Cilantro Could Help Purify Drinking Water: Research Suggests Controversial Herb Might Scrub Heavy Metals

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Depending on your tastes, cilantro is either a lovely herb that adds some zest to salsas and soups, or a vile, soapy menace. But this divisive seasoning may have a hidden benefit -- new experiments suggest that cilantro could be a useful way to purify drinking water.

At the annual meeting Thursday of the American Chemical Society in Indianapolis, Ind., Ivy Tech Community College chemist Douglas Schauer presented work by undergraduate students showing that cilantro may be an effective “biosorbent” that can remove lead and other heavy metals contaminants from water. The research doesn't yet appear to have been published in a peer-reviewed publication.

"Cilantro may seem too pricey for use in decontaminating large amounts of water for drinking and cooking," Schauer said in a statement. "However, cilantro grows wild in vast amounts in countries that have problems with heavy-metal water pollution. It is readily available, inexpensive and shows promise in removing certain metals, such as lead, copper and mercury, [which] can be harmful to human health."

Most methods of treating water -- including your home filter, if you have one -- use active carbon treatments or ion-exchange resins to remove contaminants. But for many developing countries and rural areas, these methods are out of reach. Mexico, where cilantro grows wild, may be one potential proving ground for cilantro water filtering.

Schauer’s students worked with other undergraduates at the Universidad Politécnica de Francisco I. Madero in Hidalgo, Mexico, to sample drainage water in Mexico City and screen various plants for their potential heavy metal-clearing abilities. According to Schauer, their preliminary results suggest cilantro may be more effective than activated carbon at removing certain contaminants like lead.

Schauer thinks that cilantro’s purifying secrets may lie in the outer cell walls of the plant. He envisions cilantro and some of its biosorbing cousins like parsley packed into packets like tea bags or water filter cartridges.

Other scientists have explored cilantro’s ability to remove other kinds of contaminants. In 2002, researchers working at Pacific Agri-Food Research Center in Canada found that essential oils from cilantro leaves were particularly effective at killing Listeria monocytogenes, a bacteria that is one of the most serious food-borne bugs. L. monocytogenes can cause Listeriosis, resulting in infections of the central nervous system or gastroenteritis. In the International Journal of Food Microbiology, the scientists speculated that certain chemical elements in cilantro oil -- long-chain alcohols and aldehydes -- are probably responsible for killing the bacterium.

"Our goal is to find biosorbents that people in developing countries could obtain for nothing," Schauer says. "When the filter in a water purification pitcher needs to be changed, they could go outside, gather a handful of cilantro or some other plant, and presto, there's a new filter ready to purify the water."

The one drawback may come if cilantro-purified water tastes like the herb. Cilantro borders on offensive for some people, who find that it tastes soapy. Research suggests there’s a genetic component to your love or hatred of cilantro. The genome-sequencing company 23andMe asked more than 25,000 people about their cilantro preferences, and found that distaste correlated with a particular DNA region among a bunch of odor-detecting genes, including one known to identify a “soapy” signal. But genetics isn’t the whole story -- lead author Nicholas Eriksson told NPR last September that the genes of interest “didn't make a huge a difference in cilantro preference from person to person.”

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