Wurzburg, Germany  - Unless you're allergic to it, birch trees are one of the godsends of spring, according to scientist Johannes Gottfried Mayer.

Drinking birch juice is a great way to detoxicate the body. "The leaves have a diuretic effect," explains Mayer, of an herbal medicine research group at the University of Wurzburg.

He attributes the affect to flavonoids, as well as the birch's high levels of Vitamin C.

While modern practitioners of herbal medicine focus almost exclusively on the birch's leaves, people used to use the bark, buds and tar.

"Birch leaves have received scientific recognition for their usefulness in promoting kidney function and flushing out the urinary tract of bacterial or inflammatory diseases or those that cause cramps," says Mayer.

However, the therapy should be avoided if the patient suffers from oedemas bought on by heart or kidney problems, he warns.

The leaves can also be used topically for skin problems, either in baths or scrubs. But Mayer says there is no scientific proof whether the leaves are effective against rashes.

The cosmetics industry uses birch water in hair care treatments and to combat hair loss and birch oil from buds for skin and hair care. No side effects or interactivity problems with other substances are known. (dpa)