It is thought to work by restoring the balance of certain natural substances in the brain.

He said the natural substances could be used to make more effective drugs.

It works by blocking a certain natural substance in your body to reduce pain and swelling.

It works by changing the activity of certain natural substances in the brain.

Cocaine, which comes from the coca plant, is a natural substance.

These reports also expose a myth about the safety of "natural" substances.

"A harmless natural substance that cannot be absorbed by the human body."

It works by helping to restore the balance of certain natural substances in the brain.

Cholesterol is a natural substance found in the body tissues of animals but not plants.

In the same way, it is important to exclude all natural substances from this system.