid, dihydroperillic acid, and limonene-1,2-diol. These metabolites are glucuronidated by the liver and excreted via the urine.
Serum limonene and metabolite levels are able to be elevated via food consumption. A 30-40 oz. serving of 'Mediterranean Style' lemonade (made with the whole lemons) contains 447-596mg limonene.  The termination half-life of perillic acid is shorter than that of D-limonene (in the range of 0.82-1.84 hours) and spiked serum levels of perillic acid 2.08 to 13.98 μM.
In those with Non-alcoholic Fatty Liver disease (onset by diet), supplementation with D-limonene has been shown (in rats) to reverse the hepatic fatty acid buildup as well as downstream effects caused by the hepatic impairment.
(Common misspellings for Limonene include limonen, limon, limoneen, lemonene, lemoneen)
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