Honey may pose hidden toxic risk. (Environment).The plant kingdom has developed an arsenal of poisons to deter predation. Among these are pyrrolizidine alkaloids alkaloids, n alkaline phytochemicals that contain nitrogen in a heterocyclic ring structure. They can have powerful pharmacological effects and are more often used in traditional medicine than in herbal treatments. . Some 3 percent of all flowering plants produce these chemicals, including such herbal-garden favorites as borage borage (bŏr`əj, bŭr`–), common name for the Boraginaceae, a family of widely distributed herbs and some tropical shrubs or trees characterized by rough or hairy stems, four-part fruits, and usually fragrant blossoms. and comfrey comfrey Any herb of the Eurasian genus Symphytum (borage family). Best known is the medicinal common comfrey (S. officinale), used to treat wounds and as a source of a gum used to treat wool. Traditionally it was also taken internally for various complaints. . When bees pollinate pol·li·nate also pol·len·ate tr.v. pol·li·nat·ed also pol·len·at·ed, pol·li·nat·ing also pol·len·at·ing, pol·li·nates also pol·len·ates To transfer pollen from an anther to the stigma of (a flower). such plants, the little buzzers risk seeding the honey they produce with worrisome concentrations of the poisons, a new study charges. In 1988, the World Health Organization designated pyrrolizidine alkaloids as a serious health threat. Even persistent, low-dose exposure to the poisons can cause cirrhosis of the liver Cirrhosis of the liver A type of liver disease, most often caused by chronic alcohol abuse. It is characterized by scarring of the liver, which leads to an increase in the blood pressure in the portal veins. Mentioned in: Bleeding Varices or other diseases, notes John A. Edgar, a consulting organic chemist and toxicologist in Melbourne, Australia. The alkaloids have Killed animals eating tainted feed or forage and struck people who unwittingly consumed contaminated grain or certain herbal drugs, he notes. German-government regulations issued in 1992 limit the alkaloids' concentrations in herbal medicines intended for oral use to 1 microgram microgram /mi·cro·gram/ (µg) (mi´kro-gram) one millionth (10-6) of a gram. mi·cro·gram n. Abbr. per daily dose. The regulations also prohibit pregnant women and children from using such drugs and restrict their use by other people to no more than 6 weeks annually. Germany set tolerable doses of the alkaloids 90 percent lower still for products that might be consumed regularly. Edgar says the European Union is now considering adoption of similar limits. The irony, he notes, is that the few chemical analyses of honeys from bees that visited alkaloid-producing plants reveal the poisons at concentrations that can greatly exceed their German limits in herbal drugs. In the May 8 Journal of Agricultural and Food Chemistry, Edgar and his colleagues from Germany and the United States review dozens of studies under pinning their concerns about possible pyrrolizidine-alkaloid poisonings. Some of the studies reported concentrations of the alkaloids at up to 3.9 [micro]g/g in honey. That's a hefty amount considering that some adults report consuming 90 g of honey daily over long periods, and even infants may down 30 g of the sweetener per day. People typically encounter traces of dozens of potentially deadly agents in foods, Edgar observes, such as aflatoxins aflatoxins (ăf`lətäk'sĭnz), a group of secondary metabolites that are cancer-causing byproducts of a mold that grows on nuts and grains, particularly peanuts. in peanuts and fumonisins in corn flakes. He says: "I just want regulators to take pyrrolizidine alkaloids as seriously" as other toxins--by monitoring foods and working to minimize the alkaloids' concentrations in our diets. --J.R. |
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