Lemons, lime, limonene. D-limonene, to be precise, is a member of a very fragrant class of molecules that abound in citrus-terpenoids or terpenes. And they've been shown to inhibit cancer cell progression and induce cell death.
Think lemons, limes, oranges -- especially the peel. In fact, the highest content of limonene is found in the white spongy inner parts. Steep them in water, sip in teas, munch on the softened rinds (but not too much or it will do a number on your teeth.)
And it's not just the limonene at work here. Another terpene called perillyl alcohol, derived from citrus peel (and from lavender and mint and lemongrass and more), has also demonstrated anti-cancer properties in some studies.
The research on these aromatic molecules has been done in several types of cancer cells -including liver, gastric, colon and lymphoma. Structurally some terpenes are similar to human hormones, and some research has shown them effective against breast and prostate cancer cells as well.
How do they supposedly work? The proposed mechanisms are many, including stimulating production of enzymes that help the liver detox carcinogens and causing cancer cells to differentiate into a more benign version.
So far, most of the work has been done in the petri dish and lab animals, but promising results have some scientists calling for research and use in humans. "The efficacy of terpenoids ...against breast or prostate cancers as demonstrated in pre-clinical studies provides strong support for their clinical use in treatment and even prevention of human hormone-related cancers," says one group of researchers.
Naturally, more studies are needed before science can declare them proven to help- or not, but with so much encouraging evidence, what's the harm in swigging a bit of citrus water all day long? Just make sure the citrus is organic.
Here's how to make a refreshing limonene concoction: Add lemon juice plus the rinds of organic lemons, limes and oranges to a pitcher of water, and keep refilling with liquid. Refrigerate overnight. The rinds will keep releasing their intense flavours for days.