By Maayan Lubell

SAFED, Israel (Reuters) - They grow in a secret location in northern Israel. A tall fence, security cameras and an armed guard protect them from criminals. A hint of their sweet-scented blossom carries in the air: rows and rows of cannabis plants, as far as the eye can see.

It is here, at a medical marijuana plantation atop the hills of the Galilee, where researchers say they have developed marijuana that can be used to ease the symptoms of some ailments without getting patients high.

"Sometimes the high is not always what they need. Sometimes it is an unwanted side effect. For some of the people it's not even pleasant," said Zack Klein, head of development at Tikun Olam, the company that developed the plant.

Cannabis has more than 60 constituents called cannabinoids. THC is perhaps the best known of those, less so for its medical benefits and more for its psychoactive properties that give people a "high" feeling.

But cannabis also contains Cannabidiol, or CBD, a substance that some researchers say has anti-inflammatory benefits. Unlike THC, it hardly binds to the brain's receptors and can therefore work without getting patients stoned.

"CBD plants are available in different forms all over the world," said Klein, adding that the company's plant is free of THC and very high in CBD.

Tikun Olam began its research on CBD enhanced cannabis in 2009 and about six months ago they came up with Avidekel, Klein said, a cannabis strain that contains 15.8 percent CBD and only traces of THC, less than one percent.

CANNABIS AS MEDICINE

Marijuana is an illegal drug in Israel. Medicinal use of it was first permitted in 1993, according to the health ministry.

Today cannabis is used in Israel to treat 9,000 people suffering from illnesses such as cancer, Parkinson's, multiple sclerosis, Crohn's disease and post traumatic stress disorder, according to Israel's health ministry.

Drug companies have also been interested in cannabis as a medicine. Britain's GW Pharmaceuticals, with Bayer and Almirall, sells an under-the-tongue spray called Sativex that is designed to minimize highs by manipulating ratios of active ingredients.

Raphael Mechoulam, a professor of medicinal chemistry at the Hebrew University in Jerusalem, said Avidekel is thought to be the first CBD-enriched cannabis plant with no THC to have been developed in Israel.

"It is possible that (Avidekel's) CBD to THC ratio is the highest among medical marijuana companies in the world, but the industry is not very organized, so one cannot keep exact track of what each company is doing," he explained.

Although there have been no clinical trials in humans, Mechoulam, who is a leading researcher of cannabinoids, said that Avidekel showed promise as a potent anti-inflammatory.

Ruth Gallily of the Hebrew University who works for the company and has been studying CBD for more than 12 years, said she has found that the substance has impressive anti-inflammatory qualities. She has been testing the effects of Tikun Olam's CBD-enhanced cannabis on mice and expects clinical trials to begin in a few months.

Avidekel is a new strain of a plant that is already permitted for medical use so there is nothing stopping patients who are already being treated with marijuana from trying Avidekel. About 10 patients began using it in the past six months, Klein said.

"The cannabis plant, enriched with CBD, can be used for treating diseases like rheumatoid arthritis, colitis, liver inflammation, heart disease and diabetes," she said, adding there are no side effects.

"It's a huge advantage," said one 35-year-old patient who asked not to be identified, "I can smoke during the day, function with a lot less pain and still be focused, work and drive. It is a great gift."

The woman began suffering chronic pains after a tumor was removed from her spine. She began treatment with regular THC-containing marijuana eight months ago. Two months ago she started smoking Avidekel.

"The difference is huge. Before, I would only smoke at the end of the day and stay in pain." Now, she said, with the highless marijuana "my life is so much better."

Despite Avidekel's highless benefit, Klein does not see regular marijuana disappearing any time soon. THC has its own unique effects that alleviate illness symptoms.

"Don't worry, I think that cannabis with THC will still be (around)," he said.

(Editing by Jeffrey Heller and Paul Casciato)