Although the link has been widely accepted, no major study has ever confirmed that the drugs—coupled with a 'clean' environment—are a major cause of the rising epidemic of IBD, especially in the US and Europe.

When combined with CBD, lower doses of antibiotics are proving to be effective, when previously very high doses were not killing bacteria.

Sufferers reported a reduction of 47 percent in the severity of headaches and 49 percent in migraine pain.

It stops the rapid cell division that is characteristic of colorectal cancer, and which allows it to spread, say researchers from Penn State College of Medicine.

"Every time a cell divides there's the chance that it will mutate and keep dividing when it shouldn't, which is how cancers start. So if we can block that signal that's telling cancer cells to continue to divide, then that could be a way to stop that cancer," said researcher Kent Vrana.

The EU had planned to ban from sale all CBD products for at least 18 months while their safety was evaluated. The products fell into the EU's 'novel foods' category, which includes supplements and therapeutic remedies that have been used only since 1997 and their safety hasn't been properly tested.

The plant's psychoactive chemical, THC (tetrahydrocannabinol), is very effective against a range of conditions, from epilepsy, pain relief and depression.

In fact, it had a far more dramatic effect than the 'acceptable' part of the plant, the CBD (cannabidiol), which had very little therapeutic value on its own.

People using the whole plant were seeing an immediate 30 per cent improvement in their symptoms, say researchers from the University of New Mexico.

They monitored therapeutic effects in real time by accessing a cell phone app, ReleafApp, which is used by millions of people taking cannabis products.